Abstract
This study aimed to evaluate whether skeletal development of the Pantanal Caiman (Caiman yacare) is similarly influenced by temperature variation and controlled increases in embryo motility. All eggs were incubated at 90% humidity and 29 °C for the first 45 days. Thereafter, the incubation temperature was either maintained at 29 °C and embryos were treated with 4-aminopyridine (4-AP) on days 46, 47, 48, and 49 (Group I, 29 °C 4-AP, n = 15); maintained at 29 °C (n = 14; Group II); or at 33 °C (n = 14, Group III). Embryonic movement was measured using an Egg Buddy® digital monitor on days 30, 35, 42, 49, 56, and 60, at which point embryos were euthanized and samples were collected for analysis. No differences were observed between groups with varying incubation temperatures. In contrast, embryonic motility was greater in embryos treated with 4-AP (P < 0.001) on day 49, and this was associated with higher proportions of snout-vent and hand lengths. This study demonstrates for the first time that pharmacologically induced increases in embryo motility result in phenotypic changes to the proportion of elements during prenatal ontogeny, thereby effectively altering the adaptation of the species to specific environments.
Highlights
The Pantanal Caiman belongs to the phylum Chordata, class Reptilia, subclass Archosauria, order Crocodylia, family Alligatoridae, genus Caiman, and species Caiman yacare (Azevedo, 2003; Marques, 2007; Lima et al, 2011a)
We investigated whether incubation temperature changed the proportions of limbs and snout-vent lengths of Pantanal Caiman embryos
The incubation temperature was initiated at 29 °C for all eggs and maintained for 45 days, after which some of the eggs were incubated at 33 °C and others at 29 °C
Summary
The Pantanal Caiman belongs to the phylum Chordata, class Reptilia, subclass Archosauria, order Crocodylia, family Alligatoridae, genus Caiman, and species Caiman yacare (Azevedo, 2003; Marques, 2007; Lima et al, 2011a). For this reptile class, nest temperature during the first 45-day period of incubation determines embryo sex. Temperature plays an important role in heart rate and embryonic movement of reptiles, this in turn, influences their metabolic rate, development (Du et al, 2009; Du et al, 2011), and their behavioral patterns (Towers and Tickle, 2009)
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