Contrasting scales of local persistence between monsoonal and arid biomes in closely related, low‐dispersal vertebrates

Abstract

Aim Focussing on pairs of sister species across three genera of scincid lizards, we use genomic evidence to test for larger‐scale, late‐Pleistocene changes in distributions of lizards in the Australian arid zone (AZ) than in the adjacent monsoonal tropics (MT). Location Northern and central Australia. Taxon Scincidae: Squamata. Methods We sequenced ~2000 nuclear exons and one mitochondrial gene across the distributions of species with primarily MT or AZ distributions from three genera of lizards. Using phylogenetic analysis and population structure analyses we identified major phylogeographic lineages and then compared the spatial scale of structuring and tested for recent demographic expansions. Results Two genera in particular, Proablepharus and Morethia, showed deeper and more geographically localized phylogeographic diversity in the MT than the AZ. In the MT, localized diversity was prevalent in the relatively mesic regions. By contrast, the AZ was characterized by widespread and often genetically uniform lineages and a higher proportion of these had signals of recent population expansion. Main conclusions Consistent with other recent, but mostly less genetically extensive studies, our results point to deeper and more localized diversity in MT compared to AZ. In turn, this suggests higher local persistence in more mesic and topographically diverse biome through the late Quaternary climate fluctuations. For the AZ, geographically extensive range expansions have likely contributed to the low spatial turnover of this exceptionally rich lizard fauna.

Molecular phylogeny and phylogeography of the freshwater-fish genus Pethia (Teleostei: Cyprinidae) in Sri Lanka

“…This phenomenon has been observed previously in species pairs in which one is confined to the wet zone while the other is distributed across the dry zone, such as Devario micronema vs D. malabaricus, Laubuka varuna vs. L. lankensis, Systomus pleurotaenia vs S. sarana, and Rasbora wilpita vs R. dandia [11,14,15,39]. As Potter et al [52] show, genetic diversity in low-dispersal vertebrate species tends to be higher in mesic, topographically complex biomes, compared to that of species inhabiting dry and topographically less complex biomes.…”

Life in the “dead heart” of Australia: The geohistory of the Australian deserts and its impact on genetic diversity of arid zone lizards

“…However, some studies have found significantly lower genetic diversity in this mesic upland compared to other areas of the arid zone (Laver et al., 2017; Melville et al., 2016; Oliver, Couper, et al., 2014; Pepper, Doughty, et al., 2011), much more indicative of recent recolonization than of long‐term persistence. In addition, the hypothesis that arid adapted lineages exhibit wider distributions and shallower divergences than their Monsoon Tropics counterparts, potentially a result of large‐scale expansions following relative climatic amelioration during interglacials has been supported by a number of studies (Anderson et al., 2016; Fujita et al., 2010; Jennings et al., 2003; Laver et al., 2017; Oliver & Bauer, 2011; Oliver, Couper, et al., 2014; Pepper, Ho, et al., 2011; Potter et al., 2019). However, taxa such as cf.…”

“…However, for many other species these empty sand‐coloured patches on the map represent a frustrating gap in knowledge, particularly given the phylogenetic picture emerging from other better‐sampled parts of the arid zone. While in general the patterns appear to lack the deeply divergent and geographically localized endemism typified in taxa across the adjacent Monsoon Tropics (Fujita et al., 2010; Moritz et al., 2016; Noble et al., 2017; Potter et al., 2019), all show significant genetic variation across the arid zone (see Figure 3). This includes topographically flat areas of low‐lying desert where there are no obvious barriers to dispersal and gene flow.…”

“…Using detailed sampling only possible through dedicated, extensive (and expensive!) fieldwork, these ideas have been explored in a biome‐wide context using reptiles across the Monsoon Tropics (Laver et al., 2017; Moritz et al., 2016; Noble et al., 2017; Oliver et al., 2019; Pepper, Hamilton, et al., 2017; Potter et al., 2016, 2019; Silva et al., 2017), and provide fascinating insights into the long‐term, localized persistence of taxa across this topographically complex region. The arid zone shares an almost continent‐wide boundary with the Monsoon Tropics, and the historical relationship of these adjacent biomes continues to be explored in light of molecular data using phylogenies of animal (e.g., Catullo & Keogh, 2014; Fujita et al., 2010; Laver et al., 2017; Oliver et al., 2014; Potter et al., 2019; Silva et al., 2017) and plant clades (Crisp et al., 2004; Ebach et al., 2015; Ladiges et al., 2011; Murphy et al., 2019).…”

“…For example, despite deep genetic divergences within arid zone lineages, phylogeographic structure within desert clades often is both extremely shallow and young (Laver et al., 2017; Pepper, Doughty, et al., 2011; Pepper, Ho, et al., 2011). Demographic analyses of arid zone lineages repeatedly have revealed signatures of recent population expansion (Fujita et al., 2010; Laver et al., 2017; Oliver & Bauer, 2011; Oliver, Couper, et al., 2014; Pepper, Ho, et al., 2011; Potter et al., 2019), a pattern not as frequently seen in mesic lineages outside the arid zone. Diversification rates also were found to be exceptionally high in the arid‐adapted lineages of the Australian skink genera Ctenotus and Lerista (Rabosky et al., 2007), with the authors suggesting the evolution of traits associated with climate tolerance may have played a role in the explosive diversification of these taxa in response to the expansion of the arid zone since the late Miocene.…”