Postmating isolation and evolutionary relationships among Fejervarya
species from Lesser Sunda, Indonesia and other Asian countries revealed
by crossing experiments and mtDNA Cytb gene sequences
In order to interpret the degree of postmating isolation and the
evolutionary relationships among Fejervarya species from Indonesia
(Lesser Sunda), Bangladesh, China, and Japan, crossing experiments and
molecular phylogenetic analyses were carried out using frogs of
Fejervarya species from these countries. The crossing experiments
revealed that the reciprocal hybrids among F. iskandari, F. verruculosa,
and F. sp. Large type, and those between F. multistriata and F.
kawamurai were viable through metamorphosis, but those between F.
iskandari group and F. limnocharis group were completely or partially
inviable at the tadpole stage, and those between Southeast -Asian and
South-Asian Fejervarya groups were completely inviable at the embryonic
stage. The matured reciprocal hybrids between F. iskandari and F.
verruculosa from Indonesia, Lesser Sunda showed some degree of
abnormality in spermatogenesis. The phylogenetic analyses using mtDNA
Cytb gene sequences demonstrated that F. iskandari formed a sister clade
with F. verruculosa from Lesser Sunda, Indonesia with 8.1% sequence
divergence. Fejervaraya multistriata from China made a clade with
Thailand, Malaysia and Indonesian (topotype) populations of F.
limnocharis which showed sister relationships to F. kawamurai from Japan
with 8.9% sequence divergence of Cytb gene. Fejervarya sp. small type
from Bangladesh formed a clade with the other South-Asian members of
Fejervarya group and made a sister clade with Southeast-Asian Fejervarya
group having 23.1% sequence divergence of Cytb gene. This study showed
that the degree of postmating isolation reflects the molecular
phylogenetic relationships, and that the two species, F. iskandari and
F. verruculosa from Indonesia (Lesser Sunda) are reproductively isolated
by abnormal spermatogenesis, and genetically deviated.