Scale-dependent effects of geography, host ecology, and host genetics, on species composition and co-occurrence in a stickleback parasite metacommunity

Bolnick, Daniel I.; Resetarits, Emlyn J.; Ballare, Kimberly M.; Stuart, Yoel E.; Stutz, William E.

doi:10.1101/672410

“…Then we used Mantel test to examine if the two distance matrices were correlated. A previous analysis (Bolnick et al, 2019) found no significant effect of as-the-crow-flies ( i . e ., Euclidean distance) or as-the-fish-swims ( i .…”

Section: Methodsmentioning

confidence: 82%

“…Details are provided in Bolnick & Ballare (2020). These samples were used to examine within- and between-population variation in diet (Bolnick & Ballare, 2020), parasite community composition (Bolnick, Resetarits, Ballare, Stuart, & Stutz, 2019), and parasite species richness (Bolnick, Resetarits, Ballare, Stuart, & Stutz, 2020). The parasite infection data for this study are archived at Dryad Digital Repository (Bolnick and Ballare, 2020).…”

Section: Methodsmentioning

confidence: 99%

What evolutionary processes maintain MHCIIβ diversity within and among populations of stickleback?

Peng

¹

,

Ballare²,

Woodard³

et al. 2020

Preprint

Self Cite

1

0

View full text Add to dashboard Cite

Major Histocompatibility Complex (MHC) genes encode for proteins that recognize foreign protein antigens to initiate T-cell mediated adaptive immune responses. They are often the most polymorphic genes in vertebrate genomes. How evolution maintains this diversity is still an unsettled issue. Three main hypotheses seek to explain the maintenance of MHC diversity by invoking pathogen-mediated selection: heterozygote advantage, frequency-dependent selection, and fluctuating selection across landscapes or through time. Here, we use a large-scale field parasite survey in a stickleback metapopulation to test predictions derived from each of these hypotheses. We identify over a thousand MHCIIβ alleles and find that many of them covary positively or negatively with parasite load, suggesting that these genes contribute to resistance or susceptibility. However, despite our large sample-size, we find no evidence for the widely-cited stabilizing selection on MHC heterozygosity, in which individuals with an intermediate number of MHC alleles have the lowest parasite burden. Nor do we observe a rare-allele advantage, or widespread fluctuating selection across populations. In contrast, we find that MHC diversity is best predicted by neutral genome-wide heterozygosity and between-population genomic divergence, suggesting neutral processes are important in shaping the pattern of metapopulation MHC diversity. Thus, although MHCIIβ is highly diverse and relevant to the type and intensity of macroparasite infection in these populations of stickleback, the main models of MHC evolution still provide little explanatory power in this system.

show abstract

“…11.8% variation in parasite richness could be explained by habitat type, 4.9% variation could be explained by watershed (ANOVA, habitat term, p < 2e-16), while 28.3% of variation could be explained by sample site (ANOVA, watershed/site term, p < 2e-16). See Bolnick et al (2019 and for further analysis of ecological factors structuring the parasite metacommunity (diversity, composition, co-occurrence) within and among lakes.…”

Section: Sequencing Results and Parasite Informationmentioning

confidence: 99%

“…Details are provided in . These samples were used to examine within-and between-population variation in diet , parasite community composition (Bolnick, Resetarits, Ballare, Stuart, & Stutz, 2019), and parasite species richness (Bolnick, Resetarits, Ballare, Stuart, & Stutz, 2020). The parasite infection data for this study are archived at Dryad Digital Repository .…”

Section: Fish Sampling and Parasite Identificationmentioning

confidence: 99%

“…Then we used Mantel test to examine if the two distance matrices were correlated. A previous analysis (Bolnick et al, 2019) found no significant effect of as-the-crowflies (i.e., Euclidean distance) or as-the-fish-swims (i.e., the shortest in-water path) geographic distance on parasite community structure, so we omit that as a covariate in this distance analysis.…”

Section: Fluctuating Selectionmentioning

confidence: 99%

See 1 more Smart Citation

What evolutionary processes maintain MHCIIβ diversity within and among populations of stickleback?

Peng¹,

Ballare

²

,

Woodard

³

et al. 2020

Preprint

Self Cite

0

View full text Add to dashboard Cite

Major Histocompatibility Complex (MHC) genes encode for proteins that recognize foreign protein antigens to initiate T-cell mediated adaptive immune responses. They are often the most polymorphic genes in vertebrate genomes. How evolution maintains this diversity is still an unsettled issue. Three main hypotheses seek to explain the maintenance of MHC diversity by invoking pathogen-mediated selection: heterozygote advantage, frequency-dependent selection, and fluctuating selection across landscapes or through time. Here, we use a large-scale field parasite survey in a stickleback metapopulation to test predictions derived from each of these hypotheses. We identify over a thousand MHCIIβ alleles and find that many of them covary positively or negatively with parasite load, suggesting that these genes contribute to resistance or susceptibility. However, despite our large sample-size, we find no evidence for the widely-cited stabilizing selection on MHC heterozygosity, in which individuals with an intermediate number of MHC alleles have the lowest parasite burden. Nor do we observe a rare-allele advantage, or widespread fluctuating selection across populations. In contrast, we find that MHC diversity is best predicted by neutral genome-wide heterozygosity and between-population genomic divergence, suggesting neutral processes are important in shaping the pattern of metapopulation MHC diversity. Thus, although MHCIIβ is highly diverse and relevant to the type and intensity of macroparasite infection in these populations of stickleback, the main models of MHC evolution still provide little explanatory power in this system.

show abstract

Scale-dependent effects of geography, host ecology, and host genetics on diversity of a stickleback parasite metacommunity

Bolnick

¹

,

Ej

²

,

Ballare

³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

18Many metacommunities are distributed across habitat patches that are themselves aggregated 19 into groups. Perhaps the clearest example of this nested metacommunity structure comes from 20 multi-species parasite assemblages, which occupy individual hosts that are aggregated into host 21 populations. At both spatial scales, we expect parasite community diversity in a given patch 22 (either individual host or population) to depend on patch characteristics that affect colonization 23 rates and species sorting. But, are these patch effects consistent across spatial scales? Or, do 24 different processes govern the distribution of parasite community diversity among individual 25 hosts, versus among host patches? To answer these questions, we document the distribution of 26 parasite richness among host individuals and among populations in a metapopulation of 27 threespine stickleback (Gasterosteus aculeatus). We find some host traits (host size, gape width) 28 are associated with increased parasite richness at both spatial scales. Other patch characteristics 29 affect parasite richness only among individuals (sex), or among populations (lake size, lake area, 30 elevation, and population mean heterozygosity). These results demonstrate that some rules 31 governing parasite richness in this metacommunity are shared across scales, while others are 32 scale-specific. 33

show abstract

Scale-dependent effects of geography, host ecology, and host genetics, on species composition and co-occurrence in a stickleback parasite metacommunity

Cited by 3 publications

References 71 publications

What evolutionary processes maintain MHCIIβ diversity within and among populations of stickleback?

What evolutionary processes maintain MHCIIβ diversity within and among populations of stickleback?

What evolutionary processes maintain MHCIIβ diversity within and among populations of stickleback?

Scale-dependent effects of geography, host ecology, and host genetics on diversity of a stickleback parasite metacommunity

Contact Info

Product

Resources

About