Research in our lab addresses a wide range of questions in evolutionary biology. We are particularly interested in applying genetic methods to study evolutionary questions in populations of wild birds and mammals. One focus of our current research investigates the genetic consequences of life in small populations. A second focus addresses the proximate mechanisms and evolutionary reasons for how animals choose their mates and what the consequences of these choices are. In addition, we are pursuing a range of projects addressing related questions, for example about the coevolution of the microorganisms living in bird and mammal hosts and the natural history of the species we study.
What are the genetic consequences of life in small populations?
Climate change and other anthropogenic pressures such as intensive land use and development lead to fragmentation of natural areas and thereby to previously large natural populations being broken up into small fragments. A better understanding of the genetic processes in such populations is not only of fundamental interest in evolutionary biology, but also has implications for conservation biology.
Inbreeding and outbreeding depression are important phenomena in evolutionary biology and are of large interest in applied conservation genetics. For example, inbreeding depression is invoked to explain aspects of important biological phenomena such as dispersal strategies and mating systems.
Understanding the genetic architecture of inbreeding and outbreeding depression is also crucial to the conservation management of wild and captive populations of endangered species. However, we still do not know much about the genetic architecture of inbreeding and outbreeding depression, particularly in wild populations.
We use wild populations of two species on islands at the west coast of Canada as examples of fragmented populations.
Song sparrows
Members of our lab have been investigating the consequences of inbreeding (i.e., reproduction among related individuals) in a small population of song sparrows (Melospiza melodia) on X̱O¸X̱DEȽ (Mandarte Island) in British Columbia, Canada, since 2011. All birds in this population have been color-banded and monitored closely since 1975 and genetic data for all individuals since 1993 allow us to genetically verify paternity in this population with only ~1.2 immigrants per year, resulting in one of the most completely known pedigrees of any wild population. One focus of our work on this population is investigating the fitness consequences of inbreeding (i.e., reproduction among related individuals) and to identify genomic regions responsible for these typically deleterious effects (i.e., inbreeding depression). Together with international collaborators, we have also been investigating the genetic and fitness consequences of immigration in this small populations and the genetic variation in fitness of this and many other wild populations.
North American deermice
In summer 2020, we started data collection for a new project on nine island and a mainland population of North American deermice (Peromyscus maniculatus). These populations at the west coast of Canada provide a great model system for strongly isolated populations of different population size. We recently confirmed that most of these island populations have been genetically isolated from each other for thousands of years, allowing us to study how the frequencies of differently harmful genetic variants are affected by population size. It is well known that weakly or moderately harmful genetic variants increase in small populations due to the randomness associated with small population size (i.e., genetic drift), but theoretical expectations for strongly harmful genetic variants are unclear and the few existing empirical studies are inconclusive. This study system provides a great opportunity to address this gap in knowledge. We also found that mice on small islands are bigger than on larger islands or the mainland, and that this so-called island gigantism is driven by variation in predation pressure. Additionally, annual sampling (and release) of almost all adult and many juvenile deermice on one small island, X̱O¸X̱DEȽ (Mandarte Island), every summer since 2020 allows us to study the effects of different genetic regions on fitness.
Additionally, we are collaborating with the Earth Hologenome Initiatve to study the microorganisms in the guts of these deermice, allowing for future comparisons of evolutionary histories, investigations of the interactions of deermouse hosts and microorganisms, and to gain a better understanding of the health and fitness effects of variation in microorganism gut community composition.
How do animals choose their mates and what are the evolutionary reasons for and the consequences of these choices?
Animals face a multitude of choices throughout their lives. One of the most consequential decisions is which of many potential mates they should choose for reproduction. Birds in species that typically form male-female social pairs for mating and joint care of their offspring also frequently mate outside of the social pair bond with nearby birds. The possible costs and benefits of such extra-pair reproduction are not well understood, nor is it clear how exactly animals choose their mates.
House wrens
Our lab collaborates with Charles F. Thompson and Scott K. Sakaluk, two retired faculty at Illinois State University, to study a nestbox population of house wrens (Troglodytes aedon). This population is situated 12 miles northeast of the campus of Illinois State University along the Mackinaw River and has been intensively investigated since 1980. We received funding from the US National Science Foundation to study how female house wrens use song characteristics to select males to mate with outside of their pair bond (i.e., extra-pair reproduction), and to assess what the costs and benefits of this behavior are. While contributing to fundamental research, the proximity of this house wren study site to Illinois State University makes this project well suited for extensive involvement and training of undergraduate and graduate students in ornithological field work and genetic lab work and analysis.
Additional interests
Our lab is generally interested in evolutionary and conservation genetics and genomics. Students and collaborators are welcome to discuss research proposals using other datasets or study systems.
