Deer diary - Evolution of deer antlers: allometry, adaptation or phylogenetic signal?
(2025) BION03 20242Degree Projects in Biology
- Abstract
- The variation in length of antlers in deer (Cervidae) has been attributed predominantly to body sizes and the intensity of sexual selection. However, the diversity in antler morphology goes beyond lengths. Using a time-calibrated phylogeny of Cervidae and a newly collected data of antler lengths and volumes, we investigated the evolution of antler morphology within a multi-variate phylogenetic comparative framework. Using an Ornstein-Uhlenbeck process, we modelled the adaptive evolution of antler lengths and volumes. Our analyses revealed that antler sizes are correlated with body size (i.e., allometry), sexual size dimorphism, and habitat openness. Focusing exclusively on species under strong sexual selection, we further found that... (More)
- The variation in length of antlers in deer (Cervidae) has been attributed predominantly to body sizes and the intensity of sexual selection. However, the diversity in antler morphology goes beyond lengths. Using a time-calibrated phylogeny of Cervidae and a newly collected data of antler lengths and volumes, we investigated the evolution of antler morphology within a multi-variate phylogenetic comparative framework. Using an Ornstein-Uhlenbeck process, we modelled the adaptive evolution of antler lengths and volumes. Our analyses revealed that antler sizes are correlated with body size (i.e., allometry), sexual size dimorphism, and habitat openness. Focusing exclusively on species under strong sexual selection, we further found that evolution of antler volumes was primarily driven by allometry and sexual size dimorphism, while lengths still relied on all three factors – allometry, sexual size dimorphism and habitat. Additionally, antler volumes showed consistently faster rates of adaption as compared to antler lengths, indicating different tempo and mode of evolution in correlated and sexually-selected traits. Our results suggests that a variety of extrinsic and intrinsic factors impact the pattern of evolution of a trait driven primarily by sexual selection. (Less)
- Popular Abstract
- Fashion, function or family?
Antlers are a unique cranial headgear, commonly observed in the male members of the deer family (with the sole exception of female reindeer). Based on its sex-specific occurrence, antlers have been viewed as weapons or ornaments used to attract and inform females of male quality. Extensively studied in the past, antler sizes have been correlated to male body sizes and sexual selection pressures. However, we hypothesised that the evolution of antler size does not begin here and was perhaps driven by a variety of external factors.
To study this, we gathered physical measurements from specimens housed at 17 different museums. We measured the skull lengths of males and females as an indicator of size for... (More) - Fashion, function or family?
Antlers are a unique cranial headgear, commonly observed in the male members of the deer family (with the sole exception of female reindeer). Based on its sex-specific occurrence, antlers have been viewed as weapons or ornaments used to attract and inform females of male quality. Extensively studied in the past, antler sizes have been correlated to male body sizes and sexual selection pressures. However, we hypothesised that the evolution of antler size does not begin here and was perhaps driven by a variety of external factors.
To study this, we gathered physical measurements from specimens housed at 17 different museums. We measured the skull lengths of males and females as an indicator of size for different species, categorised based on the sexes. The lengths and volumes of antlers were recorded to denote antler size for all species. Further, referring to pre-existing literature, we collected data on mating systems, habitat occupancy and breeding group sizes of different deer species.
On analysing the evolution of antler sizes across the deer family - Cervidae, we found that antler lengths and volumes increased as body sizes increased. This pattern was closely related to the social mating systems and habitats of the species. Herein, deer that live in fields and plains showed long and complex antlers. Owing to potentially steeper competitive pressures due to polygynous mating, longer antlers attract females and deter approach from other subordinate males. Contrary to this, forest-dwelling deer had short and simple antlers, following a monogamous mating pattern. Hindered by dense forest understories, these species do not support long antlers. Furthermore, since their mating does not involve competition in large groups, investing in extensive antlers is a futile expense.
Lengths versus volumes?
We found that the rates of evolution for antler lengths differed as compared to volumes! Volumes showed faster adaptation to changing environmental conditions as compared to lengths. While lengths showed a continuous increase to rising habitat openness, volumes remained comparable in broken and open habitats. A potential explanation for this could be that broken habitats hinder the growth of long antlers. Volumes on the other hand are not restrained by the habitats occupied, instead relying on the weight an individual is capable of comfortably bearing.
The results of my thesis highlight the sensitivity of antler size evolution to shifting external and internal ecological conditions, thereby ensuring mating success and longevity of the individual. Understanding the tempo and mode of evolution of antler sizes and their correlation to individuals would help in determining local and global species extinction dynamics, reconstructed based on body and antler sizes. Using this information, it might be possible to begin detangling the mystery surrounding the extinction of the famous Irish elk.
Master’s degree project, 60 credits, 2024-25
Department of Biology, Lund University
Advisor: Masahito Tsuboi
Division for Biodiversity and Evolution (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9192308
- author
- Santusht, Samanvitha
- supervisor
- organization
- course
- BION03 20242
- year
- 2025
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9192308
- date added to LUP
- 2025-06-03 08:30:06
- date last changed
- 2025-06-03 08:30:06
@misc{9192308,
abstract = {{The variation in length of antlers in deer (Cervidae) has been attributed predominantly to body sizes and the intensity of sexual selection. However, the diversity in antler morphology goes beyond lengths. Using a time-calibrated phylogeny of Cervidae and a newly collected data of antler lengths and volumes, we investigated the evolution of antler morphology within a multi-variate phylogenetic comparative framework. Using an Ornstein-Uhlenbeck process, we modelled the adaptive evolution of antler lengths and volumes. Our analyses revealed that antler sizes are correlated with body size (i.e., allometry), sexual size dimorphism, and habitat openness. Focusing exclusively on species under strong sexual selection, we further found that evolution of antler volumes was primarily driven by allometry and sexual size dimorphism, while lengths still relied on all three factors – allometry, sexual size dimorphism and habitat. Additionally, antler volumes showed consistently faster rates of adaption as compared to antler lengths, indicating different tempo and mode of evolution in correlated and sexually-selected traits. Our results suggests that a variety of extrinsic and intrinsic factors impact the pattern of evolution of a trait driven primarily by sexual selection.}},
author = {{Santusht, Samanvitha}},
language = {{eng}},
note = {{Student Paper}},
title = {{Deer diary - Evolution of deer antlers: allometry, adaptation or phylogenetic signal?}},
year = {{2025}},
}