Phenotypic plasticity has been widely documented in anuran tadpoles showing different responses to ecological conditions, such as temperature, density, food quality, predators, etc. Most studies have been focused on growth and developmental rates, but few analyze the influence of these variables in Body Condition Index (BCI), and Morphological Traits (MT) when metamorphoses is completed. BCI and MT are related to population and habitat quality parameters, mate choice, survival and resources acquisition. The aim of this study was analyze the effect of temperature and water amount on BC and MT in Agallychnis moreletii metamorphs bred in captivity. We bred tadpoles under three treatments: control, decreasing water level, and high temperature. We measured metamorphosis day (D), number of competitors (NC), weight (W), snout-vent length (SVL), head width (HW), forelimb length (FL) and hindlimb length (HL). With W and SVL data we obtained 3 body condition index: Fulton’s index (K), relative mass condition index (Wr), and residual condition index (RCI). We analyzed data with GLMs to compare the effect of Treatment and NC on each BCI and MT, and differences between GS.
Results/Conclusions
Our results indicate that D is lower when individuals are exposed to high temperature treatment (chi-squared = 50.89, df = 2, p < 0.01), and both treatments and NC affect D. NC affects W (t = -25.11, df = 822, p < 0.01), SVL (t = -25.17, df = 837, p < 0.01), HW (t = 17.510, df = 835, p < 0.01), FL (t = -4.44, df = 837, p < 0.01) and HL (t = -16.12, df = 8.37, p < 0.01). We assume that this is due to the amount of food available per capita, with a high number of competitors feeding reduces leading to lower growth of each morphological trait. BCIs are affected in different ways: K is influenced by Low water*NC interaction (t = -2.06, df = 822, p = 0.03), NC affects Wr (t = -2.819, df = 8.22, p < 0.01), and RCI is influenced by both temperature (t = 2.53, df = 8.22, p = 0.01) and NC (t = -4.04, df = 822, p < 0.01) this indicates that density is the most important factor shaping BCI, and there is a negative effect of NC in BCIs.