▪ Abstract Mammals are exposed to a diverse array of parasites and infectious diseases, many of which affect host survival and reproduction. Species that live in dense populations, large social groups, or with promiscuous mating systems may be especially vulnerable to infectious diseases owing to the close proximity and higher contact rates among individuals. We review the effects of host density and social contacts on parasite spread and the importance of promiscuity and mating structure for the spread and evolution of sexually transmitted diseases. Host social organization and mating system should influence not only parasite diversity and prevalence but may also determine the fitness advantages of different transmission strategies to parasites. Because host behavior and immune defenses may have evolved to reduce the spread and pathogenicity of infectious diseases, we also consider selective pressures that parasites may exert on host social and mating behavior and the evolutionary responses of hosts at b...

https://www.jstor.org/stable/pdfplus/30033785.pdf

Social Organization and Parasite Risk in Mammals: Integrating Theory and Empirical Studies

We reviewed papers that compared intraspecific variation in territoriality vs. alternative forms of spatial or behavioral organization with three goals: (1) to discover which ecological variables act as determinants of territorial behavior and how they might act; (2) to extract and evaluate predictions and evidence for determinants of territoriality and (3) to suggest ways for future studies to build upon what the review revealed. Twenty ecological variables have been predicted, correlated with or experimentally demonstrated to relate to territoriality within vertebrate species. These variables include several characteristics of food: quantity, predictability, distribution, quality, renewal rate, type, density and assessibility. Other variables include nonfood resources, population density, habitat features, mates, space, refuges/spawning/home sites, predation pressure, host nests (for brood parasites) and energy availability. We suggest several reasons why food resources are cited most often, in...

https://bioone.org/journals/The-American-Midland-Naturalist/volume-143/issue-1/0003-0031(2000)143[0001:AROEDO]2.0.CO;2/A-Review-of-Ecological-Determinants-of-Territoriality-within-Vertebrate-Species/10.1674/0003-0031(2000)143[0001:AROEDO]2.0.CO;2.pdf

A Review of Ecological Determinants of Territoriality Within Vertebrate Species

Evolutionary theory proposes that exaggerated male traits have evolved via sexual selection, either through female mate choice or male-male competition. While female preferences for ornamented males have been amply demonstrated in other taxa, among mammals sexual characters are commonly regarded as weapons whose main function is to enhance male competitiveness in agonistic encounters. One particularly controversial hypothesis to explain the function of male sexual characters proposes that they advertise male fertility. We test this hypothesis in red deer (Cervus elaphus), a species where sexual characters (antlers) reach an extreme degree of elaboration. We find that a global measure of relative antler size and complexity is associated with relative testes size and sperm velocity. Our results exclude the possibility that condition dependence, age or time of culling, drive these associations. Red deer antlers could signal male fertility to females, the ability to avoid sperm depletion throughout the reproductive season and/or the competitive ability of ejaculates. By contrast, male antlers could also signal to other males not only their competitive ability at the behavioural level (fighting ability) but also at the physiological level (sperm competition).

/pdf/antlers-honestly-advertise-sperm-production-and-quality-4psqlt25la.pdf

Antlers honestly advertise sperm production and quality

Socio-ecological explanations for intra- and interspecific variation in the social and spatial organization of animals predominate in the scientific literature. The socio-ecological model, developed first for the Bovidae and Cervidae, is commonly applied more widely to other groups including the Equidae. Intraspecific comparisons are particularly valuable because they allow the role of environment and demography on social and spatial organization to be understood while controlling for phylogeny or morphology which confound interspecific comparisons. Feral horse (Equus caballus Linnaeus 1758) populations with different demography inhabit a range of environments throughout the world. I use 56 reports to obtain 23 measures or characteristics of the behaviour and the social and spatial organization of 19 feral horse populations in which the environment, demography, management, research effort and sample size are also described. Comparison shows that different populations had remarkably similar social and spatial organization and that group sizes and composition, and home range sizes varied as much within as between populations. I assess the few exceptions to uniformity and conclude that they are due to the attributes of the studies themselves, particularly to poor definition of terms and inadequate empiricism, rather than to the environment or demography per se. Interspecific comparisons show that equid species adhere to their different social and spatial organizations despite similarities in their environments and even when species are sympatric. Furthermore, equid male territoriality has been ill-defined in previous studies, observations presented as evidence of territoriality are also found in non-territorial equids, and populations of supposedly territorial species demonstrate female defence polygyny. Thus, territoriality may not be a useful categorization in the Equidae. Moreover, although equid socio-ecologists have relied on the socio-ecological model derived from the extremely diverse Bovidae and Cervidae for explanations of variation in equine society, the homomorphic, but large and polygynous, and monogeneric Equidae do not support previous socio-ecological explanations for relationships between body size, mating system and sexual dimorphism in ungulates. Consequently, in spite of the efforts of numerous authors during the past two decades, functional explanations of apparent differences in feral horse and equid social and spatial organization and behaviour based on assumptions of their current utility in the environmental or demographic context remain unconvincing. Nevertheless, differences in social cohesion between species that are insensitive to intra- and interspecific variation in habitat and predation pressure warrant explanation. Thus, I propose alternative avenues of inquiry including testing for species-specific differences in inter-individual aggression and investigating the role of phylogenetic constraints in equine society. The Equidae are evidence of the relative importance of phylogeny and biological structure, and unimportance of the present-day environment, in animal behaviour and social and spatial organization.

Adaptive explanation in socio‐ecology: lessons from the Equidae

Sexual segregation outside the mating season occurs in most species of sexually dimorphic ungulates and has been extensively described in the literature, but the mechanisms causing segregation are still debated. The detailed pattern of sexual segregation throughout the year has rarely been presented for mammals, and no study, to our knowledge, has used latitudinal-related variation in breeding phenology to shed light on the underlying mechanisms. Recent methodological developments have made it possible to quantify separate components of segregation (social, habitat) and activity synchrony in animal groups, but these major improvements have so far been little used. We observed European red deer year round at two widely different latitudes (France and Norway) and tested three different mechanistic hypotheses of segregation related to: (i) predation risk; (ii) body-size-related forage selection; and (iii) activity budget. Habitat segregation peaked during calving in both populations and dropped rapidly after calving. Females with calves were more segregated from males than were females without calves, pointing to a key role of antipredator behaviour even though large predators are absent in France and extremely rare in Norway. However, at both sites individuals also grouped with their own sex within habitat types (i.e. social segregation), and individuals in mixed-sex groups were less synchronized in activity type than individuals in either unisex male or unisex female groups, suggesting that differences in activity budgets are involved. Social segregation peaked during calving and was lowest during the rut (indicating aggregation) in both populations; these activities occurred one month later in the Northern populations, corresponding well with known differences in breeding phenology. We conclude that latitude-dependent breeding phenology shapes the seasonal pattern of sexual segregation and that sexual segregation in ungulates has multiple causes.

Juan deDIOS Vargas

Papers

Experimental shifting from harem defence to territoriality in rutting red deer