{"content"=>"A biogeographical profile of the sand cockroach and its bearing on origin hypotheses for Florida scrub biota.", "i"=>{"content"=>"Arenivaga floridensis"}} (original) (raw)
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Following the acceptance of plate tectonics theory in the latter half of the 20th century, vicariance became the dominant explanation for the distributions of many plant and animal groups. In recent years, however, molecular-clock analyses have challenged a number of well-accepted hypotheses of vicariance. As a widespread group of insects with a fossil record dating back 300 My, cockroaches provide an ideal model for testing hypotheses of vicariance through plate tectonics versus transoceanic dispersal. However, their evolutionary history remains poorly understood, in part due to unresolved relationships among the nine recognized families. Here, we present a phylogenetic estimate of all extant cockroach families, as well as a timescale for their evolution, based on the complete mitochondrial genomes of 119 cockroach species. Divergence dating analyses indicated that the last common ancestor of all extant cockroaches appeared 235Ma,235 Ma, 235Ma,95 My prior to the appearance of fossils that can be assigned to extant families, and before the breakup of Pangaea began. We reconstructed the geographic ranges of ancestral cockroaches and found tentative support for vicariance through plate tectonics within and between several major lineages. We also found evidence of transoceanic dispersal in lineages found across the Australian, Indo-Malayan, African, and Madagascan regions. Our analyses provide evidence that both vicariance and dispersal have played important roles in shaping the distribution and diversity of these insects.
Habitat specificity, fragmented landscapes, and the phylogeography of three lizards in Florida scrub
Dry, sandy scrub habitats of the Florida peninsula represent naturally fragmented remnants of xeric ecosystems that were widespread during the Pliocene and early Pleistocene. This habitat is characterized by high endemism, and distribution of genetic and evolutionary diversity among scrub "islands" is of compelling interest because Florida scrub is rapidly disappearing under human development. We compare range-wide diversity in mitochondrial cytochrome b sequences for three scrub-associated lizards with contrasting levels of habitat specificity. All species show strong geographic partitioning of genetic diversity, supporting the hypothesis that scrub fauna is highly restricted by vicariant separations. The mole skink (Eumeces egregius), the least habitat specific, has the lowest phylogeographic structure among the lizards (φ st = 0.631). The mtDNA geneology for E. egregius is not entirely concordant with the five recognized subspecies and supports a link between populations in central Florida (E. e. lividus) and the Florida Keys (E.e. egregius) rather than a previously proposed affiliation between northern and southern populations. The Florida scrub lizard (Sceloporus woodi) is the most habitat specific of the lizards and has the strongest phylogeographic structure (φ st = 0.876). The sand skink (Neoseps reynoldsi) falls between the mole skink and scrub lizard in terms of habitat specificity and phylogeographic structure (φ st = 0.667). For all three species, networks of mtDNA haplotypes coalesce on two central ridges that contain the oldest scrub. The geographic structure and deep evolutionary lineages observed in these species have strong implications for conservation, including strategies for translocation, reserve design, and management of landscape connectivity.
Phylogeographic structure of the dunes sagebrush lizard, an endemic habitat specialist
PLOS ONE, 2020
Phylogeographic divergence and population genetic diversity within species reflect the impacts of habitat connectivity, demographics, and landscape level processes in both the recent and distant past. Characterizing patterns of differentiation across the geographic range of a species provides insight on the roles of organismal and environmental traits in evolutionary divergence and future population persistence. This is particularly true of habitat specialists where habitat availability and resource dependence may result in pronounced genetic structure as well as increased population vulnerability. We use DNA sequence data as well as microsatellite genotypes to estimate range-wide phylogeographic divergence, historical population connectivity, and historical demographics in an endemic habitat specialist, the dunes sagebrush lizard (Sceloporus arenicolus). This species is found exclusively in dune blowouts and patches of open sand within the shinnery oak-sand dune ecosystem of southeastern New Mexico and adjacent Texas. We find evidence of phylogeographic structure consistent with breaks and constrictions in suitable habitat at the rangewide scale. In addition, we find support for a dynamic and variable evolutionary history across the range of S. arenicolus. Populations in the Monahans Sandhills have deeply divergent lineages consistent with long-term demographic stability. In contrast, populations in the Mescalero Sands are not highly differentiated, though we do find evidence of demographic expansion in some regions and relative demographic stability in others. Phylogeographic history and population genetic differentiation in this species has been shaped by the configuration of habitat patches within a geologically complex and historically dynamic landscape. Our findings identify regions as genetically distinctive conservation units as well as underscore the genetic and demographic history of different lineages of S. arenicolus.
Cladistics, 2008
New Caledonia is a tropical hotspot of biodiversity with high rates of regional and local endemism. Despite offering an ideal setting to study the evolution of endemism, New Caledonia has received little attention compared with the other nearby hotspots, particularly New Zealand. Most studies of the Neocaledonian endemism have been carried out at the regional level, comparing the various groups and species present in New Caledonia but absent in neighboring territories. In addition, remarkably high short-range endemism has been documented among plants, lizard and invertebrates, although these have usually been done, lacking a phylogenetic perspective. Most studies of Neocaledonian endemism have referred to the geological Gondwanan antiquity of the island and its metalliferous soils derived from ultramafic rocks. Very old clades are thought to have been maintained in refugia and diversified on the metalliferous soils. The present study documents the pattern of diversification and establishment of short-range endemism in a phylogenetic context using the Neocaledonian cockroach genus Lauraesilpha. Mitochondrial and nuclear genes were sequenced to reconstruct phylogenetic relationships among the species of this genus. These relationships, in the light of the species distribution, do not support the hypothesis that species diversified via an adaptive radiation on metalliferous soils and are not consistent with areas of highest rainfall. Species of Lauraesilpha have similar altitudinal ranges and ecological habits and are short-range endemics on mountains. What our analysis did reveal was that closely related species are found on nearby or contiguous mountains, and thus these formations probably played the key role establishing short-range endemism (in association with recent climatic changes).
Molecular Ecology, 1999
The Florida scrub lizard, Sceloporus woodi , is endemic to scrub habitat patches along the central portion of the Florida peninsula and xeric coastal regions. Scrub ecosystems are the patchily distributed remnants of previously widespread habitats formed during the Pleiocene and early Pleistocene. Scrub lizards appear to have limited dispersal capabilities due to high habitat specificity and low mobility. To assess the population structure and phylogeography of S. woodi , 135 samples were collected from 16 patches on five major ridges in Florida, USA. Analysis of 273 bp of mitochondrial DNA (mtDNA) cytochrome b reveals a very strong geographic distribution of genetic diversity. Haplotype frequencies are significantly different in 63 of 66 comparisons between patches. With one exception, samples from the five major ridges are characterized by fixed differences in haplotype distribution and deep evolutionary separations (3 -10%). Fixed genetic differences were also observed between northern and southern segments of several ridges. Analysis of molecular variance ( amova ) shows an estimated 10.4% total genetic variation within patches, 17.5% among patches (within ridges), and 72.1% among ridges. This strong population structure among patches within ridges indicates that the distribution of S. woodi is tightly linked to sandy scrub habitat and that the discontinuous distribution of scrub habitats significantly inhibits dispersal and gene flow. Phylogeographic analyses indicate a pattern of dispersal down the Florida peninsula during the late Pliocene-early Pleistocene, followed by habitat fragmentation and vicariant isolation events. Therefore, the deep genetic structuring among scrub lizard populations on separate ridges is attributed to ancient isolation events induced by a shift from dry (xeric) to wet (mesic) conditions on the Florida peninsula. These findings indicate that some scrub lizard populations have persisted in isolation for time frames in excess of 1 Myr, providing a case history on the genetic consequences of habitat fragmentation.
We evaluated the mtDNA divergence and relationships within Geomys pinetis to assess the status of formerly recognized Geomys taxa. Additionally, we integrated new hypothesis-based tests in ecological niche models (ENM) to provide greater insight into causes for divergence and potential barriers to gene flow in Southeastern United States (Alabama, Florida, and Georgia). Our DNA sequence dataset confirmed and strongly supported two distinct lineages within G. pinetis occurring east and west of the ARD. Divergence date estimates showed that eastern and western lineages diverged about 1.37 Ma (1.9 Ma-830 ka). Predicted distributions from ENMs were consistent with molecular data and defined each population east and west of the ARD with little overlap. Niche identity and background similarity tests were statistically significant suggesting that ENMs from eastern and western lineages are not identical or more similar than expected based on random localities drawn from the environmental background. ENMs also support the hypothesis that the ARD represents a ribbon of unsuitable climate between more suitable areas where these populations are distributed. The estimated age of divergence between eastern and western lineages of G. pinetis suggests that the divergence was driven by climatic conditions during Pleistocene glacial-interglacial cycles. The ARD at the contact zone of eastern and western lineages of G. pinetis forms a significant barrier promoting microgeographic isolation that helps maintain ecological and genetic divergence.
2002
Dry, sandy scrub habitats of the Florida peninsula represent naturally fragmented remnants of xeric ecosystems that were widespread during the Pliocene and early Pleistocene. This habitat is characterized by high endemism, and distribution of genetic and evolutionary diversity among scrub “islands ” is of compelling interest because Florida scrub is rapidly disappearing under human development. We compare range-wide diversity in mitochondrial cytochrome b sequences for three scrub-associated lizards with contrasting levels of habitat specificity. All species show strong geographic partitioning of genetic diversity, supporting the hypothesis that scrub fauna is highly restricted by vicariant separations. The mole skink (Eumeces egregius), the least habitat specific, has the lowest phylogeographic structure among the lizards (φst = 0.631). The mtDNA geneology for E. egregius is not entirely concordant with the five recognized subspecies and supports a link between populations in centr...