Dear Marmamers, My co-authors and I would like to draw your attention to a new paper that has just been published in Scientific Reports examining the links between stress coping styles (linked to ‘personalities’) in grey seals and reproductive expenditure and fitness outcomes. The paper is Open Access and can be found at; https://www.nature.com/articles/s41598-020-66597-3 Full details and abstract: Reactive stress-coping styles show more variable reproductive expenditure and fitness outcomes Sean D. Twiss, Courtney R. Shuert, Naomi Brannan, Amanda M. Bishop & Patrick. P. Pomeroy Sci Rep 10, 9550 (2020). https://doi.org/10.1038/s41598-020-66597-3 Abstract Stress-coping styles dictate how individuals react to stimuli and can be measured by the integrative physiological parameter of resting heart-rate variability (HRV); low resting HRV indicating proactive coping styles, while high resting HRV typifies reactive individuals. Over 5 successive breeding seasons we measured resting HRV of 57 lactating grey seals. Mothers showed consistent individual differences in resting HRV across years. We asked whether proactive and reactive mothers differed in their patterns of maternal expenditure and short-term fitness outcomes within seasons, using maternal daily mass loss rate to indicate expenditure, and pup daily mass gain to indicate within season fitness outcomes. We found no difference in average rates of maternal daily mass loss or pup daily mass gain between proactive and reactive mothers. However, reactive mothers deviated more from the sample mean for maternal daily mass and pup daily mass gain than proactive mothers. Thus, while proactive mothers exhibit average expenditure strategies with average outcomes, expenditure varies much more among reactive mothers with more variable outcomes. Overall, however, mean fitness was equal across coping styles, providing a mechanism for maintaining coping style diversity within populations. Variability in reactive mothers’ expenditures and success is likely a product of their attempts to match phenotype to prevailing environmental conditions, achieved with varying degrees of success. Best wishes to all, Sean _________________________________ Dr. Sean Twiss, Associate Professor in Animal Behaviour and Behavioural Ecology, Department of Biosciences, South Road, Durham University, Durham, DH1 3LE, UK. E-mail: s.d.twiss@durham.ac.uk Web-site: https://www.dur.ac.uk/biosciences/about/schoolstaff/academicstaff/?id=1132 Blog: http://sealbehaviour.wordpress.com/ Behaviour, Ecology and Evolution Research (BEER) Centre: www.dur.ac.uk/beer-centre<https://owa.dur.ac.uk/owa/redir.aspx?C=AjvknJfcq0-zlL0498uhGGKmvrw4G9MIOkl7uzB2o0DQWJkijfaedd4PLox8gN2oJ64a8h9XCa8.&URL=http%3a%2f%2fwww.dur.ac.uk%2fbeer-centre> Tel: +44 (0)191 334 1350 (office) Tel: +44 (0)191 334 1247 (lab) Fax: +44 (0)191 334 1201 _________________________________