Schreiber, S. J., S. Patel, C. P. terHorst. 2018. Evolution as a coexistence mechanism: does genetic architecture matter? American Naturalist 2018: 407-420. PDF
Abstract: Species sharing a prey or a predator species may go extinct
due to exploitative or apparent competition. We examine whether
evolution of the shared species acts as a coexistence mechanism and
to what extent the answer depends on the genetic architecture underlying
trait evolution. In our models of exploitative and apparent competition,
the shared species evolves its defense or prey use. Evolving species
are either haploid or diploid. A single locus pleiotropically determines
prey nutritional quality and predator attack rates. When pleiotropy is
sufficiently antagonistic (e.g., nutritional prey are harder to capture),
eco-evolutionary assembly culminates in one of two stable states supporting
only two species. When pleiotropy is weakly antagonistic or
synergistic, assembly is intransitive: species-genotype pairs are cyclically
displaced by rare invasions of the missing genotypes or species. This intransitivity
allows for coexistence if, along its equilibria, the geometric
mean of recovery rates exceeds the geometric mean of loss rates of the
rare genotypes or species. By affecting these rates, synergistic pleiotropy
can mediate coexistence, while antagonistic pleiotropy does not. For
diploid populations experiencing weak antagonistic pleiotropy, superadditive
allelic contributions to fitness can mitigate coexistence via an
eco-evolutionary storage effect. Density dependence and mutations also
promote coexistence. These results highlight how the efficacy of evolution
as a coexistence mechanismmay depend on the underlying genetic
architecture.
Keywords: eco-evolutionary feedbacks, ploidy, storage effect, species
coexistence, ecological pleiotropy, mutation.
