Worse Body Condition Research Articles

On the function of a female-like signal type in the vibrational repertoire of Enchenopa male treehoppers (Hemiptera: Membracidae).

Animals often mimic the behaviours or signals of conspecifics of the opposite sex while courting. We explored the potential functions of a novel female-like signal type in the courtship displays of male Enchenopa treehoppers. In these plant-feeding insects, males produce plant-borne vibrational advertisement signals, to which females respond with their own duetting signals. Males also produce a signal type that resembles the female duetting responses. We experimentally tested whether this signal modifies the behaviour of receivers. First, we tested whether the female-like signal would increase the likelihood of a female response. However, females were as likely to respond to playbacks with or without them. Second, we tested whether the female-like signal would inhibit competing males, but males were as likely to produce displays after playbacks with or without them. Hence, we found no evidence that this signal has an adaptive function, despite its presence in the courtship display, where sexual selection affects signal features. Given these findings, we also explored whether the behavioural and morphological factors of the males were associated with the production of the female-like signal. Males that produced this signal had higher signalling effort (longer and more frequent signals) than males that did not produce it, despite being in worse body condition. Lastly, most males were consistent over time in producing the female-like signal or not. These findings suggest that condition-dependent or motivational factors explain the presence of the female-like signal. Alternatively, this signal might not bear an adaptive function, and it could be a way for males to warm up or practice signalling, or even be a by-product of how signals are transmitted through the plant. We suggest further work that might explain our puzzling finding that a signal in the reproductive context might not have an adaptive function.

Potential adverse effects of heavy metals on clinical health parameters of Caretta caretta from a nesting area affected by mining tailings in Brazil

BackgroundIn 2015, Brazil had its most notorious ecological disaster due to an iron mine dam collapse. It was considered the world's largest environmental disaster associated with mining industry. The tailings composed mostly of iron ore and silica, but with high levels of heavy metals reached the Atlantic Ocean, through the Doce River, sixteen days after the rupture. The region where the mud ran into the ocean is an important nesting area for loggerhead turtles (Caretta caretta) in Brazil (Povoação, Espírito Santo state). The aim of this study is to evaluate the heavy metal effects on the health parameters of loggerhead turtles that nest in the exposed area (Povoação, Doce river estuary) and compare them with turtles from another coastal area that was not affected by the tailings (Praia do Forte, Bahia state). MethodsAnimals’ health status was determined by a physical examination during which blood samples used to perform biochemical and hematological analysis were also obtained. Heavy metal concentrations were evaluated in the blood and carapace scutes. ResultsSea turtles from Povoação had a worse body condition with higher ectoparasitic and epibiont loads compared to Praia do Forte animals. They also showed eye lesions and more frequent fibropapillomatosis suggestive tumors. Several correlations between the contaminants and hematological and plasma biochemical analytes were found in loggerhead sea turtles from Povoação. Blood metal concentrations were distinct between nesting areas, with higher As, Cd, Cr, Fe, Pb, and Zn levels in animals from the affected area. In the carapace scute, the heavy metal levels were similar between sites. ConclusionThe occurrence of eye lesions, suggestive fibropapillomatosis tumors, worse body condition, higher ectoparasite count, greater epibiont loads, large number of correlations between health parameters and heavy metal levels, and higher levels of some metals in the blood of PV turtles indicates that the tailings could have a negative impact on the health and reproduction of these turtles. The long-term monitoring of the exposed area is important to quantify the direct and indirect impacts of the tailings on the health of these animals. Additionally, the data reported here are important for temporal and spatial comparative studies in the future.

Consequences of phenological shifts and a compressed breeding period in Magellanic penguins.

Phenological shifts may ameliorate negative effects of climate change or create carryover effects and mismatches that decrease fitness. Identifying how phenological shifts affect performance is critical for understanding how individuals and populations will respond to climate change, but requires long-term, longitudinal data. Using 34yr of data from the Magellanic penguin (Spheniscus magellanicus) colony at Punta Tombo, Argentina, we examined the consequences of the delayed onset of breeding (i.e., arrival and egg-laying dates) that has occurred at the colony since 1983. To understand how the delay propagates through the rest of the reproductive cycle, we identified phenological trends in hatch and fledge dates. Median hatch dates were 0.29d later each year, amounting to a 10-d shift over the course of the study. Median fledge dates did not shift over the 34-yr period, however, thus shortening the median nestling period duration by 14%. We tested several predictions regarding performance outcomes of the compressed nestling period, finding that later-hatched chicks fledged significantly younger than earlier-hatched chicks, and that younger fledglings left the colony with smaller bills and with more chick down. Interestingly, although younger chicks fledged significantly lighter and in worse body condition than older fledglings early in the study, this trend reversed over time, with younger chicks actually fledging heavier and in better body condition in more recent years. Smaller and lighter fledglings were less likely to recruit to the colony as adults. We find that delayed breeding has significantly compressed nestling periods at Punta Tombo, influencing chick growth and fledgling condition. These findings highlight the importance of studying phenology across multiple life events to understand the consequences of phenological shifts for organismal fitness.

Feather corticosterone does not correlate with environmental stressors or body condition in an endangered waterbird.

Physiological metrics are becoming popular tools for assessing individual condition and population health to inform wildlife management and conservation decisions. Corticosterone assays can provide information on how animals cope with individual and habitat-level stressors, and the recent development of feather assays is an exciting innovation that could yield important insights for conservation of wild birds. Due to the widespread enthusiasm for feather corticosterone as a potential bioindicator, studies are needed to assess the ability of this technique to detect meaningful differences in physiological stress across a variety of stressor types and intensities. We examined feather corticosterone from 144 individuals among the 13 known breeding populations of Hawaiian gallinule (Gallinula galeata sandvicensis), an endangered waterbird, on the island of O'ahu. These ecologically independent subpopulations are known to have low genetic connectivity and movement rates and differ largely across a number of important conditions, including level of predator management, human disturbance, proximity to urban development and conspecific population density. This system is well suited for assessing the performance of feather corticosterone as a bioindicator of different known habitat-level threats common to this and many other conservation-reliant species. We found no statistically significant relationship between feather corticosterone and level of predator control, level of human disturbance, gallinule population density, percent urban cover or body condition across all sites despite the substantial difference in stressor magnitude in our dataset. We did find that gallinules in habitats with larger population densities were in worse body condition. These findings suggest that feather corticosterone is not a consistent indicator of anthropogenic impacts on populations. Furthermore, they suggest that feather corticosterone may be a poor bioindicator of known habitat-level threats for Hawaiian gallinules and that it should be used with caution in other avian taxa of conservation concern.

Interactions between a small chronic increase in diel water temperature and exposure to a common environmental contaminant on development of Arizona tiger salamander larvae

Global climate change leading to increased temperatures may affect shifts in physiological processes especially in ectothermic organisms. Temperature-dependent shifts in developmental rate in particular, may lead to life-long changes in adult morphology and physiology. Combined with anthropogenic changes in the chemical environment, changes in developmental outcomes may affect adult functionality. The purpose of this study is to determine 1) if small increases in diel water temperature affect the development of Arizona tiger salamander (Ambystoma tigrinum nebulosum) larvae, and 2) if this change interacts with exposure to the common environmental thyroid disrupting compound, perchlorate. Larvae between Watson and Russell developmental stages 8–13 were exposed to ammonium perchlorate (AP) at doses of 0, 20 or 200ppb and then raised at either ambient or a 0.9°C elevated above ambient temperature for 81days in outdoor enclosures. During the first 5 treatment weeks, AP treatment induced slower development and smaller snout-vent length (SVL) of exposed larvae, but only in the elevated temperature group. During the later stages of development, the small increase in temperature, regardless of AP treatment, tended to decrease the time to metamorphosis and resulted in a significantly smaller body mass and worse body condition. Our results suggest that even small diel water temperature increases can affect the developmental process of salamanders and this shift in the water temperature may interact with a common environmental contaminant.

Effect of exotic mammalian predators on parasites of Cory's shearwater: ecological effect on population health and breeding success

Predator activity around the nests induces stress in breeding birds, which may have weaker immunity and are therefore more susceptible to parasite infections. The influence of predators on parasites has only been observed in land birds, and most studies are experimental. As seabird colonies offer excellent conditions for parasites, here we assess the influence of mouse, rat, and cat activity on parasites in Cory's shearwater (Calonectris diomedea borealis). Adults were examined for blood parasites and one adult and the juvenile from 53 nests were inspected for ectoparasites over two consecutive years (2010 and 2011). Nests differed in their physical characteristics and indices of mammal predator activity and were checked weekly to assess breeding success. Our results showed absence of blood parasites. Among the environmental factors, predator pressure received the most support (89 %) from the data as influencing nest ectoparasite intensity. Birds most infected had worse body condition, and breeding success was negatively influenced by predator activity and ectoparasite intensity. To our knowledge, this is the first analysis of the interaction between mammal predators and ectoparasites in seabird species and supports greater protection through eradication efforts. In addition, we provide the first data on the endoparasite fauna of Cory's shearwater.

Effectiveness of an antihelminthic treatment in improving the body condition and survival of Hawaiian monk seals

Food limitation and poor body condition are significant factors affecting the survival of juvenile Hawaiian monk seals Monachus schauinslandi in the Northwestern Hawaiian Islands. Previous research has indicated that juvenile monk seals infected with cestodes are in worse body condition than those that are uninfected. To test whether individual growth and survivorship are boosted by intermittently reducing parasites, we initiated a deworming study on juvenile seals at Laysan Island. Forty-three unique juvenile seals were captured, weighed, measured, feces-sam- pled, and either given an injectable antihelminthic (praziquantel) or used as untreated controls up to 4 times at 8 to 16 wk intervals across a 7 month period. The effect of treatment on survival, egg shedding, and gain in mass was evaluated. Survival of the subset of the 3 cohorts included in the study was 100% for the 2007 and 2008 cohorts and 85.2% for the 2009 cohorts. Egg prevalence did not differ significantly between control and treated seals. Percent daily mass gain was greatest in the March to May period. Older juveniles gained more mass than young-of-the-year (treated and control), which lost mass between the first 2 treatments. Percent mass gain was significantly greater for treated than control seals during March to May, but not during December to March or over the entire treatment period (December to May). The questionable efficacy of injectable praz- iquantel indicates that a different route of administration or dosage of praziquantel or a different antihelminthic may be more suitable for treatment of cestodes in this species.

The effects of diet on plasma and yolk steroids in lizards (Anolis carolinensis)

Steroids present in egg yolk have been shown to vary as a result of numerous social and environmental influences and to produce both positive and negative phenotypic outcomes in offspring. In the present study, we examined how quality of the diet affects plasma and yolk steroids in the green anole (Anolis carolinensis), a lizard species with genotypic sex determination. We documented the effects of body condition on plasma testosterone (T) and corticosterone (CORT)-steroids with frequently opposing effects-in breeding females and on the T and CORT content of their eggs. We chose to manipulate body condition via diet because resource availability is a relevant, fluctuating variable in the environment to which females can be expected to respond. Field-collected females were housed in the laboratory and kept on either a reduced, standard, or enhanced diet (differing in nutritional quality and/or quantity) for ten weeks. Although females did not differ in body condition at the beginning of the study, we found these diet regimes effective in producing females that differed in condition by the end of the study. Females on diets of enhanced quality were in better condition, produced more, but not heavier, eggs, and had higher plasma T concentrations than did females on a standard diet or one of reduced quality. There was also a significant positive relationship between laying sequence of eggs and yolk T for females on diets of enhanced quality, but not for the females on diets of standard or reduced quality. There were no effects of quality of diet on CORT in plasma or yolk, but yolk T and yolk CORT exhibited a strong positive correlation irrespective of treatment. Females on diets of reduced quality did not differ from females on standard diets either with respect to reproductive output or to endocrine profiles, in spite of being in worse body condition. These results demonstrate that females' body condition, physiology, and reproductive output can be manipulated by quality of diet, and that changes in deposition of yolk steroids in response to diet may be minimal.

ECOLOGICAL MECHANISMS OF A RESOURCE POLYMORPHISM IN ZENAIDA DOVES OF BARBADOS

Despite the important place of resource polymorphisms in ecological and evolutionary theories, the reason why a group of individuals sharing a common environment should diverge in the use of the resources remains poorly known. Given the existence of distinct open niches and the relaxation of interspecific competition, niche theory suggests two possible mechanisms: resource competition between conspecifics and trade-offs in resource use efficiency. We investigated the importance of these explanations in a foraging polymorphism recently developed by Zenaida Doves (Zenaida aurita) on the West Indian island of Barbados. In this polymorphism, individuals either aggressively defend feeding territories from conspecifics or feed in large unaggressive groups with conspecifics. Combining field observations and a cage experiment, we found no evidence that the polymorphism is primarily driven by age- or sex-related differences, or that it results from morphological feeding specializations or dietary preferences. Instead, our results support the hypothesis that individual specializations arise from contest competition. In the study area, competition for territories was intense, with very little undefended space left between territories and owners frequently involved in territorial contests. Replacement of territory holders from year to year was low compared to the number of potential recruits, implying that many doves were incapable of securing a territory. Approximately half the doves at territorial sites did not hold a territory but wandered between them as floaters. Compared with territory holders, floaters were smaller and had shorter wings, traits that in this species mediate territory defense. Yet floaters did not differ from group feeding doves on these morphological traits. This suggests that group feeders are floaters that shift to an alternative resource. The new resource appears to be suboptimal, as indicated by the fact that group feeders were in worse body condition than doves from the territorial sites. Taken together, our results suggest that the resource polymorphism in Zenaida Doves is primarily driven by competition for territories, which forces less competitive individuals to use alternative, subobtimal resources.

Dispersal pattern of domestic cats (Felis catus) in a promiscuous urban population: do females disperse or die?

SummaryThe domestic feral cat (Felis catusL.) is a good model for studying intraspecific variability of dispersal patterns in mammals because cats live under a large diversity of socio‐ecological conditions. We analysed both the natal and breeding dispersal patterns of domestic cats in a promiscuous urban population and tested whether or not it differed from the male‐biased natal dispersal pattern observed for polygynous rural populations.During an 8‐year study we recorded the exact date ofin situdeath for 148 marked cats and the exact date of disappearance from the population for 99 other cats. Because undiscovered deaths might over‐estimate dispersal probabilities when considering only disappearance probabilities, we made an novel application of multistrata capture–recapture methods in order to disentangle dispersal from true mortality.We showed that mature females dispersed, both before and after their first reproduction, at 1 and 2 years old. Contrary to females, no dispersal seemed to occur in males. Before sexual maturity, females that disappeared at 1 and 2 years old were in worse body condition than females that stayed in the population area after 2 years old. However, they did not reproduce less successfully before their disappearance than females that died later in the population area.The female‐biased and low natal dispersal pattern in this population was atypical compared to other promiscuous/polygynous mammals and differed from that observed in rural polygynous populations of domestic cat. Neither local mate competition nor inbreeding avoidance appeared to be sufficient pressures to counterbalance ecological constraints on dispersal in an urban environment. However, local resource competition for den sites between potential matriarchies could lead to the breeding dispersal of less competitive females.

Beziehungen zwischen Futteraufnahme, Seitenspeckdicke und ausgewählten Merkmalen der Aufzuchtleistung laktierender Sauen

Abstract. Title of the paper: Relationship between feed intake, side fat thickness and special parameters of rearing Performance of lactating sows A total of 106 Camborough sows were used to study the relationship between feed intake, side fat thickness at the end of pregnancy, their change during lactation and special parameters of rearing Performance. Sows with a high side fat thickness at the end of pregnancy realised a lower feed intake during lactation (r = −0.206*) but a higher loss of side fat thickness (r = −0.499**) than sows with worse body condition. High feed intake during lactation stimulates a high number of weaned piglets (r = 0.299*) and the weight of weaned litter (r = 0.321*). The amount of feed intake in first week of lactation is most important for it. Generally, sows with a high predisposition for mobilisation of body fat and high intake of food during lactation realised the significant highest rearing Performance (r = 0.436***).