Elephant Seal Senescence

How demography and behavior changes as elephant seals age.
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I led a class of 14 undergraduate students in designing and executing this project investigating the types of changes in elephant seal demography and behavior as they age. We found that female elephant seals experienced reproductive senescence in the form of decreased breeding probability and decreased offspring survival with advanced maternal age.

This project was published in the the Journal of Animal Ecology. Read the paper here or check out the GitHub repository here.

Breeding probability for adult female elephant seals increased up to age 11, and decreased after age 11, with the latter providing evidence for fertility senescence. Black points and error bars show the mean and 95% CI of breeding rates. Sample sizes for each age class are included above the points. Thin grey lines show the mean response for each year of the study (i.e. including the random effect of year). The thick solid lines and shaded areas show the mean response and 95% confidence interval of the fitted model, weighted by the number of seals observed in each year. The unweighted fitted model is shown by the dotted grey line. Illustrations by Alex Boersma.

Breeding probability for adult female elephant seals increased up to age 11, and decreased after age 11, with the latter providing evidence for fertility senescence. Black points and error bars show the mean and 95% CI of breeding rates. Sample sizes for each age class are included above the points. Thin grey lines show the mean response for each year of the study (i.e. including the random effect of year). The thick solid lines and shaded areas show the mean response and 95% confidence interval of the fitted model, weighted by the number of seals observed in each year. The unweighted fitted model is shown by the dotted grey line. Illustrations by Alex Boersma.

I also wrote a blog post for the journal’s blog, Animal Ecology in Focus, which talks about my experience publishing the manuscript while TAing the field class.