Individual growth of the Flathead Knob‐scaled Lizard, Xenosaurus platyceps, from tropical and temperate populations

• Published in: Biotropica 2022-09, Vol.54 (5), p.1217-1225
• Main Authors: Rojas‐González, R. Isaac, Lemos‐Espinal, Julio A., Smith, Geoffrey R.
• Format: Article
• Language: English
• Subjects: Availability; body growth; common garden; Environmental conditions; Food; Food availability; Food supply; Gardens & gardening; Geographical variations; Growth rate; High temperature; Lizards; Low temperature; Neonates; plasticity; Population; Populations; Prey; reaction norm; Temperature; tropical‐temperate comparison; Xenosaurus platyceps
• ISSN: 0006-3606; 1744-7429
• DOI: 10.1111/btp.13144

Growth rates of ectotherms are frequently affected by environmental conditions, such as temperature, precipitation, and prey availability. However, local adaptation to environmental conditions could influence geographic variation in growth rates. We studied growth rates of the Flathead Knob‐scaled Lizard, Xenosaurus platyceps, from a tropical population and a temperate population in Tamaulipas, Mexico. We used a field study and a common garden experiment to examine the extent and potential causes of variation in individual growth rates between these two populations from contrasting environments. Field‐determined growth rates in the tropical population were greater than those in the temperate population. In a laboratory common garden experiment that manipulated food availability and temperature for neonates from each population, neonates from the tropical population grew faster than those from the temperate population. Neonates kept at higher temperatures grew faster than those kept at lower temperature. In addition, growth rates of neonates from temperate and tropical populations did not differ at low temperature, but neonates from the tropical population grew faster at the higher temperature than did the neonates from the temperate population. Food treatment did not affect individual growth rates in these lizards, although there was a trend for neonates grown with higher food availability to grow faster. Our results suggest that not only does the warm environment of the tropical population contribute to the observed differences in field growth rates, but there is a genetic difference in the ability of the tropical population to take advantage of the warmer temperatures to increase growth rates in Spanish is available with online material. Resumen Las tasas de crecimiento corporal de los ectotermos se ven afectadas con frecuencia por las condiciones ambientales, como la temperatura, la precipitación y la disponibilidad de presas. Sin embargo, la adaptación local a las condiciones ambientales podría influir en la variación geográfica de las tasas de crecimiento. Estudiamos las tasas de crecimiento corporal de la lagartija de Cabeza‐plana, Xenosaurus platyceps, de una población tropical y una templada en Tamaulipas, México. Usamos un estudio de campo y un experimento de jardín común para examinar el alcance y las posibles causas de variación en las tasas de crecimiento individuales entre estas dos poblaciones de ambientes contrastantes. Las tasas de crecimie