Determining the Presence of Sexual Dimorphism in the Species Pseudoboa nigra.

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Issue Date
2015-04-10
Authors
Lavine, Jamal Omar
Reis, Paolo Mauricio Almeida Guimarães
Coelho, Rafael Damasceno Fernandes
Ribeiro, Leonardo Barros
Nicola, Patricia
Medeiros, Cleane
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Keywords
Caatinga , Pseudoboa Nigra , Brazil , Sexual Dimorphism , Sexual-Size Dimorphism Index
Abstract
Pseudoboa nigra, the Black False Boa, is a non-venomous snake (family Dipsidadae) found in the Caatinga region of Brazil. Studies in the region are not very expansive and as such, biological information is still required for this species of snake. The present study aimed to determine the level of sexual dimorphism found in Pseudoboa nigra as well as replicate earlier work testing the relationship between body size and gender. In order to calculate sexual dimorphism within the species, twenty-one preserved specimens were used to collect data by measuring snout-vent length, tail length, head length, and head width of each specimen. Each specimen, identified by the collection tags used by the university, was sexed using a probe and then dissected by making incisions along the ventral side of the snake to further verify gender. A t-test was used to analyze the data from the specimens along with the Sexual-Size Dimorphism Index. Results indicated low sexual dimorphism in the species with males larger than females with a t-score of 5.37. A calculated Pearson’s linear correlation coefficient of 0.633 indicated a moderate positive relationship between head length and head width in both sexes. This study was not able to replicate the results of the earlier research because the number of individuals used was small. For future studies, larger samples may yield results that are more accurate.
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