Habitat anthropization is a major driver of global biodiversity decline. Although most species are negatively affected, some benefit from anthropogenic habitat modifications by showing intriguing life-history responses. For instance, increased recruitment through higher allocation to reproduction or improved performance during early-life stages could compensate for reduced adult survival, corresponding to “compensatory recruitment”. To date, evidence of compensatory recruitment in response to habitat modification is restricted to plants, limiting understanding of its importance as a response to global change. We used the yellow-bellied toad ( Bombina variegata ), an amphibian occupying a broad range of natural and anthropogenic habitats, as a model species to test for and to quantify compensatory recruitment. Using an exceptional capture–recapture dataset composed of 21,714 individuals from 67 populations across Europe, we showed that adult survival was lower, lifespan was shorter, and actuarial senescence was higher in anthropogenic habitats, especially those affected by intense human activities. Increased recruitment in anthropogenic habitats fully offset reductions in adult survival, with the consequence that population growth rate in both habitat types was similar. Our findings indicate that compensatory recruitment allows toad populations to remain viable in human-dominated habitats and might facilitate the persistence of other animal populations in such environments.

The Australian frogs Geocrinia laevis and Geocrinia victoriana undergo prolonged embryonic development inside their egg capsules, before hatching as advanced tadpoles. Despite the presence of large amounts of yolk, the course of development follows the typical anuran pattern rather closely, and is essentially identical in the two species and their natural hybrids. We present a modification of Gosner's (1960) staging table, using mainly changes in the eye and the mouthparts to define stages (20 to 26) in a phase of development, when the Gosner table is not applicable to myobatrachine frogs.

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To describe variation in size of offspring across a hybrid zone between the myobatrachine frogs Geocrinia laevis and Geocrinia victoriana, the sizes of tadpoles hatching from egg masses collected in the field were measured. Hatchling size was strongly correlated with diameter of the blastula or gastrula (referred to here as "egg size"). Geocrinia victoriana had bigger offspring than G. laevis. Hybrids were generally intermediate between the two parental species in offspring size. However, the variation in size across the hybrid zone did not show a smooth cline or a distinct step coinciding with any of the sharp transitions found for behavioural or genetic characters. Variation within hybrid populations was not greater than in "pure" samples of the two species; these data correspond to findings of other studies which showed that this contact between G. laevis and G. victoriana is a "true hybrid zone" with panmictic local populations, not an overlap of the two species.

Larval growth of Geocrinia victoriana and Pseudophryne semimarmorata was studied in tanks housing tadpoles of either species and mixed groups, providing the same density (individuals/water volume) in all containers. Tadpoles of P. semimarmorata were larger at hatching than G. victoriana, they reached metamorphic climax earlier and at larger sizes. In mixed groups, P. semimarmorata experienced relaxation of intraspecific competition; they metamorphosed at bigger sizes than controls kept only with conspecifics. In the presence of P. semimarmorata, G. victoriana showed slower growth initially; they metamorphosed later than the controls, but at similar sizes.