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12 Geogenetic Patterns in Mouse Lemurs (Genus Microcebus) Reveal the Ghosts of Madagascar's Forests Past - Anne D. Yoder, C. Ryan Campbell, Marina B. Blanco, Mario Dos Reis, Jrg U. Ganzhorn, Steven M. Goodman, Kelsie E. Hunnicutt, Peter A. Larsen, Peter M. Kappeler, Rodin M. Rasoloarison, Jos M. Ralison, David L. Swofford, and David W. Weisrock
Pages 235-256

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From page 235... ... Here, we attempt to understand how the dynamic process of landscape change on Mada gascar has shaped the distribution of a targeted clade of mouse lemurs (genus Microcebus) and, conversely, how phylogenetic and population genetic patterns in these small primates can reciprocally advance our understanding of Madagascar's prehuman environment. Read the entire page →
From page 236... ... Phylogenetic and population genetic patterns in a five species clade of mouse lemurs suggest that longitudinal dispersal across the island was readily achieved throughout the Pleistocene, apparently ending at ~55 ka. By examining patterns of both inter- and intraspecific genetic diversity in mouse lemur species found in the eastern, western, and Central Highland zones, we conclude that the natural environment of the Central Highlands would have been mosaic, consisting of a matrix of wooded savanna that formed a transitional zone between the extremes of humid eastern and dry western forest types. Read the entire page →
From page 237... ... The eastern humid forest, western dry deciduous forest, and the Central Highlands zones are now covered in part with what have been referred to as "secondary grasslands" or savanna composed primarily of Poaceae dominated by the subfamily Gramineae and subject to frequent burning. Today, the Central Highlands forms a stark habitat separation between the mesic zones of the east and the arid habitats of the west and south (Fig. Read the entire page →
From page 238... ... FIGURE 12.1 A map of Madagascar with the major biome types recognized in modern times and sampling locations used in this study for all 30 samples across six species within the genus Microcebus. Sampling counts at a given location varied between one and three individuals. Read the entire page →
From page 239... ... To address these questions, we examine phylogenetic and geogenetic (Bradburd et al., 2016) patterns in mouse lemurs (genus Microcebus) Read the entire page →
From page 240... ... . Thus, mouse lemurs are likely to track environmental variation with fine temporal resolution, with the added benefit of relatively precise generation times that can readily be translated parametrically in coalescent-based modeling methods. Read the entire page →
From page 241... ... The genomewide SNP data were analyzed with coalescent methods to estimate the species tree structure and its congruence with the mtDNA gene tree and to estimate divergence times for the five targeted species. Read the entire page →
From page 242... ... The very short internal branches that separate the remaining 11 species within this lineage suggest that they experienced rapid radiation, making phylogenetic resolution highly problematic. The mtDNA gene tree illustrates the depth and diversity of the mouse lemur radiation through time and across the geographic expanse of Madagascar (Fig. Read the entire page →
From page 243... ... . The dashed box highlights the five species targeted for genomewide SNP analysis. Read the entire page →
From page 244... ... Species are identified by their contemporary geographic range (eastern versus western) ; plateau, Central Highlands plateau. Read the entire page →
From page 245... ... and in mouse lemurs in particular (Olivieri et al., 2008; Schneider et al., 2010) Read the entire page →
From page 246... ... Taking this hypothesis to its logical extreme, patterns of genetic diversity within and among these relictual habitats thus might share a signature of genetic diversification driven by long-term isolation but punctuated by periods of gene flow. These fragments thus might be described as "museums" of genetic diversity within an otherwise desolated grassland savanna. Read the entire page →
From page 247... ... lehilahytsara presumably inhabited their respective habitats for millennia before the arrival of humans, the starkly higher genetic distances relative to geographic distances in M lehilahytsara suggests that this species has long lived in a mosaic environment. Read the entire page →
From page 248... ... myoxinus and M lehilahytsara, hypothesized historical forest type labeled by color, and boxes marking the sampling locations used for short and long geographic distance t-tests of genetic distance. Read the entire page →
From page 249... ... Abbreviated names indicate the geogenetic location, and ellipses represent 95% confidence interval of geogenetic location. The true sampling site is labeled with a colored dot, and arrows indicate direction of geographic pull via admixture. Read the entire page →
From page 250... ... lehilahytsara is a further indication that this putative plateau specialist displays remarkable levels of genetic diversity, despite its fragmented distribution. CONCLUSIONS The results of this study have specific implications regarding the timing and geographic patterns of divergence events among the five species of Microcebus targeted for phylogeographic analysis, as well as more general implications for the inferred habitat of the Central Highlands during the period of their diversification. Read the entire page →
From page 251... ... The targeted species analysis consisted of ddRAD sequencing of 30 wild-caught mouse lemurs from 15 study sites Read the entire page →
From page 252... ... . mtDNA Sequencing Sequence data were collected from 18 newly collected samples and four previously unsequenced samples for both the cytb and cox2 genes. Read the entire page →
From page 253... ... . The posterior of τ and θ can be converted to geological times of divergence and effective population sizes by using priors on the per-generation mutation rate and the generation time (Angelis and dos Reis, 2015) Read the entire page →
From page 254... ... , which roughly has a 95% prior CI between 3 and 4.5 years. Estimation of Average Generation Time for Genus Microcebus We estimated an average generation time for all species of mouse lemurs using a combination of data from both wild and captive populations, yielding an informed estimate of 3.0–4.5 years. Read the entire page →
From page 255... ... lehilahytsara. Individuals were assessed at every possible within-species dyad, and the resulting genetic and geographic distances were plotted to inspect visually for isolation by distance (IBD) Read the entire page →

From page 235...

... Here, we attempt to understand how the dynamic process of landscape change on Mada gascar has shaped the distribution of a targeted clade of mouse lemurs (genus Microcebus) and, conversely, how phylogenetic and population genetic patterns in these small primates can reciprocally advance our understanding of Madagascar's prehuman environment.