[MARMAM] New paper: Individual variation of hormones and behavior in sea lions

Geno DeRango gderango at gmail.com
Sat Dec 19 15:32:01 PST 2020

Dear all,

My co-authors and I are happy to present our new paper on state conditions,
hormones, and behavior in Galapagos sea lion pups.

The PDF is available open-access on Researchgate or direct from Oecologia:

Between-individual variation in behavior can emerge through complex
interactions between state-related mechanisms, which include internal
physiological constraints or feedback derived from the external
environment. State-related conditions can be especially influential during
early life, when parental effort and exposure to social stress may canalize
consistent differences in offspring hormonal profiles and foster specific
behavioral strategies. Here, we unravel how relevant state variables,
including sex, somatic condition, local population density, and maternal
traits, contribute to within-cohort differences in stress, sex, and thyroid
hormone axes in dependent Galapagos sea lions with the primary goal of
understanding downstream effects on boldness, docility, habitat use, and
activity. Pups within denser natal sites had higher levels of cortisol and
thyroid T4, a prohormone and proxy for metabolic reserves, likely as an
adaptive physiological response after exposure to increased numbers of
conspecific interactions. Furthermore, considering maternal effects,
mothers in better body condition produced pups with higher testosterone yet
downregulated basal cortisol and thyroid T4. This hormonal profile was
correlated with increased boldness toward novel objects and attenuated
stress responsiveness during capture. Intriguingly, pups with increased
thyroid T3, the biologically active form, maintained faster somatic growth
and were observed to have increased activity and extensively explored
surrounding habitats. Collectively, these findings provide comprehensive
evidence for several links to hormone-mediated behavioral strategies,
highlighted by variation in socio-environmental and maternally derived
input during a foundational life stage.

Please do not hesitate to contact me with questions at gderango at gmail.com .

Best regards,

Geno DeRango
PhD Student
Department of Animal Behaviour
Bielefeld University
Galapagos sea lion Project
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