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ŠUMARSKI LIST 9-10/2021 str. 29     <-- 29 -->        PDF

trophy value, as well as the circumferences (coronets, lower and upper beam), may be utilized as an estimation indicator in the future, for they have managed to isolate the same cohorts—1994, 1995, 1996 and 1997—as the more high‐quality ones.
A cohort represents a group of individuals in a population calved (hatched) within the same calving (hatching) period. There are two basic cohort effects or variabilities: an abundance effect and a quality effect (Gaillard et al. 2003). An abundance effect is manifested by a calf share that has survived the first year of life and recruits a population (Gaillard et al. 1997, Forchhammer et al. 2001), whereas a quality effect represents a long‐term impact that may generate the phenotypic and genotypic differences in the condition component between the cohorts (Kruuk et al. 1999, Hik and Carey 2000). According to Gaillard et al. (2000, 2003), the ways of life namely depend on a habitat conditions that had prevailed from the moment at which an individual has come into the world (and even on the conditions during its mother’s gestation) up to the moment at which they have started to enter the adult life phase. If these conditions were better, then the ways of life of an individual will also be better, i.e., an individual has a major predisposition by comparison with those peers who grew up in the worse life conditions. Simplified, individuals from the better cohorts will have larger corporeal dimensions, will earlier enter an adult phase, will have better chances for survival, will be in a breeding phase longer and will also have a more numerous progeny.
The most frequently used indicators concerning the ways of life among the cohorts were physical growth, corporeal mass of adult individuals, an average reproduction success, the age in which a head enters into reproduction, adult head survival and yearling survival (Gaillard et al. 2003). The antlers and horns, however, are one of the most visible examples of sexual selection, since they have been developed as a result of an intensive competition between the stags during mating (Clutton‐Brock et al. 1980, Coltman et al. 2001). This mating competition is a key factor in the evolution and morphology of those male artiodactyls which demonstrate a high level of polygamy. Hereby, sexual dimorphism, manifested in a body (Weckerly, 1998) and antler size (Clutton-Brock et al. 1980, Caro et al. 2003), also increases along with a polygamy degree, but it actually pertains to a relative resource allocation, i.e., to an incorporation of environmental resources (forage and water) into the antlers, horns, corporeal size or just in the individual organs. Since the stags are fighting for a hind during a relatively short mating season, the quality lies in a close dependency on a fighting capability, i.e., on a corporeal size and age. In other words, the antlers and horns do not only play a role of weapon, but they are also a signal, i.e., a sign of readiness (Goss 1983).