How does range expansion affect genetic diversity in species with different ecologies, and do different types of genetic markers lead to different conclusions? We addressed these questions by assessing the genetic consequences of postglacial range expansion using mitochondrial DNA (mtDNA) and nuclear restriction site‐associated DNA (RAD) sequencing in two congeneric and codistributed rodents with different ecological characteristics: the desert kangaroo rat (Dipodomys deserti), a sand specialist, and the Merriam's kangaroo rat (Dipodomys merriami), a substrate generalist. For each species, we compared genetic variation between populations that retained stable distributions throughout glacial periods and those inferred to have expanded since the last glacial maximum. Our results suggest that expanded populations of both species experienced a loss of private mtDNA haplotypes and differentiation among populations, as well as a loss of nuclear single‐nucleotide polymorphism (SNP) private alleles and polymorphic loci. However, only D. deserti experienced a loss of nucleotide diversity (both mtDNA and nuclear) and nuclear heterozygosity. For all indices of diversity and differentiation that showed reduced values in the expanded areas, D. deserti populations experienced a greater degree of loss than did D. merriami populations. Additionally, patterns of loss in genetic diversity in expanded populations were substantially less extreme (by two orders of magnitude in some cases) for nuclear SNPs in both species compared to that observed for mitochondrial data. Our results demonstrate that ecological characteristics may play a role in determining genetic variation associated with range expansions, yet mtDNA diversity loss is not necessarily accompanied by a matched magnitude of loss in nuclear diversity.

The Great Basin pocket mouse, Perognathus parvus, inhabits temperate shrub-steppe and arid grassland biomes throughout the Columbia Plateau, Great Basin, and adjacent regions of western North America. We used both mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) sequences to address phylogenetic and biogeographic structure within the P. parvus species group. Phylogenetic and biogeographic analyses divide haplotypes from the mtDNA cytochrome oxidase subunit 3 (COM) gene into largely allopatric northern versus southern lineages (clades), with divergences of up to 18.8%. The southern mtDNA clade also includes at least 1 of the 2 recently extant populations of the white-eared pocket mouse, P. alticolus an endangered species with a restricted range in southern California. The northern mtDNA clade is further subdivided into several additional lineages with divergences as high as 8.8%, whereas the southern clade has no divergence greater than 1.2%. The deeper mtDNA gene tree structure was recovered by use of nDNA exon sequences from the interphotoreceptor retinoidbinding protein (IRBP) and recombination activating gene 2 (RAG2) gene regions, supporting a "gene tree species tree" congruence. We estimated through molecular clock analyses that the northern and southern clades likely diverged within a late Miocene time frame. The limited available karyological evidence is consistent with a genome-wide divergence between northern and southern clades thus, is consistent with recognition of each as a separate species. Conversely, our morphometric analysis revealed a high level of morphological conservatism without detectable diagnostic differences, rendering them as "cryptic" species. We revised species-level taxonomy, designating 2 neotypes given apparent loss of original type specimens. We postulate that bathers associated with Columbia Plateau, Snake River Plain, and Great Basin physiographic evolution, during a Neogene time frame, resulted in persistent geographic isolation driving divergence between the northern and southern clades.

.............................................................................................................................. iii Acknowledgements ............................................................................................................ vi Table of

The Nactus pelagicus complex consists of a unisexual lineage, N. pelagicus, as well as several genetically distinct bisexual lineages. The unisexual and bisexual lineages are rarely sympatric but do co-occur on two islands in southern Vanuatu. Nactus pelagicus and the bisexual N. multicarinatus co-occur on Aneityum and Tanna Islands, although the distribution of N. multicarinatus may be limited on Aneityum and may be limited to a single locality (Port Resolution) on the eastern coast of Tanna. Previous analyses suggested that these species have different chin scalation patterns. However, species identifications were assigned solely on presence or absence of males from localities. Moreover, because these species occupy different regions, morphological analyses can be confounded by interisland variation. To evaluate whether chin scalation patterns differ consistently between N. pelagicus and N. multicarinatus as previously suggested, we used molecular sequence data to delimit species from nine populations on a single island in Vanuatu. All N. multicarinatus examined had a single chin scalation pattern whereas variation in this trait was observed in N. pelagicus; there was no overlap in this trait between the species. We hypothesize that the variation in this trait in the unisexual species N. pelagicus could result from developmental instability as a result of perturbations during development caused by incompatibility between the two parental genomes that contributed to the formation of this unisexual lineage.

As currently understood, there are two species of foxsnakes (Eastern Foxsnake, Pantherophis gloydi Conant and Western Foxsnake, P. vulpinus Baird and Girard) that are separated by a large geographic disjunction that encompasses almost all of Michigan, eastern Indiana, and eastern Ohio. Phylogenetic analysis of mtDNA data of individuals from throughout the ranges of the two species inferred reciprocally monophyletic clades that revealed a new species boundary, the Mississippi River. The single key morphological character also shows a major difference at the river. Because the localities of the holotypes of P. gloydi and P. vulpinus are both within the new range of the eastern form, gloydi is recognized as a junior synonym of vulpinus and a new name, P. ramspotti, is erected for the western form. The estimates of divergence time and historical biogeography suggest that Pleistocene glaciation and the Mississippi River played a key role in speciation.

As currently understood, there are two species of foxsnakes (Eastern Foxsnake, Pantherophis gloydi Conant and Western Foxsnake, P. vulpinus Baird and Girard) that are separated by a large geographic disjunction that encompasses almost all of Michigan, eastern Indiana, and eastern Ohio. Phylogenetic analysis of mtDNA data of individuals from throughout the ranges of the two species inferred reciprocally monophyletic clades that revealed a new species boundary, the Mississippi River. The single key morphological character also shows a major difference at the river. Because the localities of the holotypes of P. gloydi and P. vulpinus are both within the new range of the eastern form, gloydi is recognized as a junior synonym of vulpinus and a new name, P. ramspotti , is erected for the western form. The estimates of divergence time and historical biogeography suggest that Pleistocene glaciation and the Mississippi River played a key role in speciation.

AimTo compare the evolutionary and ecological patterns of two extensively studied island biotas with differing geological histories (the Hawaiian Islands and the Greater Antilles). We evaluated the results from PACT (phylogenetic analysis for comparing trees), an innovative approach that has been proposed to reveal general patterns of biotic expansion (between regions) and in situ (within a region) diversification, as well as species-area relationships (SAR) and the taxon pulse dynamic.LocationThe Hawaiian Islands and Greater Antilles.MethodsWe used the PACT algorithm to construct general area cladograms and identified biotic expansion and in situ nodes. We analysed the power-law SAR and relative contribution of biotic expansion and in situ diversification events using power-law and linear regression analyses.ResultsBoth biotic expansion and in situ nodes were prevalent throughout the PACT general area cladograms (Greater Antilles, 55.9% biotic expansion, 44.1% in situ; Hawaiian Islands, 40.6% biotic expansion, 59.4% in situ). Of the biotic expansion events, both forward and backward events occurred in both regions (Greater Antilles, 85.1% forward, 14.9% backward; Hawaiian Islands, 65% forward, 35% backward). Additionally, there is a power-law SAR for the Greater Antilles but not for the Hawaiian Islands. However, exclusion of Hawai'i (the youngest, largest Hawaiian Island) produced a power-law SAR for the Hawaiian Islands.Main conclusionsThe prevalence of in situ events as well as forward and backward biotic expansion events reveals that both Hawaiian and Greater Antillean biotas have evolved through alternating episodes of biotic expansion and in situ diversification. These patterns are characteristic of the taxon pulse dynamic, for which few data have previously been recorded on islands. Additionally, our analysis revealed that historical influences on the power-law SARs are pronounced in both assemblages: old, small islands are relatively species rich and young, large islands are relatively species poor. Thus, our PACT results are consistent with hypotheses of geological influence on the evolution of island biotas and also provide greater insight into the role of the taxon pulse dynamic in the formation of island equilibria.

The South Pacific Nactus pelagicus complex (Reptilia: Squamata: Gekkonidae) consists of several genetically distinct but morphologically conserved lineages of N. multicarinatus, and a unisexual lineage, N. pelagicus, which is a hybrid of two N. multicarinatus lineages. A few discrete morphological differences occur between lineages of the N. pelagicus complex, but that is all that is known regarding this complex. This complex has been poorly studied and little is known about the general biology and ecology of N. pelagicus and N. multicarinatus. We analyzed the reproductive morphology using histochemistry in populations of N. multicarinatus and N. pelagicus from the Vanuatu Archipelago in the South Pacific, the only series of islands where the two species overlap, in order to determine if interspecific differences in reproductive patterns exist and to gather additional knowledge regarding the reproductive ecology of these species. Our findings indicate that both species carry one clutch during the dry season, however there is temporal variation in reproductive activity, with N. pelagicus ! Corresponding Author: Email: eckstutm@unlv.nevada.edu, School of Life Sciences, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas, Nevada 89154, USA Mallory E. Eckstut, Alison M. Hamilton, Christopher C. Austin et al. 296 exhibiting particular histochemical states one and a half to two months prior to N. multicarinatus. Furthermore, we found that N. multicarinatus, the bisexual lineage, does not store sperm with eggs in utero, which has only been observed in one other species of lizard (a skink). These previously unrecognized differences in Nactus reproduction provide a foundation for further study of the evolutionary transition to unisexual reproduction and supply additional data on the ecology of this poorly studied gecko complex.

The South Pacific Nactus pelagicus complex (Reptilia: Squamata: Gekkonidae) consists of several genetically distinct but morphologically conserved lineages of N. multicarinatus, and a unisexual lineage, N. pelagicus, which is a hybrid of two N. multicarinatus lineages. A few discrete morphological differences occur between lineages of the N. pelagicus complex, but that is all that is known regarding this complex. This complex has been poorly studied and little is known about the general biology and ecology of N. pelagicus and N. multicarinatus. We analyzed the reproductive morphology using histochemistry in populations of N. multicarinatus and N. pelagicus from the Vanuatu Archipelago in the South Pacific, the only series of islands where the two species overlap, in order to determine if interspecific differences in reproductive patterns exist and to gather additional knowledge regarding the reproductive ecology of these species. Our findings indicate that both species carry one clutch during the dry season, however there is temporal variation in reproductive activity, with N. pelagicus ∗ Corresponding Author: Email: eckstutm@unlv.nevada.edu, School of Life Sciences, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas, Nevada 89154, USA Mallory E. Eckstut, Alison M. Hamilton, Christopher C. Austin et al. 296 exhibiting particular histochemical states one and a half to two months prior to N. multicarinatus. Furthermore, we found that N. multicarinatus, the bisexual lineage, does not store sperm with eggs in utero, which has only been observed in one other species of lizard (a skink). These previously unrecognized differences in Nactus reproduction provide a foundation for further study of the evolutionary transition to unisexual reproduction and supply additional data on the ecology of this poorly studied gecko complex.

The storage of sperm by females is a common but variable phenomenon observed in a number of vertebrate lineages. The utility of female sperm storage has been widely debated, but has been suggested to benefit species by lengthening breeding seasons as well as enhancing colonization abilities. Additionally, the variation in sperm storage traits has been suggested to have value for assessing phylogenetic hypotheses. To date, little is known regarding the evolutionary and ecological implications of sperm storage in female squamates (lizards and snakes). Utilizing previous studies of reproductive morphology and ultrastructural studies and three competing squamate phylogenies (one morphological and two molecular, including a new hypothesis of 611 taxa), we address character state evolution of sperm storage characters and overlay a variety of ecological factors in order to assess ecological function. We also test the hypothesis that sperm storage may offer reciprocal illumination in choosing among hypotheses of squamate phylogeny. At present there is minimal value for phylogenetic inference from these reproductive characters. We found that several sperm storage characters are relatively conserved across the sampled squamates (including presence of sperm storage and sperm storage tubules (Ssts), embedding of sperm, and sperm storage with eggs in utero). Alternatively, location of Ssts, secretions within the Ssts, and length of sperm storage are highly variable traits. We suggest that these differences are correlated with ecological differences in the reproductive tactics of each species. Because of limited data available for many of the taxa, however, statements regarding the ecological utility of the traits are highly ∗ Corresponding Author: Email: eckstutm@unlv.nevada.edu Mallory E. Eckstut, David M. Sever, Mary E. White et al. 186 speculative. Additional studies will likely find that these traits are more variable than currently recognized. Despite the limited amount of information currently available, our preliminary results indicate that further comparative work on sperm storage traits may be useful in phylogenetic analyses.

The Mediterranean Gecko, Hemidactylus turcicus, is all invasive species found in warmer regions throughout the world, including the southern United States. In Louisiana, H. turcicus appears to be free of competition and has been rapidly expanding its range in the past several decades. However. in Florida and Texas, H. turcicus is heavily out-competed by closely related competitors that do not Occur in Louisiana, including H. frenatus, of which a Substantial amount of reproductive morphology and ecology is known. Although the reproductive cycle of H. turcicus, has been studied in Florida and Louisiana. little is known about the seasonal variation of their oviduct and if they are capable of storing sperm. which call have substantial implications for reproductive competition. We analysed sperm production, storage and seasonal variation in the testes and oviducts of H. turcicus using light and electron microscopy. Previous studies found that female H frenatus store sperm in the uterine-infundibular region for up to 36 weeks. and that their oviducts are active year-round. In H. turcicus, We found that sperm are stored in the uterine-infundibular region of the oviduct, and sperm are stored from May through August. Hemidactylus turcicus has one breeding season per year, producing three to four clutches between May and August, but between September and February minimal activity occurs in the oviduct. Additionally, male H. turcicus are Producing sperm throughout the entire reproductive season, but whether females utilize stored sperm to fertilize eggs or if they mate continually throughout the spring and summer is unknown.

The testes of Hemidactylus turcicus are composed of seminiferous tubules lined with continuous germinal epithelia in which multiple germ cell morphologies can be found during the active months of sperm development. Spermatogenesis is quiescent during September, with only spermatogonia A and spermatogonia B present in the seminiferous epithelia and minimal mitotic activity is observed. Recrudescence begins in October and the early stages of spermatogenesis progress through November. The onset of spermiation is observed in December and continues through August with the heaviest sperm release occurring in June and July. Multiple generations of late elongated spermatids are found In association with early mitotic and meiotic cells during the months of December-August. This temporal germ cell development strategy is similar to that described in other squamates and anamniotes and Is different from the spatial development exhibited by birds and mammals, in which germ cell populations collectively progress through the stages of spermatogenesis. The reptilian temporal model of germ cell development within a structurally amniotic testis leads to two hypotheses in character evolution: birds and mammals exhibit convergence of germ cell development strategy, or the spatial development strategy is a synapomorphy in amniotes, and reptiles represent an evolutionary reversal to the strategy employed by anamniotes. These findings, along with present and future data, may allow for more concrete phylogenetic analyses by creating more characters for phylogenetic matrices and may prove to be useful in future histopathological studies.

The seasonal variation of the renal sexual segment (RSS) of males of the Cottonmouth snake, Agkistrodon piscivorous, is described using light and electron microscopy. This study is the first to describe the ultrastructure of the RSS of a viper (Viperidae) and only the fourth on a snake. Renal sexual segments from males collected February to May and from August to November are similar in appearance. The cells are eosinophilic and react with periodic acid/Schiff procedure (PAS) for neutral carbohydrates and bromphenol blue (BB) for proteins. At the ultrastructure level, the cells contain large (2 μm diameter), electron‐dense secretory granules and smaller vesicles with a diffuse material, and these structures abut against the luminal border and upon clear vacuoles continuous with intercellular canaliculi. Evidence was found for both apocrine and merocrine processes of product release. In June and July, the RSS are significantly smaller in diameter, largely basophilic, and have only scattered granules that are PAS+ and BB+. Cytologically, the RSS from June to July lack electron‐dense secretory granules and the smaller vesicles with diffuse material. Numerous condensing vacuoles and abundant rough endoplasmic reticulum, however, indicate that active product synthesis is occurring. This is the first report of significant seasonal variation in the histology and ultrastructure of the RSS of a snake, although such reports exist for lizards. The seasons when the RSS is most highly hypertrophied correspond to the fall and spring mating seasons of A. piscivorous, as determined by other studies. J. Morphol., 2008. © 2007 Wiley‐Liss, Inc.

Sampling arboreal lizards is often problematic due to difficulties subduing and capturing live specimens. We developed a new technique using mosquito netting for sampling populations of an arboreal skink. We describe how this simple, inexpensive 'lizard net' method yields excellent results for capturing arboreal lizards. We caught an arboreal skink, Emoia sanfordi, using this technique and we compared our collection success when using the 'lizard net' to our collection success when using other widely utilized methods. The 'lizard net' was highly effective. The number of E. sanfordi we collected in one day was doubled when using the 'lizard net' and we observed far fewer injuries to lizards, as compared to other methods.