Physiological diversity, parental care, and fitness of centrarchid fishes
Summary of Research Programme
Parental care is a form of parental investment that enables a parent to increase the fitness of current offspring. However, parental care can also become sufficiently costly that it can affect survival and future fitness of the parent in iteroparous animals such as the largemouth bass, a freshwater sunfish (Centrarchidae). Male bass construct nests and court females, which chose the male(s) with which to spawn. After spawning, females depart and the male provides sole parental care until offspring have developed predator avoidance tactics, a period of several weeks. During this time, parental males fan nests to keep them oxygenated and free of silt, and provide constant vigilance against potential nest predators. This high activity, coupled with restricted food intake, makes parental care energetically costly for males. Within a population of adult sunfish, not all individuals reproduce in a given year, presumably because of energetic constraints. In addition, within a given reproductive season, not all parental males will raise successful broods. Research to date has focused on evaluating the environmental correlates associated with nest abandonment but has been equivocal. Beyond limited work on energetics, there is little known about the physiological consequences of parental care or correlates of reproductive success. Why do some individuals raise successful broods while others abandon?
Our objective is to develop a greater understanding of the inter-relationships between physiology, reproductive behaviour and fitness in fish. Using largemouth bass as a model, we are currently investigating 1) the consequences of parental care on physiology, energetics, and future reproduction and 2) the physiological factors associated with intensity of parental care and reproductive success. I will then look at how these consequences and correlates of parental care are influenced by A) annual thermal environments, behaviour during the non-reproductive period, reproductive history, and individual condition and B) predator burdens. This work will focus on variation both within and among populations and will elucidate the factors that contribute to individual variation in behaviour and fitness, providing insight into the factors that shape fish populations.
Specific projects planned for 2006-2008:
- Quantifying the physiological and energetic changes throughout the parental care period.
- Evaluating the physiological correlates of parental care behaviour and reproductive success
- Evaluating the effects of latitude on the parental investment and energetic condition
- Evaluating the consequences of winter environment and individual condition on reproduction
- Testing the effects of stress on parental care behaviour and reproductive success
- Testing the mechanisms by which nesting male bass are able to return to their nest site when displaced
Why the centrarchids?
The centrarchids are well studied fish, providing the background information required to test hypotheses that bridge physiology and behaviour. Our research efforts will focus on both the largemouth bass and smallmouth bass. These congeners exhibit substantial life history variation within and among populations and have endemic range in eastern N. Amer. that extends from Ontario to the southern United States.
How and where do we study centrarchid biology?
Our lab has been investigating this topic for about five years and is the focus of our NSERC-funded basic research programme. In addition, elements of this research are supported by the Illinois Natural History Survey and the Rainy Lake Fisheries Trust. Most student projects planned for the coming years will in some way relate to this theme. Our research will focus on populations near the Queen’s Univ. Biol. Station (QUBS) in southeastern Ontario, Rainy Lake in northwestern Ontario, field stations in Illinois operated by the Illinois Natural History Survey, and Table Rock Lake in southern Missouri. Our lab uses a number of proven techniques, many of which we helped develop, including repeated physiological sampling of individuals, advanced telemetry technology (3D whole-lake array, physiological telemetry) coupled with videography and snorkeling, and swimming performance trials. Work will include comparative sampling (short and long term), mesocosm experiments, and large-scale field interventions.
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