Population genetic structure, phylogeography and demographic history of
Hilsa shad (Tenualosa ilisha) in the Indian Ocean region
Abstract
Understanding the evolutionary processes that have molded the genetic
structure to adapt to environmental changes is an important component of
successful and sustainable long-term management for the fisheries
resources. In this study, we analyzed mitochondrial control region
(D-loop) sequence data to reveal population genetic variation,
phylogeography and demographic history of T. ilisha collected from six
locations of the Indian Ocean regions (Bay of Bengal, Arabian Sea and
Persian Gulf). High haplotype diversity was found for all of the
populations of T. ilisha. The Analysis of Molecular Variance (AMOVA) and
conventional population FST comparisons detected both high
population-level genetic variation and high degrees of divergence
between groups within the Bay of Bengal (Irrawaddy river, MP; the coast
of Cox’s Bazar, XP; the delta of Meghna, MP and Hooghly river, IP) and
Arabian Sea (the delta of Indus river, PP and the coast of Kuwait, KP).
Four cryptic genetic barriers were found for the studied populations of
T. ilisha, and the highest degree of population divergence was found
between the Eastern Indian Ocean (Arabian Sea and Persian Gulf) and
Western Indian Ocean (the Bay of Bengal region) regions based on the
Voronoï tessellation of BARRIER analysis. The gene flow analysis
detected almost no migration between Eastern and Western part of the
Indian Ocean regions. Besides, one-way migration was found from IP to MP
population in the Bay of Bengal and from PP of Arabian Sea to KP
population of Persian Gulf. Mismatch distribution showed that T. ilisha
underwent long-time stable population size. Distinct cryptic genetic
barriers, limited gene flows and complex evolutionary process resulted a
significant population genetic and phylogeographic structure, and
intricate demographic histories of T. ilisha populations. Further, the
study provided additional insights for conserving and managing of this
fishery resource in its broad geographical distribution coverage.