The influence of early‐life allocation to antlers on male performance during adulthood: Evidence from contrasted populations of a large herbivore

Abstract

To secure mating opportunities, males often develop and maintain conspicuous traits that are involved in intrasexual and/or intersexual competition. While current models of sexual selection rely on the assumption that producing such traits is costly, quantifying the cost of allocating to secondary sexual traits remains challenging. According to the principle of allocation, high energy allocation to growth or sexual traits in males should lead to reduced energy allocation to the maintenance of cellular and physiological functions, potentially causing them to age faster, with impaired survival. We evaluated the short-term and delayed consequences of energy allocation to antlers early in life in two contrasted populations of roe deer, Capreolus capreolus. Although most males mate successfully for the first time in their fourth year, antlers are grown annually from the first year of life onwards. We tested the prediction that a high level of allocation to antler growth during the first two years of life should lead to lower body mass, antler size and survival during the early and late prime stages, as well as to reduced longevity overall. Growing and carrying long antlers during the first years of life was not associated with any detectable cost in the late prime stage. The positive association between antler growth in early life and adult body mass instead supports that fawn antler acts as an honest signal of phenotypic quality in roe deer. For a given body mass, yearling males growing longer antlers displayed impaired performance during their late prime. We also found a trend for a short-term survival cost of allocation to relative antler length during the second year of life. Yearling males that grow long antlers relative to their mass might display a fast life-history tactic. We argue that differential allocation to secondary sexual traits generates a diversity of individual trajectories that should impact population dynamics.

Delivering the promises of trait‐based approaches to the needs of demographic approaches, and vice versa

“…Lemaître et al. () examine the role of complex secondary sexual traits, deer antlers, on fitness. Through a combination of trait‐based and demographic approaches, they quantify the costs of investment in antlers onto fitness components late in life evoking theories of ageing (Shefferson, Jones, & Salguero‐Gómez, ) and life history (Stearns, , ).…”

“…For example, the authors examine the sensitivity of population responses to climate change with respect to key life-history traits, such as maximum reproductive rate, and to functional traits like individual length at birth. Lemaître et al (2018) examine the role of complex secondary sexual traits, deer antlers, on fitness. Through a combination of trait-based and demographic approaches, they quantify the costs of investment in antlers onto fitness components late in life evoking theories of ageing (Shefferson, Jones, & Salguero-Gómez, 2017) and life history (Stearns, 1976(Stearns, , 1982.…”

A negative association between horn length and survival in a weakly dimorphic ungulate

“…With an increase in horn length, a lower proportion of males survived to 9 years whereas among survivors the probability of reaching 15 years slightly increased, although not significantly so. Similarly, in the weakly dimorphic roe deer, a strong allocation to antler growth for a given mass decreased the probability of surviving beyond 6 years of age in males, while no relationship occurred for longevity (Lemaître et al, ). Together with this last study, our results support the idea that a negative relationship between weapon size and survival can arise in species where sexual selection is relatively weak.…”

“…Empirical evidence for a negative relationship between horn growth and natural survival is scarce (see Table 1 in Lemaître et al, ). Previous studies have mainly focused on species with a high level of sexual dimorphism (e.g., Soay sheep, Robinson et al, ; bighorn sheep, Bonenfant, Pelletier, Garel, & Bergeron, ; Alpine ibex Capra ibex , Bergeron, Festa‐Bianchet, Hardenberg, & Bassano, ; Toïgo, Gaillard, & Loison, ).…”

Effect of Testosterone on Antler Growth in Male Sambar Deer (Rusaunicolor unicolor) in Horton Plains National Park, Sri Lanka

“…Antler growth categories were identified by physical appearance of the antlers, especially their sharpness and length (Suttie, Fennessy, Lapwood, & Corson, 1995), while the old males with irregular antler casting were not taken to the experiment. Additional characters that were considered for this study were the size of the body and antlers (Hu et al, 2017; Lemaitre et al, 2018).…”