Population genomic structure in Goodman's mouse lemur reveals long‐standing separation of Madagascar's Central Highlands and eastern rainforests

Abstract

Madagascar's Central Highlands are largely composed of grasslands, interspersed with patches of forest. The historical perspective was that Madagascar's grasslands had anthropogenic origins, but emerging evidence suggests that grasslands were a component of the pre-human Central Highlands vegetation. Consequently, there is now vigorous debate regarding the extent to which these grasslands have expanded due to anthropogenic pressures. Here, we shed light on the temporal dynamics of Madagascar's vegetative composition by conducting a population genomic investigation of Goodman's mouse lemur (Microcebus lehilahytsara; Cheirogaleidae). These smallbodied primates occur both in Madagascar's eastern rainforests and in the Central Highlands, making them a valuable indicator species. Population divergences among forest-dwelling mammals will reflect changes to their habitat, including fragmentation, whereas patterns of post-divergence gene flow can reveal formerly wooded migration corridors. To explore these patterns, we used RADseq data to infer population genetic

Diversification processes in Gerp's mouse lemur demonstrate the importance of rivers and altitude as biogeographic barriers in Madagascar's humid rainforests

“…Previous studies have already shown that microendemic mouse lemurs are susceptible to habitat fragmentation (Andriatsitohaina et al, 2020;Schäffler & Kappeler, 2014). Similar to M. lehilahytsara (Tiley et al, 2022), M. gerpi may be particularly vulnerable to such anthropogenic threats as we identified pronounced population genomic structure originating from paleoclimatic conditions. That is, populations were already highly genetically differentiated and exhibited low levels of gene flow long before human colonization of Madagascar at 2-10 ka (e.g., Dewar et al, 2013;Mitchell, 2019;Pierron et al, 2017).…”

“…of N e (Figure 4a,b) which are at the lower end of those found in populations of other mouse lemur species such as M. lehilahytsara, M. macarthurii, M. simmonsi and M. jonahi (Poelstra et al, 2021;Tiley et al, 2022). Given the high degree of ongoing fragmentation of remaining forests in the area, it can be assumed that presentday gene flow between populations is negligible and that genetic isolation and therefore loss of diversity will increase.…”

“…Biogeography, Conservation genetics, Demography, Genomics, Population genetics, Zoology time and high habitat specificity (Mittermeier et al, 2010), it can be hypothesized that they are particularly sensitive to the aforementioned geographic barriers and that genomic signatures of cyclic geographic isolation will manifest rapidly. Analyses by Poelstra et al (2021) suggest that the diversification of mouse lemurs occurred relatively recently during the Pleistocene (but see Everson et al, 2023;Herrera & Dávalos, 2016;Louis & Lei, 2016), and previous studies have already indicated that rivers (Martin, 1972;Olivieri et al, 2006;Pastorini et al, 2003;Tiley et al, 2022), watersheds (Mercier & Wilmé, 2013;Wilmé et al, 2006) and paleoclimatic fluctuations (Blair et al, 2014;Poelstra et al, 2021;Teixeira, Montade, et al, 2021; were significant determinants of mouse lemur population structure and demography, but these were only rarely modeled in an integrative way.…”

Habitat and ecological niche characteristics of the elusive Hairy‐eared Dwarf Lemur (Allocebus trichotis) with updated occurrence and geographic range data

“…Although this has not been studied so far due to its elusiveness, our direct observations indicate that it might be catchable for genetic/genomic investigations like the more frequently studied mouse lemurs (e.g., Schüßler, Blanco et al, 2020). However, A. trichotis occurs sympatrically across its whole range with other lemur species like Indri indri (Brenneman et al, 2016) or Microcebus lehilahytsara (Tiley et al, 2022) that show only little cryptic diversity. These two lemurs are also known to be found at particularly high elevations (e.g., Mittermeier et al, 2010; Radespiel et al, 2012), suggesting that altitudinal tolerance, as also indicated by our ENMs for A. trichotis , may allow for wider ranges and some level of north−south connectivity which may then prevent the further diversification into different species compared to taxa that are confined to the lowland environments of the same region (e.g., four further lowland mouse lemur species in northeastern Madagascar: M. macarthurii , M. jonahi , M. simmonsi , M. gerpi ; Schüßler, Blanco et al, 2020).…”

“…Although this has not been studied so far due to its elusiveness, our direct observations indicate that it might be catchable for genetic/genomic investigations like the more frequently studied mouse lemurs (e.g., Schüßler, Blanco et al, 2020). However, A. trichotis occurs sympatrically across its whole range with other lemur species like Indri indri (Brenneman et al, 2016) or Microcebus lehilahytsara (Tiley et al, 2022) that show only little cryptic diversity.…”