Linking the energetics of reproduction to population demography in a marine apex predator
Evolution, Anthropology
Final Report Abstract
The evolution of life histories in Galapagos sea lions happened under great environmental uncertainty. Working with Galapagos sea lions was and is still a challenge for me, but the project has been very successfully established by my predecessor Fritz Trillmich and the ongoing collaboration between us is very rewarding from my side. Despite two major problems in terms of permits and logistics during the last funding period, we have shown that there is great variation in the age at first reproduction (4-9 years), but that there are currently no significant factors explaining this variation. It appears on current evidence that once females start their reproductive careers, they do not seem to vary either inter-birth interval or pupping rate in response to whether they started early or late nor whether they were born in good or bad conditions. Females give birth to around 0.4 pups per year and there is no evidence of a decline in old ages, either due to low sample sizes or absence of effects. We have been able to produce survival rate estimates for the entire length of the life history for the first time and they are at the lower bound in comparison to other pinnipeds. Combining both vital rates in a matrix model yielded population projections that mostly predict very negative population growth rates over the next 50 years. First evidence from census data also seem to indicate that the population is in decline. Being able to closely observe the behaviour of sea lion pups and their mothers, we were able to establish protocols and tests to document animal personalities in these pups and mothers. Behaviour of pups is systematically affected by the presence of their mothers. We very recently showed that these personalities are related to space-use on the island.
Publications
- (2016) Complex interpretation of census data: insights from a study of an endangered pinniped. PLoS One 11: e0154588
Trillmich, F., Meise, K., Kalberer, S., Mueller, B., Piedrahita, P., Pörschman, U., Wolf, J. B. W. & Krüger, O.
(See online at https://doi.org/10.1371/journal.pone.0154588) - (2018) Recent demographic histories and genetic diversity across pinnipeds are shaped by anthropogenic interactions and mediated by ecology and life-history. Nature Comms. 9: 4836
Stoffel, M. A., Humble, E., Paijmans, A. J., Acevedo-Whitehouse, K., Chilvers, B. L., Dickerson, B., Galimberti F., Gemmell, N., Goldsworthy, S. D, Nichols, H. J., Krüger, O., Negro, S., Osborne, A., Pastor, T., Robertson, B. C., Sanvito, S., Schultz, J., Shafer, A. B. A., Wolf, J. B. W. & Hoffman, J. I.
(See online at https://doi.org/10.1038/s41467-018-06695-z) - (2018) Reproductive performance of a tropical apex predator in an unpredictable habitat. Behav. Ecol. Sociobiol. 72: 108
Kalberer, S., Meise, K., Trillmich, F. & Krüger, O.
(See online at https://doi.org/10.1007/s00265-018-2521-7) - (2019) Evolution of age at primiparity in pinnipeds in the absence of the quality-quantity trade-off in reproduction. Ecol. Evol. 9: 5450-5456
Kalberer, S., DeRango, E., Trillmich, F. & Krüger, O.
(See online at https://doi.org/10.1002/ece3.5138) - (2019) Intraspecific variation in boldness and exploration shapes behavioral responses to stress in Galápagos sea lion pups. Behav. Ecol. Sociobiol. 73:166
DeRango, E., Schwarz, J. F. L., Piedrahita, P., Paez-Rosas, D., Trillmich, F. & Krüger, O.
(See online at https://doi.org/10.1007/s00265-019-2775-8) - (2019) Intrinsic and maternal traits influence personality during early life in Galápagos sea lion (Zalophus wollebaeki) pups. Anim. Behav. 154: 111-120
DeRango, E., Kalberer, S., Schwarz, J., Paez-Rosas, D., Piedrahita, P., Trillmich, F. & Krüger, O.
(See online at https://doi.org/10.1016/j.anbehav.2019.06.011)
