Some of the topics that Leithen and/or lab members and/or collaborators are currently or have previously worked on:

Land-use change and restoration of pollinator habitat

The reproductive success of a vast diversity of flowering plants depends critically on animal pollen vectors and, reciprocally, the survival of these pollinators depends on the resources they obtain from their host plants. In collaboration with Dr. Claire Kremen we are working to identify the factors that make habitat restoration effective for restoring and supporting pollinator communities in agricultural landscapes.

Land-use change and species persistence in tropical bird communities

Land-use change and conversion to agriculture threatens many species. In collaboration with Dr. Luke Frishkoff, Dr. Chase Mendenhall, and Dr. Daniel Karp, we are examining the effects of land-use change on bird communities in Costa Rica using large long-term data-sets. A major component of this work is the development of new statistical methods (e.g., see our Phylogenetic Occupancy Model).

Sexual selection and species co-existence

Explaining how ecologically similar species can co-exist has been a central question in community ecology for decades. The role of sexual selection in maintaining species diversity has also been a long-standing topic of interest, and controversy; wide-spread opinion is that, because sexual selection does not lead to ecological differentiation, it cannot maintain co-existence. We are using theoretical models to identify conditions under which sexual selection might facilitate co-existence of species in the absence of ecological differentiation.

Host-parasite interactions

Host-parasite interactoins critically impact community and within-population dynamics. In many cases, hosts and parasites are locked in a tight evolutionary "arms race", with selection constantly favoring novel mechanisms that either allow hosts to better evade their parasites or parasites to better invade their hosts. Consequently, host-parasite interactions can cause rapid fluctuations in allele frequencies or species abundances which can, in turn, have dramatic consequences on the communities inhabited by those species. We use mathematical models to investigate how these types of species interactions affect things such as rates of sex and mutation.