title: Spatio-temporal population structuring and genetic diversity retention in depleted Atlantic bluefin tuna of the Mediterranean Sea.
abstract: Fishery genetics have greatly changed our understanding of population dynamics and structuring in marine fish. In this study, we show that the Atlantic Bluefin tuna (ABFT, Thunnus thynnus), an oceanic predatory species exhibiting highly migratory behavior, large population size, and high potential for dispersal during early life stages, displays significant genetic differences over space and time, both at the fine and large scales of variation. We compared microsatellite variation of contemporary (n = 256) and historical (n = 99) biological samples of ABFTs of the central-western Mediterranean Sea, the latter dating back to the early 20th century. Measures of genetic differentiation and a general heterozygote deficit suggest that differences exist among population samples, both now and 96-80 years ago. Thus, ABFTs do not represent a single panmictic population in the Mediterranean Sea. Statistics designed to infer changes in population size, both from current and past genetic variation, suggest that some Mediterranean ABFT populations, although still not severely reduced in their genetic potential, might have suffered from demographic declines. The short-term estimates of effective population size are straddled on the minimum threshold (effective population size = 500) indicated to maintain genetic diversity and evolutionary potential across several generations in natural populations.
authors.affiliation: Department of Biology and Evolution, University of Ferrara, 44100 Ferrara, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Riccioni
authors.forename: Monica
authors.initials: M
authors.lastname: Landi
authors.forename: Giorgia
authors.initials: G
authors.lastname: Ferrara
authors.forename: Ilaria
authors.initials: I
authors.lastname: Milano
authors.forename: Alessia
authors.initials: A
authors.lastname: Cariani
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Zane
authors.forename: Massimo
authors.initials: M
authors.lastname: Sella
authors.forename: Guido
authors.initials: G
authors.lastname: Barbujani
authors.forename: Fausto
authors.initials: F
authors.lastname: Tinti
mesh_terms: D000483:Alleles; D025041:Animal Migration; D000818:Animals; D001267:Atlantic Ocean; D017753:Ecosystem; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population; D008522:Mediterranean Sea; D018895:Microsatellite Repeats; D008957:Models, Genetic; D011156:Population Density; D011157:Population Dynamics; D014413:Tuna / Q000235:genetics*