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Phenotypic and genetic variation for competitive ability and their impact on long-term interactions between spider mites
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Resumo(s)
Competition is a major driver of population dynamics and species coexistence. Indeed, it affects genetic
diversity, either by decreasing it if there is strong niche segregation, reducing the fundamental niche of
each species, or by maintaining it if there are strong trade-offs between intraspecific and interspecific
competition. In turn, within population diversity is expected to affect the outcome of competition and,
thus, the probability of species coexistence. However, empirical tests of how diversity affects
competition and how evolving with competitors affects diversity are scarce. In this thesis, we aimed 1)
to characterize the individual variation for intra- and interspecific competitive ability in a population of
spider mites, 2) predict the impact of individual variation for competitive ability on coexistence with
other species, and 3) observe how evolving with competitors affects genetic diversity. For this purpose,
we characterized the competitive ability of 29 Tetranychus evansi’ inbred lines originated from one
outbred population and used these estimates to predict, through theoretical models, the long-term
interactions with Tetranychus urticae (i.e., the likelihood of coexistence). Then, we also conducted a
full-sib/half-sib analysis in T. evansi populations that have evolved under heterogeneous conditions
alone or in competition with T. urticae. We observed high phenotypic and genetic variation in intra- and
interspecific competitive ability among the inbred lines. This individual variation translated into a
plethora of possible outcomes ranging from coexistence to extinction of either competitor. Finally, we
found significant values of additive genetic variance for competitive ability in populations that have
evolved with competitors when exposed to competitive environments. Our results suggest that
competitive ability may evolve, facilitating the persistence of populations in dynamic environments and
altering the probability of coexistence with heterospecifics. However, evolving in competitive and noncompetitive environments may alter the amount of genetic diversity, having, consequently, an impact on
ecological dynamics.
Descrição
Tese de mestrado, Biologia Evolutiva e do Desenvolvimento, 2024, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Coexistência Habilidade competitiva Variação Individual Variância genética aditiva Tetranychus evansi Teses de mestrado - 2024