Landscape heterogeneity and local adaptation define the spatial genetic structure of Pacific salmon in a pristine environment

Ackerman, Michael W.; Templin, William D.; Seeb, James E.; Seeb, Lisa W.

doi:10.1007/s10592-012-0401-7

Cited by 24 publications

(15 citation statements)

References 57 publications

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“…; Ackerman et al . ), while others have found that patterns of MHC differentiation are consistent with neutrality (e.g. Seddon & Baverstock ; Campos et al .…”

Section: Introductionmentioning

confidence: 95%

“…For example, multiple studies have found that MHC differentiation among populations is larger than would be expected under a model of neutrality or balancing selection (e.g. Ekblom et al 2007;Gomez-Uchida et al 2011;Ackerman et al 2013), while others have found that patterns of MHC differentiation are consistent with neutrality (e.g. Seddon & Baverstock 1999;Campos et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Signals of heterogeneous selection at an MHC locus in geographically proximate ecotypes of sockeye salmon

et al. 2014

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The genes of the major histocompatibility complex (MHC) are an important component of the vertebrate immune system and can provide insights into the role of pathogen-mediated selection in wild populations. Here, we examined variation at the MHC class II peptide-binding region in 27 populations of sockeye salmon (Oncorhynchus nerka), distributed among three distinct spawning ecotypes, from a complex of interconnected rivers and lakes in south-western Alaska. We also obtained genotypes from 90 putatively neutral single nucleotide polymorphisms for each population to compare the relative roles of demography and selection in shaping the observed MHC variation. We found that MHC divergence was generally partitioned by spawning ecotype (lake beaches, rivers and streams) and was 30 times greater than variation at neutral markers. Additionally, we observed substantial differences in modes of selection and diversity among ecotypes, with beach populations displaying higher levels of directional selection and lower MHC diversity than the other two ecotypes. Finally, the level of MHC differentiation in our study system was comparable to that observed over much larger geographic ranges, suggesting that MHC variation does not necessarily increase with increasing spatial scale and may instead be driven by fine-scale differences in pathogen communities or pathogen virulence. The low levels of neutral structure and spatial proximity of populations in our study system indicate that MHC differentiation can be maintained through strong selective pressure even when ample opportunities for gene flow exist.

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“…; Ackerman et al . ), while others have found that patterns of MHC differentiation are consistent with neutrality (e.g. Seddon & Baverstock ; Campos et al .…”

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Signals of heterogeneous selection at an MHC locus in geographically proximate ecotypes of sockeye salmon

et al. 2014

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“…Functional genetic markers, like the ones used in this study, reveal important genetic differences among populations that may not be evident based solely on neutral genetic markers. For example, putatively adaptive SNPs have revealed population structure patterns that were not evident for neutral loci in salmonids (Ackerman, Templin, Seeb, & Seeb, ; Hand et al., ; O'Malley, Jacobson, Kurth, Dill, & Banks, ) and invasive invertebrates (Rohfritsch et al., ; Tepolt & Palumbi, ). More importantly, the functions of such genes can reveal important information about the environmental or ecological forces driving genetic differences among populations.…”

Section: Discussionmentioning

confidence: 99%

Standing genetic diversity and selection at functional gene loci are associated with differential invasion success in two non‐native fish species

et al. 2018

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Invasive species are expected to experience a unique combination of high genetic drift due to demographic factors while also experiencing strong selective pressures. The paradigm that reduced genetic diversity should limit the evolutionary potential of invasive species, and thus, their potential for range expansion has received little empirical support, possibly due to the choice of genetic markers. Our goal was to test for effects of genetic drift and selection at functional genetic markers as they relate to the invasion success of two paired invasive goby species, one widespread (successful) and one with limited range expansion (less successful). We genotyped fish using two marker types: single nucleotide polymorphisms (SNPs) in known-function, protein-coding genes and microsatellites to contrast the effects of neutral genetic processes. We identified reduced allelic variation in the invaded range for the less successful tubenose goby. SNPs putatively under selection were responsible for the observed differences in population structure between marker types for round goby (successful) but not tubenose goby (less successful). A higher proportion of functional loci experienced divergent selection for round goby, suggesting increased evolutionary potential in invaded ranges may be associated with round goby's greater invasion success. Genes involved in thermal tolerance were divergent for round goby populations but not tubenose goby, consistent with the hypothesis that invasion success for fish in temperate regions is influenced by capacity for thermal tolerance. Our results highlight the need to incorporate functional genetic markers in studies to better assess evolutionary potential for the improved conservation and management of species.

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“…In this case, locally adapted MHC alleles may exist leading to greater population differentiation (Muirhead 2001). To date, studies have found that, compared to neutral markers, MHC differentiation can be (i) greater than expected suggesting local adaptation (Ekblom et al 2007;Loiseau et al 2009;Ackerman et al 2013;Kyle et al 2014), (ii) weaker than expected consistent with balancing selection (Sommer 2003;Fraser et al 2010;Strand et al 2012) or (iii) not different than neutral markers suggesting weak selection or a strong effect of drift (Miller et al 2010;Zeisset & Beebee 2014). These differences in results may be related to the relative effects of gene flow, drift and selection (Bryja et al 2007) and the spatial scale of the study (Landry & Bernatchez 2001;Herdegen et al 2014).…”

Section: Introductionmentioning

confidence: 96%

“…; Ackerman et al . ; Kyle et al . ), (ii) weaker than expected consistent with balancing selection (Sommer ; Fraser et al .…”

Section: Introductionmentioning

confidence: 99%

Contrasting patterns of selection and drift between two categories of immune genes in prairie‐chickens

et al. 2015

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Immune-receptor genes of the adaptive immune system, such as the major histocompatibility complex (MHC), are involved in recognizing specific pathogens and are known to have high rates of adaptive evolution, presumably as a consequence of rapid co-evolution between hosts and pathogens. In contrast, many 'mediating' genes of the immune system do not interact directly with specific pathogens and are involved in signalling (e.g. cytokines) or controlling immune cell growth. As a consequence, we might expect stronger selection at immune-receptor than mediating genes, but these two types of genes have not been compared directly in wild populations. Here, we tested the hypothesis that selection differs between MHC (class I and II) and mediating genes by comparing levels of population differentiation across the range of greater prairie-chickens (Tympanuchus cupido). As predicted, there was stronger population differentiation and isolation by distance at immune receptor (MHC) than at either mediating genes or neutral microsatellites, suggesting a stronger role of local adaptation at the MHC. In contrast, mediating genes displayed weaker differentiation between populations than neutral microsatellites, consistent with selection favouring similar alleles across populations for mediating genes. In addition to selection, drift also had a stronger effect on immune receptor (MHC) than mediating genes as indicated by the stronger decline of MHC variation in relation to population size. This is the first study in the wild to show that the effects of selection and drift on immune genes vary across populations depending on their functional role.

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Landscape heterogeneity and local adaptation define the spatial genetic structure of Pacific salmon in a pristine environment

Cited by 24 publications

References 57 publications

Signals of heterogeneous selection at an MHC locus in geographically proximate ecotypes of sockeye salmon

Signals of heterogeneous selection at an MHC locus in geographically proximate ecotypes of sockeye salmon

Standing genetic diversity and selection at functional gene loci are associated with differential invasion success in two non‐native fish species

Contrasting patterns of selection and drift between two categories of immune genes in prairie‐chickens

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