Early release of eggs and embryos in a brooding ancient asexual ostracod: brood selection or a gambling strategy to increase fecundity?
- 87 Downloads
Asexual lineages lack the means to purge their genomes of (deleterious) mutations through recombination. Evolutionary theory thus predicts that such lineages will be prone to early extinction. In brooding animals, brood selection might provide a mechanism to counter the accumulation of mutations. Of the three putative ancient asexual animal groups, only the darwinulid ostracods are brooders. Here, we test the incidence of egg and juvenile abortion in a darwinulid species, Penthesilenula brasiliensis, under two temperature treatments. Part of the offspring is released without brooding (close to 30% in one treatment). The majority of these aborted eggs hatches and develops. As it is unlikely that females are such bad judges of offspring quality, either the surviving animals will present deficiencies later on in development (brood selection) or early egg release can be a (bet-hedging) strategy to increase fecundity in favourable conditions.
KeywordsBrooding Ancient asexual Ostracoda Darwinulidae Reproduction Evolution Bet-hedging
Fábio Lang da Silveira (São Paulo, Brazil) is acknowledged for allowing the use of equipment in his laboratory. Roberto Munehiza Shimizu (São Paulo, Brazil) provided advice with statistics. FAPESP allocated a Ph.D. grant (Processo: 03/13510-5) to RLP and provided financial assistance to KM (Processo: 98/05073-4). The study was also supported with a scholarship from ‘Pós-Graduação, Área Zoologia, IB-USP’ and ‘CAPES/PROAP/IBUSP-2003’. Robin Smith (Kusatsu, Shiga, Japan), Isa Schön (Brussels, Belgium) and several anonymous referees read the manuscript and suggested improvements.
- Horne, D. J., K. Martens & F. Mösslacher, 1998. A short note: is there brood selection in Darwinula stevensoni? In Crasquin-Soleau, S., E. Braccini & F. Lethiers (eds), What about Ostracoda! Actes du 3e Congrès Européen des Ostracodologistes, Paris-Bierville, France 8–12 juillet 1996. Bulletin des Centres de Recherches Exploration-Production Elf-Aquitaine 20: 33–35.Google Scholar
- Maynard-Smith, J., 1990. Evolution of Sex. Cambridge University Press, Cambridge.Google Scholar
- McGregor, D. L., 1969. The reproduction potential, life history and parasitism of the freshwater ostracod Darwinula stevensoni (Brady and Robertson). In Neale, J. W. (ed.), The taxonomy, morphology and ecology of recent Ostracoda. Oliver & Boyd, Edinburgh, 194–221.Google Scholar
- Pinto, R. L., C. E. F. Rocha & K. Martens, 2004. On the genus Penthesilenula Rossetti & Martens, 1998 (Crustacea, Ostracoda, Darwinulidae) from (semi-) terrestrial habitats in Sao Paulo State (Brazil), with the description of a new species. Journal of Natural History 38: 2567–2589.CrossRefGoogle Scholar
- Ranta, E., 1979. Population biology of Darwinula stevensoni (Crustacea, Ostracoda) in an oligotrophic lake. Annales Zoologici Fennici 16: 28–35.Google Scholar
- Rossetti, G. & K. Martens, 1996. Redescription and morphological variability of Darwinula stevensoni (BRADY & ROBERTSON, 1870) (Crustacea, Ostracoda). Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, Biologie 66: 73–92.Google Scholar
- Rossetti, G. & K. Martens, 1998. Taxonomic Revision of the Recent and Holocene representatives of the Family Darwinulidae (Crustacea, Ostracoda), with a description of three new genera. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, Biologie 68: 55–110.Google Scholar
- Schön, I. & K. Martens, 2003. No slave to sex. Proceedings of the Royal Society of London, Series B 270: 827–833.Google Scholar