Life history variation in a marine teleost across a heterogeneous seascape

Life history traits, primarily related to growth and reproduction, often reflect the process of adaptation of organisms to their natural environment. Consequently, life history parameters are expected to differ along heterogeneous habitats. Provided the pivotal role of life-history traits in determining fitness, the description and understanding of life history variation is a central goal in evolutionary ecology. In order to test the influence of the known environmental heterogeneity of Mediterranean coastal seas, populations of the striped sea bream Lithognathus mormyrus, were sampled from five distinct geographic areas within, or adjacent to, the Mediterranean basin (Aborلn Sea, Balearic Sea, Tyrrhenian Sea, Adriatic Sea and the Gulf of Cadiz in the Atlantic Ocean). Growth patterns, maturation, sex-ratio, sex change and feeding habits were investigated over two years and revealed large-scale life history variation. Similarly slanted growth, earlier maturation times and smaller size-at-sex change were found in the Tyrrhenian and the Adriatic populations, which appear in contrast with recent population genetic investigation. The potential influence of fishery exploitation on these traits is discussed as a possible determining factor. The present study provides an exemplar of life-history variation across a heterogeneous seascape and makes a case for a more judicious consideration of ecological information for the purpose of identifying population units for management and conservation.