The balance of selection on the growth trajectories of fishes

Suny At Stony Brook, Stony Brook NY

Investigators

Abstract

Growth is fundamental to an individual's fitness. Since fecundity and survival, the two primary components of fitness, typically increase with size, in the absence of trade-offs, growth should be driven to the maximum allowed by physiological and phylogenetic constraints. With few exceptions, the preponderance of field evidence seems to indicate selection for larger size and faster growth in the early life history of fishes. In contrast to this, local adaptation in growth occurs in many species, indicating that growth rates do not uniformly evolve to their maximum. Pervasive selection for fast growth in the early life history apparently contradicts the equally common observation that submaximal growth rates are adaptive. Two hypotheses may resolve this conundrum. 1) Growth during the early life history does not have a heritable genetic basis; 2) Early growth does have a genetic basis and there are delayed costs of growth that result in balancing selection on growth rates when viewed over the entire life history. This project will use Menidia menidia as a model species to test these competing hypotheses. The work will combine field collections, laboratory experiments, and quantitative genetic modeling to evaluate the genetic basis for, and fitness consequences of, growth throughout the life history. 1) The genetic covariance and heritability of growth and fecundity throughout the life history will be estimated for fish from the center of the range. 2) Selection on size and growth will be estimated for this population using otoliths from multiple samples throughout the life span. 3) The short and long term costs of growth will be evaluated using a combination of phenotypically-manipulated individuals and individuals from three locally adapted populations. Connecting processes acting in the early life history with fitness consequences throughout life will fundamentally change the way we think about larval biology and the complex processes governing recruitment. Intellectual Merit --The project will track selection on size and growth over the whole life history and evaluate the quantitative genetic basis for these characters. By connecting processes in the ELH to reproductive success late in life, the study will help resolve a major contradiction in the early life history of fishes. Broader Impacts--There is mounting evidence that heavily exploited fish stocks have evolved in response to harvest selection and recent evidence suggests that these adaptations may slow population recovery following reductions in fishing mortality. In collaboration with government fisheries scientists, the PI plans to use the models and information resulting from this project to develop evolutionarily sustainable harvest strategies. The PI will also present results to the general public through the Hudson River Foundation's seminar series, regularly attended by a diverse audience including, fishermen and environmentalists. All raw data will be made freely available for use in research and education through the PIs Stony Brook website. The PI mentors a diverse group of undergraduates throughout the year. 80% of the present cohort of students are from traditionally underrepresented groups. The project will provide these students and their successors hands-on training in high speed photography and motion analysis, fish husbandry, and otolith preparation, as well as opportunities to collect and identify of a variety of nearshore fishes. Parts of the research will form the basis of two PhD dissertations, including one by Kestrel Perez who began working with the PI through the AGEP program for minority undergraduate research and has since enrolled in Stony Brook's PhD program in Ocean Sciences. All students will be encouraged to participate in meetings relevant to their research. Financial support for the proposed project will allow the PI to continue to provide research opportunities such as these. The equipment requested will contribute to the research infrastructure for biological oceanography and marine ecology at Stony Brook.