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Control methods that target specific traits of an invasive species can produce results contrary to the aims of management. If targeted phenotypes exhibit heritability, then it follows that the invasive species could evolve greater resistance to the applied control measures over time. Additional complications emerge if those traits targeted by control are also inversely related to reproductive success. Given this, prudent considerations for invasive species management are to quantify the heritability of traits selected through control measures and gauge their relationship with reproductive success. Herein we provide a case study utilizing long-term field data and a multi-generational pedigree of an experimentally-closed population of brown treesnakes (N = 426; Boiga irregularis) on Guam. We employed an “animal model” to estimate the narrow-sense heritability (h2) for annual body condition, a trait related to both susceptibility to a primary tool used for brown treesnake control (i.e., live-lure traps) and annual reproductive success. Annual body condition displayed significant heritability [h2 = 0.149 (95% highest posterior density interval: 0.059–0.220)]. Considering a negative effect of body condition on susceptibility to trap capture but positive effect on reproductive success, significant heritability of body condition suggests the potential for live-lure traps to lose efficacy over time while also eliciting an undesirable effect on brown treesnake fecundity. Our results highlight the potential for negative repercussions that can stem from management actions, while also serving to underscore the evolutionary implications that are often overlooked but subsumed within invasive species control.

Approximately 100 years ago, unregulated harvest nearly eliminated white-tailed deer (Odocoileus virginianus) from eastern North America, which subsequently served to catalyze wildlife management as a national priority. An extensive stock-replenishment effort soon followed, with deer broadly translocated among states as a means of re-establishment. However, an unintended consequence was that natural patterns of gene flow became obscured and pre-translocation signatures of population structure were replaced. We applied cutting-edge molecular and biogeographic tools to disentangle genetic signatures of historical management from those reflecting spatially heterogeneous dispersal by evaluating 35,099 single nucleotide polymorphisms (SNPs) derived via reduced-representation genomic sequencing from 1,143 deer sampled state-wide in Arkansas. We then employed Simpson’s diversity index to summarize ancestry assignments and visualize spatial genetic transitions. Using sub-sampled transects across these transitions, we tested clinal patterns across loci against theoretical expectations of their response under scenarios of recolonization and restricted dispersal. Two salient results emerged: (A) Genetic signatures from historic translocations are demonstrably apparent; and (B) Geographic filters (major rivers; urban centers; highways) now act as inflection points for the distribution of this contemporary ancestry. These results yielded a state-wide assessment of contemporary population structure in deer as driven by historic translocations as well as ongoing processes. In addition, the analytical framework employed herein to effectively decipher extant/historic drivers of deer distribution in Arkansas are also applicable for other biodiversity elements with similarly complex demographic histories.

Model-based approaches that attempt to delimit species are hampered by computational limitations as well as the unfortunate tendency by users to disregard algorithmic assumptions. Alternatives are clearly needed, and machine-learning (M-L) is attractive in this regard as it functions without the need to explicitly define a species concept. Unfortunately, its performance will vary according to which (of several) bioinformatic parameters are invoked. Herein, we gauge the effectiveness of M-L-based species-delimitation algorithms by parsing 64 variably-filtered versions of a ddRAD-derived SNP data set collected from North American box turtles (Terrapene spp.). Our filtering strategies included: (i) minor allele frequencies (MAF) of 5%, 3%, 1%, and 0% (= none), and (ii) maximum missing data per-individual/per-population at 25%, 50%, 75%, and 100% (= no filtering). We found that species-delimitation via unsupervised M-L impacted the signal-to-noise ratio in our data, as well as the discordance among resolved clades. The latter may also reflect biogeographic history, gene flow, incomplete lineage sorting, or combinations thereof (as corroborated from previously observed patterns of differential introgression). Our results substantiate M-L as a viable species-delimitation method, but also demonstrate how commonly observed patterns of phylogenetic discordance can seriously impact M-L-classification.

The persistence of an invasive species is influenced by its reproductive ecology, and a successful control program must operate on this premise. However, the reproductive ecology of invasive species may be enigmatic due to factors that also limit their management, such as cryptic coloration and behavior. We explored the mating and reproductive ecology of the invasive Brown Treesnake (BTS: Boiga irregularis) by reconstructing a multigenerational genomic pedigree based on 654 single nucleotide polymorphisms for a geographically closed population established in 2004 on Guam (N = 426). The pedigree allowed annual estimates of individual mating and reproductive success to be inferred for snakes in the study population over a 14‐year period. We then employed generalized linear mixed models to gauge how well phenotypic and genomic data could predict sex‐specific annual mating and reproductive success. Average snout–vent length (SVL), average body condition index (BCI), and trappability were significantly related to annual mating success for males, with average SVL also related to annual mating success for females. Male and female annual reproductive success was positively affected by SVL, BCI, and trappability. Surprisingly, the degree to which individuals were inbred had no effect on annual mating or reproductive success. When juxtaposed with current control methods, these results indicate that baited traps, a common interdiction tool, may target fecund BTS in some regards but not others. Our study emphasizes the importance of reproductive ecology as a focus for improving BTS control and promotes genomic pedigree reconstruction for such an endeavor in this invasive species and others., Our study details the use of genomic tools (i.e., double‐digest restriction site‐associated DNA sequencing) to develop novel genomic resources (>6,000 SNPs) for a high‐profile and invasive vertebrate pest (i.e., Brown Treesnake). We used a subset of these SNPs to reconstruct a multigenerational genomic pedigree for a wild population of Brown Treesnakes from which we inferred patterns and predictors of annual mating and reproductive success, and we juxtaposed phenotypes of individuals with high annual mating and reproductive success against those of commonly trapped individuals to assess existing management efficacy. Our results promote the use of genomic pedigree reconstruction to elucidate the reproductive ecology of invasive species with cryptic coloration and behaviors, so as to inform and improve management.

Multi-species approaches provide valuable insight for conservation planning, yet most studies focus on only one species while generalizing across taxa. Here, we employed 5–14 microsatellite DNA loci to evaluate population genetic patterns and future vulnerability for a freshwater turtle assemblage distributed across north-eastern Illinois. Focal species (Emydoidea blandingii, Clemmys guttata, Chrysemys picta and Chelydra serpentina) differ in conservation status as well as in ecological and life-history traits, which modulate gene flow across heterogeneous landscapes. We hypothesized (1) common and more ubiquitous species (C. picta and C. serpentina) would exhibit higher levels of genetic connectivity compared to species more restricted in distributions and with an elevated conservation status (E. blandingii and C. guttata) and (2) endangered species exhibit a greater loss of future genetic diversity. We found that genetic patterns varied considerably among co-distributed species. Endangered species had lower levels of genetic diversity and gene flow, more pronounced genetic structure and a higher risk of genetic drift compared to common species, thus supporting our hypotheses. The observed patterns are potentially attributable to life-history and ecological traits and will affect the long-term viability of the four species within a modified north-eastern Illinois landscape. Our study is an important first step for understanding how landscape features and species-specific traits interact to affect gene flow and population genetic structure within altered landscapes. It also underscores how multi-species approaches can be informative for conservation actions.

Despite its imperative, biodiversity conservation is chronically underfunded, a deficiency that often forces management agencies to prioritize. Single-species recovery thus becomes a focus (often with socio-political implications), whereas a more economical approach would be the transition to multi-targeted management (= MTM). This challenge is best represented in Midwestern North America where biodiversity has been impacted by 300+ years of chronic anthropogenic disturbance such that native tall-grass prairie is now supplanted by an agroecosystem. Here, we develop an MTM with a population genetic metric to collaboratively manage three Illinois upland gamebirds: common pheasant (Phasianus colchicus; pheasant), northern bobwhite quail (Colinus virginianus; quail), and threatened-endangered (T&E) greater prairie chicken (Tympanuchus cupido pinnatus; prairie chicken). We first genotyped our study pheasant at 19 microsatellite DNA loci and identified three captive breeding stocks (N = 143; IL Department of Natural Resources) as being significantly bottlenecked, with relatedness >1st-cousin (μR = 0.158). ‘Wild’ (non-stocked) pheasant [N = 543; 14 Pheasant-Habitat-Areas (PHAs)] were also bottlenecked, significantly interrelated (μR = 0.150) and differentiated (μFST = 0.047), yet distinct from propagation stock. PHAs that encompassed significantly with larger areas also reflected greater effective population sizes (μNE = 43; P

This paper studies the origin and the genetic and morphological diversity of the pumpkinseed sunfish, a North American invader that is actively expanding its range in the Northern Black Sea Coast. Based on an analysis of variability of the nucleotide sequence of the mtDNA cytb locus, it was found that all populations of the Northern Black Sea Coast (basins of Dnieper, Dniester, and Danube rivers) are represented by one haplotype. Intraspecific variability is absent. Phylogeographic analysis revealed that the most related haplotype is in a population of pumpkinseed sunfish from New Germany Lake in the Potomac River basin (Maryland, United States), which makes it possible to consider it a parent of the investigated populations. Morphological variation in countable traits was highly homogeneous. Significant differentiation of a sample from the population of the Dnieper Reservoir from the populations of the Danube and Dniester was found for plastic traits of both the body and cranium. Analysis of the trajectories of development showed that the Dnieper is inhabited by a “pelagic” morpho-ecological form of pumpkinseed sunfish, while the Dniester and Danube are inhabited by a“littoral” form. It is suggested that the success of the settlement of this North American species in the Northern Black Sea Coast does not depend on the origin or the level of its genetic diversity but is instead likely to be ensured by the realization of its available discrete morpho-ecological variability.

The landscape can influence host dispersal and density, which in turn, affect infectious disease transmission, spread, and persistence. Understanding how the landscape influences wildlife dispersal and pathogen epidemiology can enhance the efficacy of disease management in natural populations. We applied landscape genetics to examine relationships among landscape variables, dispersal of white-tailed deer hosts and transmission/spread of chronic wasting disease (CWD), a fatal prion encephalopathy. Our focus was on quantifying movements and population structure of host deer in infected areas as a means of predicting the spread of this pathology and promoting its adaptive management. We analyzed microsatellite genotypes of CWD-infected and uninfected deer from two disease foci (Southern Wisconsin, Northern Illinois). We quantified gene flow and population structure using F ST, assignment tests, and spatial autocorrelation analyses. Gene flow estimates were then contrasted against a suite of landscape variables that potentially mediate deer dispersal. Forest fragmentation and grassland connectivity promoted deer movements while rivers, agricultural fields and large urbanized areas impeded movement. Landscape variables, deer dispersal, and disease transmission covaried significantly and positively in our analyses. Habitats with elevated host gene flow supported the concept of dispersal-mediated CWD transmission by reflecting a concomitant, rapid CWD expansion. Large, interrelated social groups isolated by movement barriers overlapped disease foci, suggesting that philopatry exacerbated CWD transmission. Our results promote adaptive management of CWD by predicting patterns of its spread and identifying habitats at risk for invasion. Further, our landscape genetics approach underscores the significance of topography and host behavior in wildlife disease transmission.

Populations of the Desert Massasauga Rattlesnake (Sistrurus catenatus edwardsii) have declined rapidly as desert grassland communities have become reduced and fragmented. To provide information useful for management of remaining populations, the genetic characteristics (based on microsatellite DNA loci) of the last demonstrably extant population in the state of Arizona were compared to a population in the Rio Grande Valley of New Mexico. Results indicated that genetic diversity was relatively high in both populations, with statistically significant heterozygote deficiencies detected at only one of six loci in each population. Contingency tests, Wright's F-statistics, and Bayesian clustering algorithms all indicated substantial subdivision between populations in Arizona and New Mexico, but only contingency tests supported differentiation within the Arizona population. A preliminary hierarchical analysis of variance (incorporating both our data and published microsatellite data for the Eastern Mass...

Aim We derived phylogenies, phylogeographies, and population demographies for two North American pitvipers, Agkistrodon contortrix (Linnaeus, 1766) and A. piscivorus (Lacepede, 1789) (Viperidae: Crotalinae), as a mechanism to evaluate the impact of rapid climatic change on these taxa. Location Midwestern and eastern North America. Methods We reconstructed maximum parsimony (MP) and maximum likelihood (ML) relationships based on 846 base pairs of mitochondrial DNA (mtDNA) ATPase 8 and ATPase 6 genes sequenced over 178 individuals. We quantified range expansions, demographic histories, divergence dates and potential size differences among clades since their last period of rapid expansion. We used the Shimodaira–Hasegawa (SH) test to compare our ML tree against three biogeographical hypotheses. Results A significant SH test supported diversification of A. contortrix from northeastern Mexico into midwestern–eastern North America, where its trajectory was sundered by two vicariant events. The first (c. 5.1 Ma) segregated clades at 3.1% sequence divergence (SD) along a continental east–west moisture gradient. The second (c. 1.4 Ma) segregated clades at 2.4% SD along the Mississippi River, coincident with the formation of the modern Ohio River as a major meltwater tributary. A single glacial refugium was detected within the Apalachicola region of southeastern North America. Significant support was also found for a hypothesis of trans-Gulf rafting by the common ancestor of A. piscivorus from eastern Mexico (possibly the Yucatan Peninsula) to northern Florida. There, a Mid–Late Pliocene marine transgression separated it at 4.8% SD from mainland North America. Significant range expansions followed compressive glacial effects in three (of four) A. contortrix clades and in two (of three) A. piscivorus clades, with the Florida A. piscivorus clade exhibiting significant distributional stasis. Main conclusions Pliocene glaciations, rapidly developing western aridity, and Pleistocene glacial meltwaters seemingly led to the diversification of A. contortrix and A. piscivorus in North America. Both species were pushed southwards by Pleistocene climate change, with subsequent northward expansions uninhibited topographically. The subspecific taxonomy used for A. contortrix and A. piscivorus today, however, appear non-representative. The monophyletic Florida subspecies of A. piscivorus may be a distinct species (at 4.8% SD), whereas two western subspecies of A. contortrix also appear to constitute a single distinct species, pending additional analyses. We conclude that both species of Agkistrodon can be used as suitable ectothermic models to gauge impacts of future climate change.

The broad and imprecise type localities of Crotalinus catenatus Rafinesque, 1818 (now Sistrurus catenatus) and Crotalinus viridis Rafinesque, 1818 (now Crotalus viridis) are re-identified based on a published account of the collector's travels as well as an examination of the relationship and contacts between the collector and the author of the type description. Both type specimens are lost. Unfortunately, enhanced resolution of the type locality of S. catenatus places it within the range of S. c. tergeminus Say, 1823 (a subsequently described subspecies). Thus, the name S. c. catenatus incontrovertibly applies to the form currently recognized as S. c. tergeminus, which in turn renders the latter as a subjective junior synonym of the former, leaving the eastern form with an unfamiliar name (Crotalus messasaugus Kirtland, 1838). To conserve prevailing usage, we are preparing an appeal to the International Commission of Zoological Nomenclature (ICZN) to allow a neotype of Sistrurus catenatus to be ...

The literature supports that unique rabies virus (RABV) variants are often compartmentalized in different species of bats. In Colorado, two divergent mtDNA lineages of big brown bats (Eptesicus fuscus) co-occur. RABV associated with this species also segregates into two clades. We hypothesized that unique RABV variants might be associated with mtDNA lineages of Colorado big brown bats. DNA was extracted from brain tissue of rabid big brown bats, the ND2 gene was amplified to determine mtDNA lineage, and the lineage was compared to a previously derived phylogenetic analysis of the RABV N gene. No correspondence was found between host bat lineage and RABV variant.

The Speckled Rattlesnake (Crotalus mitchellii) is a polytypic taxon presently composed of five subspecies that range across southwestern North America, including the Baja Peninsula and islands in the Pacific Ocean and Sea of Cortes. The principles of genealogical concordance were employed to test the taxonomic status of three of the five subspecies (C. m. mitchellii, C. m. pyrrhus, and C. m. stephensi). We used two molecular marker systems: mitochondrial (mt) DNA ATPase 8 and 6 genes (675 base pairs, bp), and introns 5 and 6 of the nuclear (n) DNA ribosomal protein (RP) gene (449 bp). These markers were evaluated across 104 individuals of C. mitchellii: C. m. mitchellii (n = 3), C. m. pyrrhus (n = 83), C. m. stephensi (n = 18), with Sistrurus c. catenatus as the distant outgroup. Deep phylogenetic splits were detected in the subspecies of C. mitchellii, with 5.0–6.4% mtDNA sequence divergence (SD) separating C. m. mitchellii and C. m. pyrrhus, while C. m. mitchellii and C. m. stephensi had ...

Several geographically distinct mitochondrial DNA (mtDNA) lineages of the big brown bat (Eptesicus fuscus) have been documented in North America. Individuals from 2 of these lineages, an eastern and a western form, co-occur within maternity colonies in Colorado. The discovery of 2 divergent mtDNA lineages in sympatry prompted a set of questions regarding possible biological differences between haplotypes. We captured big brown bats at maternity roosts in Colorado and recorded data on body size, pelage color, litter size, roosting and overwintering behaviors, and local distributions. Wing biopsies were collected for genetic analysis. The ND2 region of the mtDNA molecule was used to determine lineage of the bats. In addition, nuclear DNA (nDNA) intron 1 of the b-globin gene was used to determine if mtDNA lineages are hybridizing. Eastern and western mtDNA lineages differed by 10.3% sequence divergence and examination of genetic data suggests recent population expansion for both lineages. Differences in distribution occur along the Colorado Front Range, with an increasing proportion of western haplotypes farther south. Results from nDNA analyses demonstrated hybridization between the 2 lineages. Additionally, no outstanding distinctiveness was found between the mtDNA lineages in natural history characters examined. We speculate that historical climate changes separated this species into isolated eastern and western populations, and that secondary contact with subsequent interbreeding was facilitated by European settlement.

We utilized nine microsatellite loci and 865 bases from two mtDNA genes to estimate demographic parameters and visualize historic/contemporary connectivity among populations of a sky-island rattlesnake (New Mexico ridge-nosed rattlesnake, Crotalus willardi obscurus). This taxon is listed as threatened under the United States Endangered Species Act (ESA) and is distributed patchily within three borderland mountain ranges [Animas (ANM), Peloncillo (PEL), Sierra San Luis (SSL)] of southeastern Arizona, southwestern New Mexico and north-central Mexico. Molecular data support a hypothesis of northward range expansion from Mexico, with subsequent isolation on sky-islands through vicariant desertification that transformed intervening wooded valleys and low elevation passes into inhospitable habitat. Historic and recent movements have been within rather than among mountains. Although populations are linked via ancestral polymorphism, they do not represent a single mtDNA gene pool. All are genetically bottlenecked, with the Peloncillo reflecting deepest/sharpest declines and fewest captures per unit effort. Most recent population declines occurred ∼4 kybp (thousands of years before present). Thus, population reductions are historic and environmental rather than contemporary and anthropogenic. Our data demonstrate that PEL is ecologically non-exchangable with other sky-island populations, and thus comprises one ‘evolutionary significant unit’ (ESU), while SSL and ANM comprise ‘management units’ (MUs) within a second ESU. All three meet legal criteria for recognition as ‘distinct population segments’ (DPS) under the ESA.

During Pleistocene, the Laurentide ice sheet rearranged and diversified biotic distributions in eastern North America, yet had minimal physical impact in western North America where lineage diversification is instead hypothesized to result from climatic changes. If Pleistocene climatic fluctuations impacted desert species, the latter would reflect patterns of restricted gene flow concomitant with indications of demographic bottlenecks. Accordingly, molecular evidence for refugia should be present within these distributions and for subsequent range expansions as conditions improved. We sought answers to these questions by evaluating mitochondrial DNA (mtDNA) sequences from four species of rattlesnakes [Crotalus mitchellii (speckled rattlesnake), Crotalus cerastes (sidewinder), Crotalus tigris (tiger rattlesnake), Crotalus ruber (red diamond rattlesnake)] with distributions restricted to desert regions of southwestern North America. We inferred relationships using parsimony and maximum likelihood, tested intraspecific clades for population expansions, applied an isolation-with-migration model to determine bi-directional migration rates (m) among regions, and inferred divergence times for species and clades by applying a semiparametric penalized likelihood approach to our molecular data. Evidence for significant range expansion was present in two of eight regions in two species (Crotalus mitchellii pyrrhus, C. tigris region north). Two species (C. cerastes, C. mitchellii) showed a distribution concomitant with northward displacement of Baja California from mainland Mexico, followed by vicariant separation into subclades. Effects of Pleistocene climate fluctuations were found in the distributions of all four species. Three regional diversification patterns were identified: (i) shallow genetic diversity that resulted from Pleistocene climatic events (C. tigris, C. ruber); (ii) deep Pleistocene divisions indicating allopatric segregation of subclades within refugia (C. mitchellii, C. cerastes); and (iii) lineage diversifications that extended to Pliocene or Late Miocene (C. mitchellii, C. cerastes). Clade-diversifying and clade-constraining effects impacted the four species of rattlesnakes unequally. We found relatively high levels of molecular diversification in the two most broadly distributed species (C. mitchellii, C. cerastes), and lower levels of genetic diversification in the two species (C. tigris, C. ruber) whose ranges are relatively more restricted. Furthermore, in several cases, the distributions of subspecies were not congruent with our molecular information. We suggest regional conservation perspectives for southwestern deserts cannot rely upon subspecies as biodiversity surrogates, but must instead employ a molecular and deep historical perspective as a primary mechanism to frame biodiversity reserves within this region.

Evolution of phenotype and mode of speciation were examined for 19 Coregonus populations within and among eight lakes in the Central Alpine region of Europe. These populations reflect a mosaic of morphological, ecological, and life history traits, and thus represent numerous forms (qualitatively described according to relative body size and ecology). Each population had been previously evaluated for six microsatellite DNA loci, and herein for five meristic counts, four fin pigmentation characters, three body color variables, three measures relating to spawning ecology, an estimate of breeding tubercles, and average weight (= size). The two matrices (genotype vs. phenotype/ecology) were then tested for significance amongst themselves, and against evolutionary and geographic models. Microsatellite data associated significantly with a species flock model in which in situ diversification occurred from a common ancestor in each lake or cluster of neighboring lakes. However, phenotype/ecology associated significantly with a model invoking multiple invasions of lakes by pre-existing forms. The latter supports historic perspectives on the evolution of Central Alpine Coregonus and suggests forms within lakes have adapted to specific within-lake environmental niches that are replicated across lakes. This convergence of form and function has long clouded an understanding of coregonine biodiversity, and we suggest it represents a homoplasious condition (i.e., a similarity due not to genealogy but to iteration). This compendium of homoplasious and homologous characters is actually quite unique in nature, and the evolutionary diversification of Central Alpine Coregonus can now be evaluated according to the relative contribution of each character type.

We mapped 112 restriction sites in the mitochondrial DNA genome of the Speckled Dace (Rhinichthys osculus), a small cyprinid fish broadly distributed in western North America. These data were used to derive a molecular phylogeny that was contrasted against the hydrographic evolution of the region. Although haplotypic variation was extensive among our 59 sampled populations and 104 individuals, their fidelity to current drainage basins was a hallmark of the study. Two large clades, representing the Colorado and Snake Rivers, were prominent in our results. The Colorado River clade was divided into four cohesive and well-defined subbasins that arose in profound isolation as an apparent response to regional aridity and tectonism. The Lower and Little Colorado River subbasins are sister to one another and (with the Upper Colorado River) form a large clade of higher-elevation populations that seemingly reflect postglacial recolonization from refugia in the Middle Colorado River. The latter subbasin is ...

Biotic homogenization, the gradual replacement of native biotas by locally expanding non-natives, is a global process that diminishes floral and faunal distinctions among regions. Although patterns of homogenization have been well studied, their specific ecological and evolutionary consequences remain unexplored. We argue that our current perspective on biotic homogenization should be expanded beyond a simple recognition of species diversity loss, towards a synthesis of higher order effects. Here, we explore three distinct forms of homogenization (genetic, taxonomic and functional), and discuss their immediate and future impacts on ecological and evolutionary processes. Our goal is to initiate future research that investigates the broader conservation implications of homogenization and to promote a proactive style of adaptive management that engages the human component of the anthropogenic blender that is currently mixing the biota on Earth.

1. Fishes can often rebound numerically and distributionally from short-term (i.e. seasonal) drought, yet their capacity to recover from decades or centuries of drought is less apparent. An exceedingly warm and dry period swept the intermontane west of North America ca. 7500 years BP, concomitant with an abrupt extinction of >35 mammal species. Were larger fishes in mainstem rivers also impacted by this drought? 2. The Colorado River Basin encompasses seven states in western North America and drains 600 000 km 2 . Its endemic mainstem fish community is ancient (i.e. Miocene) but depauperate. 3. We evaluated one widely distributed candidate species (flannelmouth sucker, Catostomus latipinnis) for basin-wide genetic and geographic structure at three fast-evolving mitochondrial (mt) DNA genes, ND2 with 589 bp and ATPase 8 and 6 with 642 bp. It is hypothesized that a concomitant signature would be present in the mtDNA of this species, if indeed it had been seriously bottlenecked by post-Pleistocene drought. A total of 352 individuals were sequenced from 24 populations (4-40 individuals/population; average of 14.7). 4. Only 49 unique haplotypes were found, 53% of which represented single individuals. Haplotype diversity was high (0.905 ± 0.007) whereas nucleotide diversity was low (0.002 ± 0.000). 5. A significant and positive geographical cline (P < 0.001) in nucleotide diversity was observed as sampling locations progressed upstream from southwest to northeast. These results divided the Colorado River Basin into three reaches: the lower reach with six populations and 83 individuals; the upper reach with seven populations and 83 individuals; and the middle reach with 11 populations and 186 individuals. An analysis of molecular variance (AMOVA) revealed that 81.5% of the total genetic variation was within populations, 16% among populations within reaches and 2.5% among reaches. Only the last was significant. Populations from the three reaches diverged from one another by 3400-11 000 years BP. Haplotype distribution suggested populations in the upper Colorado River are expanding. 6. The lack of genetic variation and recent coalescence of lineages in C. latipinnis are unusual given its fossil history, broad geographical sampling, the rapid rate of mtDNA evolution and the number (and evolutionary rate) of the genes examined. The most parsimonious explanation for these data is a rapid expansion following a recent period of low effective population size at the end of the Pleistocene. 7. The intense drought is suggested at the end of the Pleistocene (late-to-mid-Holocene), severely impacted not only large mammals but also larger fishes in western North American rivers. These perspectives have important implications for management of endangered and threatened species in this region.

We isolated and characterized 16 microsatellite DNA loci in Longfin Dace, Agosia chrysogaster, a minnow native to Sonoran Desert streams (southwestern US and northwestern Mexico). After optimization, all primer pairs produced consistently scorable products. Genetic diversity metrics were determined for each locus using 50 individuals from two populations in the Gila River basin, New Mexico. Allelic richness ranged from 2 to 37 and observed heterozygosity ranged from 0.08 to 0.95 across loci. These microsatellites offer a powerful tool to study effects of habitat fragmentation, dewatering, and climate change on population connectivity and genetic diversity in this species. Moreover, Longfin Dace co-occurs with more geographically restricted and endangered desert fish species. Genetic information for Longfin Dace could provide an important comparative dataset to assist conservation and management of other imperiled fishes in the region.

Recent molecular evidence suggests that at least eight species of bonefishes (Albuliformes: Albulidae: Albula) are found worldwide (Colborn et al. 2001). Adults of most of these species, including two that are restricted to the eastern Pacific Ocean (Albula sp. A from the Gulf of California and Albula sp. C from the Gulf of Panama), have not been formally described. Because cryptic species of bonefishes are known to occur sympatrically, population genetics data provide an important tool for taxonomic studies on this group. Isozyme analyses conducted on larval, juvenile and adult bonefish from the Guaymas region of the central Gulf of California confirmed that only a single species (Albula sp. A) was present there. In addition, analysis of a segment of the cytochrome b gene from three adult Albula collected from coastal waters of southern California revealed high sequence homology with Albula sp. A, suggesting that the southern California specimens were conspecific with those from Guaymas. However, the southern distributional limit of Albula sp. A, and whether there are regions where Albula sp. A and C occur sympatrically, are unknown. The historical background of the available name Atopichthys esunculus Garman, 1899 [= Albula esuncula (Garman, 1899)], and problems associated with the nomenclature of the two species of eastern Pacific bonefishes, are summarized. The systematic status of the related shafted bonefish, Dixonina (= Albula) nemoptera Fowler, 1911, is also reviewed.

The largest population of endangered humpback chub Gila cypha inhabits the lower Little Colorado River (LCR) and the main-stem Colorado River near its confluence with the LCR in Grand Canyon, Arizona. At present, fish in both rivers spawn almost exclusively in the LCR. Flows in the main-stem Colorado River are regulated by Glen Canyon Dam, and water temperature approximates predam winter temperatures year-round. The LCR continues to provide a relatively natural hydrograph and seasonal warming patterns. Length–weight relationships among adult humpback chub from the lower Colorado River basin showed a seasonal pattern of declining condition during spring spawning season followed by recovery of condition during summer through early winter. Fish from the main stem recovered condition more rapidly after reproduction than did fish from the LCR and may have benefited from dam-mediated environmental changes. Grand Canyon Colorado River fish had the greatest weight at length of eight locations sampled in ...

Considerable reshuffling of biotas has occurred in recent decades, largely through the gradual replacement of once spatially distinct, native communities with locally expanding and cosmopolitan, non-native ones, in a process coined biotic homogenization (McKinney & Lockwood 1999; Rahel 2000; Olden & Poff 2003; Rooney et al. 2004). Implications of biotic homogenization surfaced recently within the context of discussions about the ecological and evolutionary consequences for animal life (Olden et al. 2004); the manner in which social aspects of human life may also be affected, however, is an issue that has yet to be contemplated. Here, we argue that the social repercussions resonating in the wake of biotic homogenization must not be ignored and consider the idea that the increasingly global uniformity in biological life may be linked to the loss of traditional values and quality of life and have considerable consequences for conservation-oriented advocacy and ecotourism. We draw strong parallels and linkages between biotic homogenization and a more-acknowledged process of cultural homogenization from the social sciences and discuss how this relationship offers a useful analogy for conveying to the public and policy makers the social implications of biotic homogenization. From a purely ethical perspective, one could argue that biotic homogenization will degrade the quality of human life by imbuing biological communities with an aesthetically unappealing uniformity. Biological diversity, and its endemic features, contribute to a person’s attachment to a particular place, become part of a person’s identity, and therefore support an individual’s psychological wellbeing and a community’s identity and image of itself (Horwitz et al. 2001). This so-called sense of place, which links issues of individual and community identity, or who we are, to issues of place, or where we are, is directly threatened by biotic homogenization as endemic elements of the landscape that typify geographic regions and cultures

Efforts to restore an endangered species in its former range should be based on a sound understanding of evolutionary relationships among remaining natural populations. In this study mitochondrial (mt) DNA diversity within and among Gila River drainage populations of the endangered Sonoran topminnow (Poeciliopsis occidentalis) in Arizona was compared to that from neighboring populations in Sonora, Mexico, where the species remains locally abundant. No mtDNA diversity was detected within or among samples from the Gila River basin in Arizona. But considerable variation was found within and among populations from several river systems in Sonora. Examination of mtDNA from a population that inhabits the upper reaches of the Rio Yaqui in southeastern Arizona revealed substantial divergence between it and all other populations examined. We comment on the implications of this divergent population for topminnow management in Arizona and argue for more-detailed genetic and morphological studies to determine the distributional limits and specific status of this highly divergent form. Los esfuerzos para restaurar una especie en peligro a su antigua area de distribucion debe basarse en una comprension apropiada de las relaciones evolutivas entre las poblaciones naturales remanentes. En este estudio, se comparo la diversidad de ADN mitocondrial dentro y entre poblaciones en peligro de Poeciliopsis occidentalis, que habita las corrientes del rio Gila en Arizona, con la diversidad de poblaciones vecinas de Sonora (Mexico) donde la especie es todavia abundante. No se detecto diversidad alguna de ADN mitocondrial dentro o entre muestras de la cuenca del rio Gila en Arizona. Sin embargo, se encontro una variacion considerable dentro y entre poblaciones de varios sistemas de rios en Sonora. El analisis de ADN mitocondrial de poblaciones que habitan los cauces superiores del rio Yaqui en el sudeste de Arizona revelo una divergencia substancial entre esta poblacion y todas las otras poblaciones examinadas. Discutimos las implicaciones de esta poblacion divergente para el manejo del “topminnow” en Arizona y remarcamos la necesidad de estudios geneticos y morfologicos mas detallados con la finalidad de determinar los limites del area de distribucion y el estado especifico de esta forma altamente divergente.

Six novel microsatellite loci are identified from genomic DNA of the threatened New Mexico Ridge-nosed Rattlesnake (Crotalus willardi obscurus). Data from the Animas Mountains (New Mexico) population demonstrate these loci: (i) are highly variable with 5–24 alleles per locus, expected heterozygosities between 0.35 and 0.92, and observed heterozygosities between 0.32 and 0.91; (ii) are sufficiently variable for assigning parentage with total exclusionary power for the first parent of 0.96, and 0.99 for the second parent; and (iii) amplify similar size fragments in other rattlesnakes (C. atrox, C. lutosus, C. scutulatus, and C. tigris).

Striped bass Morone saxatilis, white bass M. chrysops, and striped bass ♀ × white bass ♂ hybrids have been widely introduced into streams and reservoirs throughout the southeastern USA. Because these taxa often cooccur but are managed differently, distinguishing among them is necessary. Although single morphometric and meristic characters were unreliable discriminators, we could separate the three taxa using sheared principal components analysis and discriminant analysis of multiple characters. Snout and second dorsal spine lengths were greater, and postpectoral and third anal spine lengths were shorter, in striped bass than in white bass and hybrids. Distances between posterior of anal fin and posterior of second dorsal fin, and between orbit and preopercle, were greater in hybrids than in the parental species. White bass were separated from hybrids on the basis of second and third anal spine lengths, orbital lengths, base length of pelvic fin, and eye diameter, all of which tend to be greater i...

During Pleistocene, the Laurentide ice sheet rearranged and diversified biotic distributions in eastern North America, yet had minimal physical impact in western North America where lineage diversification is instead hypothesized to result from climatic changes. If Pleistocene climatic fluctuations impacted desert species, the latter would reflect patterns of restricted gene flow concomitant with indications of demographic bottlenecks. Accordingly, molecular evidence for refugia should be present within these distributions and for subsequent range expansions as conditions improved. We sought answers to these questions by evaluating mitochondrial DNA (mtDNA) sequences from four species of rattlesnakes [Crotalus mitchellii (speckled rattlesnake), Crotalus cerastes (sidewinder), Crotalus tigris (tiger rattlesnake), Crotalus ruber (red diamond rattlesnake)] with distributions restricted to desert regions of southwestern North America. We inferred relationships using parsimony and maximum likelihood, tested intraspecific clades for population expansions, applied an isolation-with-migration model to determine bi-directional migration rates (m) among regions, and inferred divergence times for species and clades by applying a semiparametric penalized likelihood approach to our molecular data. Evidence for significant range expansion was present in two of eight regions in two species (Crotalus mitchellii pyrrhus, C. tigris region north). Two species (C. cerastes, C. mitchellii) showed a distribution concomitant with northward displacement of Baja California from mainland México, followed by vicariant separation into subclades. Effects of Pleistocene climate fluctuations were found in the distributions of all four species. Three regional diversification patterns were identified: (i) shallow genetic diversity that resulted from Pleistocene climatic events (C. tigris, C. ruber); (ii) deep Pleistocene divisions indicating allopatric segregation of subclades within refugia (C. mitchellii, C. cerastes); and (iii) lineage diversifications that extended to Pliocene or Late Miocene (C. mitchellii, C. cerastes). Clade-diversifying and clade-constraining effects impacted the four species of rattlesnakes unequally. We found relatively high levels of molecular diversification in the two most broadly distributed species (C. mitchellii, C. cerastes), and lower levels of genetic diversification in the two species (C. tigris, C. ruber) whose ranges are relatively more restricted. Furthermore, in several cases, the distributions of subspecies were not congruent with our molecular information. We suggest regional conservation perspectives for southwestern deserts cannot rely upon subspecies as biodiversity surrogates, but must instead employ a molecular and deep historical perspective as a primary mechanism to frame biodiversity reserves within this region.

Using univariate and multivariate techniques, we evaluated sexual dimorphism in four external and 51 skeletal measures taken from 66 California Gulls (Larus californicus). Based on analyses of variance, all characters showed statistically significant sexual dimorphism. Skeletal measures of head and pectoral regions were closely correlated but-with elimination of geographic, temporal, and ontogenetic influences-we noted considerable independent variation among characters. Differences between sexes were greatest in the head region (average of 8.03%), with mandible depth being the most dimorphic head character. Differences in the wing region were somewhat less (averaging 6.98%), although still greater than the overall size difference between sexes (i.e., 6.10%; based on the cube root of body weight). Principal components analysis of skeletal characters standardized on the basis of pooled, within-sex standard deviations provided complete separation of males and females. Four skeletal measures (i.e., skull width, mandible length, keel depth, and minimum synsacral width), when used in combination in a stepwise discriminant function, correctly identified to sex all specimens that we used and, it is expected, will do so for most other specimens of this species. Classification functions were developed from the total suite of characters to assign unknown specimens to one or the other sex. Most males and females could also be separated by using combinations of characteristics taken from only one of the five body regions studied (i.e., head, pectoral, wing, pelvic, and leg regions), indicating the widespread nature of sexual dimorphism in California Gulls. Sexual dimorphism in size and shape is almost universal in birds, and numerous theoretical constructs have been developed to explain its ecological and evolutionary significance (e.g., Verner and Willson 1966, Orians 1969, Selander 1972, Ralls 1977). Darwinian sexual selection is likely the most important single cause that generates dimorphism, but other influences also have been considered to be significant. For instance, Selander (1966) presented a case for a relationship between sexual dimorphism and differential niche utilization in birds (i.e., the niche segregation theory) and suggested reasons why such dimorphism would develop. In a number of cases, this explanation has been promoted (e.g., Earhart and Johnson 1970; Robins 1971, Williamson 1971, Wallace 1974); in others, workers have found it necessary to consider alternative hypotheses that take into account bioenergetic pressures, predation pressures, non-monogamous mating systems, or various combinations of these factors (see Sigurj6nsd6ttir 1981 and references therein). The evolutionary significance of sexual dimorphism is still being actively debated. In a variety of studies, there are practical as well as theoretical reasons for wanting to elucidate sexual differences. For instance, gull species are frequent subjects of ethological investigations because gulls are highly colonial, have stereotyped displays, and are relatively easy to observe. Most gulls, however, are monomorphic in plumage, and investigators have difficulty in determining the sex of individual birds. Consequently, a series of works has appeared that provide the basis of identification to sex by using external morphometric characteristics. Studies of this type have been completed for Great Black-backed Gulls (Larus marinus; Harris 1964), Lesser Blackbacked Gulls (L. fuscus; Harris and Hope Jones 1969), Herring Gulls (L. argentatus; Harris and Hope Jones 1969, Shugart 1977, Threlfall and Jewer 1978, Fox et al. 1981), Red-billed Gulls (L. scopulinus; Mills 1971), Ring-billed Gulls (L. delawarensis; Shugart 1977, Ryder 1978), Silver Gulls (L. novaehollandiae; Wooller and Dunlop 1981), and Kelp or Southern Blackbacked Gulls (L. dominicanus; Nugent 1982). Ingolfsson (1969), in a related but more detailed analysis, compared the degree of sexual dimorphism in five species of large gulls, in

We analyzed 4 meristic and 32 morphometric cranial traits of 612 adult specimens of spotted dolphins (Stenella attenuata) from the eastern tropical Pacific Ocean for sexual dimorphism. Eleven 5” latitude/longitude blocks with five or more of each sex were assessed with a two-way ANOVA for sex and geographic differences. Interaction between these two factors was found for six measurements, suggesting that the degree of sexual dimorphism varies geographically for a few characters (although in no discernible geographic pattern). Sexual dimorphism was demonstrated for 23 of the 36 characters, with differences ranging from 0.00 to 5.88 percent. Females characteristically had a longer rostrum, while males generally had larger skulls overall. In terms of number of characters, the extent of sexual dimorphism demonstrated for skulls of spotted dolphins goes considerably beyond that shown for any other small delphine. A discriminant function involving a combination of 10 characters enabled us to identify correctly the sex of more than 75 percent of the specimens. A procedure for correcting specimen measurements is outlined that would enable an investigator to combine male and female specimens in geographic variation studies. A term (zwitter) is proposed for use when referring to specimens where measurements have been corrected to take into account differences between the sexes. When studying morphological variation within a species, it can be important and informative to apportion variability into geographic and non-geographic components. Genetically controlled, non-geographic variation manifests itself in several ways, each of which may have distinct evolutionary implications. Sexual

The spotted dolphin (Stenella attenuata), a species commonly associated with the tuna fishery, is widely distributed in the eastern tropical Pacific Ocean (ETP). Geographic patterns in morphological characteristics of this dolphin were evaluated for 36 skull measurements of 574 museum specimens allocated to 5° latitude-longitude blocks. A strong subdivision between northern and southern offshore populations was demonstrated using principal components, canonical variates and cluster (UPGMA and function-point) analyses of block means derived from standardized, sex-adjusted measurements. Classification functions derived from a stepwise multiple discriminant analysis correctly identified more than 87 percent of the specimens as being from either a northern or southern locality. These results support recognition of southern spotted dolphins as a separate management stock. Dolphins from a sample representing a far-western locality show similarities with those from the south. Patterns of geographic variation in morphology were evaluated using Mantel tests and matrix correlations; 17 of the 36 characters showed regional patterning and 18 exhibited local patterning. Morphological trends were also assessed with respect to 14 oceanographic measures that characterize environmental variability in the ETP. In general, clinal variation in morphology mirrors a north-south trend found in several environmental variables. Overall, the most striking associations between morphological and environmental variables involved Solar Insolation (Jan.). Sea surface temperatures also exhibited a strong association with morphological variables; the highest correspondence was found between width of the temporal fossa and sea surface temperature in July. In addition, the thickness of the oxygen minimum layer exhibited a pattern of variation that was statistically associated with 58 percent of the skull characters. The geographic patterns found for cranial morphology and environmental measures are strongly clinal and in general congruent, suggesting that oceanographic conditions in part determine trends in morphological characteristics of spotted dolphins.

Gradients in salinity and vegetation have been dramatically altered along shoreline of the northern Gulf of Mexico by both natural (i.e., erosion, fluctuating sea levels) and anthropogenic (i.e., dredging, habitat restoration) drivers. We gauged the impacts of salinity gradients and open water barriers on the genetic structure of a common marsh resident, western mosquitofish (Gambusia affinis) by sampling 15 populations along 440 km of Texas/Louisiana coast. We characterized 602 individuals (~40/population) using seven microsatellite loci and our results reflected significant isolation by distance (IBD) among populations, but without the hypothesized genetic substructure from local adaptation. Large tracts of open water, thought to inhibit mosquitofish movement, were apparently not significant deterrents of dispersal. There was no evidence of a significant relationship between salinity gradients and genetic divergence. Although mosquitofish dispersal is sufficiently limited to result in a strong pattern of IBD, it is high enough to maintain the connectedness of populations. Our results suggest that limited gene flow, combined with large effective size, creates conditions suitable to adaptation to local environment, suggesting that mosquitofish and other marsh residents with similar life histories will be able to adapt to changes occurring in coastal environments.

whether cells occurred in multispecies communities or sparsely colonized, monospecific communities at tips of Cladophora filaments. This may indicate that P enrichment at location 3.2 was sufficient to reduce interspecific competition among Cladophora epiphytes. Assay of polyP bodies enabled direct assessment of one form of P stores and provided substantial insight into cells' physiological condition. PolyP body assay can be useful in determining the autecology of algal populations and provided convenient measure for assessing critical phosphorus loads.