New insight on the genetic connectivity of the widespread amphidromous prawn Macrobrachium lar (Fabricius, 1798) (Crustacea: Decapoda: Palaemonidae).

Due to the sparse and unstable nature of insular
freshwater habitats, marine larval dispersal of amphidromous
species is considered a critical element of population
persistence. We assessed population genetic structure
of freshwater prawn Macrobrachium lar across its range
that encompasses two biogeographic barriers: the vast open
ocean separating Western and Central Pacific regions and
the Indo-Malay archipelago separating Indian and Pacific
oceans. A total of 173 samples collected from 21 islands
throughout the Indo-Pacific were sequenced at 16S and 28S
rDNA. We observed distinct genetic isolation of populations
located at the eastern and southwestern edge of the
species range but no evidence of an effect of the Indo-
Pacific barrier. Differentiation patterns are consistent with
a stepping-stone model of dispersal. Genetic differences of
Central Pacific populations may reflect founder events
associated with colonization of isolated islands, or be a
signature of a past bottleneck after population depletion
caused by drastic climatic events.