Dear MARMAM colleagues,
We are pleased to announce that the following paper is now available online:
Enrico Pirotta, Morgana Vighi, José María Brotons, Eileen Dillane, Margalida
Cerdà, Luke Rendell. 2020. Stable isotopes suggest fine-scale sexual
segregation in an isolated, endangered sperm whale population. Marine Ecology
Progress Series 654: 209-218.
Abstract:
Sexual segregation is common among marine mammals, leading to intraspecific
differences in diet, diving behaviour, home range size and even latitudinal
distribution and migratory patterns. Sperm whales Physeter macrocephalus
present one of the most extreme examples of sexual dimorphism both in size and
social structure, with males and females segregating at different latitudes
across most of their range, but the underlying ecological drivers remain
unclear. Studying fine-scale dietary and habitat differences where the sexes
occur in sympatry could therefore provide insights into the mechanisms
underpinning their large-scale segregation. In this study, we analysed the
carbon and nitrogen stable isotope values in the skin of males and females from
an isolated, endangered population inhabiting the Mediterranean Sea, sampled in
a region where the sexes occur and feed regularly in the summer months but show
subtle differences in habitat preference. We found marked differences in both
carbon and nitrogen isotopic values between the sexes, indicating that they
could be targeting prey items in different trophic levels and habitats.
Combined with the evidence from habitat modelling studies, our results suggest
that female and male sperm whales segregate even in the latitudinally
restricted Mediterranean population, at a much smaller scale. This sympatric,
fine-scale sexual segregation suggests that reduction of competition may have
been a key factor in the evolution of the social structure and large-scale
latitudinal segregation of this species.
Keywords: Dietary differences · Sexual segregation · Dimorphism · Sperm whale
· Physeter macrocephalus · Mediterranean Sea
A PDF copy of the paper can be downloaded from:
https://www.int-res.com/abstracts/meps/v654/p209-218/
Please do not hesitate to contact me for any question regarding our work.
Best Regards,
Enrico Pirotta
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