z-logo
Premium
Using time‐dependent models to investigate body condition and growth rate of the giant gartersnake
Author(s) -
Coates P. S.,
Wylie G. D.,
Halstead B. J.,
Casazza M. L.
Publication year - 2009
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.2009.00617.x
Subject(s) - biology , growth rate , evolutionary biology , ecology , mathematics , geometry
Identifying links between phenotypic attributes and fitness is a primary goal of reproductive ecology. Differences in within‐year patterns of body condition between sexes of gartersnakes in relation to reproduction and growth are not fully understood. We conducted an 11‐year field study of body condition and growth rate of the giant gartersnake Thamnophis gigas across 13 study areas in the Central Valley of California, USA. We developed a priori mixed effects models of body condition index (BCI), which included covariates of time, sex and snout–vent length and reported the best‐approximating models using an information theoretic approach. Also, we developed models of growth rate index (GRI) using covariates of sex and periods based on reproductive behavior. The largest difference in BCI between sexes, as predicted by a non‐linear (cubic) time model, occurred during the mating period when female body condition (0.014±0.001  se ) was substantially greater than males (−0.027±0.002  se ). Males likely allocated energy to search for mates, while females likely stored energy for embryonic development. We also provided evidence that males use more body energy reserves than females during hibernation, perhaps because of different body temperatures between sexes. We found GRI of male snakes was substantially lower during the mating period than during a non‐mating period, which indicated that a trade‐off existed between searching for mates and growth. These findings contribute to our understanding of snake ecology in a Mediterranean climate.

This content is not available in your region!

Continue researching here.

Having issues? You can contact us here