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“The present study is based on 4871 Salamandra infraimmaculata half-sib larvae belonging to 74 cohorts born in the laboratory to individually identifiable females during the study period 1974–1998. Some cohorts (37%) included between 50 and 100 larvae, 40% of the cohorts had

<50 larvae and 23% had >100 larvae. Some larvae (48.4%) were born early during October–November; the remainder were born later in the season. 17.7% of all larvae were born during the third week of December. About 3% Silmitasertib of the larvae studied here were born dead either malformed or aborted before they were ready. On one occasion, larvae were born alive free of their yolk sac. There is a significant variability in the mass of newborn larvae. The number of larvae born in cohorts of five females (F-65, F-69, F-81, F-83 and F-114) varied over the years. The variability may be due to the fact that the larvae may be of different paternal origin. This is reflected later in their differential growth and metamorphic timing. There was no relationship between cohort size and female’s age. The significance of the larval period for survival of the adult salamander is discussed. “
“A

multi-year radio-telemetric study of the copperhead Agkistrodon contortrix (Serpentes: Viperidae) was conducted at the north-eastern extreme of its range to determine the relationship of plasma sex steroids of males to the mating season. Blood Volasertib datasheet samples were collected in situ approximately every 2 weeks (repeat-test group) from radio-telemetered males during the 7-month active season (April–October) from 2001 to 2003 and assayed for concentrations of testosterone (T) and progesterone (P4). Blood samples were also obtained from a large number of incidental males (single-test group) for the analysis of seasonal levels of T and P4. The profiles of T and P4 showed a peak in August–September that corresponded to the single mating season (late July to late September). Both T and P4 had similar seasonal profiles, but absolute levels of these steroids were significantly

Phosphatidylinositol diacylglycerol-lyase different, with concentrations of T four- to fivefold greater. The mating season of the population we investigated differs from other (e.g. southern) populations, which show two mating seasons (late summer/early fall and spring) before the period of ovulation in mid- to late spring. When a mating season is absent in spring, inseminated females are obligated to store sperm over winter until ovulation in the spring. In studies of A. contortrix that document two mating seasons, peak levels of T in males are coincident with both of these periods. In contrast, we found that peak levels of T and P4 in males coincided with the occurrence of the single mating season, and levels were basal in spring.