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Variation in Western Gulf Slope Percina sciera (Teleostei: Percidae)

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Variation in Western Gulf Slope Percina sciera (Teleostei: Percidae)
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ROBINS, ROBERT HALE ( Author, Primary )
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2008

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Breeding ( jstor )
Colors ( jstor )
Fish ( jstor )
Fish scales ( jstor )
Frequency distribution ( jstor )
Pectorals ( jstor )
Peduncle ( jstor )
Population mean ( jstor )
Rivers ( jstor )
Trinity ( jstor )

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University of Florida
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University of Florida
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Copyright Robert Hale Robins. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
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8/31/2006
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VARIATION IN WESTERN GULF SLOPE Percina sciera (TELEOSTEI: PERCIDAE) By ROBERT HALE ROBINS A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2005

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Copyright 2005 by Robert Hale Robins

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iii ACKNOWLEDGMENTS I would like to thank Dr. Lawrence M. Page for directing me to this topic of study and for instruction, constructive criticism and guidance. I also thank Drs. Max A. Nickerson and Michael P. Moulton for their contributions and guidance. For help with statistical analyses I thank Marinela Capanau, UF IFAS Department of Statistics, H. L. Jelks, A. N. Piercy and A. Morgan. To G. H. Burgess I am grateful for assistance with tables and for access to his library. For specimen loans I thank B. R. Kujhada and P. M. Harris of the University of Alabama Ichthyological Collections (UAIC) and D. A. Hendrickson and J. Rosales of the Texas Natural History Collection (TNHC). For help in the field I am grateful to C. E. Johnston, C. C. Borum, H. M. Buchanan, M. Castro, A. R. Henderson, R. A. Kennon, C. T. Phillips, L. M. Page, A. L. Rypel, and A. W. Thomson. Photographs of breeding male Percina sciera were provided by C. T. Phillips (Figure 3), C. E. Johnston (Figure 4), and L. M. Page (Figure 5). Maps (Figures 1 and 2) were provided by G. E. Sheehy. Formatting assistance was provided by C. Bester and S. Morey.

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iv TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iii LIST OF TABLES...............................................................................................................v LIST OF FIGURES..........................................................................................................vii ABSTRACT.....................................................................................................................vi ii CHAPTER 1 INTRODUCTION........................................................................................................1 Natural History.............................................................................................................1 Taxonomy.....................................................................................................................2 2 METHODS...................................................................................................................8 Data Collection.............................................................................................................8 Data Analysis................................................................................................................9 3 MATERIALS EXAMINED.......................................................................................11 4 RESULTS...................................................................................................................12 Meristic Variables.......................................................................................................12 Male Breeding Color..................................................................................................14 5 DISCUSSION.............................................................................................................27 Preopercular Serrae.....................................................................................................27 Pored Lateral Line Scales...........................................................................................27 Modified Mid-Belly Scales of Males.........................................................................28 Transverse and Circumferential Caudal Peduncle Scales..........................................28 Inferences....................................................................................................................2 9 Conclusions.................................................................................................................32 LIST OF REFERENCES...................................................................................................34 BIOGRAPHICAL SKETCH.............................................................................................38

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v LIST OF TABLES Table page 1. Preopercular serrae in Percina sciera (frequency distribution)...............................19 2. Pored lateral line scales in Percina sciera (frequency distribution)........................19 3. Modified scales in male Percina sciera (frequency distribution)............................20 4. Transverse scales in Percina sciera (frequency distribution)..................................20 5. Circumferential caudal peduncle scales in Percina sciera (frequency distribution)..............................................................................................................21 6. Dorsal spines in Percina sciera (frequency distribution).........................................21 7. Pectoral rays in Percina sciera (frequency distribution).........................................22 8. Anal rays in Percina sciera (frequency distribution)...............................................22 9. Dorsal rays in Percina sciera (frequency distribution)............................................22 10. Preopercular serrae in Percina sciera (one-way ANOVA)......................................22 11. Pored lateral line scales in Percina sciera (one-way ANOVA)...............................22 12. Modified mid-belly scales of males in Percina sciera (one-way ANOVA)............23 13. Transverse scales in Percina sciera (one-way ANOVA)........................................23 14. Circumferential caudal peduncle scales in Percina sciera (one-way ANOVA)......23 15. Dorsal spines in Percina sciera (one-way ANOVA)...............................................23 16. Pectoral rays in Percina sciera (one-way ANOVA)................................................23 17. Anal rays in Percina sciera (one-way ANOVA).....................................................23 18. Dorsal rays in Percina sciera (one-way ANOVA)..................................................23 19. Tukey groupings of western Gulf slope populations of Percina sciera based on means........................................................................................................................24

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vi 20. Summary of breeding color in male Percina sciera .................................................25

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vii LIST OF FIGURES Figure page 1. Range of Percina sciera including western Gulf slope river systems.......................6 2. Distribution of subspecies of Percina sciera .............................................................7 3. Percina s. apristis (live, unanesthetized), 86.5 mm SL male...................................17 4. Percina s. apristis , male...........................................................................................17 5. Percina s. sciera . 89 mm SL male...........................................................................18

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viii Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science VARIATION IN WESTERN GULF SLOPE Percina sciera (TELEOSTEI: PERCIDAE) By Robert Hale Robins August, 2005 Chair: Max A. Nickerson Major Department: Wildlife Ecology and Conservation The Guadalupe Dusky Darter, Percina sciera apristis (Hubbs and Hubbs), is endemic to the Guadalupe River system of southern Texas. Largely defined by a greatly reduced number of preopercular serrae, apristis is peripheral to and geographically isolated from all other populations of sciera . In number of preopercular serrae, apristis differs most from adjacent populations in the Colorado River and Brazos River drainages, which have the most serrae. Considering only number of serrae, apristis appears to be diagnosable as a species. To further investigate the taxonomic status of apristis , meristic features and male breeding color of P. sciera were examined in seven river basins in Texas. In addition to number of preopercular serrae, apristis differed from all other populations examined in possessing more pored lateral-line scales and modified mid-belly scales on males. However, these characters and others fail to reveal a clear pattern of variation. In several traits, specimens from the Colorado River are intermediate between apristis and other

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ix populations of sciera . In other traits, Colorado River specimens are most similar to apristis . Patterns of morphological variation were considered in relation to geographic isolation, selection and drift, and taxonomy.

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1 CHAPTER 1 INTRODUCTION Natural History Darters are small, slender fishes that occupy benthic habitats in rivers and creeks of much of North America. The Dusky Darter, Percina sciera (Swain 1883), is a variable species inhabiting fast gravel runs and (to a lesser extent) riffles of creeks and small to medium rivers (Page and Burr, 1991). In these areas, submerged snags of branches and leaves as well as aquatic vegetation in current are preferred microhabitats (Kuehne and Barbour, 1983; Page, 1983). The species is wide-ranging, found in the Mississippi River basin from Ohio and West Virginia west to Illinois, and south to Louisiana; and in Gulf drainages from northwest Alabama south to the Guadalupe River, Texas (Page and Burr, 1991). Populations of P . sciera are recorded in fifteen states (Fig. 1). While many species of darters are notable for their bright colors, species of Percina are typically drably pigmented. Percina sciera is olive-green dorsally, with dark mottling and eight often indistinct dusky saddles (Page, 1983). Laterally, P . sciera exhibits a series of eight to twelve dusky oval blotches on a yellow background. The belly is typically lighter yellow or white, and the fins are mostly clear. Percina sciera is among the largest species of darters, obtaining a maximum standard length of 110 mm (Page, 1983) and a total length of approximately 127 mm (Page and Smith, 1970). As is common among darters, P. sciera is sexually dimorphic; males obtain a larger size than females and exhibit patterning and pigment differences that are most pronounced during the breeding season. The body and median fins of breeding male P.

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2 sciera become darkly colored, and the fish assumes a dusky appearance. Spawning occurs in late winter, spring and summer with some variation with respect to latitude or in those populations inhabiting spring-fed waters (Page and Smith, 1970; Hubbs, 1961; Brown, 1952). Six types of spawning behavior are recognized among percids, each named for the mode of egg deposition (Page, 1985). Spawning observed in P . sciera during this study was of the egg-burying type, common to Percina . The diet of P . sciera in the Embarras River, Illinois (Page and Smith, 1970) consisted entirely of the aquatic larvae of terrestrial insects. Taxonomy Darters are North American percid fishes of the tribe Etheostomatinae (Song et al., 1998). A major component of the North American freshwater fish fauna (Bailey and Etnier, 1988), one hundred-eighty species are recognized in four genera: Percina (40), Ammocrypta (6), Crystallaria (1), and Etheostoma (133) (Page, 2000; Nelson et al., 2004). Richards and Knapp (1964) reviewed the nomenclatural history of Hadropterus and provided the first diagnosis of the taxon as a subgenus of Percina , provisionally including the Freckled Darter, Percina lenticula Richards and Knapp; the Blackbanded Darter, Percina nigrofasciata (Agassiz); and the Dusky Darter, Percina sciera . Suttkus and Ramsey (1967) assigned the Goldline Darter, Percina aurolineata Suttkus and Ramsey, to Hadropterus and commented on the relationship of aurolineata to lenticula , nigrofasciata and sciera . Page (1974) examined relationships among Percina , diagnosed nine subgenera, and discussed the lack of derived character states among Hadropterus . Two subspecies of P . sciera are currently recognized: the Dusky Darter, Percina sciera sciera (Swain), found throughout the majority of the range; and the Guadalupe Dusky Darter, Percina sciera apristis (Hubbs and Hubbs), restricted to the Guadalupe

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3 River system of the San Antonio Bay drainage, Texas (Fig. 2 ). The San Antonio Bay drainage is the penultimate major southwestern drainage on the Gulf Slope between the Mississippi River and the Rio Grande (Conner and Suttkus, 1986). The drainage consists of the Guadalupe River system, comprising the northeastern portion of the catchment, and the San Antonio River system running in parallel to the southwest. Within the Guadalupe River system P. s. apristis is found only in areas of suitable habitat in the San Marcos, Comal and Guadalupe rivers (Hubbs, 1954). No specimens of P . sciera have been recorded from the San Antonio River system or any waters west or south of the Guadalupe River System (Hubbs et al., 1991). Percina s . apristis is diagnosed by a reduced number of preopercular serrae and the absence or reduction of the narrow bars that connect the dark lateral blocks in typical P . s . sciera (Hubbs and Hubbs, in Hubbs, 1954). Hubbs (1954) examined specimens from 13 river systems arranged in a north/south gradient from the Wabash River, Indiana, to the Guadalupe River, Texas. He noted that P . s . apristis differs most greatly from the nearest populations of the nominate subspecies in number of preopercular serrae. Hubbs (1954) also observed that counts of serrae formed a cline from the Arkansas River of Arkansas and Oklahoma to the Guadalupe River, Texas. Hubbs (1954) also noted differences in pectoral fin length and number of lateral line scales between P . s . apristis and the adjacent Colorado River population of P . s . sciera , recognized the peripheral distribution of apristis and its complete isolation from all other populations of dusky darters, and remarked that “ apristis may be specifically distinct from scierus ” (Hubbs, 1954: 215). However, he declined to name the taxon as a

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4 species due to concerns about overlapping variation in analyses that considered all 13 river systems. Recent studies have noted additional distinctions between P. s. apristis and P. s. sciera . Research comparing the egg complements of equal-sized female P. s. apristis and Colorado River P. s. sciera noted significant differences in egg-size and numbers of eggs between the geographically adjacent populations (Hubbs and Johnson, 1961). Laboratory hybridization trials in which Colorado River P . s . sciera and P . s . apristis were crossed produced offspring that exhibited an overall lack of hybrid vigor, prompting speculation that differences in phenotypes in the two subspecies may be correlated with an isolating mechanism (Hubbs, 1967). Despite the distinctiveness of P . s . apristis , variation within western P. sciera remains poorly understood. Hubbs and Black (1954) addressed the status and synonymy of P . sciera and, in raising the possibility of naming at least two additional subspecies from Texas, concluded “a more intensive study, based on an abundance of fresh material from throughout the wide range of the species . . . may lead to the conclusion that Hadropterus scierus , like many other darters, is a complex of local subspecies.” Following the lead of Hubbs and Black, Richards and Knapp (1964) defined Percina s. sciera as consisting only of those populations of Dusky Darter found from the eastern tributaries of the Mississippi River system and along the Gulf coast east to the Pearl River in Mississippi. With the exception of P . s . apristis , these authors relegated all populations of P . sciera west of the Mississippi River in Missouri, Arkansas, Oklahoma and Texas to uncertain status pending further study. Reference in the description of P. s. apristis to a “yellow to orange” band in the distal portion of the spinous dorsal fin (Hubbs

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5 and Hubbs, p. 52, in Hubbs, 1954) has been interpreted by some authors as a definitive character of the subspecies, although observations on its presence in other populations of P. s. sciera by other authors confounds this distinction (e.g., Kuehne and Barbour, 1983; Ross, 2001). Most features used by Hubbs in his diagnosis of P. s. apristis were morphometric (Hubbs, 1954). The present study analyzes variation in meristic features and breeding male coloration in P . sciera from seven Texas river systems and discusses the results relative to the taxonomic status of populations of the Guadalupe Dusky Darter.

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6 Figure 1. Range of Percina sciera including western Gulf slope river systems.

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7 Figure 2. Distribution of subspecies of Percina sciera .

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8 CHAPTER 2 METHODS Data Collection Sixty-one collections totaling 354 specimens of P. sciera were examined for variation in number of preopercular serrae, pored lateral line scales, modified scales (present in males only), transverse scales, circumferential caudal peduncle scales, dorsal spines, dorsal rays, pectoral rays, and anal rays. Specimens from seven Texas river systems, comprising the majority of the known range of P. sciera in the western Gulf Slope between the Mississippi River and Rio Grande basins constituted the sample. From southwest to northeast, these are the Guadalupe, Colorado, Brazos, San Jacinto, Trinity, Neches, and Sabine (Fig. 1). All counts and measurements were made on the left side using a Leica MZ75 dissecting microscope and follow Hubbs and Lagler (1964), except counts of transverse scales were made from the anal fin origin anterodorsally to the spinous dorsal fin, and counts of modified scales were those in a single mid-belly row from the anus to the posterior base of the pelvic symphysis. Although recorded separately in the manner of Hubbs and Lagler (1964), counts of pored lateral line scales include those on the body and the caudal fin. Standard length was taken with dial calipers and recorded to the nearest tenth millimeter. Sex was recorded for all specimens. Juveniles of less than 35 mm SL or damaged specimens were excluded from the study. Specimens examined were borrowed from the Texas Memorial Museum, Texas Natural History Collection (TNHC); the University of Alabama Ichthyological Collection (UAIC); and the

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9 University of Florida, Florida Museum of Natural History (UF). Institutional abbreviations follow Leviton et al. (1985) and Eschmeyer (1998). Spawning pairs of P . s . apristis were observed and photographed in the wild. Breeding adults of P . s. apristis were collected live for description of spawning coloration, courtship and spawning behavior in captivity. Brazos River specimens of P. s. sciera in breeding condition were collected and photographed. Data Analysis Frequency distribution tables were developed for all nine meristic variables. Oneway analyses of variance (ANOVA) were conducted among all seven populations for nine meristic variables using the statistical software SAS 9.0 (SAS Institute, Inc., 2002). As data were categorical, all variables were log10 transformed with the exception of counts of preopercular serrae for which the transformation log10 (preopercular serrae + .01) was used to accommodate counts of zero. Assumptions of normality were investigated through residuals analysis, AndersonDarling Test, Shapiro-Wilk Test for Normality and Cramer-von Mises Test. Homogeneity of variances was gauged using Levene’s Test. In instances where either assumption was violated, a Kruskal-Wallis non-parametric test of the non-transformed values was performed in order to check ANOVA results. Kruskal-Wallis Test requires no assumptions of normality or homogeneity of variances but is less likely than ANOVA to find a significant result (Dytham, 1999). For all tests, , the probability of rejecting the null hypothesis (no difference between means, no difference between variances) when it is in fact true was set at .05 per convention for studies of this type. Tukey’s multiple comparison procedure with a per-comparison error rate lower than that of Fisher’s Least Significant Difference method was used to compare means

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10 following an indication of a significant difference among means and to determine groupings of means for which no significant difference was determined by the test (Ott and Longnecker, 2001). As with Fisher’s LSD, means denoted by the same letter are not significantly different.

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11 CHAPTER 3 MATERIALS EXAMINED Specimen catalog numbers are arranged by drainage; numbers of specimens are in parentheses. The Guadalupe River System included 18 collections: TNHC 2287 (15), TNHC 2297 (5 of 6), THNC 2321 (12 of 14), TNHC 2609 (6), TNHC 3136 (4), TNHC 7708 (3), TNHC 10387 (2), TNHC 17332 (15), UF 14996 (9), UF 26598 (1), UF 29652 (12), UF 43396 (2 of 3), UF 50605 (4), UF 65778 (9), UF 65788 (15), UF 96807 (5), UF 96809 (8), UF 128463 (2). The Colorado River drainage included 13 collections: TNHC 2613 (2), TNHC 2653 (1), TNHC 5386 (9), TNHC 9221 (7), TNHC 9485 (1), TNHC 15633 (1), TNHC 23129 (1), TNHC 23612 (1), TNHC 23890 (2), TNHC 24995 (9 of 10), TNHC 27756 (2), UAIC 799 (3), UAIC 11412.19 (11 of 36). The Brazos River drainage included 6 collections: TNHC 3785 (1), TNHC 12347 (7), TNHC 16791 (6), UF 28104 (3), UF 50646 (10), UF 147820 (10). The San Jacinto River System included 7 collections: TNHC 2398 (9), TNHC 2806 (5), TNHC 2823 (2 of 3), TNHC 22367 (3 of 4), UAIC 11417.06 (8), UF 29467 (8), UF 29644 (3). The Trinity River System included 4 collections: TNHC 21908 (5), TNHC 22166 (5), UF 147842 (2), UF 147868 (1). The Neches River System included 5 collections: TNHC 2391 (6), TNHC 2756 (3), TNHC 2930 (4), TNHC 3832 (6), UF 29603 (4). The Sabine River System included 8 collections: TNHC 3301 (6), TNHC 3345 (4), TNHC 3353 (12), TNHC 3376 (7), TNHC 3669 (18), TNHC 15528 (3 ), UAIC 2677 (9), UF 29589 (5).

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12 CHAPTER 4 RESULTS Meristic Variables Percina s . apristis has, on average fewer preopercular serrae (X = 0.70, SD = 1.28), more total pored lateral line scales (X = 71.68, SD = 3.70), and more modified mid-belly scales (X = 27.27, SD = 3.42) than do populations of P . s . sciera examined (Tables 1, 2, and 3). Colorado River P . s . sciera is intermediate between P . s . apristis and Brazos River drainage P . s . sciera with respect to modified mid-belly scales of males (X = 27.27, SD = 3.42; X = 19.75, SD = 2.99; X = 15.14, SD = 2.51; Table 3). In number of transverse scales, Colorado River P . s . sciera (X = 24.18, SD = 1.76) is also intermediate between P . s . apristis (X = 24.89, SD = 1.69) and populations of P . s . sciera in the Brazos River drainage (X = 23.11, SD = 1.45;Table 4). Percina s . a pristis (X = 27.5, SD = 1.51) is most similar in number of circumferential caudal peduncle scales to Colorado River P . s . sciera (X = 27.16, SD = 1.11; Table 5). No clear patterns are discerned in the frequency distribution tables of dorsal spines, pectoral rays, anal rays or dorsal rays (Tables 6 to 9). Statistical analyses recorded a significant difference or differences among means (ANOVA) and medians (non-parametric tests) in eight of the nine meristic variables (ANOVA: Tables 10 to 17, P < .0001; Kruskal-Wallis: P < .0001). Despite violations of assumptions of normality or equal variance in many data distributions, statistical results obtained by ANOVA procedures were affirmed by those obtained by the non-parametric

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13 Kruskal-Wallis test. These findings are unsurprising as the ANOVA test is robust even with departures from normality, and the Kruskal-Wallis Test and the F test from ANOVA only differ when data are extremely skewed or heavy-tailed (Ott and Longnecker, 2001). No significant difference was detected in mean or median number of dorsal rays between populations (ANOVA: Table 18, F6, 347 = 1.43, P < .2030; Kruskal-Wallis: 2 6, 347 = 10.9049, P < .0914). Tukey’s Multiple Comparison Procedure revealed statistically significant groupings of populations that reflect those inferred from the frequency distribution tables. In mean number of preopercular serrae (ANOVA: Table 10, F6, 347 = 106.08, P < .0001; KruskalWallis: 2 6, 347 = 259.4857, P < .0001) and pored lateral line scales (ANOVA: Table 11, F6, 347 = 22.72, P < .0001; Kruskal-Wallis: 2 6, 347 = 101.1069, P < .0001) P. s. apristis differs significantly from all other populations (Table 19). In modified mid-belly scales of males (ANOVA: Table 12, F6, 151 = 110.25, P < .0001; Kruskal-Wallis: 2 6, 151 = 122.9333, P < .0001), P. s. apristis differs significantly from all other populations, even though Colorado River P. s. sciera is intermediate with respect to P. s. apristis and Brazos River P. s. sciera (Table 19). A statistically significant grouping of populations based on mean number of transverse scales (ANOVA: Table 13, F6, 347 = 37.49, P < .0001; Kruskal-Wallis: 2 6, 347 = 146.3048, P < .0001) includes only P. s. apristis and Colorado River P. s. sciera ; once again, the latter is intermediate between P. s. apristis and Brazos River P. s. sciera (Table 19). Percina s. apristis and Colorado River P. s. sciera are most similar in mean numbers of circumferential caudal peduncle scales (ANOVA: Table 14, F6, 347 = 43.80, P < .0001; Kruskal-Wallis: 2 6, 347 =

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14 162.5979, P < .0001), and the two populations differ significantly from all others (Table 19). Comparisons of mean numbers of dorsal spines, pectoral rays and anal rays grouped sometimes geographically disparate populations as most similar and significantly different from all other populations. More often than not a high degree of overlap was found among the groups revealed by the analyses of these characters. No significant difference was noted in the mean numbers of dorsal spines (ANOVA: Table 15, F6, 346 = 7.93, P < .0001; Kruskal-Wallis: 2 6, 346 = 44.7887, P < .0001) among populations in the Guadalupe, San Jacinto, Trinity, Neches, and Sabine or among those from the Colorado, Brazos, San Jacinto, Trinity, or Neches (Table 19). Comparisons of mean numbers of pectoral rays (ANOVA: Table 16, F6, 347 = 12.95, P < .0001; Kruskal-Wallis: 2 6, 347 = 64.9902, P < .0001) revealed three large overlapping groups: the Guadalupe, Brazos, and San Jacinto, the Colorado, Brazos, San Jacinto, Neches and Sabine, and the Colorado, San Jacinto, Trinity, Neches and Sabine (Table 19). Mean numbers of anal rays (ANOVA: Table 17, F6, 347 = 11.07, P < .0001; KruskalWallis: 2 6, 347 = 63.9707, P < .0001) aligned the geographically disjunct Guadalupe and Neches, and a second group including the Colorado, Brazos, San Jacinto, Trinity, Neches and Sabine (Table 19). Male Breeding Color Attempts to observe male breeding color in western Gulf Slope drainages in 2003 and 2005 were limited by heavy rains and associated high water in creeks and rivers. Sampling for new material was only successful in the Guadalupe and in the Brazos River drainages.

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15 The spinous dorsal fins of breeding male P. s. apristis observed in clear water in the San Marcos River near the town of San Marcos, March 23, 2003, were characterized by a black band proximally and a distinct yellow-orange band distally (Figs. 3 and 4). Two very narrow light-yellow bands were visible in the second dorsal fin. Three light yellow bands of similar intensity to those observed in the second dorsal were present in the caudal fin but graded from wide to narrow, anteriorly to posteriorly. Ventral fins exhibited the greatest degree of dusky pigment. Body ground color exhibited a suffusion of dark pigment although the underlying non-breeding pattern remained visible. A single male specimen of P. s. apristis collected from rather murky water in the San Marcos River near Gonzales, TX, March 1, 2005, exhibited a purely yellow band distally in the spinous dorsal fin, but otherwise differed little in breeding coloration from those specimens of P. s. apristis collected in 2003. Color in specimens anesthetized with MS-222 (tricaine methane sulfonate) A single male specimen of P. s. apristis collected from rather murky water in the San Marcos River near Gonzales, TX, March 1, 2005, exhibited a purely yellow band distally in the spinous dorsal fin, but otherwise differed little in breeding coloration from those specimens of P. s. apristis collected in 2003. Color in specimens anesthetized with MS-222 (tricaine methane sulfonate) became intensified and exaggerated compared to that exhibited prior to treatment. In particular, males became much darker once treated with MS-222. Specimens of P. s. apristis observed in the wild, in addition to those kept for observation in captivity, courted and spawned in the same manner as recorded for P. s. sciera (Pers. Obs.).

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16 Three males of P. s. sciera in breeding condition were collected from the Paluxy River (Brazos River drainage) near Bluff Dale, Texas, on March 2, 2005. All three fish exhibited a black band proximally and a clear band distally in the spinous dorsal fin; in one specimen a tinge of faint yellow was present in the otherwise clear distal band of the spinous dorsal fin (Fig. 5). All three specimens were suffused with dusky pigment. One specimen was considerably darker than the others and more so than any observations of male P. s. apristis . In this specimen the underlying non-breeding pattern was nearly obscured, particularly in the area of the caudal peduncle. Published descriptions of breeding color of male dusky darters is limited and sometimes contradictory, but indicates that a yellow, yellow-orange, or orange band occurs in the distal margin of the spinous dorsal fin of breeding males in a number of widespread populations (Table 20). Although two sources indicated that the presence of a pale orange or yellow-orange band in the spinous dorsal of the male is diagnostic of P. s. apristis (Kuehne and Barbour, 1983; Etnier and Starnes 1993) and one specifically noted a population or populations of P. s. sciera lacking an orange band in the spinous dorsal (Robison and Buchanon, 1988), still other authors recorded this feature in various populations of P. s. sciera (Ross, 2001; Metee et al., 1996; Smith, 1979; Jenkins and Burkhead, 1994; Table 20).

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17 Figure 3. Percina s. apristis (live, unanesthetized), 86.5 mm SL male; San Marcos River, near town of San Marcos, Texas, March 23, 2003. UF 128463. Figure 4. Percina s. apristis , male. In San Marcos River, near town of San Marcos, Texas, March 23, 2003.

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18 Figure 5. Percina s. sciera . 89 mm SL male; Paluxy River, near town of Bluff Dale, Texas, March 2, 2005. UF 147820.

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19Table 1. Preopercular serrae in Percina sciera (frequency distribution) 0 1 2 3 4 5 6 7 8 9 101112131415 16 171819202122N X SD Guadalupe 88 17 10 8 2 3 1 129 .701.28 Colorado 2 1 4 2 3 5 6 7 3 7 4 2 1 1 1 1 50 12.484.34 Brazos 1 1 8 7 6 2 3 4 3 2 37 14.322.40 San Jacinto 2 1 5 2 3 4 5 2 6 2 4 1 1 38 8.683.74 Trinity 2 1 3 2 3 1 1 13 7.004.12 Neches 1 1 1 4 1 5 4 3 1 1 1 23 10.613.75 Sabine 1 1 1 3 1 9 8 9 8 9 6 4 3 1 64 9.282.99 Table 2. Pored lateral line scales in Percina sciera (frequency distribution) 6061626364656667686970717273747576777879808187NXSD Guadalupe 52510181019161078642411 1129 71.73.7 Colorado 11223554372261222 50 68.24.1 Brazos 112462674 31 37 67.72.6 San Jacinto 1 2235266432 2 38 66.93.0 Trinity 1113 2 3 1 1 1368.24.0 Neches 1 32731121 11 23 66.03.0 Sabine 1353126812635 64 67.62.5

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20Table 3. Modified scales in male Percina sciera (frequency distribution) 101112131415161718192021222324252627282930313233 N XSD Guadalupe 1 213 548575961360 27.273.42 Colorado 221213413 1 20 19.752.99 Brazos 11214112 1 14 15.142.51 San Jacinto 111234 21 15 15.202.21 Trinity 1 2 1 415.003.46 Neches 11 1123 9 15.002.24 Sabine 37784421 36 13.781.81 Table 4. Transverse Scales in Percina sciera (frequency distribution) 20 21 22 23 24 25 26 27 28 29 30 31 N X SD Guadalupe 9 25 18 29 25 13 10 129 24.89 1.69 Colorado 4 2 10 13 15 2 3 1 50 24.18 1.76 Brazos 6 6 11 9 3 1 1 37 23.11 1.45 San Jacinto 3 10 19 4 1 1 38 21.82 1.01 Trinity 1 3 3 3 3 13 22.31 1.32 Neches 9 9 3 2 23 21.91 0.95 Sabine 2 4 16 27 8 5 2 64 22.91 1.23

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21Table 5. Circumferential caudal peduncle scales in Percina sciera (frequency distribution) 23 24 25 26 27 28 29 30 31 N X SD Guadalupe 1 1 7 23 37 28 19 9 4 129 27.50 1.51 Colorado 4 8 20 13 4 1 50 27.16 1.11 Brazos 4 3 16 9 5 37 25.22 1.13 San Jacinto 1 9 16 9 3 38 25.11 0.95 Trinity 4 6 3 13 25.92 0.76 Neches 3 6 9 3 1 1 23 24.83 1.23 Sabine 7 26 19 9 3 64 25.61 1.02 Table 6. Dorsal Spines in Percina sciera (frequency distribution) 111213141516171819NXSD Guadalupe 262586 112912.580.84 Colorado 102713 5012.060.68 Brazos 3321 3611.940.33 San Jacinto 12611 3812.260.50 Trinity 103 1312.230.44 Neches 4118 2312.170.72 Sabine 130294 6412.560.64

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22 Table 7. Pectoral rays in Percina sciera (frequency distribution) 1213141516NXSD Guadalupe 1347816 12913.840.63 Colorado 8182225014.360.80 Brazos 2287 3714.140.48 San Jacinto 2810 3814.260.45 Trinity 49 1314.690.48 Neches 1310 2314.430.51 Sabine 13033 6414.500.53 Table 8. Anal Rays in Percina sciera (frequency distribution) 891011 NXSD Guadalupe 433848 1299.740.62 Colorado 334121 509.220.58 Brazos 1288 379.190.46 San Jacinto 42311 389.180.61 Trinity 121 139.080.28 Neches 11471 239.350.65 Sabine 44020 649.250.56 Table 9. Dorsal Rays in Percina sciera (frequency distribution) 1112131415NXSD Guadalupe 2237726112913.010.69 Colorado 25321015013.060.74 Brazos 41914 3713.270.65 San Jacinto 131816 3813.290.73 Trinity 210 11313.000.71 Neches 2165 2313.130.55 Sabine 54613 6413.130.52 Table 10. Preopercular serrae in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 2114.694042352.449007106.08 <.0001 Residual 347 1152.9277013.322558 Total 353 3267.621743 Table 11. Pored lateral line scales in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 0.059420090.0099033522.72 <.0001 Residual 347 0.151239380.00043585 Total 353 0.21065947

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23 Table 12. Modified mid-belly scales of males in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 2.610443680.43507395110.25 <.0001 Residual 151 0.595864390.00394612 Total 157 3.20630806 Table 13. Transverse scales in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 0.161075880.0268459837.49 <.0001 Residual 347 0.248449990.00071599 Total 353 0.40952587 Table 14. Circumferential caudal peduncle scales in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 0.108201830.0180336443.80 <.0001 Residual 347 0.142879610.00041176 Total 353 0.25108143 Table 15. Dorsal spines in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 0.025346240.004224377.93 <.0001 Residual 346 0.184287910.00053262 Total 352 0.20963415 Table 16. Pectoral rays in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 0.026471550.0044119312.95 <.0001 Residual 347 0.118192180.00034061 Total 353 0.14466373 Table 17. Anal rays in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 0.048000360.0080000611.07 <.0001 Residual 347 0.250821950.00072283 Total 353 0.29882231 Table 18. Dorsal rays in Percina sciera (one-way ANOVA) d.f Sum of Sqrs Mean Sqr F -statistic p -value Model (Rivers) 6 0.004222960.000703831.43 0.2030 Residual 347 0.171051900.00049294 Total 353 0.17527487

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24 Table 19 . Tukey groupings of western Gulf slope populations of Percina sciera based on means. River systems with same letter are not significantly different. Character/River Guadalupe Colorado Brazos San Jacinto Trinity Neches Sabine Preopercular serrae A B B B B B C C C C C Pored Lateral Line Scales A B B B B B B Modified Midb elly Scales of Males A B C C C C C Transverse Scales A A B B B C C C C D D D E E E Circumf. Caudal Peduncle Scales A A B B B B C C C C Dorsal Spines A A A A A B B B B B Pectoral Rays A A A B B B B B C C C C C Anal Rays A A B B B B B B Dorsal Rays A A A A A A A

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25Table 20. Summary of breeding color in male Percina sciera State and reference / male breeding color Breeding coloration comments? Mention of yellow or orange sub marginal band? Degree of dusky pigment? TX (Etnier and Starnes, 1993) Yes, but P. s. apristis only. ".in subspecies P. s. apristis of the Edwards Plateau, Texas, band is pale orange ." X TX (Kuehne and Barbour, 1983) Yes, but P. s. apristis only. "Males of ssp. apristis may develop a submarginal orange band in spiny dorsal fin." X TX (Author's personal obs.) Yes, but P. s. apristis only. Apristis with well defined yellow-orange submarginal band, some faint narrow yellow banding in soft dorsal and caudal fins. Dusky, but with non-breeding pattern still evident. See results section of paper. OK (Miller and Robison, 1973) No X X LA (Douglas, 1974) Yes X "breeding males are sometimes highly melanistic with bar like lateral blotches." AR (Robison and Buchanan, 1988) Yes " lacking orange submarginal band in the spinous dorsal" "Breeding males become darkened and develop black vertical bars on sides which extend over the dorsum." MO (Pflieger, 1975) No X X MS (Ross, 2001) Yes " orange marginal band in the spinous dorsal" "very dark and have vertically elongated blotches on the sides that extend upward onto the back." AL (Metee et al., 1996) Yes "Occasionally develop a yellow or orange band" "marked and mottled with dark pigment." TN (Etnier and Starnes, 1993) Yes "may show a vague submarginal clear band" "overall charcoal gray coloruniformally gray fins."

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26Table 20. Continued State and reference / male breeding color Breeding coloration comments? Mention of yellow or orange sub marginal band? Degree of dusky pigment? KY (Clay, 1975) No X X IL (Smith, 1979) Yes "In the breeding male a pale orange band is present on the distal margin of the dorsal fin and its posterior membranes develop a blackish blotch." "The breeding male darkens overall and the lateral blotches become broad lateral bands." IN (Gerking, 1945) No X X OH (Trautman, 1981) Yes X "Has much of the yellow replaced with a suffusion of dusky" WV (Stauffer et al., 1995) Yes X "Breeding males aredarker appearing almost black." VA (Jenkins and Burkhead, 1994) Yes "sometimes with faint yellow-orange band distally." "fins dusky to dark and body very dark, lateral blotching often obscuredLarge breeding male dark brown-black; dark vertical bars extending dorsally over back; upper body with blue green irridescence." NC (Menhinick, 1991) No X X General treatment (Page, 1983) Yes "The blotch at the back of the first dorsal fin intensifies and a yellow or orange band develops distally." "The breeding male darkens and the midlateral row of blotches becomes obliterated by blackish vertical bars extending over the dorsum." General treatment (Kuehne and Barbour, 1983) Yes Only in P. s. apristis : "Males of ssp. apristis may develop a submarginal orange band in spiny dorsal fin." "Breeding males may develop a bluish sheen on back and a little yellow on body. All fins but pectoral are variably darkened."

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27 CHAPTER 5 DISCUSSION The present study has quantified differences between P. s. apristis and western Gulf Slope P. s. sciera not previously reported and confirmed a number of distinctions already known. Whether these differences contribute ample evidence to effect a change in our understanding of the taxonomic rank of P. s. apristis is largely an artifact of how well the patterns of variation fit our understanding of the processes of speciation. Preopercular Serrae The reduced number of preopercular serrae in P. s. apristis was cited by Hubbs (1954: 213) as “the most significant and consistent difference” in the recognition of the subspecies. Results of the present study agree with this finding (Tables 1, 10, 19). Not only is P. s. apristis distinct, it differs most from those populations of the nominate subspecies in closest proximity. The presence of “serrae,” or small tooth like structures of irregular size and spacing found along the posterior margin of the preopercle, is a diagnostic feature common to the subgenus Hadropterus and one of a number of characters that suggests the group is among the least derived of Percina subgenera (Page, 1974). In the sister percid tribe Percini (Song et al., 1998) the preopercle is strongly serrate (Collette, 1963), and the presence of serrae in Hadropterus seems likely to have been retained from earlier percid ancestry (Bailey and Etnier, 1989). Pored Lateral Line Scales Hubbs (1954) noted a greater number of pored lateral line scales on the body of P. s. apristis , but considered overlap with populations of P. s. sciera too great to distinguish

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28 P. s. apristis . An examination of total pored lateral line scales (those on the body plus those extending onto the caudal fin) indicates that P. s. apristis differs significantly in having a greater number of pored lateral line scales from all other populations examined (Tables 2, 11, 19). High meristic values in species of Percina suggest a lack of divergence from the ancestral condition (Page, 1974). Modified Mid-Belly Scales of Males Modified scales in one or more rows along the mid-belly is a feature unique to Percina (Page, 1976). These scales likely play a tactile role in spawning similar to that of the breeding tubercles of nuptial males common to many groups of fishes (Loos and Woolcott, 1969). The number of modified mid-belly scales in P. s. apristis is significantly greater than in other populations examined. Although Page (1976) reported that Hadropterus males possess scales in a nearly complete row, a proportion of individuals of both P. s. apristis and P. s. sciera exhibited complete rows of modified mid-belly scales. Page (1976) speculated that the origins of a mid-belly row of modified scales in Percina stem from a selective advantage for those individuals with larger and more strongly toothed scales. Transverse and Circumferential Caudal Peduncle Scales The pattern of distinctions relative to P. s. apristis thus far summarized becomes less clear in weighing the significance of the characters of mean number of transverse and circumferential caudal peduncle scales. Percina s. apristis is most similar to Colorado River P. s. sciera in the character of transverse scales, which in turn is intermediate to a grouping of Brazos River and the geographically disjunct Sabine River. In scales around the caudal peduncle, P. s. apristis and Colorado River P. s. sciera are most similar and

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29 are significantly different from all other populations examined. In both instances the distinction is of a greater number of scales than other populations. Inferences Although the evolution of biological diversity is widely assumed to be driven by mutation, natural selection, genetic drift, geographic separation and genetic recombination, we rarely understand the relative contributions of each (Hey, 2001). While the present study has revealed patterns of variation in western Gulf Slope P. sciera , the forces driving these differences are not easily recognized, especially in light of confounding trends. Of particular interest in evaluating the taxonomic status of the Guadalupe Dusky Darter is assessing the degree of isolation. Knapp (1953) was the first to attempt to explain the distribution of Texas freshwater fishes in terms of geologic and climatic history (Conner and Suttkus, 1986). He contended that during the Pleistocene, the major drainage patterns of the region were not greatly different than they are today, but there existed a much better developed system of tributaries among which stream piracy was common (Knapp, 1953). To explain what he viewed as a high degree of present-day endemism in southwestern drainages, Knapp (1953) speculated that the Brazos River, in more arid times, with its highly turbid conditions and higher ionic concentrations, grew to represent a barrier to the westward expansion of eastern freshwater fishes. Investigations by Conner and Suttkus (1986) largely concur with the premise of the Brazos as a barrier to dispersal, but consider other drainage divides as well. These authors presented evidence for three drainage barriers to dispersal in the region, noting the divide between the Brazos and the Colorado as the most significant. Calculation of distinction indices for western Gulf Slope drainages revealed the divide between the Colorado and

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30 Brazos Rivers, the divide between the Brazos and the Trinity, and the divide between the Colorado and the Guadalupe as barriers to dispersal (Conner and Suttkus, 1986). These three divides form a cluster of the most significant distributional barriers in the region (Conner and Suttkus, 1986). Comparing ichthyofaunas on the basis of number of species and number of shared taxa revealed much the same result as the distinction indices analysis (Conner and Suttkus, 1986). An abrupt faunal change between the Colorado and Brazos River drainages divides the region into two broad groupings of drainages associated with some sort of ichthyogeographic barrier. Within the region, the Colorado and Brazos, distinctive in their faunas, constitute poor fits with their respective western and eastern groupings (Conner and Suttkus, 1986). The findings of these authors suggest a historical explanation for the patterns presented by the results of the current study. There exists little doubt that P. sciera colonized Texas from the east, with the founding stock of P. s. apristis stemming almost certainly from populations of P. sciera in the adjacent Colorado River drainage. The presence of a strong ichthyogeographic barrier to the east of the Colorado River drainage and a lesser barrier to the west explains the intermediacy of Colorado River P. s. sciera between P. s. apristis and Brazos River P. s. sciera, in the counts of transverse scales and modified mid-belly scales. The outright affinity exhibited between Colorado River P. s. sciera and P. s. apristis in mean numbers of circumferential caudal peduncle scales supports the concept of an ichthyogeographic divide between the Colorado and Brazos, cited by Conner and Suttkus (1986) as the most significant in the region.

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31 With the possible exception of the modified mid-belly scales of males, selective pressure on meristic features is likely to be weak. Therefore, resemblance between P. s. apristis and the populations from which it originated does not dispel the possibility that P. s. apristis is isolated. The Guadalupe River system harbors a greater number of endemic fishes than any of the other western Gulf Slope drainages, certainly a hallmark of biogeographic isolation (Conner and Suttkus, 1986). Insofar as the Guadalupe Dusky Darter may be isolated, the divergence of P. s. apristis from other populations in numbers of preopercular serrae, pored lateral line scales and modified mid-belly scales of males is considered relative to genetic drift and sexual selection. The function of preopercular serrae in Percina , as previously discussed, would appear to be limited. With no apparent selective force fixing the character in these fishes it seems plausible to conclude that genetic drift may be responsible for the reduced number of preopercular serrae in P. s. apristis . Variation in number of preopercular serrae is high in all populations of western Gulf Slope drainage P. s. sciera , and specimens with zero or few serrae are recorded from the Colorado River drainage and all other populations with the exception of those in the Brazos (Table 1). Drift tends to act most powerfully on small founder populations, and it is reasonable to speculate that presentday P. s. apristis may owe its origins to a small founding stock characterized by relatively few preopercular serrae. Likewise, little selective advantage can be perceived in variation in mean number of lateral line scales. While statistically significant differences in features such as mean lateral line scales may be indicative of isolation and in effect constitute a functional

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32 surrogate for identifying genetic differences among populations, there is likely little selective advantage for those fishes with slightly more or fewer lateral line scales. Darters are sexually dimorphic fishes characterized by strong evidence of sexual selection. The modified mid-belly scales of Percina males are actively utilized in courtship and spawning (New, 1966) and are likely susceptible to selective pressures in the form of female mate selection. The shift in number of modified mid-belly scales of males in P. s. apristis could be driven by sexual selection. However, again, genetic drift could be the cause of the shift. Next to P. s. apristis , specimens of Colorado River P. s. sciera show the next highest mean number of modified scales. Conclusions Despite the variation revealed by this study, much of which points to the peripheral distribution of P. s. apristis , some doubt remains regarding reproductive isolation. While it is true that the Guadalupe River system exhibits the highest degree of endemism of western Gulf Slope drainages, all endemics in the system ( Gambusia geiseri , Gambusia georgei , and Etheostoma fonticola ) are San Marcos River spring isolates, and are adapted to a small and unique portion of the overall river system. The range of P. s. apristis is not restricted to springs, and there is no reason to suppose the subspecies fits this pattern of endemism. A number of the characteristics analyzed by the present study further distinguishes P. s. apristis from P. s. sciera in the western Gulf Slope drainages of Texas. However, other characteristics raise questions concerning the pattern of variation and the degree to which P. s. apristis exists in isolation. Considering that the process of speciation is gradual, there must exist a period of ambiguity wherein boundaries are not clear (Hey, 2001). Presently the distinction between P. s. apristis and P. s. sciera is not so

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33 great or the pattern of variation so clear that one appears to be fully reproductively isolated from the other.

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34 LIST OF REFERENCES Bailey, R. M. and D. A. Etnier. 1988. Comments on the subgenera of darters (Percidae) with descriptions of two new species of Etheostoma ( Ulocentra ) from Southeastern United States. Miscellaneous Publications Museum of Zoology, University of Michigan, Ann Arbor, 175: 1-47. Brown, W. H. 1952. Egg production of the fish Hadropterus scierus apristis in San Marcos River, Texas. Copeia, 1955: 149-150 Clay, W. M. 1975. The Fishes of Kentucky. Kentucky Department of Fish and Wildlife Resources, Frankfort, KY. Collette, B. B. 1963. The subfamilies, tribes, and genera of the Percidae (Teleostei). Copeia, 1963: 615-623. Conner, J. V. and R. D. Suttkus. 1986. Zoogeography of freshwater fishes of the western Gulf Slope of North America. Pages 413 – 456 in C. H. Hocutt and E. O. Wiley, editors. The Zoogeography of North American Freshwater Fishes. Wiley, New York. Douglas, N. H. 1974. Freshwater Fishes of Louisiana. Claitor’s Publishing Division, Baton Rouge, Louisiana. Dytham, C. 1999. Choosing and Using Statistics, a Biologist’s Guide. Blackwell Science Ltd., London Eschmeyer, W. N. (ED.). 1998. Catalog of Fishes. California Academy of Sciences, San Francisco. Etnier, D. A. and W. C. Starnes. 1993. The Fishes of Tennessee. University of Tennessee Press, Knoxville. Gerking, S. D. 1945. The Distribution of the Fishes of Indiana. Investigations of Indiana Lakes and Streams (3): 1-137 Hey, J. 2001. Genes, Categories, and Species. Oxford University Press Inc., New York. Hubbs, C. 1954. A new Texas subspecies, apristis, of the darter Hadropterus scierus, with a discussion of variation within the species. The American Midland Naturalist 52 (1): 211-220.

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35 Hubbs, C. 1967. Geographic variations in survival of hybrids between Etheostomatine Fishes. Bulletin of the Texas Memorial Museum, No.13. Hubbs, C. and M. V. Johnson. 1961. Differences in the egg complement of Hadropterus scierus from Austin and San Marcos. The Southwestern Naturalist 6 (1): 9-12. Hubbs, C., Edwards R. J., and G. P. Garrett. 1991. An annotated checklist of the freshwater fishes of Texas, with keys to identification of species. Special Supplement. The Texas Journal of Science 43 (4): 1-56. Hubbs, C. L. and J. D. Black. 1954. Status and synonymy of the American percid fish Hadropterus scierus . The American Midland Naturalist 52 (1): 201-210. Hubbs, C. L. and C. Hubbs. In C. Hubbs, 1954. A new Texas subspecies, apristis , of the darter Hadropterus scierus , with a discussion of variation within the species. American Midland Naturalist 52 (1): 211-213. Hubbs, C. L. and K. F. Lagler. 1964. Fishes of the Great Lakes Region. University of Michigan Press, Ann Arbor. Jenkins, R. E. and N. M. Burkhead. 1994. Freshwater Fishes of Virginia. American Fisheries Society, Bethesda, Maryland. Knapp, F. T. 1953. Fishes found in the fresh waters of Texas. Ragland Studio and Litho Printing Company, Brunswick, GA. Kuehne, R. A. and R. W. Barbour. 1983. The American Darters. University Press of Kentucky, Lexington, KY. Leviton, A. E., R. H. Gibbs Jr., E. Heal, and C. E. Dawson. 1985. Standards in herpetology and ichthyology. Part I. Standard symbolic codes for institutional resource collections in herpetology and ichthyology. Copeia, 1985: 802-832. Loos, J. J. and W. S. Woolcott. 1969. Hybridization and behavior in two species of Percina (Percidae). Copeia, 1969: 374-385. Menhinick, E. F. 1991. The Freshwater Fishes of North Carolina. North Carolina Wildlife Resources Commission, Raleigh, NC. Mettee, M. F., P. E. O’Neil, and J. M. Pierson. 1996. Fishes of Alabama and the Mobile Basin. Oxmoor House, Inc. Birmingham, Alabama. Miller, R. J. and H. W. Robison. 1973. The Fishes of Oklahoma. Oklahoma State University Press, Stillwater.

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36 Nelson, J. S., E. J. Crossman, H. Espinosa-Prez, L. T. Findley, C. R. Gilbert, R. N. Lea, and J. D. Williams. 2004. Common and Scientific Names of Fishes from the United States, Canada, and Mexico. American Fisheries Society, Special Publication 29, Bethesda, Maryland. New, J. G. 1966. Reproductive behavior of the shield darter, Percina peltata peltata , in New York. Copeia, 1966 (1): 20 – 28. Ott, R. L. and M. Longnecker. An Introduction to Statistical Methods and Data Analysis, 5th edition. Duxbury. Pacific Grove, California. Page, L. M. 1974. The subgenera of Percina (Percidae: Etheostomatini). Copeia, 1974 (1): 66-86. Page, L. M. 1976. The modified midventral scales of Percina (Osteichthyes; Percidae). Journal of Morphology. 148 (2): 255-264. Page, L. M. 1983. Handbook of Darters. TFH Publications, Inc., Neptune City, NJ. Page, L. M. 1985. Evolution of reproductive behaviors in percid fishes. Illinois Natural History Survey Bulletin, 33 (3): 275-295. Page, L. M. 2000. Etheostomatinae. In Craig, J. F. Percid Fishes: Systematics, Ecology, and Exploitation. Blackwell Science Ltd., Oxford. Page, L. M. and B. M. Burr. 1991. A Field Guide to Freshwater Fishes of North America North of Mexico. The Peterson Field Guide Series, volume 42. Houghton Mifflin, Boston. Page, L. M. and P. W. Smith. 1970. The life history of the dusky darter, Percina sciera , in the Embarras River, Illinois. Illinois Natural History Survey Biological Notes No. 69. Pflieger, W. L. 1975. The Fishes of Missouri. Missouri Dept. Conservation, Jefferson City, MO. Richards, W. J. and L. W. Knapp. 1964. Percina lenticula , a new percid fish, with a redescription of the subgenus Hadropterus . Copeia, 1964: 690-701. Robison, H. W. and T. M. Buchanan. 1988. Fishes of Arkansas. University of Arkansas Press, Fayetteville, AR. Ross, S. T. 2001. Inland Fishes of Mississippi. University Press of Mississippi, Oxford, MS. SAS Institute, Inc. 2002. SAS user’s guide: statistics version 9 edition. SAS Institute Inc., Cary, North Carolina.

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37 Smith, P. W. 1979. The Fishes of Illinois. University of Illinois Press, Urbana. Song, C. B., T. J. Near and L. M. Page. 1998. Phylogenetic relations among percid fishes as inferred from mitochondrial cytochrome b DNA sequence data. Molecular Phylogenetics and Evolution. 10 (3): 343-353. Stauffer, J. R., Jr., J. M. Boltz, and L. R. White. 1995. The Fishes of West Virginia. West Virginia Department of Natural Resources. Academy of Natural Sciences of Philadelphia, Philadelphia. Trautman, M. B. 1981. The Fishes of Ohio. Ohio State University Press, Columbus.

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38 BIOGRAPHICAL SKETCH Robert H. Robins was born on November 16, 1972, in Miami, Florida. One of three children, he developed a keen appreciation for living things at an early age, particularly fishes and snakes. He received his Bachelor of Arts degree from the University of Miami in May, 1994 and moved to Gainesville, Florida to work as a Biological Technician with the Department of the Interior’s National Biological Survey. In December 1996 he left DOI employment for a position with the Florida Museum of Natural History at the University of Florida. In August of 2001 he enrolled in UF’s Department of Wildlife, Ecology and Conservation as a part-time graduate student supported by the University of Florida’s employee education program. He is currently a Senior Biologist and Ichthyology Division Collection Manager at the Florida Museum of Natural History, a position he has held since 2002.