Colonization, population dynamics, predatory behaviour and cannibalism in Heterocypris incongruens (Crustacea: Ostracoda)

Abstract

We followed the artificial colonization of a temporary pond in Northern Italy by the freshwater ostracod Heterocypris incongruens. The species had not been found in the pond in previous years. In May 2009 we released five laboratory reared, genetically identical, parthenogenetic females and observed the population during colonization and growth until desiccation (May- July 2009) and two subsequent hydro-periods (February-March and May-July 2010). High population density was always reached in few weeks, although in late winter 2010 no ovigerous female was observed and in spring 2010 the population was recruited only from resting eggs. In all three hydro-periods swarms formed every day and could be easily seen near the border of the pond to the eye around the median time of the sun path. In laboratory observations, individuals sampled from the swarm forming population showed predatory behaviour: H. incongruens attack, kill and consume live, actively self-defending organisms (Chironomid and mosquito larvae). We also observed cannibalism among adult females. We found low fecundity and high mortality in females sampled from the crowded population and kept in low density laboratory conditions. We discuss how cannibalism, delayed egg hatching, fecundity loss and high mortality by crowding regulate high density populations of H. incongruens, a typical r strategy species. Key words

Hatching phenology and voltinism of Heterocypris barbara (Crustacea: Ostracoda) from Lampedusa (Sicily, Italy)

“…According to McLay (1978), difference in hatching phenology and recruitment of resting eggs are among the factors that allow the coexistence of Cyprinotus (Heterocypris) carolinensis and Herpetocypris reptans in temporary pools. In Heterocypris incongruens, clones with a different genetic make up modulate their survival, production and hatching of resting eggs so that, by seasonal clonal succession, the species is present through the drastically different seasonal environmental conditions of northern Italy temporary ponds (Rossi et al, 1996(Rossi et al, , 2011. In different European clones of the vernal species Eucypris virens, resting egg production, variation in voltinism and hatching delay are the result of latitudinal adaptation in response to day-length duration, a reliable predictor of drought or adverse conditions (Otero et al, 1998).…”

Zoogeography of the ostracod genusNannocandona(Podocopa) with description of two new species from Europe and East Asia

“…In comparison with other parthenogenetic ostracods, especially surface water ones that lay many more eggs (Rossi et al, 2011) or lineages that display a brooding care, such as darwinulids (see Pinto et al, 2007), the strategy of parthenogenetic subterranean Candoninae does not promise much success when it comes to the species dispersal strategies. The importance of resting eggs and parthenogenesis in freshwater ostracod evolutionary success has already been discussed elsewhere (Horne, 1993).…”

Assessing the role of canopy cover on the colonization of phytotelmata by aquatic invertebrates: an experiment with the tank-bromeliad Aechmea lingulata

“…The abundances of Ostracoda and Hydracarina in the tanks of A. lingulata are likely related to the high resistance of these organisms to stressful environmental conditions, including desiccation (Smith et al, 2001;Di Sabatino et al, 2008;Rossi et al, 2011). The ability of some aquatic invertebrates to produce dormant eggs is an adaptation that favors success in bromeliad tanks (Williams, 1997(Williams, , 2005.…”