Genetic data suggest a natural prehuman origin of open habitats in northern Madagascar and question the deforestation narrative in this region

Abstract

The impact of climate change and anthropogenic deforestation on biodiversity is of growing concern worldwide. Disentangling how past anthropogenic and natural factors contributed to current biome distribution is thus a crucial issue to understand their complex interactions on wider time scales and to improve predictions and conservation strategies. This is particularly important in biodiversity hotspots, such as Madagascar, dominated by large open habitats whose origins are increasingly debated. Although a dominant narrative argues that Madagascar was originally entirely covered by woodlands, which were destroyed by humans, a number of recent studies have suggested that past climatic fluctuations played a major role in shaping current biome distributions well before humans arrived. Here, we address the question of the origin of open habitats in the Daraina region in northern Madagascar, using a multiproxy approach combining population genetics modeling and remote-sensing analyses. We show that (i) contrary to most regions of Madagascar, the forest cover in Daraina remained remarkably stable over the past 60 y, and (ii) the golden-crowned sifaka (Propithecus tattersalli), a forest-dwelling lemur, underwent a strong population contraction before the arrival of the first humans, hence excluding an anthropogenic cause. Prehuman Holocene droughts may have led to a significant increase of grasslands and a reduction in the species' habitat. This contradicts the prevailing narrative that land cover changes are necessarily anthropogenic in Madagascar but does not preclude the later role played by humans in other regions in which recent lemur bottlenecks have been observed. habitat loss | primate | population bottleneck | coalescent

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

“…Although charcoal records (Burney,1987a;Burney 1987b), stratigraphic pollen occurrence (Gasse & Van Campo, 1998;Burns et al, 2016), and megafauna subfossil extinctions (Hansford et al, 2018) all point to human-mediated largescale ecological changes in the Central Highlands (Virah-Sawmy et al, 2010), our analyses implied that fundamental M. lehilahytsara population divergence coincides with Pleistocene climate change near the LGM -not after. A similar narrative has been recovered in other analyses of lemur populations (Quémére, Amelot, Pierson, Crouau-Roy, & Chikhi, 2012;Salmona et al, 2017) and in an endemic olive tree (Salmona et al 2019). In summary, phylogeographic analysis of multiple species and localities agree with ecological (Bond et al 2008) and evolutionary (Vorontsova et al, 2016;Hackel et al, 2018) (Burney, 1987a;Gasse & Van Campo, 1998;Virah-Sawmy et al, 2010;Burns et al, 2016;Samonds et al, 2019), leading to devastating forest loss in Madagascar (Vieilledent et al, 2018), ongoing habitat fragmentation is occurring on a background of habitat mosaicism that is likely associated with Pleistocene climate change.…”

Challenges of next‐generation sequencing in conservation management: Insights from long‐term monitoring of corridor effects on the genetic diversity of mouse lemurs in a fragmented landscape

“…Our comparison between the two sampling periods spanning close to 18 years of genetic monitoring demonstrates the high levels of genetic diversity in terms of heterozygosity in both the MHC II DRB gene and microsatellite markers before and after the establishment of corridors ( H Exp , Table ). Evidence of low genetic diversity derived from neutral markers with respect to a reduction in fragment size has been found in the Milne‐Edwards' sportive lemur, Lepilemur edwardsi (Craul et al, ), in the golden‐brown mouse lemur, Microcebus ravelobensis (Guschanski, Olivieri, Funk, & Radespiel, ) and postulated for Tattersall's sifaka ( Propithecus tattersalli ) (Quemere, Amelot, Pierson, Crouau‐Roy, & Chikhi, ). Apart from these three examples, neutral genetic diversity appears to be maintained despite discontinuities of species within their geographical range, for example mouse lemurs Microcebus bongolavensis , Microcebus danfossi (Olivieri, Sousa, Chikhi, & Radespiel, ) and Microcebus murinus (Fredsted, Pertoldi, Schierup, & Kappeler, ; Radespiel, Sarikaya, Zimmermann, & Bruford, ; Wimmer & Kappeler, ) and redfronted lemurs (Wimmer & Kappeler, ).…”

Exploring Approximate Bayesian Computation for inferring recent demographic history with genomic markers in nonmodel species

“…Unfortunately, the state-of-the-art statistical inference techniques applied to human data are currently out of reach for studies of natural populations of nonmodel organisms. Knowledge from demographic inference of these species is, however, crucial: it is often the most efficient way to determine how to manage invasive species (Benazzo, Ghirotto, Vilac ßa, & Hoban, 2015;Guillemaud, Beaumont, Ciosi, Cornuet, & Estoup, 2010), to conserve endangered species or ecosystems (Chan, Schanzenbach, & Hickerson, 2014;Dussex, Wegmann, & Robertson, 2014;Lopez, Mathers, Ezzati, Jamison, & Murray, 2006; Qu em er e, Amelot, Pierson, Crouau-Roy, & Chikhi, 2012), and to predict the future distribution and abundance of widespread species that are of economical or ecological importance (Holliday, Yuen, Ritland, & Aitken, 2010;Zinck & Rajora, 2016). The good news is the genomic revolution has reached non model organisms, creating a spectrum of levels of genetic knowledge across a broad range of taxa.…”