Molecular Ecology

During my research projects, I have been using molecular ecology to answers specific questions about the studied populations and species, such as determining their regional or worldwide genetic connectivity or investigating their breeding system.

1) Parentage analyses to infer breeding patterns and reproductive philopatry

I used parentage analyses to assign juveniles that were sampled in their nursery area around the island of Moorea every year to their parents that were sampled on their home reef around the island. This resulted in the identification of reproductive philopatry where female blacktip reef sharks returned every year to give birth in the same nursery area. In addition, some females even migrated across open waters to reach nurseries at the nearby atoll Tetiaroa located about 50 km from Moorea. We also suspected the presence of natal philopatry, where females return to their birth place to give birth like turtle or salmon do, as we found several sisters using the same nursery area for parturition.

This program is still underway at CRIOBE in order to fill the life cycle and confirm the presence of natal philopatry by trying find if females that were sampled as juveniles 10 years ago come back to their birth place for parturition.

Migrations of female blacktip reef sharks from their home reef, to their nursery area in Moorea. Note that some are going to the same nursery on multiple years to give birth. This was demonstrated using genetic parentage analysis that assigned juveniles back to their parents within the population (Mourier & Planes 2013).

Reproductive migrations between Moorea and Tetiaroa, 2 islands separated by about 50 km and deep water (>2000 m) (Mourier & Planes 2013).

Similar research have been conducted on the sicklefin lemon shark (Negaprion acutidens) to investigate reproductive philopatry and demonstrate the presence of multiple paternity (polyandrie) (Mourier et al. 2013)

2) Genetic population structure

Genetic analyses were also conducted using microsatellite markers to investigate the regional or global genetic population structure and reveal patterns of connectivity.

Genetic structure diagram of blacktip reef sharks (Carcharhinus melanopterus) produced by DAPC analysis—each vertical bar represents an individual, and each colour represents the probability of belonging to one of the genetic clusters (top). Sampling locations are shown on the bottom in the Indian and Pacific oceans (left) and in French Polynesia (right). (Vignaud et al. 2014)