"The evolution of life cycles and mating systems"Mackintosh, CarlCompetition for mating can occur at different stages of the life cycle. Diploid adults fight for mating opportunities while haploid gametes compete for fertilisation. In organisms with separate sexes, the intensity of competition between male gametes from different individuals can be modulated by anisogamy (the difference in size and number of gametes between the sexes) and by the female, who could choose to mate multiply at her own cost. Alternatively, some may choose to forego this route through self-fertilisation, leading to competition between their own gametes. Both mating system and life cycle have profound effects on long term evolution, as genes could be expressed in heterozygotes, homozygotes, or haploids. For example, self-fertilisation (which generates an excess of homozygotes) and selection in the haploid phase purge the genome by fully exposing deleterious alleles to selection, but also result in an immediate decline in fitness. This also applies to sex determination systems: one sex may be heterogametic (eg XY males, ZW females) while the other is homogametic (XX females, ZZ males), masking harmful mutations on one sex chromosome. This symposium brings together researchers who use mathematical techniques to answer questions related to the evolution of life cycles, mating systems, and their co-evolution, from a diverse range of perspectives, with the hope that it fosters stimulating discussions and future collaborations. |
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