Early and late maternal effects on hatching phenology of heterocypris incongruens (crustacea: Ostracoda)

Abstract

In ephemeral ponds, the hatching asynchrony of resting eggs may be adaptive and the result of a maternal bet-hedging strategy. A mother can influence the progeny phenology through conditions experienced during life cycle even in early development stages. We investigated the consequences of a hatching delay for offspring and compared early and late maternal effects in a clonal lineage of Heterocypris incongruens. We used females from genetically identical, 40 months old, resting eggs that hatched, asynchronically, after a first (FI) or a second (SI) inundation event. Maternal origin (FI or SI) was considered an early effect involving the maternal response to hatching stimuli during the embryological dormant stage. Maternal age at deposition and egg size were considered late effects that account for maternal conditions during active stage. We compared size and development time of eggs produced by FI and SI females under laboratory condition (24°C 12:12 L:D photoperiod). Maternal origin affected development time to adulthood which was later in FI than in SI females, and fecundity that was higher in FI than in SI females. SI eggs were smaller than FI eggs: size was affected by maternal age at deposition and was directly related to the egg development time. Development time varied from 1 to 117 days and was shorter in SI eggs than in FI eggs. Our results showed that maternal response during embryological stage affects the performance in successive active stages and suggested that hatching asynchrony may be considered a risk spread strategy.

Mother's Age and Hatching Phenology Strategy ofHeterocypris incongruens(Crustacea: Ostracoda) in Unpredictable Environment

“…Similar results are reported by Havel and Talbott (), Rossi and Menozzi (), and Rossi et al. (, ). It is well known that, in ectotherms, development time is closely related to temperature (Angilletta et al., ) and empirical studies on delayed embryonic development are rare (De Block and Stocks, ).…”

“…) may justify statements of generalities about the multiclonal population of Cavallo Bianco. Moreover, while more than one clone of H. incongruens from Lampedusa exhibit this kind of maternal effect, we have evidence that the widespread winter clone from Northern Italy did not (Rossi et al., ). We suggest that this maternal‐age trait might be an adaptation to the unpredictability of Lampedusa ephemeral ponds.…”

“…In Heterocypris , we described resting eggs that prolonged dormancy over more than one hydroperiod (Rossi et al., , , ). We showed that hatching asynchrony of resting eggs affects the performance of females and may be considered as a risk‐spreading strategy (Rossi et al., ). In E. virens , we reported the effect of mother presence that is probably linked to behavior (i.e., releasing chemicals in the medium or “handling”) as a possible mechanism for the expression of a risk‐spreading strategy in nonresting eggs (Rossi and Menozzi, ).…”

Duration of life‐cycle toxicity tests with the ostracod Heterocypris incongruens

“…Heterocypris incongruens produces some long‐dormant (diapausing) eggs (> 150 d for hatching) as well as early eggs that hatch within 30 d after laying . Egg development time is influenced by factors such as photoperiod, temperature, genotype differences, and maternal effects and thus cannot be well predicted by the egg size . The net reproductive rate ( R 0 ; number of hatchlings per female) is a frequently used endpoint in life‐cycle tests; nevertheless, the long monitoring of egg development over 150 d is not practical for a routine toxicity assessment.…”

Postembryonic development of nonmarine ostracod Chlamydotheca arcuata (Sars, 1901) (Crustacea: Ostracoda), reared in the laboratory

“…Therefore, the A-1 instar corresponds to the last juvenile stage before adulthood (Aguilar-Alberola and Mesquita-Joanes, 2013). Nevertheless, Roessler (1982aRoessler ( , 1982bRoessler ( , 1998 found an earlier instar called the "prenauplius" or A-9 in some species of the family Cyprididae, and Aguilar-Alberola and Mesquita-Joanes (2013) and Rossi et al (2015) described a prenauplius or postembryonic stage A-9 in Heterocypris bosniaca and H. incongruens, respectively. Usually, the ontogeny of the species of the family Cyprididae is similar, with specific limbs forming during the same instar stages.…”