Reproductive Ecology of the Common South American Toad Rhinella arenarum (Anura: Bufonidae): Reproductive Effort, Clutch Size, Fecundity and Mate Selection.

BIONDA, C.; LAJMANOVICH R; SALAS, N; A. L. MARTINO; DI TADA, I.

JOURNAL OF HERPETOLOGY

SOC STUDY AMPHIBIANS REPTILES

Año: 2011 vol. 45 p. 661 - 664

0022-1511

Understanding the causes of population declines is difficult when the ecology of the organisms themselves is insufficientlyknown. The common South American toad, Rhinella arenarum, inhabits a wide variety of habitats. Their populations are abundant; however,life-history characteristics of the adult, including reproductive traits, are poorly known. We studied the reproductive ecology of R. arenarum forseveral populations in central Argentina during two breeding seasons (2007–08). Breeding activity was compared for the two seasons withrespect to variation in habitat variables. Females deposited a mean of 23,226.67 eggs per clutch (N = 10), and snout–vent length did not show anysignificant effect on the number of eggs. Spawning females lost 27% of their mass when spawning occurred, and the heavier females hadgreater reproductive output. We found a significantly positive relationship between amplexed male and female snout–vent lengths, indicatingsize-assortative mating. Females in good body and somatic condition produced larger clutches independent of snout–vent length. Becauseclutch hydration in ponds occurs, reproductive effort as a function of body loss mass of spawning females is a more appropriate estimate ofreproductive output for R. arenarum. Trends in the number of egg strings over several breeding periods can provide information about changesin population size. Long-term studies designed to monitor populations are needed to determine the impacts and consequences ofenvironmental changes.