Aagesensutton1464

Despite it is widely accepted that intrapopulation variation is fundamental to ecological and evolutionary processes, this level of information has only recently been included into network analysis of species/population interactions. When done, it has revealed non-random patterns in the distribution of trophic resources. Nestedness in resource use among individuals is the most recurrent observed pattern, often accompanied by an absence of modularity, but no previous studies examine bipartite modularity. We use network analysis to describe the diet composition of the Balearic endemic lizard Podarcis lilfordi in 2 islets at population and individual levels, based on the occurrence of food items in fecal samples. Our objectives are to 1) compare niche structure at both levels, 2) characterize niche partition using nestedness and modularity, and 3) assess how size, sex, season, and spatial location influence niche structure. At population-level niche width was wide, but narrow at the level of the individual. Both islet networks were nested, indicating similar ranking of the food preferences among individuals, but also modular, which was partially explained by seasonality. Sex and body size did not notably affect diet composition. Large niche overlap and therefore possibly relaxed competition were observed among females in one of the islets and during spring on both islets. Likewise, higher modularity in autumn suggests that higher competition could lead to specialization in both populations, because resources are usually scarce in this season. The absence of spatial location influence on niche might respond to fine-grained spatio-temporally distribution of food resources. Behavioral traits, not included in this study, could also influence resource partitioning.Nest survival is a vital component of breeding success, and affects population dynamics, as the loss of nests is the main cause of reproductive failure in birds. To identify key factors for the conservation of Chinese grouse Tetrastes sewerzowi, we tested the effects of nest concealment, nest age, nesting season, and habitat edge on nest daily survival rate (DSR) of Chinese grouse using 54 nests found at Lianhuashan Nature Reserve, Gansu, China, 2009-2012. Moreover, we controlled for the effect of research activity by testing the effect of nest checks on DSR. Overall, mammal predation caused 93% of nest failures. DSR was 0.986 ± 0.0038 in the constant model and the probability of a nest with a full clutch of 6 eggs surviving the entire 40-day nesting period was 0.526 ± 0.090. DSR decreased with nest age and nesting season (from 19 May to 3 July). Mammals instead of avian predators being responsible for most nest failures suggest that nest sites might be selected to avoid visual avian predators, but not olfactory mammalian predators, and the decreasing trend of DSR with nest age and nesting season could attribute to an additive exposure effect. Moreover, nest checks conducted by investigators significantly lowered nest DSR, especially during the late period of nesting season and for older nests. Mammalian predators might locate the nest site by following the investigator's odor. Based on our results, we suggest that the late incubation stage is a particularly vulnerable period for nest survival of Chinese grouse and those researchers should adjust their activities around nests to balance the need of acquiring accurate data and decreasing nest predation risk.In many animals, catabolic and anabolic periods are temporally separated. Migratory birds alternate energy expenditure during flight with energy accumulation during stopover. The size of the energy stores at stopover affects the decision to resume migration and thus the temporal organization of migration. We now provide data suggesting that it is not only the size of the energy stores per se that may influence migration scheduling, but also the physiological consequences of flying. In two subspecies of the northern wheatear Oenanthe oenanthe, a long-distance migrant, estimated energy stores at a stopover during autumn migration were positively related with both constitutive innate and acquired immune function, and negatively related with oxidative damage to lipids. In other words, migrants' physiological condition was associated with their energetic condition. Although time spent at stopover before sampling may have contributed to this relationship, our results suggest that migrants have to trade-off the depletion of energy stores during flight with incurring physiological costs. This will affect migrants' decisions when to start and when to terminate a migratory flight. The physiological costs associated with the depletion of energy stores may also help explaining why migrants often arrive at and depart from stopover sites with larger energy stores than expected. We propose that studies on the role of energy stores as drivers of the temporal organization of (avian) migration need to consider physiological condition, such as immunological and oxidative states.Energy conservation is paramount for small mammals because of their small size, large surface area to volume ratio, and the resultant high heat loss to the environment. To survive on limited food resources and to fuel their expensive metabolism during activity, many small mammals employ daily torpor to reduce energy expenditure during the rest phase. We hypothesized that a small terrestrial semelparous marsupial, the brown antechinus Antechinus stuartii, would maximize activity when foraging conditions were favorable to gain fat reserves before their intense breeding period, but would increase torpor use when conditions were poor to conserve these fat reserves. Female antechinus were trapped and implanted with small temperature-sensitive radio transmitters to record body temperature and to quantify torpor expression and activity patterns in the wild. Most antechinus used torpor at least once per day over the entire study period. ZLN005 nmr Total daily torpor use increased and mean daily body temperature decreased significantly with a reduction in minimum ambient temperature. Interestingly, antechinus employed less torpor on days with more rain and decreasing barometric pressure. In contrast to torpor expression, activity was directly related to ambient temperature and inversely related to barometric pressure. Our results reveal that antechinus use a flexible combination of physiology and behavior that can be adjusted to manage their energy budget according to weather variables.