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Abstract Detail


Molecular Ecology and Evolution

Liao, Pei-Chun [1], Huang, Shong [1].

Is Kra Isthmus an effective barrier for the gene flow of Ceriops tagal (Rhizophoraceae)?

Malay Peninsula or the ancient Sundaland is commonly considered a barrier for isolating organisms living in the South China Sea and the Bay of Bengal. However, approximately 5 Mya there were leaks at Kra Isthmus, the narrowest part of this peninsula, due to interglacial sea-level rise. Organisms living in both sides of Kra Isthmus thus had opportunities to migrate or disperse to each other’s territory. In this paper, we examined the genetic composition of Ceriops tagal, a eumangrove species, that grows along the coasts of both sides of Kra Isthmus to retrace the event of divergence and evaluate the probability of long distance dispersal. The relatively higher Nm of populations within the same side than that of trans-isthmus, and the approximate one-third variations contributed by the differences between either sides of the populations illustrate the consequences of the vicariance of Kra Isthmus. The divergent time between populations at either side is consistent with the emergence of the Kra Isthmus, indicating that the genetic continuity was disrupted by geographic barrier. However, recent gene flow has led to the unresolved phylogenetic relationships of eastern and western haplotypes. In addition, based on the nested clade analysis of both a pre-isthmus range expansion event and a post-isthmus long distance dispersal event in the lower level clades, a restricted gene flow resulted from isolation by distance could be inferred in the total cladogram by a user-defined-distance (circling around the Malay Peninsula via sea route) algorithm. The trans-isthmus long distance dispersal was most probable through the southern Malay Peninsula. These results indicate that although the Malay Peninsula separates different populations, the interglacial leaks at the Strait of Malacca could serve as a corridor for crossing-sea-area gene flow. Thus, the allopatric speciation was arrested due to genetic homogenization via rare long distance dispersal.


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1 - National Taiwan Normal University, Department of Life Science, No.88, Sec. 4, Tingzhou Rd., Wenshan District, Taipei, Taiwan, 116, Republic of China

Keywords:
Ceriops tagal
Kra Isthmus
land barrier
long distance dispersal
vicariance.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P74002
Abstract ID:1104


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