Influences of facultative paedomorphosis on kin selection in a larval salamander, Ambystoma talpoideum

Kin selection in larval amphibians is hypothesized to increase survival to metamorphosis. While kin selection may benefit amphibians with obligate metamorphosis, increased survival within sibships may exert fitness costs on facultatively paedomorphic species, such as increased competition among kin. Consequently, it is unclear whether such species should engage in kin selection. We investigated kin selection in a facultatively paedomorphic salamander, Ambystoma talpoideum, using laboratory behavioural trials and microcosm experiments. Individuals were most aggressive towards familiar siblings, and full-sibship groups incurred more injuries than mixed-sibship groups; however, familiar siblings ultimately exhibited higher survival. Thus, while short-term responses appeared to reflect the hypothesized costs of kin recognition, long-term patterns of survival did not support this hypothesis. The inconsistencies between results suggest that short-term studies may not capture ontogenetic variation in kin selection, and that long-term studies are needed to better test the hypothesized effects of kin selection on survival and metamorphosis.

On the occurrence of facultative paedomorphosis in the three newt species of Southern Iberian Peninsula (Amphibia, Salamandridae)

We report the occurrence of facultative paedomorphosis in the three species of newts (Pleurodeles waltl, Lissotriton boscai and Triturus pygmaeus) from dry and seasonal Mediterranean areas from southern Spain. These are the first records of paedomorphosis for P. waltl and L. boscai, and the second for T. pygmaeus. Other than the previous T. pygmaeus record, these are the first observations of paedomorphosis in the southern half of the Iberian Peninsula. Most of specimens demonstrating paedomorphosis live in artificially permanent aquatic environments. Nevertheless, a paedomorphic individual of L. boscai was found in a natural yearly temporary brook that held water during the previous two years. Paedomorphs are at low frequency in most cases. However, a single isolated population of P. waltl is probably composed entirely of paedomorphs.