Early release of eggs and embryos in a brooding ancient asexual ostracod: brood selection or a gambling strategy to increase fecundity?
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.
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