Estratégia e comportamento reprodutivo de Ameerega hahneli (Anura, Dendrobatidae) na Amazônia Central

Abstract

Amphibians frequently show plasticity in reproductive traits throughout their distribution range, particularly those of wide geographic distribution. Intraspecific variations in behavioural and life history traits occur mainly in relation to the reproductive period. During the breeding season, competition for partners lead to different strategies to increase reproductive success, which may be associated with morphological or behavioral variables. I studied two populations of Ameerega hahneli (Dendrobatidae), a diurnal frog with terrestrial egg-laying and semi-aquatic larval development, inhabiting two distinct forest environments 15 km apart in central Amazonia cental (Brazil) ˗ a terra firme forest area (data from six years of non regular monthly samplings) and a seasonally flooded forest area (data from one year monthly monitoring). I compared the period of reproductive activity and population structure aspects between the two populations and their relationship with the rainfall and river flooding patterns. For the seasonally flooded forest area I described courtship, mating and territorrial defense behaviour based on intensive individual focal monitoring. Male territories and female home ranges were mapped within a sampling plot, and the space use dynamics of the population in relation to the flooding of the area was acessed through capture-recapture over one hydrological cycle. Male reproductive success indicators (number of egg-clutches obtained, mean clutch size obtained and clutch survival until carrying of tadpoles to the water) were related to male phenotipic traits and territory characteristics. Populations of A. hahneli at both study sites showed continuous activity throughout the year, but the peak of reproductive activity was at the beginning of the dry season in the terra firme and in the rainy season in the flooded forest, most probably reflecting an adaptation of the latter population to avoid the flooding period. In the terra firme forest the activity pattern of the population was negatively influenced by monthly rainfall. The size of female home ranges was twice the size of male territories. The mating behavior of A. hahneli was long with no tactical interactions, but two cephalic amplexi before oviposition, which was previously known for only one other species. Females showed apparent selectivity for oviposition sites, having been observed to reject sites shown by the male on several occasions. Average clutch size was 18 eggs and was not related to female body size. Eggs took about 12 days to reach Gosner 25 stage. Males obtained from zero to five clutches. Male reproductive success was not significantly related to independent variables. Studies on more populations are needed to access the variability of the activity pattern and reproductive success correlates in this species