T.M. Vignaud, J. Mourier, J.A. Maynard, R. Leblois, J.L.Y. Spaet, E. Clua, V. Neglia, S. Planes
Molecular Ecology, 23(21), pp. 5193-5207, (2014)
Blacktip reef sharks, Demographic history, French Polynesia, Genetic structure, Microsatellites, Population genetics
For free-swimming marine species like sharks, only population genetics
and demographic history analyses can be used to assess population
health/status as baseline population numbers are usually unknown. We
investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus;
one of the most abundant reef-associated sharks and the apex predator
of many shallow water reefs of the Indian and Pacific Oceans. Our
sampling includes 4 widely separated locations in the Indo-Pacific and
11 islands in French Polynesia with different levels of coastal
development. Four-teen microsatellite loci were analysed for samples
from all locations and two mitochondrial DNA fragments, the control
region and cytochrome b, were examined for 10 locations. For
microsatellites, genetic diversity is higher for the locations in the
large open systems of the Red Sea and Australia than for the fragmented
habitat of the smaller islands of French Polynesia. Strong significant
structure was found for distant locations with FST
values as high as ~0.3, and a smaller but still significant structure is
found within French Polynesia. Both mitochondrial genes show only a few
mutations across the sequences with a dominant shared haplotype in
French Polynesia and New Caledonia suggesting a common lineage different
to that of East Australia. Demographic history analyses indicate
population expansions in the Red Sea and Australia that may coincide
with sea level changes after climatic events. Expansions and flat
signals are indicated for French Polynesia as well as a significant
recent bottleneck for Moorea, the most human-impacted lagoon of the
locations in French Polynesia.