Studying demographic and genetic connectivity can help assessing marine meta-population structure. Rays and skates have no larval phase hence population connectivity can only result from active movement of individuals. Using thornback ray (Raja clavata) in European waters as a case study, demographic and genetic connectivity were studied for 11 putative populations for unequal population abundances and two hypotheses of dispersal rates. Genetic simulation results highlighted three large meta-populations: in the Mediterranean, around the Azores and on the Northeast Atlantic shelf. Demographic results highlighted a finer population structure indicating that several pairs of putative populations might be demographically linked. Results were highly sensitive to dispersal assumptions and relative population abundances, which provided insights into the potential magnitude of genetic and demographic connectivity differences. Accounting for demographic connectivity appears to be crucial for managing and conserving rays and skates while genetic connectivity provides a longer term perspective and less subtle spatial structures. Moreover, accounting for heterogeneity in population abundances is a key factor for determining or interpreting meta-population connectivity.

Studying demographic and genetic connectivity can help assessing marine meta-population structure. Rays and skates have no larval phase hence population connectivity can only result from active  movement of individuals. Using thornback ray (Raja clavata) in European waters as a case study, demographic  and genetic connectivity were studied for 11 putative populations for unequal population abundances and two  hypotheses of dispersal rates. Genetic simulation results highlighted three large meta-populations: in the  Mediterranean, around the Azores and on the Northeast Atlantic shelf. Demographic results highlighted a finer  population structure indicating that several pairs of putative populations might be demographically linked.  Results were highly sensitive to dispersal assumptions and relative population abundances, which provided  insights into the potential magnitude of genetic and demographic connectivity differences. Accounting for  demographic connectivity appears to be crucial for managing and conserving rays and skates while genetic  connectivity provides a longer term perspective and less subtle spatial structures. Moreover, accounting for  heterogeneity in population abundances is a key factor for determining or interpreting meta-population  connectivity.