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Poor Body Condition (poor + body_condition)
Selected AbstractsVariation in food availability influences prey-capture method in antlion larvaeECOLOGICAL ENTOMOLOGY, Issue 5 2008EFRAT ELIMELECH Abstract 1.,Larvae of a Myrmecaelurus sp. are unique among antlions because they have two prey-capture methods; they either ambush prey at the surface, or dig pit traps that prey fall in to. It was hypothesised that larvae will use the capture method that maximises their net rate of energy gain, which will be influenced by food availability (encounter rate) and by past energy inputs (body condition). 2.,Costs were estimated by measuring resting and activity metabolic rates and determining the duration of pit maintenance at various encounter rates with ants that served as prey. Benefits were estimated from the energy gained per ant captured at different encounter rates. 3.,Net energy gained was higher with a pit than without one, and was influenced more by the differences in prey capture rate between the two capture methods, and less by the differences in energy costs associated with each method. The proportion of larvae that constructed pits was higher when they were in intermediate body condition than when in good or in poor body condition. 4.,Thus, the use of one capture method or the other depends on a combination of the influences of past net energy gain and the antlion's most recent change in encounter rate with prey. Ambushing without a pit may serve as a default when physiological constraints limit the larvae's ability to invest in pit construction and maintenance, or when larvae are sated, and saving the energy of pit construction and maintenance is worthwhile. [source] Factors affecting the survival of founding individuals in translocated New Zealand Saddlebacks Philesturnus carunculatusIBIS, Issue 4 2007SABRINA S. TAYLOR Successful founders of new populations may represent a non-random sample of potential founding individuals. Using a recent Saddleback Philesturnus carunculatus translocation as a natural experiment, we related morphology, parasite load and genetic variation of translocated individuals to subsequent survivorship to assess the traits of successful founders. We also included capture location and holding time in our models to account for variables particular to translocations. Generalized linear model results suggest that, in addition to capture location, poor body condition (males) and the presence of ectoparasites (females) significantly reduced survivorship. Despite recent claims in the literature, we found no evidence that genetic variation was associated with survivorship or parasite load. [source] State-dependent risk-taking by green sea turtles mediates top-down effects of tiger shark intimidation in a marine ecosystemJOURNAL OF ANIMAL ECOLOGY, Issue 5 2007MICHAEL R. HEITHAUS Summary 1A predictive framework of community and ecosystem dynamics that applies across systems has remained elusive, in part because non-consumptive predator effects are often ignored. Further, it is unclear how much individual-level detail community models must include. 2Previous studies of short-lived species suggest that state-dependent decisions add little to our understanding of community dynamics. Body condition-dependent decisions made by long-lived herbivores under risk of predation, however, might have greater community-level effects. This possibility remains largely unexplored, especially in marine environments. 3In the relatively pristine seagrass community of Shark Bay, Australia, we found that herbivorous green sea turtles (Chelonia mydas Linnaeus, 1758) threatened by tiger sharks (Galeocerdo cuvier Peron and LeSueur, 1822) select microhabitats in a condition-dependent manner. Turtles in poor body condition selected profitable, high-risk microhabitats, while turtles in good body condition, which are more abundant, selected safer, less profitable microhabitats. When predation risk was low, however, turtles in good condition moved into more profitable microhabitats. 4Condition-dependent use of space by turtles shows that tiger sharks modify the spatio-temporal pattern of turtle grazing and their impacts on ecosystem dynamics (a trait-mediated indirect interaction). Therefore, state-dependent decisions by individuals can have important implications for community dynamics in some situations. 5Our study suggests that declines in large-bodied sharks may affect ecosystems more substantially than assumed when non-lethal effects of these top predators on mesoconsumers are not considered explicitly. [source] Climate predictability and breeding phenology in red deer: timing and synchrony of rutting and calving in Norway and FranceJOURNAL OF ANIMAL ECOLOGY, Issue 4 2005L. E. LOE Summary 1Timing and synchrony of reproduction are regarded as crucially important factors for fitness in seasonal environments. Natural selection has probably favoured temperate and arctic female herbivores that match reproduction with onset of plant growth in spring. However, breeding synchrony may also be affected by variation in phenotypic quality of females in a population, because females in poor body condition have been found to delay ovulation and subsequent calving. 2We compared breeding phenology, i.e. the timing and synchrony of rutting (roaring, sexual aggregation) and calving of red deer (Cervus elaphus L.) in France (latitude: 49°N) and Norway (latitude: 63°N). We hypothesized (H1) that calving and rutting were later at the site with latest onset of plant growth. 3We further quantified overall environmental predictability as the sum of annual constancy and seasonality and tested three different (not mutually exclusive) hypotheses about breeding synchrony: (H2a) the population experiencing most seasonal plant phenology should show the highest breeding synchrony; (H2b) overall predictability of plant phenology should determine breeding synchrony; and (H2c) breeding should be more synchronized in the population with lowest female body weight variation within age classes because they ovulate more synchronously. 4Calving and rutting, as well as onset of plant phenology, were later in Norway than in France, complying with the first hypothesis. Plant growth in spring was overall more predictable and also more seasonal in Norway than France. Hence we expected higher breeding synchrony in Norway than in France according to H2a and H2b. Variance in female body weight was slightly higher in France than in Norway, which should also cause more synchronized breeding in Norway than in France (H2c). Contrary to all predictions, variance in rutting and calving dates was around two times higher in Norway than in France. 5We suggest two alternative explanations of breeding synchrony. A more variable topography in Norway can make optimal birth date more variable on a local scale than in France, thereby maintaining a higher genetic variance for calving date in Norwegian red deer. Further, population age structure may play a role, as ovulation varies according to female age. Clearly, processes of breeding synchrony are far more complex than previously realized. [source] Impacts of sudden winter habitat loss on the body condition and survival of redshank Tringa totanusJOURNAL OF APPLIED ECOLOGY, Issue 3 2006NIALL H. K. BURTON Summary 1Recent theoretical modelling has provided important insights into how habitat loss may affect local populations through impacts on individual fitness (survival, body condition, fecundity). Despite this, attempts to provide empirical evidence of such impacts on displaced individuals have been limited. Using a before-after-control-impact (BACI) approach, we report how a sudden loss of wintering habitat impacted on the body condition and survival of redshank Tringa totanus. 2The intertidal mudflats of Cardiff Bay, UK, were inundated with freshwater in November 1999 following impoundment by a barrage, resulting in the displacement of c. 300 redshank to adjacent habitat on the Severn Estuary. Movements and the survival of these birds were monitored through observations of colour-marked individuals. Comparative survival rates were calculated for marked populations at the main recipient site, Rhymney, and a control site. 3Displaced redshank had difficulty maintaining their mass in the first winter post-barrage closure: adults previously only recorded at Cardiff Bay were significantly lighter than those previously recorded at Rhymney. 4Survival rates of displaced redshank also declined. The estimated annual survival of adult Cardiff Bay redshank fell from 0·846 in the 2 years pre-barrage closure to 0·778 in the 3 following years because of a significant decline in winter survival (P = 0·0006). In comparison, there was no significant change in the survival of adult Rhymney redshank, and adult survival at the control site was actually greater post-barrage closure than beforehand. The lack of decline in these rates and the similarity between those of Cardiff Bay adults pre-barrage closure and Rhymney adults indicate that the increase in winter mortality of Cardiff Bay birds resulted from their displacement. 5Synthesis and applications. This study provides the first conclusive empirical evidence that habitat loss can impact individual fitness in a bird population. Adult redshank displaced from Cardiff Bay experienced poor body condition and a 44% increase in mortality rate. Without an increase in the recruitment of first-winter birds, such a change is likely to reduce substantially local population size. The results reported here should help to inform governments, planners and non-governmental organizations (NGOs) seeking to understand how developments might impact on animal populations. [source] Hepatic coccidiosis of the blue whiting, Micromesistius poutassou (Risso), and horse mackerel, Trachurus trachurus (L.), from Galician watersJOURNAL OF FISH DISEASES, Issue 6 2001E Abollo The aetiology, epidemiology and pathology of coccidiosis in commercially-exploited populations of Micromesistius poutassou and Trachurus trachurus from Galician waters were investigated. Sporogonic stages of Goussia clupearum and G. cruciata were found in the liver. Although the descriptive statistics of Goussia infrapopulations and demographic infection values were always higher in M. poutassou than in T. trachurus, parasite distribution was highly skewed for both coccidian species. In both fish species, the number of oöcysts showed a similar cumulative effect as parasite counts increased with increasing length and weight of fish, but did not change with host sex or sexual maturity. Pathological changes in infected liver parenchyma of both species were moderate (in T. trachurus) to severe (in M. poutassou), with greatly reduced livers in the most heavily infected fish. Large areas of liver tissue were replaced with oöcysts. Host response to infection included the formation of a fibrous capsule prior to infiltration by melanin and lymphocytes. Although post-recruit individuals of both fish species apparently tolerate a severe infection, there was statistical evidence of a serious contribution by the parasite to poor body condition in M. poutassou shown by changes in the hepatosomatic and K-Fulton indices and in the length- to-weight relationship. [source] Intestinal Neoplasia in HorsesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2006S.D. Taylor Background:Intestinal neoplasia of horses is inadequately described. Hypothesis:Intestinal neoplasia of horses has characteristic clinicopathologic features. Animals:Thirty-four horses with intestinal neoplasia. Methods:Retrospective study. Results:Anamnesis, clinical signs, clinicopathologic and pathologic findings in 34 adult horses diagnosed histologically with intestinal neoplasia were reviewed. The horses ranged in age from 2 to 30 years (mean 16.6 years at presentation). The Arabian breed was most represented and there was no sex predisposition. The most common presenting complaints were weight loss, colic, anorexia, and fever. The most consistent clinical signs were poor body condition, tachycardia, tachypnea, fever, and diarrhea. Useful diagnostic tools included rectal examination, routine blood analyses, abdominocentesis, ultrasonographic examination, rectal biopsy, and exploratory laparotomy. Alimentary lymphoma was the most common intestinal neoplasia identified, followed by adenocarcinoma and smooth muscle tumors. The small intestine was the most common segment of intestine affected for all neoplasms. Intestinal neoplasia was diagnosed antemortem in 13 of 34 (38%) horses. The median time from onset of clinical signs to death or euthanasia was 1.9 months. The discharge rate was 15%. Although the longest survival was observed in horses with jejunal adenocarcinoma, all horses were eventually euthanized because of intestinal neoplasia. Conclusions: Arabian horses were 4.5 times more likely to have intestinal neoplasia diagnosed than were other breeds. [source] | ||||||||||