Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection
Thesis (M.S.) University of Alaska Fairbanks, 2019 Due to the mediating role of body size in determining fitness, the 'bigger is better' hypothesis still pervades evolutionary ecology despite evidence that natural selection on phenotypic traits varies in time and space. For Pacific salmon...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/10533 2023-05-15T17:04:40+02:00 Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection Ree, Marta Elizabeth Westley, Peter Finkle, Heather Beaudreau, Anne 2019-05 http://hdl.handle.net/11122/10533 en_US eng http://hdl.handle.net/11122/10533 Department of Fisheries sockeye salmon Alaska Kodiak Island growth Thesis ms 2019 ftunivalaska 2023-02-23T21:37:31Z Thesis (M.S.) University of Alaska Fairbanks, 2019 Due to the mediating role of body size in determining fitness, the 'bigger is better' hypothesis still pervades evolutionary ecology despite evidence that natural selection on phenotypic traits varies in time and space. For Pacific salmon (genus Oncorhynchus), the size at which juveniles migrate to sea (i.e., smolts) has been linked to survival during the early marine period, where larger smolts typically survive at a higher rate than their smaller counterparts. However, the relationship of smolt size and survival becomes more ambiguous when considering confounding factors of age, ocean entry timing, and environmental variability. Despite equivocal results, smolt size appears to be a key trait and therefore changes in freshwater conditions may have consequences for population productivity. Furthermore, due to differences in site-specific habitats, trophic dynamics, and population traits the response of specific populations to these changes is likely to be context specific. The objective of this thesis was to 1) quantify the direction and magnitude of natural selection on smolt size for three age classes of sockeye salmon in a small watershed on Kodiak Island, AK and 2) explore stock-specific effects of temperature and conspecific density on smolt size over a multi-decade time-series to understand historic and possible future trends. To address our first objective, we calculated standardized selection differentials by comparing observed size distributions of out-migrating juvenile salmon to back-calculated smolt length from the scales of surviving, returning adults. Results reveal the magnitude of selection on size was very strong and consistent among years. However, the direction of selection on size consistently varied among age classes. The absolute magnitude of selection was negatively correlated to apparent marine survival and positively correlated to late mean ocean entry timing. To address our second objective, we back-calculated smolt size from ... Thesis Kodiak Alaska University of Alaska: ScholarWorks@UA Fairbanks Pacific Sockeye ENVELOPE(-130.143,-130.143,54.160,54.160) |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
topic |
sockeye salmon Alaska Kodiak Island growth |
spellingShingle |
sockeye salmon Alaska Kodiak Island growth Ree, Marta Elizabeth Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection |
topic_facet |
sockeye salmon Alaska Kodiak Island growth |
description |
Thesis (M.S.) University of Alaska Fairbanks, 2019 Due to the mediating role of body size in determining fitness, the 'bigger is better' hypothesis still pervades evolutionary ecology despite evidence that natural selection on phenotypic traits varies in time and space. For Pacific salmon (genus Oncorhynchus), the size at which juveniles migrate to sea (i.e., smolts) has been linked to survival during the early marine period, where larger smolts typically survive at a higher rate than their smaller counterparts. However, the relationship of smolt size and survival becomes more ambiguous when considering confounding factors of age, ocean entry timing, and environmental variability. Despite equivocal results, smolt size appears to be a key trait and therefore changes in freshwater conditions may have consequences for population productivity. Furthermore, due to differences in site-specific habitats, trophic dynamics, and population traits the response of specific populations to these changes is likely to be context specific. The objective of this thesis was to 1) quantify the direction and magnitude of natural selection on smolt size for three age classes of sockeye salmon in a small watershed on Kodiak Island, AK and 2) explore stock-specific effects of temperature and conspecific density on smolt size over a multi-decade time-series to understand historic and possible future trends. To address our first objective, we calculated standardized selection differentials by comparing observed size distributions of out-migrating juvenile salmon to back-calculated smolt length from the scales of surviving, returning adults. Results reveal the magnitude of selection on size was very strong and consistent among years. However, the direction of selection on size consistently varied among age classes. The absolute magnitude of selection was negatively correlated to apparent marine survival and positively correlated to late mean ocean entry timing. To address our second objective, we back-calculated smolt size from ... |
author2 |
Westley, Peter Finkle, Heather Beaudreau, Anne |
format |
Thesis |
author |
Ree, Marta Elizabeth |
author_facet |
Ree, Marta Elizabeth |
author_sort |
Ree, Marta Elizabeth |
title |
Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection |
title_short |
Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection |
title_full |
Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection |
title_fullStr |
Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection |
title_full_unstemmed |
Linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection |
title_sort |
linking freshwater growth to size-dependent marine survival of sockeye salmon: interactions between processes of climate, density, and natural selection |
publishDate |
2019 |
url |
http://hdl.handle.net/11122/10533 |
long_lat |
ENVELOPE(-130.143,-130.143,54.160,54.160) |
geographic |
Fairbanks Pacific Sockeye |
geographic_facet |
Fairbanks Pacific Sockeye |
genre |
Kodiak Alaska |
genre_facet |
Kodiak Alaska |
op_relation |
http://hdl.handle.net/11122/10533 Department of Fisheries |
_version_ |
1766058979956359168 |