Factors influencing scaling relationships of body mass and antler mass in white-tailed deer (Odocoileus virginianus)

Date

2022-05

Authors

Sontheimer, Willis

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Abstract

Antlers are a costly trait that require skeletal reserves to grow to a large size. Thus, insight into variation in antler size requires understanding the connection between antler and body size, which can be summarized through ontogenetic and static scaling relationships. Both types of scaling relationships are needed to examine the influence of factors besides body mass on antler growth at different ages and whether the influence of these factors diminish with age. Size deficits influenced by diet variability and maternal effects might decline during ontogeny through compensatory growth. I sought insight into the influences of diet and maternal attributes of mother’s age at birth of offspring and litter size on body-antler size relationships throughout ontogeny and at discrete ages. I also examined whether diet and maternal effects diminished with age of males. Data on age, maternal characteristics, body mass, and antler mass was gathered from captive, penraised white-tailed deer (Odocoileus virginianus, n = 168) that consumed either a low energy (1.77 kcal/gm) or standard energy diet (2.65 kcal/gm) from the time they were weaned until they died by age 5.5 years of age. Both types of scaling relationships were estimated with linear mixed effects models to account for repeated measurements of focal males and parents. Diet affected ontogenetic scaling relationships. Males consuming the low energy diet had a higher rate of increase in antler mass in relation to body mass when young and a lower rate of increase rate when old than males consuming the standard energy diet. A Bayesian Information Criterion model selection analysis indicated that diet and litter size (singleton or multiple births), but not mother’s age at birth of offspring influenced static scaling relationships. Static scalar coefficients up to 3.5 years of age were positively allometric, but isometric in 4.5- and 5.5-year-old-males. Furthermore, diet and litter type influenced both intercepts and slopes in only the youngest males (1.5- years) lending support to the idea that diet and maternal effects diminish with age. Body size – antler size relationships are complex. My findings indicate that diet and litter type had greater effect at younger ages during rapid growth than at older ages. Young males that are small because of maternal effects, for example, might still be able to possess larger body and antler sizes at older ages.

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Keywords

Allometry, Large mammal ecology

Citation

Sontheimer, W. (2022). <i>Factors influencing scaling relationships of body mass and antler mass in white-tailed deer (Odocoileus virginianus)</i> (Unpublished thesis). Texas State University, San Marcos, Texas.

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