Small populations in novel habitats: extinction risk, inbreeding depression and adaptation

Ruth Hufbauer
Colorado State University, Ruth.Hufbauer@ColoState.edu

(Seminar in English)

The eco-evolutionary dynamics of small populations in novel habitats are crucial to understanding and managing biological invaders as well as rare and endangered species. I will present findings from a model biological system (Tribolium castaneum) focused the ability of adaptive evolution, with or without migration, to “rescue” small populations from extinction, as well as the constraints on adaptive evolution due to inbreeding depression. Even in very small populations (e.g. founded with 10 individuals) evolution can reduce short-term extinction risk. However, the benefits of adaptation are quickly masked by inbreeding depression if populations are closed and carrying capacity is low. In environments enabling spread and thus with a larger carrying capacity, adaptive evolution can increase population size several fold. This has knock-on effects on rates of spread, both via spatial selection on dispersal, and via density dependent dispersal. Rapid evolution is thus highly effective at reducing extinction risk and driving population growth and expansion of colonizers across a new range. The use of a model biological system can help elucidate patterns that are difficult to study in nature.

Recent publications:

Hufbauer, RA, M Szucs, E Kasyon, C Youngberg, MJ Koontz, C Richards, T Tuff, BA Melbourne (2015) Three types of rescue can avert extinction in a changing environment. PNAS. 112:10557-10562.

Szucs, M, B Melbourne, T Tuff, RA Hufbauer (2014) The roles of demography and genetics in the early stages of colonization. Proceedings of the Royal Society of London, B. 281: 20141073.

Hufbauer, RA, A Rutschmann, B Serrate, H Vermeil De Conchard, B Facon (2013) Role of propagule pressure in colonization success: disentangling the relative importance of demographic, genetic and habitat effects. Journal of Evolutionary Biology. 26:1691–1699