[C05] Evolution and Genetics

[C05-02] Evolution of allelopathy of macroalgae in the infinite island model

*Bessho Dr.Kazuhiro¹ (1. Saitama Medical University (Japan))

Keywords:

kin selection,life cycle,polyploidy,class structure,algae

Allelopathy, a chemically mediated biotic interaction in terrestrial plants, has been reported in marine macroalgae. For example, the cases in which macroalgae produce inhibitors that suppress the growth of competitors, such as algal species or corals, and predators, and produce chemical substances that inhibit the predation by fishes or marine invertebrates are reported. In addition, although this does not provide a direct benefit, producing inhibitors against common predators may indirectly increase the fitness of other individuals. These biological interactions have mainly focused on the relationship between different species, but interactions between different stages within the same species are particularly interesting in macroalgae. In the population of macroalgae with a biphasic (haploid-diploid) life cycle, due to the alternation of generations between haploid and diploid phases, two physiologically distinct independent stages, haploid gametophytes and diploid sporophytes, coexist. These ecological and genetic characteristics present the question of whether chemical-mediated interactions exist between different ploidy stages in the same species of macroalgae. This study discusses this question within the framework of kin selection. First, I consider a single population to examine the evolution of the trait that any stage pays the cost for producing chemical substances that increase or decrease the fitness of other individuals, which are the same or different ploidy stages. As we can easily imagine, I show that such social traits cannot evolve in a single population. Second, I examine the effect of spatial structure on the evolution of allelopathy of macroalgae. In this study, I adopt the infinite islands model and analyze whether the selection favors the altruistic and spiteful allelopathy among kin due to the bias of dispersal.