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Data from: Genetic diversity is largely unpredictable but scales with museum occurrences in a species-rich clade of Australian lizards
- 负责人：
- DOI：
- doi:10.5061/dryad.kk73p
- 摘要：
- Genetic diversity is a fundamental characteristic of species and is affected by many factors, including mutation rate, population size, life history and demography. To better understand the processes that influence levels of genetic diversity across taxa, we collected genome-wide restriction-associated DNA data from more than 500 individuals spanning 76 nominal species of Australian scincid lizards in the genus Ctenotus. To avoid potential biases associated with variation in taxonomic practice across the group, we used coalescent-based species delimitation to delineate 83 species-level lineages within the genus for downstream analyses. We then used these genetic data to infer levels of within-population genetic diversity. Using a phylogenetically informed approach, we tested whether variation in genetic diversity could be explained by population size, environmental heterogeneity or historical demography. We find that the strongest predictor of genetic diversity is a novel proxy for census population size: the number of vouchered occurrences in museum databases. However, museum occurrences only explain a limited proportion of the variance in genetic diversity, suggesting that genetic diversity might be difficult to predict at shallower phylogenetic scales.
Data from: The challenge of species delimitation at the extremes: diversification without morphological change in Philippine sun skinks
- 负责人：
- DOI：
- doi:10.5061/dryad.307g0
- 摘要：
- Species represent one of the fundamental units of the evolutionary process, and an accurate understanding of species diversity is essential to studies across a wide range of biological subdisciplines. However, delimiting species remains challenging in evolutionary radiations where morphological diversification is rapid and accompanied by little genetic differentiation or when genetic lineage divergence is not accompanied by morphological change. We investigate the utility of a variety of recently developed approaches to examine genetic and morphological diversity, and delimit species in a morphologically conserved group of Southeast Asian lizards. We find that species diversity is vastly underestimated in this unique evolutionary radiation, and find an extreme case where extensive genetic divergence among lineages has been accompanied by little to no differentiation in external morphology. Although we note that different conclusions can be drawn when species are delimited using molecular phylogenetics, coalescent-based methods, or morphological data, it is clear that the use of a pluralistic approach leads to a more comprehensive appraisal of biodiversity, and greater appreciation for processes of diversification in this biologically important geographic region. Similarly, our approach demonstrates how recently developed methodologies can be utilized to obtain robust estimates of species limits in “non-adaptive” or “cryptic” evolutionary radiations.
Data from: Recent grazing reduces reptile richness but historic grazing filters reptiles based on their functional traits
- 负责人：
- Val, James
- DOI：
- doi:10.5061/dryad.nh773s0
- 摘要：
- 1. Grazing by mammalian herbivores can alter vegetation structure and composition. It can therefore affect critical habitat features used by native wildlife for shelter, feeding and breeding. This can have variable effects, which advantage or disadvantage particular species, depending on habitat requirements. 2. We tested the relative effects of recent and historic livestock grazing and recent rabbit and kangaroo grazing on all reptiles, and on specific groups of reptiles based on three functional traits: habitat preference (semi-arboreal, terrestrial, fossorial), activity pattern (diurnal, nocturnal) and primary foraging habitat (tree, litter, open). 3. We used structural equation modelling to assess the direct and indirect impacts of mammalian herbivores (livestock, and free-ranging kangaroos and rabbits) on reptile richness at 108 semi-arid woodland sites in eastern Australia. We used a trait-based approach to classify reptiles according to their: (1) habitat preference, (2) activity pattern and, (3) foraging preference. 4. We recorded 42 reptile species from 1736 specimens caught over 13,824 trap nights. Sites grazed by rabbits were associated with greater richness of semi-arboreal species. Kangaroo grazing had virtually no effects on total richness or richness within trait groups. The effects of recent and historic livestock grazing differed among reptile trait groups. Increasing intensity of recent livestock grazing reduced the richness of most reptile groups directly, and indirectly suppressed the positive effect of native plant richness on reptile richness. The effects of historic livestock grazing, however, filtered reptiles based on their traits, reducing the richness of tree-shrub foraging reptiles only. Increasing woody cover had direct suppressive effects on all reptiles, but particularly open foragers and terrestrial species. Overall, the effects of recent livestock grazing were stronger than those of plant richness or woody cover. 5. Synthesis and applications. We therefore demonstrate how grazing by all herbivores, both domestic and free-ranging, needs to be managed according to seasonal conditions in order to meet the conservation needs of semi-arid reptiles within landscapes dominated by livestock .
