Evol Ecol Res 11: 57-77 (2009) Full PDF if your library subscribes.
Alternation of haploid and diploid generations: evolution by gamete amplification
Priya Iyer and Joan Roughgarden
Department of Biological Sciences, Stanford University, Stanford, California, USA
Correspondence: P. Iyer, Department of Biological Sciences, Stanford University, Herrin 424 Serra Mall, Stanford, CA 94305, USA.
Question: What selects for the alternation of haploid and diploid generations in algal taxa?
Mathematical methods: We derive the growth rates of haplontic, diplontic, and haplo-diplontic populations as functions of ploidy-dependent survival probabilities and propagule production rates. We use a population genetic model with a single locus coding for haplonty, diplonty, and haplo-diplonty to obtain the evolutionarily stable conditions for the fixation of each of the three ploidy-cycles. We simulate the evolutionary dynamics to demonstrate the convergence to these equilibria.
Key assumptions: Non-overlapping generations, ploidy-dependent propagule production and survival rates, and the synchronous release of gametes into water by the entire population. We assume that the fertilization probability of eggs increases as a function of the sperm density encountered.
Conclusions: The ploidy-cycle selected is predicted to be the one with the highest population growth rate defined by propagule production and survival rates. Haplo-diplonty may be selected in low fertilization environments because it mitigates the problem of sperm limitation, as the gamete concentration amplifies over subsequent generations. Diplonty may be favoured in more variable environments because diploidy confers higher viability in such environments.
Keywords: algae, alternation of generations, fertilization probability, haplo-diplonty, ploidy, sperm limitation.
DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.
© 2009 Priya Iyer. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.
Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.
All copies of abstracts and articles must preserve their copyright notice without modification.