6,778 research outputs found
A New 3D Potential-Density Basis Set
A set of bi-orthogonal potential-density basis functions is introduced to
model the density and its associated gravitational field of three dimensional
stellar systems. Radial components of our basis functions are weighted integral
forms of spherical Bessel functions. We discuss the properties of our basis
functions and demonstrate their shapes for the latitudinal Fourier number
.Comment: 2 pages. To appear in the proceedings of IAU Symposium 245,
"Formation and Evolution of Galaxy Bulges," M. Bureau, E. Athanassoula, and
B. Barbuy, ed
The Wild and the Tame
The Western belief that the world is divided into the human and the natural stems from the philosophy, first propounded by the ancient Greeks, notably Aristotle, that all living organisms could be placed in a Scale of Nature or Great Chain of Being with primeval slime at its base and Man at its summit. This belief, which is imbued in Christianity and in all aspects of western civilization, has led to a great divide with the wild on one side and the tame , that is all the animals and plants that are exploited by human, on the other
Recommended from our members
Social evolution in mammals
Long-term, individual-based field studies, the application of genetic techniques and phylogenetic reconstructions have led to substantial advances in our understanding of the diversity and evolution of mammalian breeding systems and their consequences. They show how contrasts in ecology, life histories and phylogeny affect the distributions of breeding females and breeding males; how the distributions of both sexes affect the evolution of breeding systems and the composition and kinship structure of social groups; how contrasts in breeding systems and the social environment that individuals encounter affect the selection pressures operating on both sexes and the evolution of their behavior, physiology and morphology; and how these differences affect the demography and dynamics of populations and their responses to variation in density, climate and human impact.European Research Counci
Costs of mating competition limit male lifetime breeding success in polygynous mammals.
This is the accepted version of the paper. The final published version is available from the Royal Society at http://rspb.royalsocietypublishing.org/content/281/1786/20140418.abstract.Although differences in breeding lifespan are an important source of variation in male fitness, the factors affecting the breeding tenure of males have seldom been explored. Here, we use cross-species comparisons to investigate the correlates of breeding lifespan in male mammals. Our results show that male breeding lifespan depends on the extent of polygyny, which reflects the relative intensity of competition for access to females. Males have relatively short breeding tenure in species where individuals have the potential to monopolize mating with multiple females, and longer ones where individuals defend one female at a time. Male breeding tenure is also shorter in species in which females breed frequently than in those where females breed less frequently, suggesting that the costs of guarding females may contribute to limiting tenure length. As a consequence of these relationships, estimates of skew in male breeding success within seasons overestimate skew calculated across the lifetime and, in several polygynous species, variance in lifetime breeding success is not substantially higher in males than in females.The Leverhulme Trust, the Isaac Newton Trust, and the European Research Council provided the funding for this study
Recommended from our members
The evolution of social monogamy in mammals.
The evolution of social monogamy has intrigued biologists for over a century. Here, we show that the ancestral condition for all mammalian groups is of solitary individuals and that social monogamy is derived almost exclusively from this social system. The evolution of social monogamy does not appear to have been associated with a high risk of male infanticide, and paternal care is a consequence rather than a cause of social monogamy. Social monogamy has evolved in nonhuman mammals where breeding females are intolerant of each other and female density is low, suggesting that it represents a mating strategy that has developed where males are unable to defend access to multiple females.The Leverhulme Trust, the Isaac Newton Trust, and the European Research Council provided the funding for this study.This version is the author accepted manuscript. The final published version can be found here: http://www.sciencemag.org/content/341/6145/526.ful
Maternal longevity and offspring sex in wild ungulates
In species with sexual size dimorphism, the offspring of the larger sex usually have greater energy requirements and may lead to greater fitness costs for parents. The effects of offspring sex on maternal longevity, however, have only been tested in humans. Human studies produced mixed results and considerable debate mainly owing to the difficulty of distinguishing the effects of sexual dimorphism from sociocultural factors. To advance this debate, we examined how the relative number of sons influenced maternal longevity in four species of free-living ungulates (Soay sheep Ovis aries ; bighorn sheep, Ovis canadensis ; red deer, Cervus elaphus ; mountain goat, Oreamnos americanus ), with high male-biased sexual size dimorphism but without complicating sociocultural variables. We found no evidence for a higher cumulative cost of sons than of daughters on maternal longevity. For a given number of offspring, most females with many sons in all four populations lived longer than females with few sons. The higher cost of sons over daughters on maternal lifespan reported by some human studies may be the exception rather than the rule in long-lived iteroparous species
Social complexity and kinship in animal societies
Studies of eusocial invertebrates regard complex societies as those where there is a clear division of labour and extensive cooperation between breeders and helpers. In contrast, studies of social mammals identify complex societies as those where differentiated social relationships influence access to resources and reproductive opportunities. We show here that, while traits associated with social complexity of the first kind occur in social mammals that live in groups composed of close relatives, traits associated with the complexity of social relationships occur where average kinship between female group members is low. These differences in the form of social complexity appear to be associated with variation in brain size and probably reflect contrasts in the extent of conflicts of interest between group members. Our results emphasise the limitations of any unitary concept of social complexity and show that variation in average kinship between group members has farâreaching consequences for animal societies.This project was funded by the European Research Commission (grant no. 294494âTHCB2011)
- âŠ