Evol Ecol Res 20: 317-329 (2019)     Full PDF if your library subscribes.

Effects of temperature and desiccation on the morphology, body condition, and metamorphosis
of tadpoles and froglets of Agalychnis moreletii

C.I. Hernández-Herrera1,H.A. Pérez-Mendoza1 and J. Golubov2

1aboratorio de Ecología Evolutiva de Anfibios y Reptiles, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla, México and2Laboratorio de Ecología y Sistemática Vegetal, Universidad Autónoma Metropolitana Xochimilco, Coyoacán, Ciudad de México, México

Correspondence: H.A. Pérez-Mendoza, Laboratorio de Ecología Evolutiva de Anfibios y Reptiles, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Av. De Los Barrios 1, Hab. Los Reyes Ixtacala, 54090 Tlalnepantla, México. email: hibraimperez@cien cias.unam.mx

ABSTRACT

Hypothesis:Temperature and desiccation will increase growth rates in Agalychnis more letii tadpoles, reducing size at metamorphosis and other morphological traits. Time to metamorphosis will also be reduced for froglets, and synchrony of metamorphosis will be decoupled.

Organism: Tadpoles and early froglets of the black-eyed tree frog (Agalychnis more letii).

Site of experiments: Área de Protección de Flora y Fauna Nahá-Metzabok, Chiapas, Mexico.

Methods: We performed controlled experiments where we exposed tadpoles from natural populations to contrasting desiccation and temperature conditions. We measured snout–vent length (SVL) and tail length to obtain growth rates. Once metamorphosis was complete, we recorded day of metamorphosis and the number of conspecifics remaining in each replicate. We measured froglet mass, SVL, head width, fore limb length, hind limb length, and three different body condition indices. Finally, we calculated the synchrony index and coefficient of variation of metamorphosis. We used a Kruskal-Wallis test or analysis of variance (ANOVA) to compare residuals of morphological traits among treatments, ‘derived variable statistics’ to analyse growth rate, a generalized linear model (GLM) to analyse the effect of number of individuals on morphological traits, and ANOVA and χ2 to compare the synchrony index and the coefficient of variation.

Results: Growth rates differed significantly between treatments for body size and head width. Time to water emergence was shorter under high temperature conditions, but delayed under desiccation. In addition, we found a negative relationship between all morphological traits and body condition with number of individuals. Synchronization of metamorphosis was also different among treatments. Thus, temperature and desiccation affect the morphology, time of metamorphosis, and synchrony of tadpoles of A. more letii, but there is also an effect of the number of individuals on morphological traits. In contrast to other studies, we found no increase in growth rate, or early metamorphosis, associated with desiccation risk. Also contrary to other studies, body condition did not differ among treatments, but there was an effect of number of individuals in each replicate. Finally, the synchrony of metamorphosis and coefficient of variation differed among treatments.

Keywords: Phenotypic plasticity, tree frog, larval development, growth rate, developmental plasticity, metamorphosis synchrony

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