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Aethycteron robisoni n. sp. is described from the sunburst darter, Etheostoma mihileze Mayden (Perciformes: Percidae), in the Arkansas River Drainage of the Ozark Region in the Central Highlands of Arkansas, USA. Aethycteron robisoni morphologically most closely resembles A. caerulei Suriano & Beverley-Burton, 1982, A. moorei (Mizelle, 1940) and A. nigrei Suriano & Beverly-Burton, 1982, by possessing a male copulatory organ with a distinct distal curvature and spiraling sheath. The haptoral sclerites of A. robisoni, with the exception of the hooks, are distinctly larger than those of the other three species. This is the first time a monogenean parasite has been reported from E. mihileze as well as the first time the genus Aethycteron Suriano & Beverley-Burton, 1982 has been reported from Arkansas, USA.

Metal pollution issues are afforded the highest priority in developing countries. Only one previous study has addressed metals in African bird eggs. We determined the concentration of metals and metalloids in bird eggs from four sites in the Vaal River catchment (VRC) of South Africa to provide data on the current situation. We analysed 16 pools of 77 heron, ibis, darter, egret, and cormorant eggs for 18 metals and metalloids using ICP-MS. We found high concentrations of gold (Au), uranium (U), thallium (Tl), and platinum (Pt) in Grey Heron eggs from Baberspan. Great white egrets from Bloemhof Dam had high concentrations of mercury (Hg). Multivariate analyses revealed strong associations between Au and U, and between palladium (Pd) and Pt. The toxic reference value (TRV) for Hg was exceeded in seven pools. Selenium exceeded its TRV in one pool; in the same pool, copper (Cu) reached its TRV. Compared with other studies, VRC bird eggs had high concentrations of contaminants. Based on these high concentrations, human health might be at risk as Grey Herons and humans share similar food and are therefore exposed to the same contaminants.

Darters (Perciformes, Percidae), sculpins (Perciformes, Cottidae), and gobioids (Gobiiformes, Gobioidei) exhibit convergent life history traits, including a benthic lifestyle and a cavity nesting spawning mode. Soniferous species within these taxa produce pulsed and/or tonal sounds with peak frequencies below 200 Hz (with some exceptions), primarily in agonistic and/or reproductive contexts. The reduced or absent swim bladders found in these taxa limit or prevent both hearing enhancement via pressure sensitivity and acoustic amplification of the contracting sonic muscles, which are associated with the skull and pectoral girdle. While such anatomies constrain communication to low frequency channels, optimization of the S/N (signal-to-noise) ratio in low frequency channels is evident for some gobies, as measured by habitat soundscape frequency windows, nest cavity sound amplification, and audiograms. Similar S/N considerations are applicable to many darter and sculpin systems. This chapter reviews the currently documented diversity of sound production in darters, sculpins, and gobioids within a phylogenetic context, examines the efficacy of signal transmission from senders to receivers (sound production mechanisms, audiograms, and masking challenges), and evaluates the potential functional significance of sound attributes in relation to territorial and reproductive behaviours.

Understanding relationships between habitat associations for individuals and habitat factors that limit populations is a primary challenge for managers of stream fishes. Although habitat use by individuals can provide insight into the adaptive significance of selected microhabitats, not all habitat parameters will be significant at the population level, particularly when distributional patterns partially result from habitat degradation. We used underwater observation to quantify microhabitat selection by an imperiled stream fish, the Candy Darter Etheostoma osburni, in two streams with robust populations. We developed multiple-variable and multiple-life-stage habitat suitability indices (HSIs) from microhabitat selection patterns and used them to assess the suitability of available habitat in streams where Candy Darter populations were extirpated, localized, or robust. Next, we used a comparative framework to examine relationships among (1) habitat availability across streams, (2) projected habitat suitability of each stream, and (3) a rank for the likely long-term viability (robustness) of the population inhabiting each stream. Habitat selection was characterized by ontogenetic shifts from the low-velocity, slightly embedded areas used by age-0 Candy Darters to the swift, shallow areas with little fine sediment and complex substrate, which were used by adults. Overall, HSIs were strongly correlated with population rank. However, we observed weak or inverse relationships between predicted individual habitat suitability and population robustness for multiple life stages and variables. The results demonstrated that microhabitat selection by individuals does not always reflect population robustness, particularly when based on a single life stage or season, which highlights the risk of generalizing habitat selection that is observed during nonstressful periods or for noncritical resources. These findings suggest that stream fish managers may need to be cautious when implementing conservation measures based solely on observations of habitat selection by individuals and that detailed study at the individual and population levels may be necessary to identify habitat that limits populations. Received March 30, 2016; accepted July 19, 2016Published online October 7, 2016

Eastern sand darter (Ammocrypta pellucida) is listed as Threatened under the Canadian Species at Risk Act. Little relevant biological information is available for most Canadian populations and only limited information is available for populations in the United States. To supplement the paucity of information, this study collected biological information on eastern sand darter during field surveys in 2006-2007 from 10 sites in the lower Thames River, Ontario, Canada. Collected data were used to estimate critical life history traits including: longevity, fecundity, clutch size and number, growth, survival, age-at-first-maturity and cohort age structure. Longevity was 3+ years, with age-at-first-maturity being 1+ for both sexes. Examination of egg sizes from preserved females in 2007 showed a bimodal distribution, suggesting two spawning occurrences of 71 eggs each. Quantitative comparison of lower Thames River biological information with a more southerly eastern sand darter population in the Little Muskingum River, Ohio, demonstrated little variation between the populations. Data comparisons suggest that localised environmental factors are affecting biological traits (growth), in particular water temperature that may be controlled by differences in riparian cover and/or groundwater input.

Notropis photogenis (Silver Shiner) and Etheostoma zonale (Banded Darter) were collected from the Flint River in Madison County, AL, a northern tributary to the Tennessee River. Both species have been found in other northern tributaries to the Tennessee River in Alabama, but have not been widely reported from the Flint River. The Flint River is currently considered to be impaired water due to elevated turbidity, and has also been impaired in recent years from organic enrichment/low dissolved oxygen and pathogens in the form of fecal coliform.

Introgressive hybridization and incomplete lineage sorting complicate the inference of phylogeny, and available species-tree methods do not simultaneously account for these processes. Both hybridization and ancestral polymorphism have been invoked to explain divergent phylogenies inferred from different datasets for Stigmacerca, a clade of 11 North American darter species. Species of Stigmacerca are characterized by a mating system involving parental care with males guarding nesting territories and fertilized eggs. Males of four species of Stigmacerca develop egg-mimic nuptial structures on their second dorsal fins during the breeding season. Previous phylogenies suggest contrasting scenarios for the evolution of this nuptial trait. Using a combination of coalescent-based methods, we analyzed a dataset comprising a mitochondrial gene and 15 nuclear loci to estimate relationships and simultaneously test for introgressive hybridization. Our analyses identified several instances of interspecific gene flow involving both cytoplamsmic haplotypes and nuclear alleles. The new phylogeny was used to infer a single origin and recent loss of egg-mimic structures in Stigmacerca and led to the discovery of a phylogenetically distinct species. Our results highlight the limited strategies available to account for introgressive hybridization in the inference of species relationships and the likely effects of this process on reconstructing trait evolution.

The Barrens Darter (Etheostoma forbesi) is a rare darter in subgenus Catonotus endemic to the Caney Fork River system in middle Tennessee. Hybridization with the closely related Fringed Darter (E. crossopterum) has been assumed as a risk to E. forbesi. To assess chronology and similarity of nesting habitat between these species, nests of both egg-clustering darters were observed through the spring nesting seasons in four streams during 2008 and 2009. Microhabitat variables associated with nests exhibited evidence of headwater specialization by E. forbesi that may isolate spawning populations from E. crossopterum. Etheostoma forbesi used nest rocks of smaller average dimensions and bottom surface area, and nested at shallower depths where water velocities were higher than nesting individuals of E. crossopterum. Nesting chronology and clutch sizes were similar between species, with spawning periods similar to those reported for other darter species in subgenus Catonotus and with clutch sizes up to 2,000 egg...

Like many fishes native to western Great Plains streams, the Arkansas darter Etheostoma cragini has declined, apparently in response to changes in flow regimes and habitat fragmentation. We investigated the effectiveness of translocation as a management strategy to conserve this threatened species in the Arkansas River basin of southeastern Colorado. We used a multiscale design to sample the darter and several attributes of its habitat at the local 10-m site scale, the 3.25-km translocation segment scale, and the 10-km riverscape scale in all 19 streams where it had been previously translocated. The darter was captured in 11 of the 19 streams, although 5 were completely dry when visited. Arkansas darters had reproduced in 10 of the 11 streams (one criterion in the state recovery plan), and 6 streams also met a second criterion for abundance (>500 individuals). However, the populations in only two streams unequivocally met a third criterion of being self-sustaining, because the other four streams ...

Speciation research focuses on the evolutionary mechanisms responsible for the origin of species, and recent treatments have distinguished ecological and mutation-order speciation as distinct evolutionary processes. Using a research framework that considers ‘speciation phenotypes’ (sensu Shaw and Mullen in Genet 139(5):649–661, 2011) and a modified hierarchy of speciation models, we address whether speciation in benthic fishes commonly called darters proceeds under divergent ecological selection or a mutation-order process. We examined neutral genetic divergence, sexual signal (male color) divergence, environmental differences, and geographic distance in 66 species pair comparisons. Modified Mantel tests detected significant relationships between genetic distance and overall male color differences, as well as geographic distance and overall male color differences; however, after accounting for the correlation of male color and geographic distance with genetic distance using a partial Mantel test, no relationship was observed between male color and geographic distance. Neither microhabitat nor climatic measures of environmental differences correlated with overall male color differences. Color difference scores for discrete color categories (i.e., red/orange/yellow, black, and blue/green) differed in their correlations with explanatory variables, implying different selection regimes may be influencing each component of darter color patterns. Our results do not support a primary role for divergent ecological selection shaping early divergence of darter sexual signals. Instead, a model of mutation-order speciation may best explain the clock-like manner of changes in male color among darter species.

The threatened Okaloosa darter ( Etheostoma okaloosae ) is found almost exclusively on the Eglin Air Force Base in the Choctawhatchee Bay watershed of Florida. Portions of this limited habitat are threatened with soil erosion, altered hydrology, and impaired water quality. In the present study, general water quality parameters (i.e., dissolved oxygen, specific conductance, pH, temperature, relative turbidity, and primary productivity) were characterized in East Turkey Creek, which is a body of water potentially impacted by treated wastewater sprayfields, and Long Creek, an adjacent reference stream that does not border the sprayfields. Water quality was assessed during a 30-day exposure using passive samplers for both non-polar and polar effluent parameters. Because the Okaloosa darter was listed as endangered at the time of sampling we chose a closely related species from the same creeks, the sailfin shiner ( Pteronotropis hypseleotris ) in which to measure metal body burdens. Additionally, fathead minnows ( Pimephales promelas ) were used for microarray analysis on gonad and liver tissues after 48 h exposures to water collected from the two creeks and brought into the laboratory. Waters from all sites, including reference sites, affected the expression of genes related to various biological processes including transcription and translation, cell cycle control, metabolism, and signaling pathways, suggesting that the sum of anthropogenic compounds in the site waters may cause a generalized stress response in both liver and testis, an effect that could be related to the generally low populations of the Okaloosa darter. Furthermore, effects of site waters on fish gene expression may be related to the impact of human activities other than the wastewater sprayfields, as nearby areas are closed to the public for military testing, training, and administrative activities and due to ordnance contamination.

While extensive empirical and theoretical work has focused on the evolution of costly cooperation (particularly in group-living species), less attention has been paid to more low-risk or immediately beneficial forms of cooperation. In some non-group-living darters, alloparental care (or allocare) by subordinates has been noted to result from by-product benefits as small territorial (subordinate) males adopt and provide care to the abandoned eggs of large territorial (dominant) males. In the tessellated darter (Etheostoma olmstedi), allocare also results from sneak fertilization. However, information on the rate of allocare by tessellated darters is contradictory: prior behavioral work suggested that it is very common, while a genetic examination showed males to primarily care for their own young. We found behavioral and genetic evidence of very high levels of allocare at our study location. The relative size of the assigned fathers of young to the alloparental male is consistent with the idea that initial allocare primarily results from sneak fertilization (“cuckoldry-based allocare”), but later allocare results from subordinate males caring at previously abandoned nests (“adoption-based allocare”). Larger males appeared to breed more frequently at different nests, but did not father more individual offspring than smaller males. Finally, low relatedness between abandoning and alloparenting males suggests that kin selection does not contribute to alloparental care. We discuss how variation in nest availability may explain the inconsistent findings of the rate of alloparental care in the tessellated darter, and how increased research in this and similar systems can expand our understanding of the evolution of cooperation.

Male-only care is the most frequent parental care behaviour in teleost fishes, but little is known about its evolutionary origins and patterns of diversity in species-rich lineages. Darters are a clade of North American freshwater fishes that contain both nonparental care species and species with male-only care. In darters, paternal care takes the form of egg-guarding and other egg-tending behaviours that are dependent on the female mode of egg deposition. Male care has been hypothesized to evolve independently in darters at least three times, and it has been thought to be irreversible. We investigated the diversification of egg-deposition behaviours and the evolution of complex male care using published descriptions of darter reproductive behaviours and a multilocus molecular phylogeny that included all 146 species for which reproductive behaviours are known. We find support for two origins of male-only care behaviour. One origin of paternal care occurred relatively early in the radiation of Etheostoma and is characteristic of a recently discovered clade, Goneaperca. The other origin of male-only care occurred much more recently in a derived clade of Nothonotus. Our analyses of character diversification demonstrate reversals from care to noncare and multiple transitions between egg-deposition behaviours that are not associated with parental care.

Published version reproduced here with permission., A single fossil tarsometatarsus from the Etadunna Formation, of Late Oligocene–Early Miocene age, at the Snake Dam Locality in South Australia reveals the ï¬ rst pre-Pliocene record of anhingids in Australia. Anhinga walterbolesi sp. nov. provides the oldest record globally for the Anhingidae and, with the contemporary presence of stem-group phalacrocoracids in the same formation, indicates a probable Early Oligocene to Eocene age for the common ancestor of anhingids and phalacrocoracids.

The eastern sand darter (Ammocrypta pellucida Agassiz) is a small (

Standard and active metabolisms determine the key aspects of the development and survival of fish species. We describe the first bioenergetic model for the standard metabolic rate (SMR) and active metabolic rate (AMR) of the Chilean native darter Percilia irwini. Adult individuals (5.5 ± 1.2 cm, 2.1 ± 0.9 g) were tested in a Blaska-type respirometer at 19.5 ± 0.5°C. Fish held a position by resting at the bottom at low velocities (5 and 15 cm s−1) and by swimming at higher velocities (25 and 35 cm s−1). SMR = 0.166 M 1.39 with an average of 220 mg O2 h−1 kg−1. Two bioenergetic models for AMR were adjusted. AMR = 0.16 M 1.16 U 0.23 at low velocities and AMR = 0.026 M 0.77 U 0.97 at higher velocities. Therefore, low velocities have little effect on the active metabolism of this species, but it is the main factor at higher velocities. Metabolic scope per unit weight was larger for smaller individuals, which is consistent with the faster growth of younger individuals.

Rivers and streams are among the most threatened ecosystems worldwide, and their fish assemblages have been modified by anthropogenic habitat alteration and introductions of non-native species. Consequently, two frequently observed patterns of assemblage change over time are species loss and biotic homogenization. In the present study, we compared contemporary (2006–2007) and historical (1948–1955) assemblages of darters, a group of small benthic fishes of the family Percidae, in the Arkansas River drainage of northeastern Oklahoma, USA. Results showed species loss between the two sampling periods, with historical estimates of overall species diversity across the study area exceeding contemporary estimates by five to eight species. Assemblages showed a low degree of darter similarity based on species presence and absence, with pairwise site comparisons (Jaccard’s similarity index) between historical and contemporary samples averaging  0.35. No significant homogenization or differentiation of assemblages occurred. Range expansion of widespread species, one of the primary mechanisms of biotic homogenization, was not observed; rather, all species occurred at a smaller proportion of sites in contemporary samples. Our results highlight the threat posed by anthropogenic habitat alteration to taxonomic groups such as darters, most of which are habitat specialists. However, our results suggest that biotic homogenization is unlikely to occur in the absence of immigration, especially if assemblages are subjected to ‘novel disturbances’ such as dam construction and watershed-scale habitat degradation which negatively affect all components of the assemblage.

Adaptive cluster sampling (ACS) designs were tested against simple random sampling (SRS) designs to determine whether ACS designs were more suitable sampling protocols for monitoring rare fish species. To test the utility of these designs, baseline data on the tuxedo darter Etheostoma lemniscatum (a rare, federally endangered fish) were collected at three sites on the Big South Fork of the Cumberland River and used in computer simulation of ACS designs. Based on the simulation models, five ACS designs were chosen and tested at 13 potential monitoring sites. In terms of efficiency, ACS designs performed better than SRS designs, providing estimates with smaller standard errors. Adaptive cluster sampling design efficiency increased with effort; therefore, the two goals—minimizing effort and maximizing accuracy—are incompatible. Because it had less error, an inverse ACS design was recommended, although it required more sampling effort than other designs. Factors possibly affecting overall design perf...

Animal colour patterns are among the most striking examples of biological diversity. Elaborate coloration is thought to play a role in mate choice within populations and to pose a barrier to interbreeding between species, with individuals preferring the coloration of conspecifics. Ideally, the importance of coloration as a reproductive barrier would be tested by holding all traits constant and manipulating only colour to test its effect. In butterflies, researchers use paper models to manipulate female colour patterns and show strong male preference for conspecific female coloration. In African cichlids and poison frogs, researchers manipulate the light environment to test the importance of male colour in female preference for conspecifics. Here we use motorized models to test whether females in a pair of sexually dimorphic fish species (genus: Etheostoma ) prefer conspecific over heterospecific male coloration. By isolating and manipulating specific components of male coloration, we show that females of both species significantly prefer conspecific male colour (red versus green) and pattern (stripe versus bars). These results provide strong evidence that female preference for conspecific male nuptial coloration may play a critical role in behavioural isolation.

Imperiled Okaloosa darters (Etheostoma okaloosae) are small, benthic fish limited to six streams that flow into three bayous of Choctawhatchee Bay in northwest Florida, USA. We analyzed the complete mitochondrial cytochrome b gene and 10 nuclear microsatellite loci for 255 and 273 Okaloosa darters, respectively. Bayesian clustering analyses and AMOVA reflect congruent population genetic structure in both mitochondrial and microsatellite DNA. This structure reveals historical isolation of Okaloosa darter streams nested within bayous. Most of the six streams appear to have exchanged migrants though they remain genetically distinct. The U.S. Fish and Wildlife Service recently reclassified Okaloosa darters from endangered to threatened status. Our genetic data support the reclassification of Okaloosa darter Evolutionary Significant Units (ESUs) in the larger Tom’s, Turkey, and Rocky creeks from endangered to threatened status. However, the three smaller drainages (Mill, Swift, and Turkey Bolton creeks) remain at risk due to their small population sizes and anthropogenic pressures on remaining habitat. Natural resource managers now have the evolutionary information to guide recovery actions within and among drainages throughout the range of the Okaloosa darter.

When individuals defend and care for young that are not their own (alloparental care), it raises the question of what benefits might lead to the evolution and persistence of such care. Here, we examine how male and female preferences affect the direct benefits of alloparental care. In the tessellated darter, alloparental care by some males often follows nest abandonment by others (Stiver KA, Wolff S, Alonzo SH, in preparation). We hypothesize that alloparental care may have evolved due to mating benefits: Alloparental care could be favored if females prefer to breed at nests that contain eggs. We found that, on average, males and females prefer nests with young eggs to those without eggs. Consequently, although young eggs increase the attractiveness of the nest, this positive effect is lost as the age of the eggs on the nest increases. We also found that alloparental care is costly in terms of future potential mating success as the amount of new eggs deposited in a nest decreases as nests become more filled. Therefore, alloparental males may initially increase their attractiveness to females by defending nests with another male’s eggs but still potentially gain fewer eggs relative to those received by males defending empty nests. Our findings shed light on the evolution of alloparental care in the tessellated darter, suggesting that female mating preferences may underlie this well-documented cooperative relationship between males. Key words: cooperation, female choice, mate-choice copying, predation dilution, sexual selection, tessellated darter. [Behav Ecol]

The Stippled Darter, Etheostoma punctulatum, has long been recognized as a single species of the subgenus Ozarka, endemic to the clear, high-gradient creeks and rivers of the Arkansas, White, and Missouri river drainages in the Ozark Plateau of the Interior Highlands of North America. Etheostoma punctulatum is redescribed and two new species are described based on morphological and allozyme characters, and phylogenetic analyses. The Stippled Darter, E. punctulatum, is restricted to tributaries of the Missouri River. The Autumn Darter, E. autumnale, new species, is endemic to the White River system, Missouri and Arkansas. The Sunburst Darter, E. mihileze, new species, is known only from the Arkansas River system, Missouri, Arkansas, Oklahoma, and Kansas. The three species are found to be divergent and diagnosable from one another and represent valid species under a variety of species concepts. Phylogenetic analyses indicate that E. punctulatum is sister to E. mihileze, new species, plus E. autumna...

The distribution of imperiled stream fish, crayfish, salamander, and freshwater mussel species of Maryland streams in relation to urban land cover and nonnative species was investigated. Over the last 30 years, extinction or extirpation of 13 stream animal species (including the endemic Etheostoma sellare [Maryland Darter]) was observed within the Piedmont region of Maryland, where urbanization has spread extensively outward from Baltimore and Washington, DC, and many non-native species have become established. The presence of imperiled species in this area was correlated with urbanization and non-native species occurrence. However, correlations with land-cover data were stronger than with non-native occurrence. The majority of sites with imperiled species contained less than 10% urban land cover and less than 5% impervious land cover in their catchments. In contrast, stream reaches with non-native species spanned the entire gradient of urban, agriculture, and forested land cover, with the majori...

Ten new county records and significant extensions of known geographic ranges are reported for 10 taxa of fishes within 6 families (Atherinopsidae, Catostomidae, Centrarchidae, Cyprinidae, Fundulidae, and Percidae) from five rivers in Arkansas. Records are presented for the shoal chub (Macrhybopsis hyostoma), highfin carpsucker (Carpiodes velifer), golden redhorse (Moxostoma erythrurum), pealip redhorse (Moxostoma pisolabrum), northern starhead topminnow (Fundulus dispar), Mississippi silverside (Menidia audens), dollar sunfish (Lepomis marginatus), crystal darter (Crystallaria asprella), mud darter (Etheostoma asprigene), and river darter (Percina shumardi).

New bird fossils from the Santa Cruz Formation (lower–middle Miocene), Santa Cruz Province, Patagonia, Argentina, are described. They represent an indeterminate species of the extinct anhingid Macranhinga and a new genus and species of basal Anatidae Ankonetta larriestrai. The record of the giant darter Macranhinga constitutes the southernmost record for the family, and expands the known stratigraphic range of the genus, previously restricted to the upper Miocene. Based on an analysis of the fossil anhingid record from South America, we hypothesize that giant darters disappeared from South America in the early Pliocene due to climatic deterioration, regression of marine and freshwater environments, the arrival of placental carnivorous mammals, and also probably by competition with phalacrocoracid cormorants. The new anatid Ankonetta is based on an incomplete but informative tarsometatarsus, with superficial similarities to extant Dendrocygna. A brief overview of several fossil ducks from the Patagonian Ce...

We characterised microhabitat availability and use by adult and young-of-year (YOY) snail darters (Percina tanasi Etnier 1976) while snorkelling in the French Broad and Hiwassee rivers, TN, USA. Both age groups of snail darters disproportionately used most microhabitat variables compared to their availability. Snail darters primarily occupied moderately deep, swift water over gravel substrates with little macrophyte coverage and no silt. Univariate comparisons indicated that adult and YOY darters occupied different habitat, but there was no marked differences between principal components analysis plots of multivariate microhabitat use within a river. Although the availability of microhabitat variables differed between the French Broad and Hiwassee rivers, univariate means and multivariate plots illustrated that the habitats used were generally similar by age groups of snail darters between rivers. Because our observations of habitat availability and use were constrained to low flow periods and depths

Hypotheses of diversification in eastern North American freshwater fishes have focused primarily on allopatric distributions of species between disjunct highland areas and major river systems. However, these hypotheses do not fully explain the rich diversity of species within highland regions and river systems. Relatively old diversification events at small geographic scales have been observed in the Barcheek Darter subclade that occurs in the Cumberland River drainage (CRD) in Kentucky and Tennessee, United States of America, but it is unknown if this pattern is consistent in other darter subclades. We explored phylogeographic diversity in two species of Nothonotus darters, N. microlepidus and N. sanguifluus, endemic to the CRD to compare phylogenetic patterns between Barcheek Darters and species of Nothonotus. We collected sequence data for a mitochondrial gene (cytb) and three nuclear genes (MLL, S7 and RAG1) from 19 N. microlepidus and 35 N. sanguifluus specimens. Gene trees were estimated using maximum likelihood and Bayesian methods, and a 'species tree' was inferred using a Bayesian method. These trees indicate that species diversity in Nothonotus is underestimated. Five distinct lineages were evident, despite retained ancestral polymorphism and unsampled extirpated populations. Comparison of chronograms for Barcheek Darters and Nothonotus revealed that microendemism resulting from species diversification at small geographic scales in the CRD is a consistent pattern in both old and young darter subclades. Our analyses reveal that geographic isolating mechanisms that result in similar phylogeographic patterns in the CRD are persistent through long expanses of evolutionary time.

Elaborate visual communication signals characterize many animal lineages. Often sex-limited, these signals are generally assumed to result from sexual selection, and in many cases, their evolution is thought to play a central role in speciation. The co-evolution of male visual signals and female preferences is hypothesized to result in behavioral isolation between divergent lineages; however, for many lineages characterized by elaborate visual signals, the importance of visual differences in behavioral isolation is not well established. Darters (fish genus Etheostoma) are particularly appropriate for examining the role of visual signals in behavioral isolation. They comprise one of the most diverse groups of North American freshwater fish, and nearly every species is characterized by unique nuptial coloration. Multiple darter species co-exist in sympatric populations, indicating that reproductive barriers are central to maintaining these extraordinarily diverse color patterns. This study demonstrates the presence of behavioral isolation between a pair of distinctly colored sympatric darter species, Etheostoma barrenense and Etheostoma zonale, through experimental observations using an artificial stream. In addition, a series of dichotomous mate-choice trials indicate that females prefer conspecific males over heterospecifics based on visual differences alone. We therefore provide the first evidence that visual signals are a critical trait maintaining behavioral isolation in darters, a lineage of fishes with spectacular diversification in visual communication.

The federally endangered watercress darter (Etheostoma nuchale) is restricted to only five springs within the greater Birmingham (AL) metropolitan area. Restricted range, subpopulation isolation and threats from the urban landscape are the major factors endangering the species. The preferred habitat of E. nuchale has been described as the deeper, slow-moving portions of spring pools with dense aquatic vegetation, but its habitat use patterns have not been carefully studied. Because the long-term survival of E. nuchale will likely depend on the protection and restoration of suitable habitat, more needs to be known about its preferred habitats. We studied habitat use patterns of E. nuchale and the geomorphologic and environmental conditions associated with these habitats in Seven Springs, a population recently discovered in 2003. Geomorphology and vegetation were surveyed throughout the spring pool and the spring run connecting it to the nearest tributary. Fish were surveyed via seining in eight di...

Populations of Etheostoma tallapoosae (Tallapoosa Darter) have previously been shown to be genetically divergent for mitochondrial DNA. In this study, PCR primers were developed to amplify portions of six nuclear genes, and sequences of these genes were assessed in three of the most divergent Tallapoosa Darter populations. This analysis shows that these populations are also highly divergent for nuclear gene sequences and thus any adaptive or potentially adaptive variation is likely to be partitioned among the populations. Sequences of the six nuclear genes have also been determined in the closely related species E. coosae and E. brevirostrum, and the utility of these nuclear gene sequences to the elucidation of darter phylogeny is discussed.

Darters are a species-rich radiation of small benthic and benthic-associated stream fishes that comprise approximately 20% of the diversity of the North American freshwater fish fauna. Here, we gather data from 165, or 87%, of described species and use this information to characterize the morphological diversity of the darter radiation. We focus on characters of the oral jaws known to function in prey capture and consumption in other perciform taxa in order to explicitly link morphological diversity to ecological diversity. In addition to a quantitative description of the morphospace occupied by darters, we identify several instances of significant morphological convergence. We also describe three groups of darter species that exhibit unusual jaw morphologies that are used in previously undescribed prey capture behaviours. Despite these new ecomorphs, we find that darters exhibit relatively low variation in trophic morphology when compared with two other radiations of teleost fishes, and that the observed variation is related more to differences in microhabitat use than to differences in prey type. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 30‐45.

Ammocrypta clara Jordan and Meek (western sand darter) occurs primarily in the western portions of Mississippi River system, but also has been reported from a Lake Michigan drainage and a few eastern Texas Gulf Slope rivers. Additional range records depict a semi-disjunct distribution within the Ohio River drainage, including collections from Wabash River in Indiana, the Cumberland, Green, Kentucky and Big Sandy rivers of Kentucky, and the upper Tennessee River in Tennessee and Virginia. This paper documents the occurrence of A. clara from the upper Ohio River drainage within the lower Elk River, West Virginia, based on collections from 1986, 1991, 1995, 2005 and 2006. The Elk River population, consistent with those of other Ohio River drainages, has slightly higher counts for numbers of dorsal-fin rays, scales below lateral line and lateral line scales when compared to data from populations outside of the Ohio River drainage. Modal counts of meristic characters are similar among populations, except for higher modal counts of lateral line scales in the Ohio River population. The discovery of the Elk River population extends the range distribution of A. clara in the Eastern Highlands region, documents wide distributional overlap and additional sympatry with its sister species, A. pellucida (eastern sand darter), and softens support for an east-west Central Highlands vicariance hypothesis for the present distribution of A. clara and A. pellucida.

The life history and population demography of the endangered birdwing pearlymussel (Lemiox rimosus) were studied in the Clinch and Duck rivers, Tennessee. Reproducing populations of L. rimosus now occur only in the Clinch, Duck and Powell rivers, as the species is considered extirpated from the remaining portions of its range in the Tennessee River drainage. Females are long-term winter brooders, typically gravid from Oct. to May. Glochidia are contained in the outer gills and are released in association with a mantle-lure that resembles a small freshwater snail. Estimated fecundity, based on 8 gravid females collected from the Clinch and Duck rivers, ranged from 4132 to 58,700 glochidia/mussel. Seven fish species were tested for suitability as hosts for glochidia, and five darter species were confirmed through induced infestations: Etheostoma blennioides, E. camurum, E. rufilineatum, E. simoterum and E. zonale. Ages of L. rimosus shells were determined by thin-sectioning and ranged from 3 to 15 ...

Theory suggests that males that are larger than their competitors may have increased mating success, due to both greater competitive ability and increased attractiveness to females. We examined how male mating success varies with male size in the tessellated darter Etheostoma olmstedi. Previous work has shown that large males tend to move around and breed in vacant breeding sites, and consequently provide less care for their eggs, while smaller individuals can be allopaternal, caring for the eggs of other males as well as for their own. We studied female egg deposition in a natural breeding population using artificial breeding sites and in the laboratory, where female choice of spawning site was restricted to two breeding sites tended by two males of different sizes. In both the field and the laboratory, nests tended by larger males were more likely to receive new eggs. Additionally, the mean size of males associated with a nest was positively correlated with both the maximum coverage of eggs at the nest and the number of times new eggs were deposited. We discuss how the increased mating success of larger males, despite their decreased parental care, may help explain allopaternal care in this species.

Hybridization is an evolutionarily important process with varied outcomes that depend on interacting factors of time since common ancestry, behavioral differences, and environmental conditions. Hybridization is relatively common in teleost fishes, and patterns from naturally occurring hybrids and experimental interspecific crosses provide insight into the evolution of reproductive barriers that lead to speciation. It has been several decades since records of hybrid darter specimens (Percidae: Etheostomatinae) have been collected and analyzed. We assembled a dataset of 252 reported natural hybrids from museum collections and literature reports that comprise 67 unique hybrid combinations involving 63 darter species. Frequencies of unique hybrid combinations decrease with phylogenetic distance and are lower between species with different egg deposition behaviors. Large range size and egg burying reproductive behavior were characteristics of the species most frequently identified as a parental specie...

Recent investigations of darter phylogeny have been based almost entirely on analyses of DNA sequence data. External morphological characters have, at times, been used to infer phylogenetic relationships among species in specific darter clades, but these types of characters are most often used in the discovery and description of darter species. Datasets that comprise more than a dozen discretely coded characters from osteology and myology are surprisingly absent from the investigation of darter phylogeny. It is unknown whether phylogenetic analyses of discretely coded morphological characters can result in resolved hypotheses of darter phylogeny, and whether these inferences would agree with those resulting from phylogenetic analyses of DNA sequence data. This study uses a dataset of 135 discretely coded morphological characters scored for 83 darter species originally presented in an unpublished doctoral dissertation. The phylogenetic utility of this morphological dataset was investigated with bo...

The goals of this study were to characterize the genetic structure of 6 populations of Etheostoma moorei (Yellowcheek Darter), endemic to the Little Red River watershed of central Arkansas, to estimate the levels of gene flow within isolated streams, and to compare AFLP genetic diversity and distance data to our previously published allozyme data. The Yellowcheek Darter is a candidate species for listing under the Endangered Species Act. This darter is found in previously connected headwater streams presently isolated and partially inundated downstream by Greers Ferry Reservoir. AFLP data for the Yellowcheek Darter was concordant with previous work utilizing allozymes ( r s = 0.682; p F ST = 0.003 − 0.010), with genetic structuring indicating distinct populations among streams.

The Yazoo Darter, Etheostoma raneyi (Percidae: subgenus Ulocentra), is a narrowly restricted endemic occurring in small tributaries in the Loessial Hills of the upper Yazoo River basin in northern Mississippi. The range of the species is shared between the Little Tallahatchie and adjacent upper Yocona rivers, but populations in the two rivers are separated by unsuitable habitat in the Mississippi Alluvial Plain. The Chickasaw Darter, Etheostoma cervus, and Firebelly Darter, E. pyrrhogaster, show analogous distributions in the Forked Deer and Obion rivers, respectively, of western Tennessee and Kentucky. Phylogenetic analyses of cyt b and control region mtDNA (1497 sites) data from E. raneyi (n = 12), E. cervus (n = 4), and E. pyrrhogaster (n = 5) recovered two clades of E. raneyi with high bootstrap and decay support that are congruent with localities of specimens from the Little Tallahatchie and Yocona drainages, respectively. Divergence between the clades of E. raneyi was 1.3% (SE = 0.3...

A new species of darter, Etheostoma erythrozonum, is described from the Meramec River drainage of Missouri, USA. Etheostoma erythrozonum is the first known fish species endemic to the Meramec River drainage. It differs morphologically and genetically from populations of its sister species, Etheostoma tetrazonum, from the Gasconade River, Osage River, and Moreau River drainages.

We characterized the summer habitat frequented by the channel darter (Percina copelandi) in the Gatineau River and the Richelieu River of southwest Quebec. Water velocity was the only explicative variable the two rivers had in common. The channel darter showed a strong preference for environments with mean water velocities between 39 and 48 cm.s−l. Moreover, the presence of periphyton in the Gatineau River, presenting high substrate heterogeneity, and the presence of woody debris and plant cover in the Richelieu River were linked to the occurrence of the channel darter.

We determined densities of orangethroat darter (Etheostoma spectabile) from different channel units during winter, the relation between fish size and channel unit used, and the microhabitat conditions related to the densities of this species. A quadrat sampler and backpack electrofishing were combined to sample darters from different channel units in an Ozark border region stream in central Missouri, USA. Analysis of variance revealed significant differences between mean densities of orangethroat darters in channel units. Densities were highest in pool and lowest in riffle habitats. Darter length was significantly greater in riffles than runs or pools. Variables significant to our model were velocity (negative correlation), percent cobble (positive correlation), and percent boulder (negative correlation). We found darters used all channel units during winter, though disproportionately. Identifying microhabitat conditions (low-velocity microhabitats) used by darters without channel unit use could ...

We surveyed the habitat and fish assemblages of four impounded and three unimpounded neighboring headwater streams, separated longitudinally into multiple upstream and downstream reaches. Instream habitat characteristics were similar between reaches of unimpounded streams and reaches above impoundments, and differed significantly from reaches below impoundments that included deeper water and more stable flows. Species richness was similar above and below impoundments, and between impounded and unimpounded streams, but fish assemblage composition and structure differed. Stream reaches above impoundments supported higher percentages of centrarchids compared to upper reaches of unimpounded streams, which had more obligate stream cyprinids. Reaches below impoundments supported mainly centrarchid species whereas lower reaches of unimpounded streams supported a balanced mix of cyprinids and centrarchids. Percina maculata (Blackside Darter) occurred throughout the study area except in upper reaches of i...

In the present study, five species of Contracaecum Railliet & Henry 1912 (Nematoda: Ascaridida), including Contracaecum bancrofti, Contracaecum microcephalum, Contracaecum variegatum, Contracaecum eudyptulae, and Contracaecum ogmorhini, were redescribed using light and scanning electron microscopy. In addition, in order to elucidate their taxonomic status, first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) of nuclear ribosomal DNA of each morphospecies were characterized. Analyses of sequence and morphological data sets suggested that C. bancrofti, infecting the Australian pelican Pelecanus conspicillatus, is a valid species and is distinct from C. micropapillatum reported from pelicans in the northern hemisphere. C. microcephalum from cormorants Phalacrocorax melanoleucos and C. variegatum from the darter Anhinga melanogaster and from P. conspicillatus as well as C. eudyptulae from the little penguin Eudyptula minor were also considered as distinct species, which can be differentiated from one another morphologically based on the lengths of spicules and genetically based on the sequences of ITS-1 and ITS-2. Comparison of sequence data of ITS-1 and ITS-2 for the members of C. ogmorhini sensu lato from pinnipeds with those of previous studies suggested that only ITS-2 can be used for differentiation between C. ogmorhini sensu stricto and Contracaecum margolisi, occurring in the southern and northern hemispheres, respectively. Analyses of the ITS-1 and ITS-2 sequence data of Contracaecum spp. in the present study supported the distinction among species of Contracaecum based on morphological data and were useful in confirming the taxonomic status of individual species in Australia.

The federally endangered Duskytail Darter, Etheostoma percnurum Jenkins, is known from only six highly disjunct populations in the Tennessee and Cumberland river drainages of Kentucky, Tennessee, and Virginia. Only four are extant. Variation in morphology including meristics, morphometrics, and pigmentation was examined among the four extant populations and limited specimens from the two extirpated populations (Abrams Creek and South Fork Holston River). Analyses of these data found each of the extant populations is morphologically diagnosable. The few specimens available from Abrams Creek and South Fork Holston River prevented thorough assessment of variation, and these were grouped with their closest geographic counterparts, Citico Creek, and Little River, respectively. Three new morphologically diagnosable species are described: E. sitikuense, the Citico Darter, from Citico Creek, Abrams Creek, and Tellico River (Tennessee River system); E. marmorpinnum, the Marbled Darter, from the Little River and South Fork Holston River (Tennessee River system); and E. lemniscatum, the Tuxedo Darter, from the Big South Fork (Cumberland River system). Each species warrants federal protection as an endangered species.

The Iowa darter (Etheostoma exile) was first captured in Little Yampa Canyon, Yampa River, Colorado, by electrofishing in autumn 2003, and abundance of this nonnative species increased during 2004–2007. The Iowa darter also expanded downstream 229 river km, based on captures of young fish in a drift net at the confluence of the Yampa and Green rivers in 2005, and in light traps in the Green River near Jensen, Utah, in 2005–2007. Likely introduction of the Iowa darter via bait-bucket transfer suggests that additional legal deterrents might be needed to reduce further illicit introductions of potentially problematic nonnative fishes in the Colorado River Basin.

Etheostoma moorei (Yellowcheek Darter), a candidate species for federal listing, is endemic and obligate to headwater riffles of the upper Little Red River drainage in north central Arkansas. Downstream segments of these tributaries were inundated in 1964 as a result of filling of Greers Ferry Reservoir. We compared riffle densities during drought (1999–2001) and non-drought periods (2003–2004), and to historic data (1979–1980). Upstream sites dried periodically during the drought of 1999–2001, and Yellowcheek Darters occupying those sites were extirpated; even at downstream sites, densities were significantly lower than historical levels. During normal precipitation levels during 2003–2004, densities increased significantly, yet several upstream sites and one complete stream remained extirpated. The loss of downstream refugia as a result of the construction of Greers Ferry Dam in 1964 may exacerbate natural climatic cycles, which include drought, resulting in stream-wide extirpations.

The strong connection between ecology and morphology in fishes predicts that ecologically relevant morphological features will change in concert with changes in habitat use and feeding ecology even over relatively short timescales following species introduction. Here, this hypothesis is tested by examining the trophic morphology of specimens of the native Tessellated Darter, Etheostoma olmstedi, collected at Catatonk Creek, Candor, Tioga Co., NY, USA, between 1961 and 2002. The collections of E. olmstedi bracket a 1980 range expansion by the non-native Banded Darter, E. zonale. Examination of the E. olmstedi specimens revealed that the length of the buccal cavity relative to body size increased following the invasion of Catatonk Creek by E. zonale. An increase in buccal cavity length (BCL) is expected to result in higher suction feeding performance measured as volumetric flow rate of water through the mouth. Such an increase in BCL may enable E. olmstedi to exert greater suction forces on prey an...

Using mark-recapture methods, we studied movements of endangered Roanoke logperch (Percina rex Jordan & Evermann), a benthic darter, at 12 riffle-run sites over a 9-year-long period in the Roanoke River, Virginia, USA. Our primary objective was to characterise movements among transects within sites, but we opportunistically recorded two between-site movements as well. Our recapture rate was low (22 of 485 marked fish), but most recaptured fish exhibited movements between tagging and recapture, relocating either to another transect within a site (12 fish) or to another site altogether (two fish). Within sites, Roanoke logperch exhibited fidelity over time to the areas in which they were initially marked. These restricted areas were lengthier than transects (>15 m) but shorter than entire riffle-runs (

Environmental factors affecting growth of the threatened eastern sand darter ( Ammocrypta pellucida (Putnam, 1863)) were examined using specimens sampled from the northern edge of its range to determine the species’ critical habitat. Length-at-age increments were determined from scale samples as surrogates for growth rates based on back-calculated lengths using the Fraser–Lee method. During the first year of life, 82% of total length is attained, suggesting considerable energetic partitioning towards reproduction following age-0. Positive relationships between age-0 length increments and sand substrates and between age-0 length increments and mean annual channel discharge indicated greatest first-year growth within sand-dominated, high-discharge habitats. Environmental factors that occurred at coarse spatial and temporal levels (i.e., mean annual channel discharge) explained more of the growth variability among eastern sand darters than those occurring at fine levels (i.e., site-level substrate composition). This study indicates that environmental factors can be used to explain variability in cohort-structured population and site-level growth of eastern sand darters.

In order to investigate a potential hybrid zone between the candy darter, Etheostoma osburni, and variegate darter, Etheostoma variatum, and examine population variation within E. osburni, a suite of primers for 15 polymorphic microsatellite loci were developed. The average number of alleles per locus was 5.5 in E. osburni and 7.6 in E. variatum, and the average observed heterozygosities were 62.5% and 71.4%, respectively. There were no deviations from Hardy-Weinberg equilibrium and no observed linkage disequilibrium after Bonferroni correction. The utility of these primers was also tested in 11 species of darters representing all four genera of darters. Success of cross-species amplification was largely consistent with phylogenetic relationships of darters.