Is there evidence for population regulation in amphibians and reptiles?

NICOLÁS PELEGRIN; SUELEM MUNIZ LEÃO; PIANKA, E. R.

JOURNAL OF HERPETOLOGY

SOC STUDY AMPHIBIANS REPTILES

Lugar: Salt Lake City; Año: 2018 vol. 52 p. 28 - 33

0022-1511

From the 1950´s to the present day, many researchers have tested time-series data for density dependence. All kinds of organisms have been studied, from microorganisms to insects, vertebrates and plants. A variety of techniques and population growth models were developed, and the conceptual frame to study populations has been improved. We searched for long time-series data on amphibians and reptiles in the literature. From 102 population time series, and after filtering the dataset, we tested for density-dependence in time series data for 69 populations (52 species) of amphibians (anura and caudata), snakes, lizards, crocodilians, and the Tuatara. We used Exponential Growth State Space (EGSS), and Ornstein-Uhlembeck State Space (OUSS) as proxy models for density-independent and density-dependent population growth models, selecting between them with Parametric Bootstrap Likelihood Ratio Test (PBLRT). We were able to reject density independence for 2 amphibians, 3 turtles, 1 Tuatara, 11 snakes, 1 alligator, and 1 caiman populations. Detailed data for snakes and turtles allowed identification of external factors such as changing food supplies and habitats as drivers of observed changes in population densities. We highlight the need of both long-term and experimental studies on reptile and amphibian populations in semi-pristine or preserved areas.