Breeding activity of Scinax centralis (Anura, Hylidae) in Central Brazil

Mariana B Alcantara,Leôncio P Lima,Rogério P Bastos

doi:10.1590/s0073-47212007000400008

Abstract

From January, 1997 to April, 1998, we studied breeding activity in a population of Scinax centralis Pombal & Bastos, 1996, in the state of Goiás, inside the Cerrado Biome, Brazil. The behavior of males and females in the choruses, the relationships between environmental variables and the presence of individuals, the spatial distribution pattern, amplexus and clutches were analyzed. The breeding season occurred from November to May. The majority of males began to call when they entered the chorus; they were defending their calling sites against other males. We found a positive correlation between the number of females and males in the choruses, but no significant correlation was observed between the operational sexual ratio (OSR, number of reproducing females/number of reproducing males) and the number of calling males. OSR was highly male-biased; on average, there were 40 males for each female. The presence of individuals was positively correlated with air temperature of two previous days and negatively correlated with rainfall on the observation day. Generally, males were non-randomly distributed and satellite males were observed. Females were larger and heavier than males. Egg number, but not diameter of the egg, was correlated with the female size.

Highlights

IntroductionEntre janeiro de 1997 e abril de 1998, estudou-se a atividade reprodutiva em uma população de Scinax centralis Pombal & Bastos, 1996 no estado de Goiás, no bioma Cerrado, Brasil
We found a positive correlation between the number of females and males in the choruses, but no significant correlation was observed between the operational sexual ratio (OSR, number of reproducing females/number of reproducing males) and the number of calling males
We examined the breeding activity of Scinax centralis Pombal & Bastos, 1996, a small hylid of the S. catharinae Boulenger, 1888 group, which is found in gallery forest, one of the physiognomies of the Cerrado biome (OLIVEIRA-FILHO & RATTER, 2002)

Summary

Introduction

Entre janeiro de 1997 e abril de 1998, estudou-se a atividade reprodutiva em uma população de Scinax centralis Pombal & Bastos, 1996 no estado de Goiás, no bioma Cerrado, Brasil. Analisou-se o comportamento de machos e fêmeas nos agregados reprodutivos, as relações entre variáveis ambientais e a presença de indivíduos, o padrão de distribuição espacial, amplexos e desovas. In the choruses, males greatly outnumber females, so they exhibit territorial behavior which may involves acoustics interactions, postures, and combat (MARTINS et al, 1998; BASTOS & HADDAD, 2002). A consequence of territorial behavior in anurans is the maintenance of a uniform distance between males (ARAK, 1983; DYSON & PASSMORE, 1992a; BASTOS & HADDAD, 1999). We intend to answer the following questions: (a) What are the relationships between choruses and environmental variables? (b) How are males spatially distributed in choruses? (c) Is there operational sexual ratio bias for males? (d) Are clutches correlated with physical attributes of females?

Methods

Results

Conclusion