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Signals of recent spatial expansions in the grey mouse lemur (Microcebus murinus).

Schneider N, Chikhi L, Currat M, Radespiel U - BMC Evol. Biol. (2010)

Bottom Line: Pleistocene events have shaped the phylogeography of many taxa worldwide.Demographic simulations detected signals of two successive spatial expansions that could be preliminarily dated to the late Pleistocene and early Holocene.The haplotype network revealed geographic structure and showed deep molecular divergences within and between the IRSs that would be congruent with a two-step colonization scenario.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Zoology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.

ABSTRACT

Background: Pleistocene events have shaped the phylogeography of many taxa worldwide. Their genetic signatures in tropical species have been much less explored than in those living in temperate regions. We analysed the genetic structure of a Malagasy primate species, a mouse lemur with a wide distribution (M. murinus), in order to investigate such phylogeographic processes on a large tropical island. We also evaluated the effects of anthropogenic pressures (fragmentation/deforestation) and natural features (geographic distance, rivers) on genetic structure in order to complement our understanding of past and present processes of genetic differentiation.

Results: The analysis of the mitochondrial D-loop sequences of 195 samples from 15 study sites (10 from a continuous forest and five from isolated forest fragments) from two adjacent Inter-River-Systems (IRSs) revealed that forest fragmentation and the river restrict gene flow, thereby leading to an increased genetic differentiation between populations beyond the effect of isolation-by-distance. Demographic simulations detected signals of two successive spatial expansions that could be preliminarily dated to the late Pleistocene and early Holocene. The haplotype network revealed geographic structure and showed deep molecular divergences within and between the IRSs that would be congruent with a two-step colonization scenario.

Conclusions: This study supports the hypothesis of a relatively recent spatial expansion of the grey mouse lemur in northwestern Madagascar, which may also explain why this taxon, in contrast to its congeners, has not yet undergone allopatric speciation in the studied area and possibly across its presently wide range.

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Schematic map of the sampling populations in the IRS1 with the outline of the ANP as a thin black line. The proportion of individuals of each site belonging to clusters 1-4 (see Figure 6 for the delineation of the clusters) are indicated in site-specific pie-charts.
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Figure 7: Schematic map of the sampling populations in the IRS1 with the outline of the ANP as a thin black line. The proportion of individuals of each site belonging to clusters 1-4 (see Figure 6 for the delineation of the clusters) are indicated in site-specific pie-charts.

Mentions: The network analysis revealed three distinct sets of haplotypes which were separated by more than 23 mutation steps from each other (Figure 6). The first set was within IRS1. It contained 43 different haplotypes which showed 1-37 pairwise differences, and could be grouped into four clusters separated by more than 10 mutational steps. Even though the most divergent haplotypes are very different, there are many intermediate haplotypes. The other haplotypes were located within the IRS2 and were separated by at least 30 mutation steps from each other and by 24-26 mutations from the closest IRS1 haplotype. One haplotype was limited to Maroakata and the other three to Tsinjomitondraka. In contrast, the spatial structure was not as obvious within the IRS1, as haplotypes observed within one site were not always more similar to each other than to haplotypes from other sites. However, a spatial structure was revealed after mapping the representation of the four clusters in IRS1 (Figure 7). The sites in the ANP could be partitioned into a homogenous western and eastern division, respectively, and a zone of heterogeneous composition in the centre. The four westernmost sites in the ANP (Komandria, Bealana, JBA, Ambodimanga) mainly contained haplotypes of cluster 2, whereas the four eastern sites in the ANP (Beronono, Bevazaha, Ankoririka, Andoharano) and the fragment Mangatelo mainly contained haplotypes of cluster 1. Haplotypes of cluster 3 were only found in three heterogeneous central park populations (Ambanjakely, Andoharano, Andofombobe) and the two fragments Ste Marie and Tanambao. Finally, cluster 4 which consists of one haplotype, was only present in the northernmost fragment Tanambao.


Signals of recent spatial expansions in the grey mouse lemur (Microcebus murinus).

Schneider N, Chikhi L, Currat M, Radespiel U - BMC Evol. Biol. (2010)

Schematic map of the sampling populations in the IRS1 with the outline of the ANP as a thin black line. The proportion of individuals of each site belonging to clusters 1-4 (see Figure 6 for the delineation of the clusters) are indicated in site-specific pie-charts.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2875232&req=5

Figure 7: Schematic map of the sampling populations in the IRS1 with the outline of the ANP as a thin black line. The proportion of individuals of each site belonging to clusters 1-4 (see Figure 6 for the delineation of the clusters) are indicated in site-specific pie-charts.
Mentions: The network analysis revealed three distinct sets of haplotypes which were separated by more than 23 mutation steps from each other (Figure 6). The first set was within IRS1. It contained 43 different haplotypes which showed 1-37 pairwise differences, and could be grouped into four clusters separated by more than 10 mutational steps. Even though the most divergent haplotypes are very different, there are many intermediate haplotypes. The other haplotypes were located within the IRS2 and were separated by at least 30 mutation steps from each other and by 24-26 mutations from the closest IRS1 haplotype. One haplotype was limited to Maroakata and the other three to Tsinjomitondraka. In contrast, the spatial structure was not as obvious within the IRS1, as haplotypes observed within one site were not always more similar to each other than to haplotypes from other sites. However, a spatial structure was revealed after mapping the representation of the four clusters in IRS1 (Figure 7). The sites in the ANP could be partitioned into a homogenous western and eastern division, respectively, and a zone of heterogeneous composition in the centre. The four westernmost sites in the ANP (Komandria, Bealana, JBA, Ambodimanga) mainly contained haplotypes of cluster 2, whereas the four eastern sites in the ANP (Beronono, Bevazaha, Ankoririka, Andoharano) and the fragment Mangatelo mainly contained haplotypes of cluster 1. Haplotypes of cluster 3 were only found in three heterogeneous central park populations (Ambanjakely, Andoharano, Andofombobe) and the two fragments Ste Marie and Tanambao. Finally, cluster 4 which consists of one haplotype, was only present in the northernmost fragment Tanambao.

Bottom Line: Pleistocene events have shaped the phylogeography of many taxa worldwide.Demographic simulations detected signals of two successive spatial expansions that could be preliminarily dated to the late Pleistocene and early Holocene.The haplotype network revealed geographic structure and showed deep molecular divergences within and between the IRSs that would be congruent with a two-step colonization scenario.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Zoology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.

ABSTRACT

Background: Pleistocene events have shaped the phylogeography of many taxa worldwide. Their genetic signatures in tropical species have been much less explored than in those living in temperate regions. We analysed the genetic structure of a Malagasy primate species, a mouse lemur with a wide distribution (M. murinus), in order to investigate such phylogeographic processes on a large tropical island. We also evaluated the effects of anthropogenic pressures (fragmentation/deforestation) and natural features (geographic distance, rivers) on genetic structure in order to complement our understanding of past and present processes of genetic differentiation.

Results: The analysis of the mitochondrial D-loop sequences of 195 samples from 15 study sites (10 from a continuous forest and five from isolated forest fragments) from two adjacent Inter-River-Systems (IRSs) revealed that forest fragmentation and the river restrict gene flow, thereby leading to an increased genetic differentiation between populations beyond the effect of isolation-by-distance. Demographic simulations detected signals of two successive spatial expansions that could be preliminarily dated to the late Pleistocene and early Holocene. The haplotype network revealed geographic structure and showed deep molecular divergences within and between the IRSs that would be congruent with a two-step colonization scenario.

Conclusions: This study supports the hypothesis of a relatively recent spatial expansion of the grey mouse lemur in northwestern Madagascar, which may also explain why this taxon, in contrast to its congeners, has not yet undergone allopatric speciation in the studied area and possibly across its presently wide range.

Show MeSH
Related in: MedlinePlus