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Sökning: WFRF:(Siljestam Mattias) > (2024) > Mathematical Soluti...

Mathematical Solutions to Divergent Evolution

Siljestam, Mattias, 1989- (författare)
Uppsala universitet,Zooekologi
Rüffler, Claus (preses)
Uppsala universitet,Zooekologi
Arnqvist, Göran, Professor, 1961- (preses)
Uppsala universitet,Zooekologi
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Kisdi, Eva, Senior University Lecturer (opponent)
Department of Mathematics and Statistics, University of Helsinki, Finland
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 (creator_code:org_t)
ISBN 9789151321462
Uppsala : Acta Universitatis Upsaliensis, 2024
Engelska 63 s.
Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 2407
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)
Abstract Ämnesord
Stäng  
  • Diversity is ubiquitous in nature and manifests through various forms of divergent evolution. Using mathematical models that consider the interplay between ecology and evolution, I explore mechanisms driving two types of such divergence: the emergence of genetic diversity in diploid organisms, and the initial sexual dimorphism of anisogamy.Genetic diversity is typically studied as a consequence of competition or local adaptation. However, diploidy introduces an alternative mechanism: heterozygote advantage (HA), where alleles provide complementary functionalities. A classical example is the immune genes of the Major Histocompatibility Complex (MHC), where alleles can protect against complementary sets of pathogens. HA can emerge if individuals encounter multiple pathogens. When pathogens are distributed over habitats, divergence can be driven by local adaptation, or an emerging HA if migration is high. Alternatively, if MHC alleles provide full defence as a single copy (adaptive context-specific dominance), HA can also emerge under low migration. I challenge the view that HA alone cannot explain the high polymorphism observed at MHC loci by demonstrating that over 100 alleles can be maintained based on two critical assumptions: pathogens can be lethal if not properly countered by an immune response, and the combined effect of multiple pathogens can exceed the sum of their individual impacts.For loci under sexually antagonistic selection, divergent evolution can facilitate the coexistence of alleles, each producing a homozygote genotype with an optimal phenotype in one sex while the heterozygote exhibits an intermediate maladapted phenotype. However, I show that sex-specific dominance is expected to evolve, resulting in a marginal HA across the sexes: a heterozygote carrying alleles optimal for each sex exhibits an optimal phenotype in both sexes, whereas the corresponding homozygotes are maladapted in one sex. This leads to further divergence and the coexistence of many alleles, for wide parameter ranges.Additionally, I challenge the traditional view that male-biased competition for mating is an inevitable consequence of anisogamy---the evolutionary differentiation in gamete size between the sexes. I present the first theoretical description of the coevolution of anisogamy and mating competition, demonstrating that anisogamy does not inherently favour male competition. Instead, the specific evolutionary conditions and the nature of the competition trait significantly influence which sex invests more in mating competition.This thesis not only enhances our understanding of the underlying drivers of genetic and phenotypic diversity but also challenges longstanding evolutionary paradigms, shedding light on the complex dynamics that shape life’s vast diversity.

Ämnesord

NATURVETENSKAP  -- Biologi -- Evolutionsbiologi (hsv//swe)
NATURAL SCIENCES  -- Biological Sciences -- Evolutionary Biology (hsv//eng)

Nyckelord

evolutionary dynamics
heterozygote advantage
sexual selection
evolutionary dynamics
MHC
adaptive dynamics

Publikations- och innehållstyp

vet (ämneskategori)
dok (ämneskategori)

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