Monday, 13 October 2014

Biosciences Seminar Speaker - 16 October 2014

Biosciences Seminar Series - Autumn 2014
16 October 2014 - 1pm - Zoology Museum (Wallace 129)

Dying without wings: ecological drivers of lifespan variation in mammals and birds

Dr. Natalie Cooper

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No, do not take the title too literally. If you attempt to strap on a pair of wings chances are you might end up as Otto Lilienthal and decrease your lifespan, not lengthen it. But certainly this is one of most basic questions - why do certain individuals, and especially, certain species live so much longer than others? Well, chances are that if you have given your kids a mice or hamster or similar small mammal as pet, within a few years you will have to explain and console them about the certainty of death. If you had chosen a cat, dog, this might get postponed until the kids will be in their teens at least, and if it was a parrot, the latter might well outlive yourself (parrots can live up to 80 years).

As these examples suggest, body size might perhaps be linked to variation in lifespan and this is indeed true. However, body size explains at best 30% of the variation in lifespan among mammals and birds, as also the example of the parrot suggests (parrots are smaller than most dogs and cats). This is where the research by our seminar speaker of this weeks comes into play. Dr. Natalie Cooper from Trinity College Dublin (Ireland) and coauthors recently published a new study investigating this fundamental question, as she will explain us in her seminar.

Natalie is broadly interested in questions in macroecology and macroevolution and her research spans from questions about convergent evolution and echolocation in Malagasy tenrecs, to analyses on how to use primate fossil data to better inform our interpretation of present-day biodiversity patterns, to studies of parasite sharing among primates.

Maximum lifespan in birds and mammals varies strongly with body mass such that large species tend to live longer than smaller species. However, many species live far longer than expected given their body mass. This may reflect interspecific variation in extrinsic mortality, as life-history theory predicts investment in long-term survival is under positive selection when extrinsic mortality is reduced. 

Here, we investigate how multiple ecological and mode-of-life traits that should reduce extrinsic mortality (including volancy (flight capability), activity period, foraging environment and fossoriality), simultaneously influence lifespan across endotherms. Using novel phylogenetic comparative analyses and to our knowledge, the most species analysed to date (n = 1368), we show that, over and above the effect of body mass, the most important factor enabling longer lifespan is the ability to fly. Within volant species, lifespan depended upon when (day, night, dusk or dawn), but not where (in the air, in trees or on the ground), species are active. However, the opposite was true for non-volant species, where lifespan correlated positively with both arboreality and fossoriality. 

Our results highlight that when studying the molecular basis behind cellular processes such as those underlying lifespan, it is important to consider the ecological selection pressures that shaped them over evolutionary time.

Hope to see many of you attending!

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