Vilaiwan Fernandes
Speciation and hybrid vigor of populations can more generally be thought of as incompatibility and compatibility. These evolutionary principles are not well understood despite 150 years of study. Here, we successfully attempt to evolve the endocycle network for both a haploid and diploid network. We set up evolutionary games among sexual and asexual haploids and diploids by placing identical founders into three different criteria: 1) extreme deterministic selection for slow cell cycle oscillations, 2) deterministically neutral conditions and 3) extreme deterministic selection for fast cell cycle oscillations. We find that on average, for conditions of extreme selection, sexual haploid populations self-hybridize with higher efficacy than sexual diploids do due to the accumulation of hemi lethal alleles. Outcrossing in the case of sexual haploids is generally unfavorable while hybrid vigor by sexual diploid outcrossing is common and most frequent with populations subjected to deterministically neutral conditions. From our results we conclude that distance between selection criteria is not directly translatable to genetic distance between populations and that evolution follows a random walk rather than a purely deterministic one. Based on the assumption that a successful switch from asexual reproduction to sexual reproduction is dependent on self-hybridization success, our results for asexual reproducers suggest that sexual reproduction (i.e. reproduction with recombination) pre-dates an increase in ploidy for early diploid sexual reproducers.
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Results of 4 simulated populations (in different colors) for 500 generations showing mean period of a cell cycle. Individuals were selected for ability to produce faster cycles, and the period of cycle decreases over time. |
Plot of frequency of alleles vs. generation number for an evolving population. The prevalence of different alleles are plotted in different colors. Initially, the population is clonal at generation 1, but mutation rapidly produces new alleles, leading to a diversity of alleles. |
