Ancient Divergence Time Estimates In Eutropis Rugifera Support The Existence Of Pleistocene Barriers On The Exposed Sunda Shelf
Episodic sea level changes that repeatedly exposed and inundated the Sunda Shelf characterize the Pleistocene. Available evidence points to a more xeric central Sunda Shelf during periods of low sea levels, and despite the broad land connections that persisted during this time, some organisms are...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
PeerJ
2017
|
| Subjects: | |
| Online Access: | http://ir.unimas.my/id/eprint/18584/ http://ir.unimas.my/id/eprint/18584/7/Ancient%20divergence%20time%20estimates%20%28abstract%29.pdf |
| Summary: | Episodic sea level changes that repeatedly exposed and inundated the Sunda Shelf
characterize the Pleistocene. Available evidence points to a more xeric central Sunda
Shelf during periods of low sea levels, and despite the broad land connections that
persisted during this time, some organisms are assumed to have faced barriers to
dispersal between land-masses on the Sunda Shelf. Eutropis rugifera is a secretive,
forest adapted scincid lizard that ranges across the Sunda Shelf. In this study, we
sequenced one mitochondrial (ND2) and four nuclear (BRCA1, BRCA2, RAG1, and
MC1R) markers and generated a time-calibrated phylogeny in BEAST to test whether
divergence times between Sundaic populations of E. rugifera occurred during
Pleistocene sea-level changes, or if they predate the Pleistocene. We find that
E. rugifera shows pre-Pleistocene divergences between populations on different Sundaic
land-masses. The earliest divergence within E. rugifera separates the Philippine samples
from the Sundaic samples approximately 16 Ma; the Philippine populations thus cannot
be considered conspecific with Sundaic congeners. Sundaic populations diverged
approximately 6 Ma, and populations within Borneo from Sabah and Sarawak separated
approximately 4.5 Ma in the early Pliocene, followed by further cladogenesis in
Sarawak through the Pleistocene. Divergence of peninsular Malaysian populations from
the Mentawai Archipelago occurred approximately 5 Ma. Separation among island
populations from the Mentawai Archipelago likely dates to the Pliocene/Pleistocene
boundary approximately 3.5 Ma, and our samples from peninsular Malaysia appear to
coalesce in the middle Pleistocene, about 1 Ma. Coupled with the monophyly of these
populations, these divergence times suggest that despite consistent land-connections
between these regions throughout the Pleistocene E. rugifera still faced barriers to
dispersal, which may be a result of environmental shifts that accompanied the sea-level
changes. |
|---|