Ecological and genetic mechanisms of adaptive radiation

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The aim of my research program is to uncover the mechanisms that drive adaptive radiation -- the rapid origin and divergence of new species from a common ancestor. Many (perhaps even most) species on earth have arisen during such bursts, so they are key to understanding the origins of life’s extraordinary diversity. Cases of adaptive radiation still in their early stages have great advantages for study because the rate of evolution is sped up, new species are still forming, intermediate forms are still extant, evolutionary events are frequently repeated, and young species remain capable of hybridizing. These features allow us to make rapid progress using a combination of observational, experimental, and genetic studies. Much theory has accumulated to explain how new species form, the mechanisms driving their divergence from one another, and how new species continue to persist. Work in my lab tests these fundamental ideas by addressing the role of natural selection and genetic variation in a species complex of threespine stickleback fish, which inhabit young lakes and streams of coastal British Columbia. This system includes some of the youngest species on earth in any organism. This study system has many advantages for study (it has been called an evolutionary “supermodel”). With collaborators, we have developed exceptional genetic and experimental tools for stickleback. These allow us to test fundamental hypotheses by manipulating the causes of natural selection (for example, predation), and measure evolution by tracking the resulting genetic changes across generations. The current proposal describes new experiments that focus especially on the role of competition and intraguild predation on the origin of species and their simultaneous divergence. Our work contributes to the development of fundamental concepts in biodiversity science. The work will lead to a better understanding of the factors driving the rapid origin of new species, and that enable their long-term persistence in nature. Our work has also provided a better understanding of how ecosystems change when new species collapse. Some of this work has immediate practical benefits. The stickleback species pairs that are the focus of much of our work are the most highly endangered group of fishes in BC, with two pairs already extinct. All are federally listed Species at Risk, and our work on species origins and differences continues to inform recovery planning.