Adaptation of the reproductive cycle in Triturus alpestris apuanus to an unpredictable habitat

Abstract

The annual reproductive cycle was studied in a Triturus alpestris apuanus population from northwestern Italy. Adult and larval newts were captured and measured monthly. By using histological techniques, the status and evolution of male gonads were examined. T. a. apuanus shows a post-nuptial gametogenesis, and testes reach their smallest size and weight in spring, when there are mainly mature sperm ampullae and yellow glandular tissue. Secondary sexual characters reach their maximum development during this period, decreasing during gametogenesis and increasing again in early autumn. Breeding activity begins at the same time, and is interrupted by the winter. Reproduction starts again in spring, lasting until summer. Eggs are laid at least twice a year, and the two larval cohorts live together. It is suggested that all these biological features are adaptations to unpredictable aquatic environments in a Mediterranean dry climate. These results suggest high levels of flexibility and variability in newt seasonal cycles.

The crested newt (Triturus carnifex) in the Submediterranean: Reproductive biology, body size, and age

“…However, variability and flexibility of cycles are found within the same species, depending on geographic location , especially in unpredictable environments (e.g., Andreone & Dore, 1992).…”

“…The reproductive cycle of European newts has been the subject of a number of recent studies (e.g., Vendl & Halliday, 1985;Fraile et al, 1989;Andreone & Dore, 1992;Guarino et al, 1992). However, less attention has been paid to species belonging to Triturus cristatus superspecies (e.g., Galgano, 1944Galgano, , 1947Malacarne & Cortassa, 1983), particularly to simultaneous analysis of both sexes.…”

“…Most previous studies dealt with specific aspects (biochemical, endocrine, behavioural) of male reproduction Vellano et al, 1967;Malacarne & Giacoma, 1980;Malacarne et al, 1984). It is known that reproductive cycles of temperate-zone urodeles may be modified, depending on geographical location ; particularly interesting in this respect are newt populations from Mediterranean and Submediterranean regions (Andreone & Giacoma, 1989;Andreone & Dore, 1992;Fasola & Canova, 1992).…”

Active ion transport and morphofunctional organization in the skin of the alpine newt,Triturus alpestrisduring the life cycle

“…They were classified according to Dubois (1985;Breuil, 1986;Andreone et al, 1992) as larvae, pedomorphic, and metamorphosed specimens. a. Larvae: gilled sexually immature individuals with a total length < 40 mm, mean body weight (b.w.)…”

“…Among European urodele species the alpine newt, Triturus alpestris, lives a relatively aquatic life (Andreone & Dore, 1992) and has a high incidence of pedomorphism . In order to complement information on variations in thyroids and gonads in larval, pedomorphic and metamorphosed individuals , this paper reports data on skin morphology and ion exchange.…”