Steven Seiler | Lock Haven University of Pennsylvania (original) (raw)
Papers by Steven Seiler
Canadian Journal of Zoology
The cutthroat trout (Oncorhynchus clarkii (Richardson, 1836)) is one of the most widely distribut... more The cutthroat trout (Oncorhynchus clarkii (Richardson, 1836)) is one of the most widely distributed species of freshwater fish in western North America. Occupying a diverse range of habitats, they exhibit significant phenotypic variability that is often recognized by intraspecific taxonomy. Recent molecular phylogenies have described phylogenetic diversification across cutthroat trout populations, but no study has provided a range-wide morphological comparison of taxonomic divisions. In this study, we used linear- and geometric-based morphometrics to determine if phylogenetic and subspecies divisions correspond to morphological variation in cutthroat trout, using replicate populations from throughout the geographic range of the species. Our data indicate significant morphological divergence of intraspecific categories in some, but not all, cutthroat trout subspecies. We also compare morphological distance measures with distance measures of mtDNA sequence divergence. DNA sequence div...
Red maple (Acer rubrum) establishes in diverse habitats across the eastern United States and prio... more Red maple (Acer rubrum) establishes in diverse habitats across the eastern United States and prior research suggests that ecotypic variation may occur in the shape of red maple leaves. Our first objective was to determine if shape differences were present in red maple leaves from different geographical locations and if any differences are correlated with environmental conditions found across a cline. Our second objective was to assess if red maples exhibit ecotypic differences in the leaf shape within regions. We applied geometric morphometric analyses on red maple leaves collected from locations in Pennsylvania, coastal Virginia, and Michigan to test for geographical differences. We compared leaves collected from trees on valley bottoms and upland habitat within Pennsylvania to test for ecotypic differences. We found both leaf shape differences among locations (Pennsylvania, Michigan, and Virginia) and between habitats (upland, lowland). Lobes and sinuses were most defined in leave...
North American Journal of Fisheries Management, 2009
... With further development of genetic markers that are diagnostic to parental species, the only... more ... With further development of genetic markers that are diagnostic to parental species, the only limit to the precision in estimates of hybridization and introgression within individual fish is the number of markers to be screened (Boecklen and Howard 19975. Boecklen, WJ and ...
Canadian Journal of Fisheries and Aquatic Sciences, 2007
We hypothesized that body shape differences between Yellowstone cutthroat trout (Oncorhynchus cla... more We hypothesized that body shape differences between Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri), rainbow trout (Oncorhynchus mykiss), and their hybrids may influence swimming ability and thus play an important role in the invasion of nonnative rainbow trout and hybrid trout into native cutthroat trout populations. We reared Yellowstone cutthroat trout, rainbow trout, and reciprocal hybrid crosses in a common environment and conducted sustained swimming trials in order to test for genetically based morphological and swimming stamina differences. Linear and geometric morphometric analyses identified differences in body shape, with cutthroat trout having slender bodies and small caudal peduncles and rainbow trout having deep bodies and long caudal peduncles. Hybrid crosses were morphologically intermediate to the parental genotypes, with a considerable maternal effect. Consistent with morphological differences, cutthroat trout had the lowest sustained swimming velocity ...
Transactions of the American Fisheries Society, Nov 1, 2008
Given the strong influence of water temperature on salmonid physiology and behavior, in the summe... more Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex,
Transactions of the American Fisheries Society, Nov 1, 2008
Given the strong influence of water temperature on salmonid physiology and behavior, in the summe... more Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex,
Http Dx Doi Org 10 1577 T07 138 1, Jan 9, 2011
ABSTRACT Given the strong influence of water temperature on salmonid physiology and behavior, in ... more ABSTRACT Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex, tissue biochemistry, and infection with multiple parasite species influence swimming performance. Sex differences in habitat selection distribution were apparent; proportionately more females occupied the cooler, upper reach, and males predominated in the warmer, lower reach. Despite having similar genotypes, fish in the upper reach had deeper bodies and higher condition factors, regardless of sex. These fish also had higher blood lipids and elevated citrate synthase activity in epaxial white muscle, suggesting a greater potential for aerobic metabolism. Critical swimming speeds measured streamside at 18°C and endurance time were influenced by sex, females performing much better than males. Plasma lactate levels were inversely correlated with swimming performance, indicating that females relied more on aerobic metabolism for energy production. We also found a high prevalence of tissue-specific myxozoans (Myxobolus insidiosus and M. kistuchi) and larval trematodes (Nanophyetus salmincola and Apophallus sp.) in the muscle and “black spot” in the skin. The prevalence of these parasites was higher in the warmer, lower reach than in the upper reach and the lower-reach fish lower condition indices. The degree of parasitism was not correlated with the swimming ability or sex of fish.
Canadian Journal of Fisheries and Aquatic Sciences, 2009
When nonnative species become established within new communities, competition may play a role in ... more When nonnative species become established within new communities, competition may play a role in determining the persistence of ecologically similar native species. In western North America, many native cutthroat trout ( Oncorhynchus clarkii ) populations have been replaced by nonnative rainbow trout ( Oncorhynchus mykiss ). Superior competitive ability of rainbow trout and cutthroat–rainbow trout hybrids is often cited for this replacement; however, few studies have tested for mechanisms that might allow introduced rainbow trout to out-compete native trout species. Our previous work found individual-based differences in swimming and foraging ability among cutthroat trout, rainbow trout, and their hybrids. In this study, we tested for the presence and strength of competition between cohorts of cutthroat trout, rainbow trout, and their reciprocal hybrids. We assayed the growth rate of juvenile cutthroat trout in allopatry versus cutthroat trout when sympatric with rainbow trout and e...
Canadian Journal of Fisheries and Aquatic Sciences, 2007
Transactions of the American Fisheries Society, 2008
Given the strong influence of water temperature on salmonid physiology and behavior, in the summe... more Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex,
North American Journal of Fisheries Management, 2009
... With further development of genetic markers that are diagnostic to parental species, the only... more ... With further development of genetic markers that are diagnostic to parental species, the only limit to the precision in estimates of hybridization and introgression within individual fish is the number of markers to be screened (Boecklen and Howard 19975. Boecklen, WJ and ...
Canadian Journal of Zoology
The cutthroat trout (Oncorhynchus clarkii (Richardson, 1836)) is one of the most widely distribut... more The cutthroat trout (Oncorhynchus clarkii (Richardson, 1836)) is one of the most widely distributed species of freshwater fish in western North America. Occupying a diverse range of habitats, they exhibit significant phenotypic variability that is often recognized by intraspecific taxonomy. Recent molecular phylogenies have described phylogenetic diversification across cutthroat trout populations, but no study has provided a range-wide morphological comparison of taxonomic divisions. In this study, we used linear- and geometric-based morphometrics to determine if phylogenetic and subspecies divisions correspond to morphological variation in cutthroat trout, using replicate populations from throughout the geographic range of the species. Our data indicate significant morphological divergence of intraspecific categories in some, but not all, cutthroat trout subspecies. We also compare morphological distance measures with distance measures of mtDNA sequence divergence. DNA sequence div...
Red maple (Acer rubrum) establishes in diverse habitats across the eastern United States and prio... more Red maple (Acer rubrum) establishes in diverse habitats across the eastern United States and prior research suggests that ecotypic variation may occur in the shape of red maple leaves. Our first objective was to determine if shape differences were present in red maple leaves from different geographical locations and if any differences are correlated with environmental conditions found across a cline. Our second objective was to assess if red maples exhibit ecotypic differences in the leaf shape within regions. We applied geometric morphometric analyses on red maple leaves collected from locations in Pennsylvania, coastal Virginia, and Michigan to test for geographical differences. We compared leaves collected from trees on valley bottoms and upland habitat within Pennsylvania to test for ecotypic differences. We found both leaf shape differences among locations (Pennsylvania, Michigan, and Virginia) and between habitats (upland, lowland). Lobes and sinuses were most defined in leave...
North American Journal of Fisheries Management, 2009
... With further development of genetic markers that are diagnostic to parental species, the only... more ... With further development of genetic markers that are diagnostic to parental species, the only limit to the precision in estimates of hybridization and introgression within individual fish is the number of markers to be screened (Boecklen and Howard 19975. Boecklen, WJ and ...
Canadian Journal of Fisheries and Aquatic Sciences, 2007
We hypothesized that body shape differences between Yellowstone cutthroat trout (Oncorhynchus cla... more We hypothesized that body shape differences between Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri), rainbow trout (Oncorhynchus mykiss), and their hybrids may influence swimming ability and thus play an important role in the invasion of nonnative rainbow trout and hybrid trout into native cutthroat trout populations. We reared Yellowstone cutthroat trout, rainbow trout, and reciprocal hybrid crosses in a common environment and conducted sustained swimming trials in order to test for genetically based morphological and swimming stamina differences. Linear and geometric morphometric analyses identified differences in body shape, with cutthroat trout having slender bodies and small caudal peduncles and rainbow trout having deep bodies and long caudal peduncles. Hybrid crosses were morphologically intermediate to the parental genotypes, with a considerable maternal effect. Consistent with morphological differences, cutthroat trout had the lowest sustained swimming velocity ...
Transactions of the American Fisheries Society, Nov 1, 2008
Given the strong influence of water temperature on salmonid physiology and behavior, in the summe... more Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex,
Transactions of the American Fisheries Society, Nov 1, 2008
Given the strong influence of water temperature on salmonid physiology and behavior, in the summe... more Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex,
Http Dx Doi Org 10 1577 T07 138 1, Jan 9, 2011
ABSTRACT Given the strong influence of water temperature on salmonid physiology and behavior, in ... more ABSTRACT Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex, tissue biochemistry, and infection with multiple parasite species influence swimming performance. Sex differences in habitat selection distribution were apparent; proportionately more females occupied the cooler, upper reach, and males predominated in the warmer, lower reach. Despite having similar genotypes, fish in the upper reach had deeper bodies and higher condition factors, regardless of sex. These fish also had higher blood lipids and elevated citrate synthase activity in epaxial white muscle, suggesting a greater potential for aerobic metabolism. Critical swimming speeds measured streamside at 18°C and endurance time were influenced by sex, females performing much better than males. Plasma lactate levels were inversely correlated with swimming performance, indicating that females relied more on aerobic metabolism for energy production. We also found a high prevalence of tissue-specific myxozoans (Myxobolus insidiosus and M. kistuchi) and larval trematodes (Nanophyetus salmincola and Apophallus sp.) in the muscle and “black spot” in the skin. The prevalence of these parasites was higher in the warmer, lower reach than in the upper reach and the lower-reach fish lower condition indices. The degree of parasitism was not correlated with the swimming ability or sex of fish.
Canadian Journal of Fisheries and Aquatic Sciences, 2009
When nonnative species become established within new communities, competition may play a role in ... more When nonnative species become established within new communities, competition may play a role in determining the persistence of ecologically similar native species. In western North America, many native cutthroat trout ( Oncorhynchus clarkii ) populations have been replaced by nonnative rainbow trout ( Oncorhynchus mykiss ). Superior competitive ability of rainbow trout and cutthroat–rainbow trout hybrids is often cited for this replacement; however, few studies have tested for mechanisms that might allow introduced rainbow trout to out-compete native trout species. Our previous work found individual-based differences in swimming and foraging ability among cutthroat trout, rainbow trout, and their hybrids. In this study, we tested for the presence and strength of competition between cohorts of cutthroat trout, rainbow trout, and their reciprocal hybrids. We assayed the growth rate of juvenile cutthroat trout in allopatry versus cutthroat trout when sympatric with rainbow trout and e...
Canadian Journal of Fisheries and Aquatic Sciences, 2007
Transactions of the American Fisheries Society, 2008
Given the strong influence of water temperature on salmonid physiology and behavior, in the summe... more Given the strong influence of water temperature on salmonid physiology and behavior, in the summers of 2004 and 2005 we studied juvenile male and female coho salmon Oncorhynchus kisutch in two reaches of Oregon's West Fork Smith River with different thermal profiles. Our goals were to compare the body morphology, tissue biochemistry, genetics, and parasite load and determine whether sex,
North American Journal of Fisheries Management, 2009
... With further development of genetic markers that are diagnostic to parental species, the only... more ... With further development of genetic markers that are diagnostic to parental species, the only limit to the precision in estimates of hybridization and introgression within individual fish is the number of markers to be screened (Boecklen and Howard 19975. Boecklen, WJ and ...