Showing papers by "David G. Chapple published in 2011"

Phylogeographic divergence in the widespread delicate skink (Lampropholis delicata) corresponds to dry habitat barriers in eastern Australia

Abstract: The mesic habitats of eastern Australia harbour a highly diverse fauna. We examined the impact of climatic oscillations and recognised biogeographic barriers on the evolutionary history of the delicate skink (Lampropholis delicata), a species that occurs in moist habitats throughout eastern Australia. The delicate skink is a common and widespread species whose distribution spans 26° of latitude and nine major biogeographic barriers in eastern Australia. Sequence data were obtained from four mitochondrial genes (ND2, ND4, 12SrRNA, 16SrRNA) for 238 individuals from 120 populations across the entire native distribution of the species. The evolutionary history and diversification of the delicate skink was investigated using a range of phylogenetic (Maximum Likelihood, Bayesian) and phylogeographic analyses (genetic diversity, ΦST, AMOVA, Tajima's D, Fu's F statistic). Nine geographically structured, genetically divergent clades were identified within the delicate skink. The main clades diverged during the late Miocene-Pliocene, coinciding with the decline and fragmentation of rainforest and other wet forest habitats in eastern Australia. Most of the phylogeographic breaks within the delicate skink were concordant with dry habitat or high elevation barriers, including several recognised biogeographic barriers in eastern Australia (Burdekin Gap, St Lawrence Gap, McPherson Range, Hunter Valley, southern New South Wales). Genetically divergent populations were also located in high elevation topographic isolates inland from the main range of L. delicata (Kroombit Tops, Blackdown Tablelands, Coolah Tops). The species colonised South Australia from southern New South Wales via an inland route, possibly along the Murray River system. There is evidence for recent expansion of the species range across eastern Victoria and into Tasmania, via the Bassian Isthmus, during the late Pleistocene. The delicate skink is a single widespread, but genetically variable, species. This study provides the first detailed phylogeographic investigation of a widespread species whose distribution spans virtually all of the major biogeographic barriers in eastern Australia.

Know when to run, know when to hide: can behavioral differences explain the divergent invasion success of two sympatric lizards?

Abstract: Invasive species represent a select subset of organisms that have successfully transitioned through each stage of the introduction process (transportation, establishment, and spread). Although there is a growing realization that behavior plays a critical role in invasion success, few studies have focused on the initial stages of introduction. We examined whether differences in the grouping tendencies and exploratory behavior of two sympatric lizard species could contribute to their divergent invasion success. While the nondirected activity of the two species did not differ, the invasive delicate skink (Lampropholis delicata) was found to be more exploratory than the congeneric noninvasive garden skink (L. guichenoti), which enabled it to more effectively locate novel environments and basking site resources. The delicate skink also exhibited a greater tendency to hide, which may act to enhance its probability of ensnarement in freight and cargo and decrease its likelihood of detection during transit. The grouping tendencies of the two species did not differ. Together, our results suggest that while the two species have an equivalent “opportunity” for unintentional human-assisted transportation, several pre-existing behavioral traits may enhance the success of the delicate skink in negotiating the initial stages of the introduction process, and subsequent post-establishment spread.

Biogeographic barriers in south‐eastern Australia drive phylogeographic divergence in the garden skink, Lampropholis guichenoti

Abstract: Aim To investigate the impact of climatic oscillations and recognized biogeographic barriers on the evolutionary history of the garden skink (Lampropholis guichenoti), a common and widespread vertebrate in south-eastern Australia. Location South-eastern Australia. Methods Sequence data were obtained from the ND4 mitochondrial gene for 123 individuals from 64 populations across the entire distribution of the garden skink. A range of phylogenetic (maximum likelihood, Bayesian) and phylogeographic analyses (genetic diversity, Tajima’s D, ΦST, mismatch distribution) were conducted to examine the evolutionary history and diversification of the garden skink. Results A deep phylogeographic break (c. 14%), estimated to have occurred in the mid–late Miocene, was found between ‘northern’ and ‘southern’ populations across the Hunter Valley in northern New South Wales. Divergences among the geographically structured clades within the ‘northern’ (five clades) and ‘southern’ (seven clades) lineages occurred during the Pliocene, with the location of the major breaks corresponding to the recognized biogeographic barriers in south-eastern Australia. Main conclusions Climatic fluctuations and the presence of several elevational and habitat barriers in south-eastern Australia appear to be responsible for the diversification of the garden skink over the last 10 Myr. Further molecular and morphological work will be required to determine whether the two genetic lineages represent distinct species.

Phylogeography and taxonomic revision of the New Zealand cryptic skink ( Oligosoma inconspicuum ; Reptilia: Scincidae) species complex

Abstract: The New Zealand skink fauna is highly diverse and contains numerous cryptic, undescribed or hitherto undiscovered species. We completed a taxonomic revision of the cryptic skink (Oligosoma inconspicuum) species complex using molecular (550 bp of the ND2 mitochondrial gene) and morphological analyses. Four new species are described, with each diagnosable by a range of morphological characters and genetic differentiation from several closely related species: O. inconspicuum (sensu stricto), O. notosaurus, O. maccanni, O. stenotis and O. grande. Oligosoma tekakahu sp. nov. is restricted to Chalky Island in Fiordland, and is most closely related to O. inconspicuum and O. notosaurus. The other three new species are restricted to particular mountainous regions in central and western Otago (O. burganae sp. nov., Lammermoor and Rock and Pillar Ranges; O. toka sp. nov., Nevis Valley; O. repens sp. nov., Eyre Mountains) and are most closely related to O. stenotis and O. grande. We also re-described O. inconspicuum. Two proposed new taxa, the ‘Big Bay’ skink and ‘Mahogany’ skink, were found to represent Westland/Fiordland populations of O. inconspicuum rather than distinct taxa. We discuss the evolutionary and phylogeographic implications of cryptic and ‘anti-cryptic’ species within the O. inconspicuum species complex, and suggest that morphologically aberrant populations are the result of local adaptation to novel selective regimes.