Climate and mating systems as drivers of global diversity of parental care in frogs

Aim Amphibians exhibit unusually diverse reproductive modes, including a
wide array of parental care strategies. The evolutionary drivers of this
diversity, however, remain unclear. Here we investigate three major
factors which may predict interspecific variation in parental care
strategies: climate, intrasexual selection and social environment. We
hypothesise that some care forms evolved to cope with harsh conditions
such as dry or unpredictable habitats. We contrast this prediction with
the hypothesis that parental roles have coevolved with the social
environment and mating systems.  Location Global. Major taxa
studied Frogs and toads (Anura, Amphibia). Time period Extant taxa that
represent approximately 220 million years of evolutionary history Methods
Using geographic and behavioural data for 971 species of frogs and toads
that represent 45 anuran families, we quantify the global distribution of
four forms of parenting separately for males and females: nest building,
nest and/or tadpole attendance, carrying and nourishment. We use
phylogenetic comparative analyses to investigate whether climate, social
environment and mating systems predict interspecific variation in parental
care. Results Our results show that climatic effects contribute to
parental care diversity: under cool and humid climates males provide
offspring attendance, while endotrophy, whereby the female provides all
nutrients for the offspring until metamorphosis, occurs under predictable
temperatures. In addition, we found other associations between mating
systems and parental care forms: uniparental clutch attendance by males is
present in species with territorial defence, while cooperative nest
building co-occurs with sperm competition. The type of parental care is
not associated with adult sex ratios. Main conclusions No specific form of
care is associated with hostile environments; actually, some care forms
occur under beneficial conditions, while others are used independently
from the climate. Instead, parenting diversity has closely coevolved with
mating systems in frogs.