Accurate assessment of species identity is fundamental for conservation biology. Using molecular markers from the mitochondrial and nuclear genomes, we discovered that many putatively native populations of greenback cutthroat trout (Oncorhynchus clarkii stomias) comprised another subspecies of cutthroat trout, Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus). The error can be explained by the introduction of Colorado River cutthroat trout throughout the native range of greenback cutthroat trout in the late 19th and early 20th centuries by fish stocking activities. Our results suggest greenback cutthroat trout within its native range is at a higher risk of extinction than ever before despite conservation activities spanning more than two decades.

The concept of ecological exchangeability, together with genetic exchangeability, is central to both the Cohesion Species Concept as well as to some definitions of Evolutionarily Significant Units. While there are wellestablished criteria for measuring genetic exchangeability, the concept of ecological exchangeability has generated considerable confusion. We describe a procedure that uses the complementary strengths, while recognising the limitations, of both molecular genetic data and ecological experiments to determine the ecological exchangeability of local populations within a species. This is the first synthesis of a combined approach (experiments and genetics) and the first explicit discussion of testing ecological exchangeability. Although it would be ideal to find functional genes that interact to influence quantitative traits resulting in ecological differences (e.g. growth, size, fecundity), we suggest that our current knowledge of functional markers is too limited for most species to use them to differentiate adaptively different local populations. Thus, we argue that ecological experiments using whole organisms combined with neutral markers that indicate evolutionary divergence, provide the strongest case for detecting adaptive differences among local populations. Both genetic divergence and ecological experiments provide the best information for infering ecological exchangeability. This procedure can be used to decide which local populations should be preserved to maintain intraspecific variation and to determine which populations would enhance captive-breeding programs, augment endangered local populations and could best be used to re-introduce native species into historically occupied areas.

Intense geological activity caused major topographic changes in Western North America over the past 15 million years. Major rivers here are composites of different ancient rivers, resulting in isolation and mixing episodes between river basins over time. This history influenced the diversification of most of the aquatic fauna. The genus Pantosteus is one of several clades centered in this tectonically active region. The eight recognized Pantosteus species are widespread and common across southwestern Canada, western USA and into northern Mexico. They are typically found in medium gradient, middle-elevation reaches of rivers over rocky substrates. This study (1) compares molecular data with morphological and paleontological data for proposed species of Pantosteus, (2) tests hypotheses of their monophyly, (3) uses these data for phylogenetic inferences of sister-group relationships, and (4) estimates timing of divergence events of identified lineages. Using 8055 base pairs from mitochondrial DNA protein coding genes, Pantosteus and Catostomus are reciprocally monophyletic, in contrast with morphological data. The only exception to a monophyletic Pantosteus is P. columbianus whose mtDNA is closely aligned with C. tahoensis because of introgression. Within Pantosteus, several species have deep genetic divergences among allopatric sister lineages, several of which are diagnosed and elevated to species, bringing the total diversity in the group to 11 species. Conflicting molecular and morphological data may be resolved when patterns of divergence are shown to be correlated with sympatry and evidence of introgression.

Summary Parsimony analysis of endemicity (PAE) was used to assess patterns in the distribution of harpacticoid copepods (all freshwater species and stream species only) at global and regional scales. These analyses provided a focus for reviewing large scale patterns and processes in freshwater meiofauna. On a global scale, PAE suggested that large‐scale biogeographical events have been most important in shaping present‐day distributions in the Canthocamptidae. A small proportion (4%) of canthocamptid species were widespread (i.e. occurred in more than one biogegraphical region), suggesting that dispersal may also play a role in determining distribution at the species level. Global distribution patterns for other meiofauna suggest varying roles for dispersal and vicariant events. No consistent latitudinal trends in species diversity were evident, although a lack of distributional data for many regions, and uncertainty over the status of many cosmopolitan species, precludes more robust analyses. Molecular techniques should prove useful in identifying truly cosmopolitan taxa. On a regional scale, a PAE within Western Europe demonstrated a clear link between the distribution of canthocamptid species and the extent of the Last (Wiechselian) glaciation. Northern and southern areas of Europe contain distinctive harpacticoid faunas and the recolonisation of northern Europe appears to have been from the Balkans rather than other Mediterranean peninsulae. The high harpacticoid diversity in southern Europe, may reflect a lack of glacial disruption of groundwater habitats. A PAE of lotic data for harpacticoid copepods within the Holarctic reflected the global PAE for freshwater harpacticoids as a whole, but not the regional PAE. A high proportion of stream‐dwelling harpacticoids are widespread species, but only one (Bryocamptus zschokkei) was found in streams across the Holarctic. Other cosmopolites were restricted to streams in Europe or North America, suggesting that species‘ niche requirements might differ among regions. There appeared to be some convergence in the composition of lotic copepod communities in terms of the number of species within genera. We conclude that large‐scale processes inevitably have a major influence on the local composition of lotic meiofaunal communities, but that the relative importance of small scale vs. large scale processes is unclear at present, largely due to a paucity of suitable data.

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The phylogenetic or evolutionary relationships of species of Cypriniformes, as well as their classification, is in a era of flux. For the first time ever, the Order, and constituent Families are being examined for relationships within a phylogenetic context. Relevant findings as to sister-group relationships are largely being inferred from analyses of both mitochondrial and nuclear DNA sequences. Like the vast majority of Cypriniformes, due to an overall lack of any phylogenetic investigation of these fishes since Hennig's transformation of the discipline, changes in hypotheses of relationships and a natural classification of the species should not be of surprise to anyone. Basically, for most taxa no properly supported phylogenetic hypothesis has ever been done; and this includes relationships with reasonable taxon and character sampling of even families and subfamilies. As such, like others, many western North American cyprinid genera have had a controversial taxonomic and systematic history.Our effort to better understand the evolutionary history of this artificial geographic grouping of species (Western) surveyed taxa and characters broadly. We analyzed 127 taxa (71 species) from 36 genera, including representative taxa from all 22 western genera hypothesized to form the Western Clade sensu Coburn and Cavender (1992). Our evaluation also included additional sampling from a heterogeneous array of species from the western genera Algansea, Gila, Lepidomeda, Ptychocheilus and Siphateles. Resulting phylogenetic inferences, based on one mitochondrial and three nuclear genes (mtDNA: cytb; nDNA: Rag1, Rhod, S7), consistently resolved a well-supported Western Clade, but one inclusive of Chrosomus erythrogaster. This taxon, always formed the sister group to the extant species of Gila plus 10 other western genera. Our Western Clade is qualitatively different from that of prior studies and does not include the genera Agosia, Algansea, Iotichthys, Lepidomeda, Meda, Mylocheilus, Plagopterus, Pogonichthys, Rhinichthys, Tiaroga or Yuriria. All of these taxa were, however, included in Coburn and Cavender´s (1992) Western Clade. Our broader-scale survey and increased character sampling were always resolved these latter taxa within one of two different major clades: the OPM Clade (sensu Mayden 1989) and the Creek Chub-Plagopterin Clade (sensu Simons et al. 2003). Our hypothesized Western Clade places Orthodon sister to a Western Chub-Pikeminnow Clade also inclusive of Acrocheilus, Eremichthys, Gila, Hesperoleucus, Lavinia, Moapa, Mylopharodon, Ptychocheilus, Relictus and Siphateles. The latter taxa have traditionally been recognized at the generic level, simply on the basis of their morphological distinctiveness and not on the basis of a phylogenetic evaluation of relationships. Composition of our Western Chub-Pikeminnow Clade also reveals genetic divergences between species of some genera (Gila, Ptychocheilus, Siphateles) comparable to genetic divergences documented between genera within the Western Clade. Relationships for th...

Microcrustaceans represent a poorly known component of stream systems. This study examined the seasonal abundance of copepods and cladocerans found in Valley Creek, Washington County, Minnesota. Both benthic densities as well as drift rates were quantified. A total of 16 species was collected in quantitative benthic samples and two additional species occurred in drift samples. The Valley Creek microcrustaceans could be classified into two general groups, those residing in depositional stream habitats similar to a lake or pond littoral and favoring an epibenthic lifestyle, and those found in more erosional habitats where a hyporheic lifestyle is more likely. The microcrustacean community also demonstrated a distinct seasonality with peak abundance in the spring and early summer. Sediment size compositon also demonstrated a seasonal change but detrital composition did not. Microcrustacean drift generally paralleled changes in benthic density but in several cases it tended to lag behind the changes in the benthos. This lag could be due to a seasonal siltation of the sediments, which would compress the habitat volume available to interstitial meiofaunal elements.