Scientific Annals of the Danube Delta Institute (Sep 2011)
Reproductive success of the Bombina hybrids in a Transylvanian hybrid area
Abstract
Amphibians are vertebrates with complex life cycles, they require different habitats often spatially separated, to complete their life histories. There are highly flexible strategies regarding the egg laying in Bombina species. In water bodies with instable hydroperiod besides the spatial aspect of breeding, the right timing of thedeposition of eggs is also important. Toads were captured and eggs counted in the Vişea area (Transylvania hybrid zone, Romania) during the field seasons in 2001 and 2002. The studied water bodies were resampled every two days. The total egg production was 11811 eggs in 2001 and 3630 eggs in 2002. There is a difference (ca. 50%) in the number of females observed (152 females in 2001, 88 females in 2002). The observed difference in reproductive output between seasons is more than the difference in female number (ca. 70%) which indicates that the drought caused decreased reproductive output in 2002. Moreover, there is a difference in the mean size of the batches laid (17.9 in 2001, 13.28 in 2002). Also, a difference wasobserved between egg batches laid in the non-stable puddles (13.6 in 2001, 12.29 in 2002), and in more stable puddles (19.8 in2001 and 15.5 in 2002). This confirms our assumption, that the measure of egg batches depends highly on the environment andit is important in the maximizing of reproductive success over unstable conditions. In Vişea hybrid zone - where mostlytemporary water bodies are found - we have the evidence of conservative reproduction over unfavorable conditions.
