Ontogenetic changes in activity, locomotion and behavioural complexity in tadpoles

Abstract

Metamorphosis is a widespread developmental process that involves considerable changes in morphology, habitat use, ecology and behaviour between early developmental (larval) stages and adult forms. Among amphibians, anuran larvae (tadpoles) undergo massive morphological and ecological changes during their development, with early stages characterized by somatic growth, whereas more conspicuous changes (i.e. metamorphosis) occur later during development. In this study, we examined how locomotor and behavioural traits covary with morphology (body size) and metamorphosis (hindlimb and forelimb development) across developmental stages in spined toad (Bufo spinosus) tadpoles. As expected, we found that locomotion and behaviour undergo significant changes during tadpole development. These changes are curvilinear across developmental stages, with a phase of increasing activity and locomotion followed by a phase of stasis and/or reduction in locomotion and behavioural complexity. All the metrics we investigated indicate that the peak of activity and associated behaviour is situated at a pivotal stage when somatic growth decreases and significant morphological changes occur (i.e. hindlimb growth). Future studies that aim to investigate determinants of locomotion should include developmental stages as covariates in order to assess whether the sensitivity of locomotion to environmental variables changes across developmental stages.

Can predators stabilize host–parasite interactions? Changes in aquatic predator identity alter amphibian responses and parasite abundance across life stages

“…However, given that trematodes rely on physical and chemical cues to locate their hosts (Combes et al, 1994 ; Haas, 2003 ), parasites may have responded to bluegill particularly given that tadpole activity was reduced with bluegill exposure, which may have made tadpoles less detectable. Across all treatments, we observed an increase in tadpole activity after week 4, which is likely attributable to changes in tadpole behavior with development, as larval anurans increase activity as they develop until they near metamorphosis (Cheron et al, 2021 ).…”

“…Across all treatments, we observed an increase in tadpole activity after week 4, which is likely attributable to changes in tadpole behavior with development, as larval anurans increase activity as they develop until they near metamorphosis (Cheron et al, 2021).…”

What are the contributions of maternal and paternal traits to fecundity and offspring development? A case study in an amphibian species, the spined toadBufo spinosus

“…We found that females in better condition produced clutches with greater hatching success. In this species and its close relative B. bufo ( Trujillo et al 2017 ), hatching success has been either related to fertilization success ( Touzot et al 2020 ) or to embryonic mortality ( Cheron et al 2021b ). Our result demonstrates that the quality (body condition) of females positively influenced embryonic survival while our analyses revealed that male phenotype does not significantly affect hatching success.…”

Maternal body condition affects the response of larval spined toads’ faecal microbiome to a widespread contaminant

“…Although there are some controversies about using faecal microbiome to reflect gut microbiome comprehensively (Tang et al, 2020), we still privileged this non-invasive sampling method to release the toadlets upon metamorphosis. During pre-metamorphic larval development, spined toad tadpoles are the most active swimming and feeding at Gosner stage 37 (Cheron et al, 2021), resulting in a more significant production of faeces. Therefore, we started sampling tadpoles’ faeces for gut microbiota analyses once they reached Gosner stage 37.…”

“…During pre-metamorphic larval development, spined toad tadpoles are the most active swimming and feeding at Gosner stage 37 (Cheron et al, 2021), resulting in a larger production of faeces. We therefore started sampling tadpoles' faeces for gut microbiota analyses once they reached Gosner stage 37.…”