Mechanisms of Life History Evolution in an Ancient Vertebrate

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Survival of the fittest' refers to the idea that, in nature, there is competition to survive and reproduce. In addition to morphological and physiological traits, an organism's fitness is affected by life history traits (e.g., age and size at maturity, lifespan, number of offspring). Life history traits show tremendous variation among individuals, environments, and species, and much research has been devoted to understanding the trade-offs and fitness consequences of these traits. They are very important, for example, in predicting the effect of human-induced changes in age- or size-specific mortality rates in species of management concern. Recent advances in genomics are now facilitating important research into the genetic mechanisms underlying these traits.******Lampreys, ancient vertebrates occurring at one of the key branch points in the tree of life, are excellent models to study life history evolution. Living lampreys have a highly conserved body plan, looking very much like fossil lampreys from 360 million years ago, but they exhibit a diversity of life history types. All lampreys filter feed on microscopic organisms during a prolonged larval stage in fresh water but, following metamorphosis, they diverge into different adult feeding and migratory types. In non-parasitic forms, which remain protected within their natal streams and become sexually mature without further feeding, adult mortality rates are low but their small body size limits the number of eggs produced. Parasitic forms delay sexual maturation and migrate to sea or large lakes to feed on other fishes; growth and fecundity are much higher in these forms, but so is mortality. Non-parasitic forms have evolved from parasitic forms, and many of these species are of conservation concern. Conversely, the parasitic sea lamprey in the Atlantic Ocean has given rise to a freshwater form in the Great Lakes, and it is a significant pest causing billions of dollars of damage to the commercial fishery. ******My proposed research seeks to identify the genetic basis of feeding and migratory type in lampreys by investigating: 1) whether gonadal development during the larval stage predetermines' adult life history type; 2) which genes are turned on' or turned off' at the key developmental branch points when the feeding and migratory types diverge; and 3) ways in which the genome of the Great Lakes sea lamprey has diverged from the ancestral Atlantic population since colonization.******This research has conservation and management implications (e.g., to be able to predict the potential for lampreys to become invasive in other freshwater systems), and will further enhance Canada's reputation on life history evolution in fishes. It will also provide at least 12 students with technical training in cutting-edge technologies (e.g., next-generation sequencing) and analysis of large genomic datasets, thus producing personnel highly qualified for employment in research and development in academia and industry.