You cannot have it all: Heritability and constraints of predator‐induced developmental plasticity in a Neotropical treefrog

Abstract

Many organisms have evolved phenotypic plasticity but examples of a heritable genetic basis or genetic constraints for plasticityacross environments remain scarce. Tadpoles of the Neotropical treefrog Dendropsophus ebraccatus alter tail coloration and shape differently in response to fish or aquatic insect predators. To assess the genetic basis of plasticity we raised 1020 tadpoles from 17 maternal half-sib pairs (34 unique families) individually with chemical cues of fish or aquatic insects, or with cue-free control water. We used Bayesian animal models to estimate narrow sense heritability of morphology and cross-trait genetic correlations in all three treatments, heritability of plasticity in response to each predator, and genetic correlations between responses to fish and insects. Families showed remarkably different responses to predators and heritability was often high (0.45-0.75), as was heritability of plasticity itself (0.42-0.62). We detected strong negative genetic correlations for responses to each predator (-0.45 and -0.59), providing clear evidence of a limit to plasticity. Most importantly, we show that prey genotypes are constrained in their capacity to respond to different types of predators, which likely maintains genetic variation for plasticity in a temporally and spatially dynamic landscape where there is no single adaptive peak.

Intraspecific developmental variation in the life cycle of the Andean Treefrog (Boana riojana): A temporal analysis

“…Among amphibians, different morphotypes within a species have been described and related to intraspecific changes in the timing of development (Collins, Zerba & Sredl, 1993), dietary conditions (Pfennig, 1990), geographical variation (Bruschi et al, 2013), or in response to predators (Kishida & Nishimura, 2005;Van Buskirk, 2017;Touchon & Robertson, 2018). The two morphs of B. riojana occurred simultaneously in the same sites and at the same developmental stages and body sizes, and with the same tooth formula, so, it is unlikely that they represent two different species or that diet or geographical variation may be directing the early appearance of the two morphotypes.…”

Nothing as it seems: behavioural plasticity appears correlated with morphology and colour, but is not in a Neotropical tadpole

“…Larval amphibians are among the most studied animals for understanding predator-induced plasticity and research has examined responses in morphology [21][22][23], coloration [23][24][25], behaviour [26,27] and the timing of development [28][29][30], as well as the potential for plastic phenotypes to evolve [31]. A recent meta-analysis concluded that plastic tadpole morphological and behavioural defences positively covary but are mechanistically independent of one another [18].…”

Tadpoles of hybridising fire-bellied toads (B. bombina and B. variegata) differ in their susceptibility to predation

“…There was no evidence that relatively higher tail fins caused better survival in either taxon. The large variances that rendered differences between group means (taxon, survival) non-significant ( Figs 4C and 5B) may reflect heritable variation among families in the amplitude and type of morphological plasticity [104]. This trait warrants further study using more detailed morphometrics [72].…”