Variation, selection and heritability of thermal reaction norms for juvenile growth in Orchesella cincta (Collembola: Entomobryidae)

Abstract

Abstract. Genetic variation for thermal plasticity plays an important role in the success or failure of a species with respect to the colonization of different thermal habitats and the ability to deal with climatic change. The aim of this paper is to study the relative contribution of the additive and non-additive components of genetic variation for the slope of the temperature reaction norm for juvenile growth rate in the springtail Orchesella cincta. We present the outcome of an artificial selection experiment for steep and flat temperature reaction norms and the results of a parent-offspring heritability experiment. There was a considerable phenotypic variation for the slope of the reaction norm. The selection experiment and the offspring to parent regression analysis, however, yielded no evidence for significant additive genetic variance. There were also no indications for maternal effects. The full-sib analysis, on the other hand, revealed a significant broad sense heritability of 0.76. An unforeseen result was that the slopes of females were steeper than those of males. This influenced the broad sense heritability of the full-sib analysis, since accidental female or male biased broods inflate the estimate of heritability. A randomization test showed that the probability level of the observed "between group" variance on the basis of the sexual differences alone was less than 10 -5 . From this we conclude that autosomal genetic variation played its own separate role. In conclusion, the thermal reaction norm for growth in juvenile O. cincta is not very much determined by the additive effects of a large number of independent genes, but more likely based on a still unknown but mainly non-additive, partially sex-related genetic mechanism, possibly including both dominance and epistatic effects. Hypotheses about the role of phenotypic plasticity in processes of local adaptation and speciation should thus be alert to such a complex genetic architecture.

Adapting to climate change: a perspective from evolutionary physiology

“…Moreover, it has also been widely documented in laboratory studies of responses to environmental temperature and water availability (e.g. Bennett et al 1992, Cavicchi et al 1995, Bull et al 2000, Gibbs et al 2003, Bubliy & Loeschcke 2005, Driessen et al 2007, Sørensen et al 2007, Vera et al 2008.…”

“…Plastic changes have an underlying genetic basis and the extent of plasticity may thus also evolve (Scheiner 2002, Driessen et al 2007). For example, Nussey et al (2005) showed that great tits Parus major in the Netherlands have increased their phenotypic plasticity to cope with more unpredictable spring weather in the Netherlands over the last 32 yr.…”

Genetic variation in heat resistance and HSP70 expression in inbred isofemale lines of the springtail Orchesella cincta

“…Each line was initiated by one parental pair from a mass-bred population that had been cultured in the laboratory for 5 generations (Driessen et al 2007). The mass-bred population initially consisted of a mix of 4 populations: Poland (Pilica: 50°29.1' N, 19°39.6' E), Sweden (Ringarum: 58°21.5' N, 16°13.7' E) and The Netherlands (Roggebotzand: 52°34.4' N, 05°47.9' E; Amsterdamse Waterleidingduinen: 52°1.5' N, 04°33.1' E).…”

Interaction Milieu Explains Performance of Species in Simple Food Webs along an Environmental Gradient

“…The parameters w i and w m were fixed for all scenario's ( Table 1) and were derived from empirical data on growth curves and life history of Collembola, which show that individuals show exponential growth until reaching maturity after repeated moult cycles, after which growth rate slows down (Jansen & Joosse 1987;Ernsting & Isaaks 1997;Driessen et al 2007). Salinity of the habitat varies among simulations from nonsaline to saline conditions (S 0-10 ).…”

“…A generalist response curve provides a constant growth rate independent of salinity. Exponential growth determines the body weight at time t according to w t+1 = w t · e r , and an individual reaches maturity if w t ≥ w m (Driessen et al 2007). A mature individual has a reproductive rate m of one surviving offspring per time step.…”