Habitat characteristics influence the breeding of Rose's dwarf mountain toadlet Capensibufo rosei (Anura: Bufonidae)

摘要

Direct anthropogenic factors (e.g., habitat loss, fragmentation, and degradation) threaten many amphibian populations, however some declines have occurred in supposedly pristine environments with no obvious causes. These enigmatic declines may be due to shifts in environmental factors influencing development and ultimately adult survival. Rose's mountain toadlet Capensibufo rosei has undergone such an enigmatic decline, with several populations presumed to be locally extinct at historic breeding sites. The two remaining breeding sites (Silvermine (SILV) and Cape of Good Hope (CGH)) on the Cape Peninsula of South Africa were monitored for three years (2012-2014) for life history traits and ecological requirements. Males congregate at ephemeral pools during the middle of the austral winter, with females arriving to lay eggs and then immediately leaving. Breeding only occurs in a few of the available pools. We hypothesised that larval development in colder, deeper pools would result in smaller-bodied tadpoles, and ultimately in relatively smaller adults. Pools at SILV were significantly deeper and colder compared to CGH, with breeding occurring in pools that were 27.05 +/- 10.21 mm and 21.55 +/- 6.95 mm deep at SILV and CGH, respectively. Contrary to expectations, breeding adults and developing tadpoles at SILV were larger than CGH individuals. The percentage of non-developing eggs at CGH was high compared to SILV and other anuran species. Development within this threatened species may be influenced by pool characteristics, which could provide clues as to the factors that influenced local extinctions in historical populations.