Alternative Mating Tactics and Their Impact on Survival in Adult Male Alpine Ibex (Capra ibex ibex)

Adult male Alpine ibex (Capra ibex ibex) have been shown to exhibit unusually high survival to relatively advanced ages (>10 years), leading to speculation that males may engage in an energetically conservative reproductive strategy that increases survival. We investigated the extent to which the adoption of alternative mating tactics contributes to the extraordinary survival of adult males in this species. Because basic information on the mating system of Alpine ibex is scarce, we 1st characterized the temporal and spatial distribution of receptive females. Our observations during 3 consecutive rutting seasons revealed 2 alternative mating tactics. Apparently dominant males monopolized individual receptive females by following and defending them, a tactic known as tending. In contrast, apparently subordinate males tried to achieve temporary access to tended females when the latter started to run, a tactic referred to as coursing. In total, 24 copulations were observed, of which 20 (83.3%) were the result of tending and 4 were the result of coursing. The adoption of the 2 tactics was strongly age-dependent; older males (9-12 years) engaged primarily in tending, whereas younger males (2-6 years) engaged mainly in coursing. Males adopting the coursing tactic spent more time in low-cost and less time in high-cost behaviors than males adopting the tending tactic. Time-budget comparisons with another ungulate species suggested that although tending is a relatively costly tactic, coursing is a low-cost tactic that may contribute to the exceptional adult survival in male Alpine ibe

Social dominance and conflict reduction in rutting male Alpine ibex, Capra ibex

In polygynous ungulates, male mortality is thought to be linked to high-energy expenditures during the rut. However, Alpine ibex (Capra ibex) adult males show an unusually high survival during this time. Male Alpine ibex live in social groups and thus, we assumed that they might reduce energy-intensive interactions during the rut by establishing, early on, strict dominance hierarchies. To evaluate this hypothesis, we studied social interactions and mating behavior in a population of Alpine ibex in the Swiss Alps. In accordance with our prediction, and in contrast to other polygynous ungulates, male Alpine ibex decreased time spent in agonistic interactions and the number of fights during the rut compared with the prerut, irrespective of their age. Changes between access-holding males always occurred without foregoing fights and were entirely based on preestablished and stable dominance relationships. Therefore, dominant males always gained and held access to receptive females and thus managed to adopt the tending tactic. Subordinate males either left the consort pair or they adopted the coursing tactic in order to achieve temporary access to estrous females. They behaved extremely reluctantly toward dominants, as they never made use of overt aggression to challenge them or to create actively transient mating opportunities. Our study supports the hypothesis that costly intramale interactions are reduced during the mating season in Alpine ibex by the adherence to preestablished and stable dominance relationships. Accordingly, male Alpine ibex appear to be able to cut down on energy expenditures, which in turn, likely contributes to their superior surviva

Many-to-Many Graph Matching: a Continuous Relaxation Approach

Graphs provide an efficient tool for object representation in various computer vision applications. Once graph-based representations are constructed, an important question is how to compare graphs. This problem is often formulated as a graph matching problem where one seeks a mapping between vertices of two graphs which optimally aligns their structure. In the classical formulation of graph matching, only one-to-one correspondences between vertices are considered. However, in many applications, graphs cannot be matched perfectly and it is more interesting to consider many-to-many correspondences where clusters of vertices in one graph are matched to clusters of vertices in the other graph. In this paper, we formulate the many-to-many graph matching problem as a discrete optimization problem and propose an approximate algorithm based on a continuous relaxation of the combinatorial problem. We compare our method with other existing methods on several benchmark computer vision datasets.Comment: 1

Dietary control of the renal reabsorption and excretion of α2u-globulin

Dietary protein supply is a factor in controlling the excretion of proteins in the urine. As early as 1926, Addis, Mackay, and Mackay observed that male rats on a 69% protein diet excreted more urinary proteins than did those on a 17% diet [1]. Protein deficiency had the opposite effect, resulting in a suppression of the proteinuria [2]. Of the total urinary proteins excreted by the adult male rat, approximately 30% is a sex-dependent globulin called α2u [3,4], which is synthesized by the liver [5] and controlled synergistically by androgens and glucocorticoids [6]. Dietary protein supply also had a profound influence on the excretion of α2u [4]. On a 0% casein diet, the excretion was reduced to approximately 1 mg/24 hours compared with a normal of 10 to 15mg. On a 50% casein diet, rats excreted 30 to 50 mg/24 hours, an increase of more than 100% above the normal [4].Early studies also suggested that high protein diets exaggerated the leakage of plasma proteins caused by a spontaneous nephrotic syndrome observed in male rats [7, 8]. Rats previously castrated did not exhibit an increased excretion of urinary protein on a 50% casein diet, whereas supplementation with testosterone restored the augmented proteinuria [9]. This suggested that the elevated excretion of urinary protein was dependent on the presence of androgens. It is now known that a high-protein diet caused an increased excretion of α2u without at the same time leading to a compensatory, stimulated hepatic biosynthesis. Conceivably, the increased excretion of α2u was the consequence of an altered state of renal reabsorption [4]. The purpose of the present communication was to compare the degree of renal reabsorption under three different dietary conditions and to determine whether the kidneys controlled the urinary excretion of α2u by altering its reabsorption

Classical and Quantum Annealing in the Median of Three Satisfiability

We determine the classical and quantum complexities of a specific ensemble of three-satisfiability problems with a unique satisfying assignment for up to N=100 and N=80 variables, respectively. In the classical limit we employ generalized ensemble techniques and measure the time that a Markovian Monte Carlo process spends in searching classical ground states. In the quantum limit we determine the maximum finite correlation length along a quantum adiabatic trajectory determined by the linear sweep of the adiabatic control parameter in the Hamiltonian composed of the problem Hamiltonian and the constant transverse field Hamiltonian. In the median of our ensemble both complexities diverge exponentially with the number of variables. Hence, standard, conventional adiabatic quantum computation fails to reduce the computational complexity to polynomial. Moreover, the growth-rate constant in the quantum limit is 3.8 times as large as the one in the classical limit, making classical fluctuations more beneficial than quantum fluctuations in ground-state searches

High-pressure phases and transitions of the layered alkaline earth nitridosilicates SrSiN2 and BaSiN2

We investigate the high-pressure phase diagram of SrSiN2 and BaSiN2 with density-functional calculation. Searching a manifold of possible candidate structures, we propose new structural modifications of SrSiN2 and BaSiN2 attainable in high-pressure experiments. The monoclinic ground state of SrSiN2 transforms at 3 GPa into an orthorhombic BaSiN2 type. At 14 GPa a CaSiN2-type structure becomes the most stable configuration of SrSiN2. A hitherto unknown Pbcm modification is adopted at 85 GPa and, finally, at 131 GPa a LiFeO2-type structure. The higher homologue BaSiN2 transforms to a CaSiN2 type at 41 GPa and further to a Pbcm modification at 105 GPa. Both systems follow the pressure-coordination rule: the coordination environment of Si increases from tetrahedral through trigonal bipyramidal to octahedral. Some high-pressure phases are related in structure through simple group–subgroup mechanisms, indicating displacive phase transformations with low activation barriers

Commensurability effects in superconducting Nb films with quasiperiodic pinning arrays

We study experimentally the critical depinning current Ic versus applied magnetic field B in Nb thin films which contain 2D arrays of circular antidots placed on the nodes of quasiperiodic (QP) fivefold Penrose lattices. Close to the transition temperature Tc we observe matching of the vortex lattice with the QP pinning array, confirming essential features in the Ic(B) patterns as predicted by Misko et al. [Phys. Rev. Lett, vol.95, 177007 (2005)]. We find a significant enhancement in Ic(B) for QP pinning arrays in comparison to Ic in samples with randomly distributed antidots or no antidots.Comment: 4 pages, 3 figure