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Adult Body Mass (adult + body_mass)
Selected AbstractsMass invariance of population nitrogen flux by terrestrial mammalian herbivores: an extension of the energetic equivalence ruleECOLOGY LETTERS, Issue 9 2008Christopher W. Habeck Abstract According to the energetic equivalence rule, energy use by a population is independent of average adult body mass. Energy use can be equated with carbon flux, and it has been suggested that population fluxes of other materials, such as nitrogen and phosphorus, might also be independent of body mass. We compiled data on individual nitrogen deposition rates (via faeces and urine) and average population densities of 26 species of mammalian herbivores to test the hypothesis of elemental equivalence for nitrogen. We found that the mass scaling of individual nitrogen flux was opposite to that of population density for the species in our dataset. By computing the product of individual nitrogen flux and average population density for each species in our dataset, we found that population-level nitrogen flux was independent of species mass, averaging c. 3.22 g N ha,1 day,1. Results from this analysis can be used to understand the influence of mammalian herbivore communities on nitrogen cycling in terrestrial ecosystems. [source] Seasonal field metabolic rate and dietary intake in Arabian Babblers (Turdoides squamiceps) inhabiting extreme desertsFUNCTIONAL ECOLOGY, Issue 5 2000A. Anava Abstract 1.,Arabian Babblers (Turdoides squamiceps Cretzsch.; mean adult body mass = 72·5 g) inhabit extreme deserts of Israel. They consume invertebrates and fruits and, at least at our study site, do not drink. It was hypothesized that babblers (1) in general, use relatively less energy and water than other birds of its body mass; and (2) consume a more water-rich diet (mainly fruits) in summer and more energy-rich diet (mainly invertebrates) in winter. Doubly labelled water was used to determine seasonal field metabolic rate (FMR) and water influx rate (WIR) and to estimate dietary selection in free-living Arabian Babblers. 2.,Babblers in winter weighed significantly more than in summer, and males weighed more than females in both seasons. Tritiated water (TOH) space, as a proportion of body mass, was higher in males than in females in summer but no difference between sexes was found in winter. Males in summer had a higher TOH space, proportionally, than males in winter but there was no difference between seasons in females. Mass-specific WIR did not differ between sexes in any season and averaged 0·475 ml g,1 d,1 in winter which was significantly higher than the 0·283 ml g,1 d,1 in summer. 3.,The mean daily energy expenditure of the babblers did not differ either between seasons or between sexes within seasons and averaged 1·61 kJ g,1 d,1 in winter and 1·68 kJ g,1 d,1 in summer. It was calculated that each babbler consumed an average of 5·09 g dry matter invertebrates and 1·83 g dry matter fruits in summer (for a 68·2-g bird; mean adult body mass in summer) and 3·49 g dry matter invertebrates and 6·61 g dry matter fruits in winter (for a 76·9-g bird; mean adult body mass in winter). 4.,When compared with other avian species, FMR and WIR of babblers were lower than bird species in general, but were similar to those of other desert birds. It was calculated that proportional dietary intake, on a dry matter basis, included 0·79 insects and 0·21 fruits in summer and 0·35 insects and 0·65 fruits in winter. Therefore, the babblers consumed a relatively energy-rich diet in summer and water-rich diet in winter which refuted our hypothesis. Most of the metabolizable energy was provided by invertebrates in both seasons; invertebrates provided more water in summer but fruits provided more in winter. [source] Fast fuelling but light flight in Broad-billed Sandpipers Limicola falcinellus: stopover ecology at a final take-off site in spring (Sivash, Ukraine)IBIS, Issue 2 2006YVONNE VERKUIL We studied phenology, staging time and refuelling in Broad-billed Sandpipers Limicola falcinellus stopping over during spring migration in the Sivash (Black Sea, Ukraine) in May 1991,94. In the study area, peak staging numbers of 2000,2500 individuals occurred in the third week of May. In May 1993, 460 birds were marked with a yellow dye and 126 of these were colour-ringed. Before 28 May no departure of birds dyed yellow could be detected; by 3 June all birds had departed. Colour-ringed adults in mid May 1993 staged for a minimum of 8.2 days. After the observed departure of large flocks (24 May and later) the staging time of colour-ringed birds decreased significantly with body mass at the time of capture. Of birds mist-netted in 1991,94, 99.3% were in full summer plumage and 89% were adults. In second-year birds, fuel deposition rate (measured between individuals) was 0.44 g/day. In adults caught from early May to 24 May, overall fuel deposition rate was 1.04 g/day (3.4% of lean body mass). Mean adult body mass in early May was 34.8 g, increasing to 45.5 g after 24 May. Estimated body mass at departure was 51 g. Departure body mass and flight range estimates suggest that although birds refuelled quickly, fuel loads are only just sufficient for an unbroken flight to Scandinavia and the Kola Peninsula. We suggest that Broad-billed Sandpipers use the Sivash as a crucial final take-off stopover site, and that they follow a ,jumping' migration strategy, performed under narrow time constraints. [source] Can selection on nest size from nest predation explain the latitudinal gradient in clutch size?JOURNAL OF ANIMAL ECOLOGY, Issue 5 2010Luis Biancucci Summary 1.,Latitudinal variation in clutch sizes of birds is a well described, but poorly understood pattern. Many hypotheses have been proposed, but few have been experimentally tested, and none have been universally accepted by researchers. 2.,The nest size hypothesis posits that higher nest predation in the tropics favours selection for smaller nests and thereby constrains clutch size by shrinking available space for eggs and/or nestlings in the nest. We tested this hypothesis with an experiment in a tropical forest and a comparative study between temperate and tropical field sites. 3.,Specifically, we tested if: (i) predation increased with nest size; (ii) tropical birds had smaller nests controlled for body size; and (iii) clutch size was explained by nest size controlled for body size. 4.,Experimental swapping of nests of different sizes showed that nest predation increased with nest size in the tropical site. Moreover, nest predation rates were higher in species with larger nests in both sites. However, nest size, corrected for body mass and phylogeny, did not differ between sites and was not related to clutch size between sites. 5.,Hence, nest predation can exert selection on nest size as predicted by the hypothesis. Nest size increased with adult body mass, such that adult size might indirectly influence reproductive success through effects on nest size and nest predation risk. Ultimately, however, selection from nest predation on nest size does not explain the smaller clutch sizes typical of the tropics. [source] The diapause decision as a cascade switch for adaptive developmental plasticity in body mass in a butterflyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2010K. GOTTHARD Abstract Switch-induced developmental plasticity, such as the diapause decision in insects, is a major form of adaptation to variable environments. As individuals that follow alternative developmental pathways will experience different selective environments the diapause decision may evolve to a cascade switch that induces additional adaptive developmental differences downstream of the diapause decision. Here, we show that individuals following alternative developmental pathways in a Swedish population of the butterfly, Pararge aegeria, display differential optimization of adult body mass as a likely response to predictable differences in thermal conditions during reproduction. In a more northern population where this type of selection is absent no similar difference in adult mass among pathways was found. We conclude that the diapause decision in the southern population appears to act as a cascade switch, coordinating development downstream of the diapause decision, to produce adult phenotypes adapted to the typical thermal conditions of their expected reproductive period. [source] Mass-dependent reproductive strategies in wild bighorn ewes: a quantitative genetic approachJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2000RÉale In the Ram Mountain bighorn sheep (Ovis canadensis) population, ewes differing by more than 30% in body mass weaned lambs with an average mass difference of only 3%. Variability in adult body mass was partly due to additive genetic effects, but inheritance of weaning mass was weak. Maternal effects could obscure genetic effects in the phenotypic expression of weaning mass, particularly if they reflected strategies of maternal expenditure that varied according to ewe mass. We performed a quantitative genetic analysis to assess genetic and environmental influences on ewe mass and on maternal expenditure. We used the mean daughters/mother regression method and Derivative Free Restricted Maximum Likelihood models to estimate heritability (h2) of ewe mass and indices of maternal expenditure. We found additive genetic effects on phenotypic variation in maternal mass, in lamb mass at weaning (absolute maternal expenditure) and in weaning mass relative to maternal mass at weaning (relative maternal expenditure). Heritability suggests that maternal expenditure has the potential to evolve. The genetic correlation of ewe mass and absolute maternal expenditure was weak, while ewe mass and relative maternal expenditure were strongly negatively correlated. These results suggest additive genetic effects on mass-dependent reproductive strategies in bighorn ewes. Mass-dependent reproductive strategies could affect lamb survival and phenotypic variation in adult mass. As population density increased and reproduction became costlier, small females reduced maternal expenditure more than large females. Constraints on reproductive strategy imposed by variations in resource availability are therefore likely to differ according to ewe mass. A general trend for a decrease in maternal expenditure relative to maternal size in mammals suggests that size-dependent negative maternal effects may be common. [source] | ||||||||||