Inheritance of adult velvet antler weights and live weights in farmed red deer

Variation of antlers in individual red deer (Cervus elaphus) stags: repeatability, age and side effects

Antlers are formed anew each year to realise an optimal relationship between their size and weight and the physical body condition in Cervidae. This results in the objective to match fighting abilities with size and mechanical performance of the antlers, as well as to advertise these correlated abilities to other males and females. The resulting variation in individual antler characteristics from year to year can show considerable differences. To characterise and understand these differences is important in hunting, game management and deer breeding, as well as potentially to assess the habitat quality. However, relatively few traits of the antler have been scientifically tested for this purpose, and only a few studies were conducted on the same individual in free-ranging red deer over the years. The objective of the present study was to quantify the influence of the individual (repeatability), the age and the site on the expression of 125 antler characteristics. For this purpose, we collected 35 stags with an average of about 10 consecutive antlers per individual (confirmed by genetic analysis), a total of 355 antlers. The antlers were scanned 3-dimensionally and measured semi-automatically. Numbers, lengths, distances, circumferences, bending, curvatures, angles, forms and CIC (International Council for Game and Wildlife Conservation) characteristics were compiled and evaluated in a generalised linear mixed model adapted to the distribution of the characteristics. The complete model explained 1.6 to 83% of character variation. Mean repeatability of the characteristics varied between 2.7 and 74.4%. The stags’ age explained 0 to 36.4%, and the side explained 0 to 2.5% of the variability. Some characteristics of burr, signet, beam and the lower tines reached the highest repeatability; the highest variability was found in characteristics of the crown. Values of 11 features that are frequently used in other studies corresponded very well with the present study. However, some features reached higher repeatability every year, whereas others varied more closely with age. Such characteristics might be selectively included into further research or practical applications to increase informative value.

Genomic analysis reveals a polygenic architecture of antler morphology in wild red deer (Cervus elaphus)

Sexually selected traits show large variation and rapid evolution across the animal kingdom, yet genetic variation often persists within populations despite apparent directional selection. A key step in solving this long-standing paradox is to determine the genetic architecture of sexually selected traits to understand evolutionary drivers and constraints at the genomic level. Antlers are a form of sexual weaponry in male red deer (Cervus elaphus). On the island of Rum, Scotland, males with larger antlers have increased breeding success, yet there has been no evidence of any response to selection at the genetic level. To try and understand the mechanisms underlying this observation, we investigate the genetic architecture of ten antler traits and their principal components using genomic data from >38,000 SNPs. We estimate the heritabilities and genetic correlations of the antler traits using a genomic relatedness approach. We then use genome-wide association and haplotype-based regional heritability to identify regions of the genome underlying antler morphology, and an empirical Bayes approach to estimate the underlying distributions of allele effect sizes. We show that antler morphology is highly repeatable over an individual's lifetime, heritable and has a polygenic architecture and that almost all antler traits are positively genetically correlated with some loci identified as having pleiotropic effects. Our findings suggest that a large mutational target and genetic covariances among antler traits, in part maintained by pleiotropy, are likely to contribute to the maintenance of genetic variation in antler morphology in this population.

Nutrition of antler growth in deer

Stags are susceptible to the effects of nutrition at several stages during their lives and during the antler cycle. Nutrition during the in utero, post-natal (suckling) and yearling stages influences the size of spike antlers, and, generally, there is a close relationship between bodyweight and antler weight in stags aged up to 5 years. While antler size is not greatly affected by nutrition during the growth of immature (velvet) antler, it is influenced by body size and condition at casting, i.e. at the beginning of new antler growth. Antler growth appears to have a high priority for nutrients, especially energy, protein and calcium. Antler growth in adult stags is little affected by diet protein concentrations over 7%, but supplements of protected protein or methionine may improve antler growth. Substantial amounts of calcium and phosphorus are sequestered in antlers as they become mineralised, and calcium is withdrawn from the skeleton in support of this. Feeding programs to obtain good antler growth involve recognising the periods when juvenile stags are susceptible to under-nutrition, and providing sufficient nutrients to re-establish adequate body condition in adult stags between the end of the rut and antler casting.

Genetic differentiation among 6 populations of red deer (Cervus elaphus L.) in Poland based on microsatellite DNA polymorphism

Recently, there has been considerable interest in genetic differentiation in the Cervidae family. A common tool used to determine genetic variation in different species, breeds and populations is DNA analysis, which allows for direct determination of the differences and changes within a group of animals. Because the analysis of microsatellite polymorphism in different Cervidae populations revealed considerable genetic variability in individual populations, it was important to test a set of markers in animals from these populations.The study was performed with muscle tissue and blood samples collected from a total of 793 red deer. Six groups (subpopulations) of red deer were defined according to region: Masurian (330 animals), Bieszczady (194 animals), Małopolska (80 animals), Sudety (76 animals), Lower Silesian (62 animals) and Lubusz (51 animals). The analysis involved 12 STR markers (BM1818, OarAE129, OarFCB5, OarFCB304, RM188, RT 1, RT 13, T26, T156, T193, T501, TGLA53), for which conditions for simultaneous amplification were established.Based on this study, it is concluded that the chosen set of 12 microsatellite markers could be used to evaluate the genetic structure and to monitor changes in Poland's red deer population.

Variance component analysis of body mass in a wild population of deer (Odocoileus virginianus): results from two decades of research

Context Long-term studies of large, vertebrate mammals using capture–recapture data are scarce, even though long-term ecological studies are requisite to understanding quantitative genetics and evolutionary processes that can be applied as part of management programs. Aims Objectives were to (1) partition components of variation in body mass to understand the differential effects of environmental variation on the sexes during ontogeny, to better prescribe habitat-improvement projects, and (2) estimate repeatability to assess potential for selection on body mass. Methods We used a 23-year dataset (1983–2005) of capture–recapture records of wild white-tailed deer (Odocoileus virginianus) to estimate components of variance and repeatability of body mass. We used an animal-model approach that employed the use of general linear mixed models and restricted maximum likelihood to adjust for the effects of age (i.e. fixed effect), and to partition the total phenotypic variance into among-individual (i.e. the deer), permanent environmental (i.e. year of birth) and temporary environmental (i.e. year of measurement and residual) effects (all modelled as random effects). Key results We found that body mass increased with age in both sexes, repeatability of body mass was 0.595 for females and 0.716 for males, and among-individual variation was more influential on body mass than were permanent and temporary environmental effects combined. Year of birth was more important in males than females, but changed during the course of ontogeny for both sexes. Year of measurement did not influence post-rut body mass in males, but did contribute to variation in body mass of females. Conclusions These long-term data offer insights into the sources of variation that influence body mass of deer, which can be used to understand how environmental sources of variation influence phenotypic traits, and for developing management plans and making selection decisions. Implications Knowledge of repeatability (as an upper limit to heritability) can be used to make management decisions related to selection, culling and breeding, whereas understanding environmental effects can lead to better management recommendations (e.g. habitat-improvement projects).

Antler size in red deer: heritability and selection but no evolution

We present estimates of the selection on and the heritability of a male secondary sexual weapon in a wild population: antler size in red deer. Male red deer with large antlers had increased lifetime breeding success, both before and after correcting for body size, generating a standardized selection gradient of 0.44 (+/- 0.18 SE). Despite substantial age- and environment-related variation, antler size was also heritable (heritability of antler mass = 0.33 +/- 0.12). However the observed selection did not generate an evolutionary response in antler size over the study period of nearly 30 years, and there was no evidence of a positive genetic correlation between antler size and fitness nor of a positive association between breeding values for antler size and fitness. Our results are consistent with the hypothesis that a heritable trait under directional selection will not evolve if associations between the measured trait and fitness are determined by environmental covariances: In red deer males, for example, both antler size and success in the fights for mates may be heavily dependent on an individual's nutritional state.

Heritability of body mass varies with age and season in wild bighorn sheep

Heritabilities (h2) of body mass at different ages and seasons were estimated using offspring-mother regression and restricted maximum likelihood (REML) methods for bighorn sheep on Ram Mountain, Alberta. Both methods resulted in similar estimates of h2 for adults, but for lambs and yearlings heritability was underestimated by offspring-mother regression relative to REML, possibly because of higher maternal-effects bias for offspring-mother regression. Heritabilities of body mass in bighorn were similar to published estimates for domestic sheep. Heritability estimated by offspring-mother regression increased after 2 years of age. The REML method suggested that heritability was moderate for lambs and yearlings, very low at 2 years of age, and increased afterwards. The increase in heritability with age was attributed to declining negative maternal effects. Very low h2 estimates at 2 years of age, obtained with both methods, appeared to be caused by a combination of high environmental variance and very low genetic variance. Body mass of bighorn sheep has a pronounced seasonal cycle, and h2 was lower in June than in September for 2-year-olds and older sheep, and associated with both lower VA and higher VE in spring.