Smaller does not mean worse: variation of roe deer antlers from two distant populations in their mechanical and structural properties and mineral profile

Abstract

Antler size, structure, composition and mechanics have been shown to reflect nutrition, climate and body effects in red deer, but studies have only assessed effects on size in the roe deer (Capreolus capreolus). Roe deer show little sexual dimorphism, lower inter‐male fighting and could form groups during part of the year but does not form harems, in contrast to red deer. Thus, it is interesting to assess how nutrition and habitat affects investment in antlers as compared to red deer. Antlers were collected from adult males of two game estates differing in location, climate and management: 13 from the south‐east of Spain (mild winter, hot summer, dry habitat and rich supplementary feeding), and 10 specimens came from central‐southern part of the Czech Republic (snowy winter, mild summer, humid habitat and limited supplementary feeding). After measuring whole‐antler parameters, a destructive sampling was performed to obtain a full‐transversal section and cortical bone samples from two sampling position along the main beam. Then bone structure, mechanical properties (three‐point bending test, impact test) and the mineral profile were studied. Roe deer from Spain had heavier and longer antlers than Czech roe deer. Their bone material had a higher mechanical quality, although Czech roe deer compensated by developing antlers with thicker walls. Mineral composition also differs, particularly by greater contents in Czech antlers in 3 minerals associated with nutrient stress: Fe, K and Zn. We concluded that the differences found between populations may be caused by differences in habitat quality and diet, in a similar way as reported for red deer, despite interspecific differences. Our study suggests that habitat affects antler parameters and, as previous results in red deer, suggests that improving diet quality may affect size, composition and mechanical quality of antler material. Certainly, antlers of roe deer provide information useful for population management.

Antiquity and fundamental processes of the antler cycle in Cervidae (Mammalia)

“…Each species is characterized by a specific antler morphology, and in many species, sexual selection has even forced up the regrowth by larger and more complex successors with every antler generation. On the other hand, physical condition and morphology of antlers is extremely sensitive to nutrition, health and social status (Landete-Castillejos et al 2007a , 2007b ; Caecero et al 2019 ; Cappelli et al 2020 ) and, hence, serve as a mirror of life factors.…”

Early life investment in antlers and body growth reflects adult performance in roe deer population under supplementary feeding conditions

“…Age‐specific body and antler measurements of roe deer in Valsemana were similar or slightly higher to those reported in other studies carried out in Mediterranean environments in wild conditions (Horcajada‐Sánchez & Barja 2016; Cappelli et al . 2020), as our population was supplemented during the periods of nutritional constraint and received veterinary care (i.e. vaccination and anti‐parasite treatment).…”

“…In addition, while roe deer population characteristics have been widely studied in northern regions, more information is needed to describe Mediterranean populations (but see Horcajada‐Sánchez & Barja 2016; Cappelli et al . 2020). Roe deer in Mediterranean environments is thought to be smaller in size (see Aragón 1993; Horcajada‐Sánchez & Barja 2016) following Bergmann's rule (Bergmann 1847).…”

Effects of environmental variation on the reproduction of two widespread cervid species

“…As roe deer body mass has been described as a proxy of individual fitness, early life antler investment acts as a sign of male phenotypic quality (Lemaître et al, 2018). However, while cervid antlers have been widely studied in northern regions, more information is needed to understand the individual and environmental factors that influence antler growth in Mediterranean environments (but see Gaspar-López et al, 2010;Gómez et al, 2012;Cappelli et al, 2020) as trade-offs may be more easily detected at the edge of a species range of distribution (Kawecki, 2008).…”

“…One of the most important energy demanding times in the life cycle of male cervids is the formation of secondary sexual traits such as antlers (Goss, 1970 on Cervidae; Van Ballenberghe, 1982 on moose Alces alces; Vanpé et al, 2007 on roe deer Carpreolus capreolus). Antlers are costly to produce and maintain as they are grown and shed yearly and, thus, they require the allocation of large amounts of nutrients and energy (Goss, 1970;HyvÄrinen et al, 1977 -López et al, 2010;Gómez et al, 2012;Peláez et al, 2018;Cappelli et al, 2020) as trade-offs may be more easily detected at the edge of a species range of distribution (Kawecki, 2008).…”