Patterns and Causes of Life History Variation in Lake Trout, Salvelinus Namaycush PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Patterns and Causes of Life History Variation in Lake Trout, Salvelinus Namaycush PDF full book. Access full book title Patterns and Causes of Life History Variation in Lake Trout, Salvelinus Namaycush by Jenni L. McDermid. Download full books in PDF and EPUB format.
Author: Jenni L. McDermid Publisher: ISBN: 9780494279519 Category : Languages : en Pages : 354
Book Description
Lake trout (Salvelinus namaycush) exhibit substantial life history variation across their range, but considerable local variation also occurs. Life history traits play a critical role in shaping population dynamics. As such, the observed life history variation makes it difficult to build conservation and management models. Populations should respond to varied environmental conditions by selecting the most favourable combination of life history traits. However, life history traits may alter as a result of phenotypic plasticity and/or genetic response to environmental conditions. This thesis examines the degree and mechanisms behind life history variation in lake trout. Variability is examined over the species range and within small geographic areas. Results indicate a strong association between enviromnental and lake trout life history variability. In particular, climate variables such as net thermal input and winter length and severity are correlated with a number of lake trout life history characteristics across the range. Lake morphology was associated with asymptotic sizes of lake trout, and shows contrasting associations with longevity and size at maturity in northern versus southern ranges. On a local scale, divergence in life history traits represented a combination of plastic responses and genetic adaptations to local conditions. The majority of life history traits examined in this thesis appeared to have a genetic basis; however stunted populations showed a plastic response to lack of forage fish. Yet, not all stunted populations within a region showed similar adaptive responses in early life history characteristics and we propose that the different responses may be predator mediated. Finally, the phenotypic divergence in life history traits among populations introduced from a common source approximately a century ago exhibited rapid plastic and genetic responses to novel environments. This thesis identifies that both plastic and genetic responses are common in lake trout, that these responses can occur quite rapidly, and that a significant number of environmental variables need to be considered before we can predict life history variation. These findings may be even more critical as populations continue to face stresses from climate change, overexploitation, habitat destruction, and introduced species.
Author: Jenni L. McDermid Publisher: ISBN: 9780494279519 Category : Languages : en Pages : 354
Book Description
Lake trout (Salvelinus namaycush) exhibit substantial life history variation across their range, but considerable local variation also occurs. Life history traits play a critical role in shaping population dynamics. As such, the observed life history variation makes it difficult to build conservation and management models. Populations should respond to varied environmental conditions by selecting the most favourable combination of life history traits. However, life history traits may alter as a result of phenotypic plasticity and/or genetic response to environmental conditions. This thesis examines the degree and mechanisms behind life history variation in lake trout. Variability is examined over the species range and within small geographic areas. Results indicate a strong association between enviromnental and lake trout life history variability. In particular, climate variables such as net thermal input and winter length and severity are correlated with a number of lake trout life history characteristics across the range. Lake morphology was associated with asymptotic sizes of lake trout, and shows contrasting associations with longevity and size at maturity in northern versus southern ranges. On a local scale, divergence in life history traits represented a combination of plastic responses and genetic adaptations to local conditions. The majority of life history traits examined in this thesis appeared to have a genetic basis; however stunted populations showed a plastic response to lack of forage fish. Yet, not all stunted populations within a region showed similar adaptive responses in early life history characteristics and we propose that the different responses may be predator mediated. Finally, the phenotypic divergence in life history traits among populations introduced from a common source approximately a century ago exhibited rapid plastic and genetic responses to novel environments. This thesis identifies that both plastic and genetic responses are common in lake trout, that these responses can occur quite rapidly, and that a significant number of environmental variables need to be considered before we can predict life history variation. These findings may be even more critical as populations continue to face stresses from climate change, overexploitation, habitat destruction, and introduced species.
Author: Elizabeth Stebbins Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 0
Book Description
Correctly characterizing growth of fish within a population is a crucial component of fish biology and fishery management because, among other things, it informs population dynamics that affect management decisions. Size-at-age is a common metric of fish growth and is often measured at the population level with the assumption that, on average, all fish of a given age are a given size. Over time, several studies have shown that ignoring individual variability in growth can influence population parameter estimates and these inaccuracies can be propagated in population models that are used to calculate reference points for management. In the first chapter we develop a hierarchical, mixed-effects statistical growth model that measures individual variability in growth model parameters and partitions it into two sources. We fit this model to length-at-age data of lake trout (Salvelinus namaycush) from six populations in Lake Superior and show that individual-level variability exceeds population-level variability for this system, and persistent error contributes more to variability in length-at-age. In our second chapter, we simulate a population of fish and predict biological reference points, yield-per-recruit, and spawning stock biomass-per-recruit curves from the population using a 'standard' method that ignores individual variability and a 'true' method that accounts for size-selective mortality and its interaction with individual fish. We show that ignoring individual variability in these models results in overestimation of yield-per-recruit and the biological reference points F0.1 and FMAX. Further, spawning stock biomass-per-recruit is underestimated at low levels of fishing intensity and overestimated at high levels of fishing intensity when individual variability is ignored.
Author: Sivani Baskaran Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Because eating fish is often a major vector of human exposure to persistent organic pollutants (POPs), much effort is directed towards a quantitative understanding of fish bioaccumulation using mechanistic models. Many such models fail to consider how uptake and loss rate constants relate to fish physiology. Here, we calculate the bioaccumulation factor (BAF) of hypothetical POPs, with octanol-water partition coefficients values ranging from 104.5 to 108.5, in lake trout (Salvelinus namaycush), with a food web bioaccumulation model that uses bioenergetics to ensure that physiological parameters applied to a species are internally consistent and energetically balanced. Fish in six Canadian lakes were modelled to understand what causes the BAFs of differently sized lake trout to vary between and within lakes. Lake trout activity, diet composition, prey contamination levels and the fraction of the total energy intake spent on growth were found to affect the bioaccumulation potential of chemicals.
Author: Seth Robert Smith Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 292
Book Description
Here I describe the development of novel genomic resources that will be fundamental for advancing a new generation of genomic research on Lake Trout (Salvelinus namaycush) including a high-density linkage map, an annotated chromosome-anchored genome assembly, and three high-throughput genotyping panels. We used these resources to identify genomic regions exhibiting signals of adaptive divergence between Lake Trout hatchery strains, some of which were found to underlie differences in fitness (survival and reproduction) between strains in the contemporary Lake Huron environment. Loci associated with differences in fitness between Seneca and Great Lakes origin strains were localized using local ancestry inference and local ancestry outlier tests. By evaluating locus specific allelic contributions of the ancestral Seneca Lake and Great Lakes-derived hatchery strains to naturally-produced wild Lake Huron populations across the genomes of F2 wild born individuals, we were able to determine that a subset of 7 genomic regions contributed to differences in fitness between Seneca Lake and Great Lakes origin individuals during the re-emergence of wild populations in Lake Huron. We also identified 2 genomic regions where Great Lakes origin alleles were favored by selection, 4 regions associated with hybrid vigor, and 2 regions potentially associated with hybrid inferiority in recovering wild Lake Trout populations. We also found that some Seneca origin alleles are only favored by selection on certain genetic backgrounds. For instance, F2 hybrids between the Seneca strain and Lake Michigan origin strains have an excess of Seneca origin haplotypes on chromosome Sna11, while this is not the case in hybrids between Lake Superior and Seneca origin individuals. Collectively, these results indicate that elevated performance of the Seneca strain can at least be partially attributed to a number of adaptive alleles at a small subset of genes. Additionally, the fact that Great Lakes origin alleles were favored by selection at two loci indicates that native strains contain some variation that provides a fitness advantage in Lake Huron. These admixture outlier regions contained a significant excess of genes related to swimming behavior and negative regulation of vascular wound healing, which strongly suggests that differences in fitness between strains are due to behavioral and physiological factors associated with the ability to avoid and survive predation by Sea Lamprey. Additionally, we carried out two studies seeking to identify genetic variation associated with habitat occupancy and phenotypic variation in Lake Trout. First, we carried out a quantitative trait locus (QTL) mapping study in which we identified loci associated with length and condition related traits, skin pigmentation, and body shape. We produced a linkage map for Lake Trout as a prerequisite for this work. The information on locus order obtained from the linkage map was also critical to the assembly of the Lake Trout genome and recombination rate estimates obtained from the linkage map were critical to the goal of assigning haplotype segments to their hatchery strain of origin for wild-born Lake Huron individuals. This study also allowed us to determine the location of the Lake Trout sex determination locus, determine centromere locations, and characterize structural differences (i.e., chromosomal inversions and translocations) between Lake Trout and other salmonid species. Second, we performed a genome-wide scan for loci associated with ecomorphological divergence in Lake Superior Lake Trout (specifically between lean, siscowet, and humper forms), and identified numerous regions with abnormally high levels of divergence between forms. These loci likely underlie variation in traits that differentiate forms, as well as traits that contributed to reproductive isolation historically. For example, the genomic region most strongly associated with length and condition (from our QTL mapping study) was also associated with ecomorphological divergence in Lake Superior and this region also contains a putative chromosomal inversion. Interestingly, we find that hybridization primarily occurred between humpers and siscowets and humpers and leans immediately preceding a genetic homogenization event that occurred in the late 1990s or early 2000s. Using a collection of samples over a multi-decade time series collected from the Apostle Islands, we show that levels of hybridization with humpers increased substantially starting in the 1980s.
Author: Jenni L. McDermid
Author: Jenni L. McDermid
Author: Terrence R. Dehring
Author: 
Author: Michael A. Halbisen
Author: Christopher Todd Weeks
Author: Elizabeth Stebbins
Author: 
Author: Wesley T. Tibbits
Author: Sivani Baskaran
Author: Seth Robert Smith