Variability in Survival, Growth and Metamorphosis in the Larval Fire Salamander (Salamandra Salamandra): Effects of Larval Birth Size, Sibship and Environment

Abstract

Salamandra salamandra has an unusual mode of reproduction. Females retain eggs in their oviducts and give birth to aquatic larvae or, in some populations, to fully metamorphosed juveniles. We investigated how variation in the birth size of larvae of five different sibships of S. salamandra affected larval survival, larval growth rates, time to metamorphosis, and size at metamorphosis under different food and temperature conditions. Maternal effects, via the effect of larval birth size, attenuated throughout development in all environments but still affected metamorphic traits at lower temperatures. Larval developmental time was negatively correlated with larval birth size and positively correlated with size at metamorphosis. After controlling for the effect of larval birth size, broad-sense heritabilities were obtained for residual values of metamorphic traits, indicating that enough genetic variability exists at lower temperature environments and that responses to selection of metamorphic traits are possible. The size at and the time to metamorphosis were phenotypically and genetically correlated. Since both traits presumably affect fitness, genetic dependence between size and time to metamorphosis may act as a constraint on adaptive evolution through antagonistic pleiotropy. Mass-specific growth, time to metamorphosis, and size at metamorphosis were plastic under different temperature and food conditions, but no significant sibship 3 environment interaction was found for any trait. In addition, significant cross-environment correlation for size at metamorphosis with respect to the food gradient indicates low potential for the adaptive evolution of reaction norms to heterogeneous food environments.Key words: Maternal effects; Metamorphosis; Plasticity; Salamandra salamandra; Sibship variation; Trade-offs VARIATION in offspring traits that confer fitness upon which natural selection may act is due to inter-individual differences in genotype, environmental conditions (including maternal effects), and genotype 3 environment interactions (the variation in the relative expression of genotypes in different environments; Lewontin, 1974). Maternal effects are considered the source of individual phenotypic variation attributable not to an organism's own genotype or its interaction with the environment but to the phenotype or environment of its mother (Wade, 1998). Since maternal effects are the expression of the maternal phenotype and have an inherent genetic component, such traits should evolve in much the same way as any other trait that shows Mendelian inheritance. Maternal effects in species that provide no parental care to their offspring are basically limited to the investment the female may provide to the eggs. Usually, maternal effects have their maximal influence during the earlier stages of ontogeny (a period of greatest mortality). Egg and propagule size variations have been empirically demonstrated to have strong effects on offspring fitness traits in plants and animals (Azevedo et al., 1997; Roach...

The more the better – polyandry and genetic similarity are positively linked to reproductive success in a natural population of terrestrial salamanders (Salamandra salamandra)

“…Size and weight at birth are positively related with fitness in fire salamanders (Alcobendas et al . ), but in our study, they did not show any dependence on the number of sires (Data S5, Supporting Information). Similarly, heterozygosity is often assumed to be advantageous in general (Amos et al .…”

Poor Nutritional Conditions During the Early Larval Stage Reduce Risk-Taking Activities of Fire Salamander Larvae (Salamandra salamandra)

“…After metamorphosis, fire salamanders are completely terrestrial, only returning to the water for the deposition of larvae. Accordingly, during the larval phase, fire salamander larvae can be exposed to stressful periods (Alcobendas et al. 2004; Eitam et al.…”

Variation in timing of ossification affects inferred heterochrony of cranial bones in Lissamphibia

“…Abiotic environmental variables such as pH (Cummins 1989;Pahkala et al 2001), ultraviolet radiation (Belden and Blaustein 2002), and temperature (Alcobendas et al 2004) are known to influence the outcome of developmental morphology. Abiotic environmental variables such as pH (Cummins 1989;Pahkala et al 2001), ultraviolet radiation (Belden and Blaustein 2002), and temperature (Alcobendas et al 2004) are known to influence the outcome of developmental morphology.…”