Abstract
Many genera of terrestrial vertebrates diversified exclusively on one or the other side of Wallace’s Line, which lies between Borneo and Sulawesi islands in Southeast Asia, and demarcates one of the sharpest biogeographic transition zones in the world. Macaque monkeys are unusual among vertebrate genera in that they are distributed on both sides of Wallace‘s Line, raising the question of whether dispersal across this barrier was an evolutionary one-off or a more protracted exchange—and if the latter, what were the genomic consequences. To explore the nature of speciation over the edge of this biogeographic divide, we used genomic data to test for evidence of gene flow between macaque species across Wallace’s Line after macaques colonized Sulawesi. We recovered evidence of post-colonization gene flow, most prominently on the X chromosome. These results are consistent with the proposal that gene flow is a pervasive component of speciation—even when barriers to gene flow seem almost insurmountable.
Highlights
If no gene flow occurred after macaques colonized Sulawesi from Borneo, phylogenetic analyses presented below indicate that most genomic regions of the Sulawesi macaques would be expected to be monophyletic with respect to the pigtail macaque M. nemestrina, with the exception of regions with incomplete lineage sorting (ILS)
If gene flow occurred among macaques on either side of Wallace’s Line after macaques reached Sulawesi, there might be an excess of derived mutations that are shared by a pigtail macaque from eastern Borneo and a macaque from western Sulawesi (e.g. M. tonkeana) when compared with derived sites that are shared between a pigtail macaque and a macaque from eastern Sulawesi (e.g. M. nigra)
We did not find evidence that variation in the rate of evolution could account for this pattern, it is conceivable that population structure, for example due to isolation by distance, of the X chromosome existed in the ancestor of (M. nemestrina + the Sulawesi macaques) prior to dispersal of a subpopulation from Borneo to Sulawesi
Summary
A species is a group of reproductively compatible individuals with ancestor–descendant relationships that evolve through time [1]. Ideas about the drivers of speciation recognized geographical isolation as an important prezygotic barrier to reproduction that contributes to this process, with this reasoning being heavily influenced by zoogeographic patterns [12]), the evolutionary consequences of gene flow and adaptation during speciation Wallace’s Line is an important evolutionary arena for studying speciation because some groups have anomalous distributions that span this barrier. These groups permit us to test whether allopatric lineages on either side of a precipitous biogeographic barrier are isolated genetically and, if not, what genomic regions were affected by gene flow, and what were the adaptive implications
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
