Poster Presentation Society for Molecular Biology and Evolution Conference 2016

Comparison of adaptive mechanism between sexual and asexual reproduction in Tetrahymena thermophila based on the experimental evolutionary genomics (#507)

Guangying Wang 1 , Jie Xiong 1 , Kai Chen 2 , Wentao Yang 1 , Wei Miao 1
  1. Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China
  2. Northwest Normal University, Lanzhou, Gansu, China

The evolution and maintenance of sex is an important problem in evolutionary biology. The advantage of sexual reproduction was thought that it increases the rate of adaptation to the novel environment comparing to the asexual reproduction, but the molecular basis of this adaptive advantage and the similarities/differences between sexual and asexual reproduction are still unclear. Tetrahymena thermophila, as a classical unicellular model organism, has made outstanding contributions to the discovery of foundational biology, such as telomere, telomerase and RNA self-splicing. Using its advantages including possessing sexual and asexual stages during its life cycle, culture in the lab, complete genomic and transcriptomic database and techniques of omics and bioinformatics, we dynamically detect the changes of DNA, transcriptional regulation and genome organization during the continuous culture in the lab. Five parallel cell lines were set up. Currently, 1100 asexual fissions and 11 times sexual reproduction had been completed. The fitness tests (growth rate) indicated sexual populations grew significantly faster than asexual populations. Moreover, base on the re-sequencing genome/transcriptome data, we found sexual populations can produce much more genetic variation and accumulate more beneficial mutations than those of asexual populations. In addition, as for sexual group, all the populations had losed mating ability after at most six rounds of sexual reproduction because of the purification of mating types, which resulted in them switching from sexual reproduction to asexual reproduction. Followed by this switching, the fixation of beneficial mutations produced by sex was completed in short 100-200 fissions through asexual reproduction.