Competitive asymmetry and local adaptation in Trinidadian guppies

1. The outcome of competition between individuals often depends on body size. These competitive asymmetries can drive variation in demographic rates, influencing the ecology and evolution of life histories. The magnitude and direction of such asymmetries differ among taxa, yet little is known empirically about how adaptation to resource limitation alters competitive asymmetries. 2. Here, we investigate the relationship between size‐dependent competitive ability and adaptation to resource limitation. 3. We examined size‐dependent competition in two ecotypes of Trinidadian guppy, adapted to high or low levels of resource competition. Using aquaria‐based competition experiments, we describe how the size and ecotype of competitors influence somatic growth rate, whilst controlling for the confounding effect of niche differentiation. We replicated our study across two independent evolutionary origins of the “competitive” ecotype. 4. The two “competitive” ecotypes differed markedly in size‐dependent asymmetry, indicating that adaptation to resource limitation alone is insufficient to explain changes in size‐dependent competitive asymmetry. For one origin, the ecotype adapted to resource limitation was a superior competitor over a wide range of size pairings. 5. The equivalence of competitors varied over fivefold, dependent on size and ecotype; in three of four populations, larger individuals had a competitive advantage. 6. Our results demonstrate that competitive asymmetry has strong effects on somatic growth. Because somatic growth contributes to demographic parameters, intraspecific trait variation is likely to play a key role in regulating demographic rates. Our findings imply that the evolution of size‐dependent asymmetries under conditions of intense competition is likely to be constrained by niche availability, although further research is needed to verify this

Social vs. practical problems in attaining a colonoscopy: Different patient profiles?

Background: Colonoscopy is an effective procedure for identifying precancerous polyps and cancerous lesions, but it is unlike other cancer screening tools in that it requires sedation and thus assistance from at least one other individual. The intent of this paper was to identify logistical problems in completing the colonoscopy and to examine their relationships with sociodemographic characteristics. Methods: All eligible patients (n = 2500) from two academic-affiliated colonoscopy centers (one free standing, one hospital-based) were invited to participate in an onsite, pre-colonoscopy survey; patients agreeing to participate (n = 1841, RR = 73.6%) received a $5.00 gift card. Multiple correspondence analysis (MCA) was used to identify the underlying dimensional structure of the problems. Bivariate statistics were performed to compare demographic variables and health literacy levels among patients reporting problems. Multivariate logistic regression with a backwards conditional solution was used to determine the demographic variables independently associated with problems. Results: Multiple correspondence analyses indicated two dimensions of problems (social and practical). Using logistic regression, social problems (e.g., finding someone to accompany the patient) were associated with not living in the same home as the driver, not working due to disability, and younger age. Practical problems (e.g., making an appointment) were associated with “other” minority race, poorer health, lower health literacy, and younger age. Conclusion: Patients experience different problems completing the colonoscopy based on socio-demographics. Particularly at risk are patients who find it difficult to navigate the system, are of younger age, or who may have smaller social networks

Optical Perfusion and Oxygenation Characterization in a Liver Phantom

Continuous monitoring of blood perfusion and oxygenation is essential in assessing the health of a transplanted organ. Particularly, monitoring the perfusion and oxygenation of the organ during the two-week period after the transplant procedure is crucial in detecting a sustained loss in perfusion or a reduction in oxygen saturation before these changes render irreversible damage to the organ or patient. Pulse oximetry is a clinically accepted method of monitoring the arterial oxygen saturation of a patient in a non-invasive manner. Pulse oximeters exploit the wavelength-dependent absorption of oxygenated and deoxygenated hemoglobin to measure a patient's arterial oxygen saturation. However, traditional pulse oximeters do not provide perfusion information and produce erroneous oxygen saturation measurements under low perfusion levels. An optical blood perfusion and oxygenation sensor, based on a modified reflectance pulse oximeter, has been developed for in situ monitoring of transplanted organs. To reduce the number of animal experiments, phantoms that mimic the optical and anatomical properties of liver parenchyma have also been developed. In this work, in vitro data was gathered from dye solutions mimicking oxygenated blood that were pumped through single and multi-layer phantoms mimicking liver parenchyma and through a phantom mimicking the portal vein. A portion of the phantom data was compared to data collected from in vivo occlusion studies performed on female swine to assess the ability of the phantoms to mimic the response observed with changes in blood perfusion through liver parenchyma. Both the single layer and multilayer phantoms showed a similar response to changes in perfusion as the in vivo case. With each phantom, the signal increased linearly with increases in perfusion, but the multilayer phantom showed a higher sensitivity (approximately 30% higher) to changes in perfusion than the single layer phantom. This higher sensitivity would provide the ability to measure smaller changes in perfusion and increase the resolution of the sensor. Also, both parenchymal phantoms showed similar trends in the oxygenation studies, with the R value decreasing with increasing oxygenation. While the observations in this research demonstrate the ability to use both phantoms for in vitro experiments, the results show the multilayer phantom is a better option for mimicking perfusion because it displays similar occlusion patterns as the liver parenchyma in vivo, a higher sensitivity to changes in perfusion than the single layer phantom, and it is only slightly more complex in design (contains only two more layers of sinusoids) than the single layer phantom

Impact of cow milk production on cow–calf performance in the Nebraska Sandhills

Livestock producers have tended to select for increased output traits like milk production and growth to increase productivity. Even with the increased selection for greater calf growth potential, some regions in the United States have seen a plateau in calf body weight (BW) at weaning (Lalman et al., 2019). When focusing on reaching maximum potential of these output traits, it is important to consider the multitude of variables that affect a production system. With increased milk production, nutrient requirements for cows become increased (Ferrell and Jenkins, 1984; Montaño-Bermudez et al., 1990), which may not be met if range and forage availability for grazing is already limited at meeting lactation demands. Historically, weaning weight and milk production have been associated with a positive relationship with greater milk production resulting in heavier calves at weaning (Clutter and Nielsen, 1987; Abdelsamei et al., 2005). In contrast, others have only observed the benefit of increased milk production improving calf performance within the first 60 d after birth (Clutter and Nielsen, 1987; Ansotegui et al, 1991; Edwards et al., 2017). Gleddie and Berg (1968) reported the correlation between average daily gain (ADG) of calves and milk yield estimates increased between the first and second month and continued to decrease thereafter as the forage consumption increased. The reliance on milk for dietary energy can result in increased calf BW at peak lactation (Edwards et al., 2017), but benefits of increased milk production may decrease as stage of lactation increases. Our hypothesis was that increasing milk production would negatively affect cow reproductive performance while having no effect on calf performance. Therefore, the objective of this study was to determine the impact milk production has on subsequent cow reproductive performance and calf performance throughout the preweaning and postweaning phases

Impact of cow milk production on cow–calf performance in the Nebraska Sandhills

Livestock producers have tended to select for increased output traits like milk production and growth to increase productivity. Even with the increased selection for greater calf growth potential, some regions in the United States have seen a plateau in calf body weight (BW) at weaning (Lalman et al., 2019). When focusing on reaching maximum potential of these output traits, it is important to consider the multitude of variables that affect a production system. With increased milk production, nutrient requirements for cows become increased (Ferrell and Jenkins, 1984; Montaño-Bermudez et al., 1990), which may not be met if range and forage availability for grazing is already limited at meeting lactation demands. Historically, weaning weight and milk production have been associated with a positive relationship with greater milk production resulting in heavier calves at weaning (Clutter and Nielsen, 1987; Abdelsamei et al., 2005). In contrast, others have only observed the benefit of increased milk production improving calf performance within the first 60 d after birth (Clutter and Nielsen, 1987; Ansotegui et al, 1991; Edwards et al., 2017). Gleddie and Berg (1968) reported the correlation between average daily gain (ADG) of calves and milk yield estimates increased between the first and second month and continued to decrease thereafter as the forage consumption increased. The reliance on milk for dietary energy can result in increased calf BW at peak lactation (Edwards et al., 2017), but benefits of increased milk production may decrease as stage of lactation increases. Our hypothesis was that increasing milk production would negatively affect cow reproductive performance while having no effect on calf performance. Therefore, the objective of this study was to determine the impact milk production has on subsequent cow reproductive performance and calf performance throughout the preweaning and postweaning phases

Effect of Supplemental Protein and Glucogenic Precursors on Digestibility and Energy Metabolism

A metabolism study was conducted to evaluate the impact of increasing levels of glucogenic precursors on diet digestibility and acetate clearance. Four supplementation strategies containing 0, 30, 40, and 70 g of supplemental glucogenic potential were supplied to a basal diet of bromegrass hay. Addition of glucogenic potential in the form of rumen undegradable protein improved dry matter, organic matter, and acid detergent fiber digestibility efficiency of acetate utilization in growing lambs fed moderate- quality hay. However, no additive effect of supplementing propionate salts and rumen undegradable protein were observed in this study. Th is would suggest that rumen undegradable protein requirements must be met to observe effects from increasing levels of glucogenic potential

The variability and seasonality of the environmental reservoir of Mycobacterium bovis shed by wild European badgers

This is the final version of the article. Available from the publisher via the DOI in this record.The incidence of Mycobacterium bovis, the causative agent of bovine tuberculosis, has been increasing in UK cattle herds resulting in substantial economic losses. The European badger (Meles meles) is implicated as a wildlife reservoir of infection. One likely route of transmission to cattle is through exposure to infected badger urine and faeces. The relative importance of the environment in transmission remains unknown, in part due to the lack of information on the distribution and magnitude of environmental reservoirs. Here we identify potential infection hotspots in the badger population and quantify the heterogeneity in bacterial load; with infected badgers shedding between 1 × 10(3)- 4 × 10(5) M. bovis cells g(-1) of faeces, creating a substantial and seasonally variable environmental reservoir. Our findings highlight the potential importance of monitoring environmental reservoirs of M. bovis which may constitute a component of disease spread that is currently overlooked and yet may be responsible for a proportion of transmission amongst badgers and onwards to cattle.We acknowledge funding from Defra, H.C.K. was in receipt of a BBSRC DTG studentship and E.M.W. and O.C. acknowledge support from BBSRC for collaboration with Eamonn Gormley, UCD. We are also grateful to the APHA field team at Woodchester Park for support during fieldwork, and to Defra who fund the long-term stud

\u3ci\u3eClinostomum poteae\u3c/i\u3e n. sp. (Digenea: Clinostomidae), in the trachea of a double-crested cormorant \u3ci\u3ePhalacrocorax auritus\u3c/i\u3e Lesson, 1831 and molecular data linking the life-cycle stages of \u3ci\u3eClinostomum album\u3c/i\u3e Rosser, Alberson, Woodyard, Cunningham, Pote & Griffin, 2017 in Mississippi, USA

Clinostomum spp. (Digenea: Clinostomidae) are a group of trematodes commonly found in the buccal cavity and oesophagus of a variety of piscivorous birds. The metacercariae, colloquially known as ‘‘yellow grubs,’’ have been reported from a diverse group of freshwater fishes worldwide. In the catfish farming region of the southeastern USA, piscivorous birds present a continuous challenge for aquaculturists in the form of fish depredation and the introduction of trematodes into these static, earthen pond systems. Clinostomum spp. are commonly encountered in farmraised catfish. While generally considered pests of minimal importance, heavy infections can result in unmarketable fillets. Of the piscivorous birds that frequent catfish aquaculture operations in the southeastern US, the double-crested cormorant (Phalacrocorax auritus Lesson) is one of the most damaging, although reports of Clinostomum spp. from P. auritus are limited. In this study, adult trematodes morphologically consistent with Clinostomum sp. were found in the trachea of a double-crested cormorant captured in Lowndes Co., Mississippi, USA. These specimens differed from other recognised Clinostomum spp. in several key morphological characters. Moreover, sequence data of mitochondrial cytochrome c oxidase subunit 1 gene (cox1), nicotinamide adenine dinucleotide dehydrogenase subunit 1 gene (nad1) and ribosomal internal transcribed spacer (ITS) regions did not match any known Clinostomum sp. for which sequence data are available. While genetically similar to C. marginatum and C. album Rosser, Alberson, Woodyard, Cunningham, Pote & Griffin, 2017 reported from the great egret Ardea alba L. in Mississippi, these adult clinostomids were larger in size and limited to the trachea, whereas both C. marginatum Rudolphi, 1819 and C. album are found in the oral cavity and esophagus. Given these distinct morphological and molecular characters we propose a new member of the genus, known hereafter as Clinostomum poteae n. sp. Additionally, larval stages in the life-cycle of C. album are morphologically and molecularly identified for the first time from ramshorn snails Planorbella trivolvis Say and fathead minnows Pimephales promelas Rafinesque

Los xenartros de Honduras: nuevos registros, principales amenazas y comentarios sobre su estado de conservación

The Xenarthra are one of the least studied mammalian groups in Honduras. Their ecology, natural history, and distribution in the country are poorly known. Here we compile and discuss, for the first time, the available information about the seven species of Xenarthra that occur in Honduras. We also present new distribution records and comment on their main threats. The lack of specific scientific studies, poaching, illegal traffic, cultural beliefs, and deforestation are among the main threats to xenarthrans in Honduras.Xenarthra es uno de los grupos de mamíferos menos estudiados en Honduras, y de los que menos se sabe sobre su ecología, historia natural y distribución en el país. Aquí recopilamos y discutimos, por primera vez, la información disponible de cada una de las siete especies de Xenarthra que ocurren en Honduras. También presentamos nuevos registros de distribución y comentamos sobre las principales amenazas. La falta de estudios científicos, la cacería y el tráfico ilegal, creencias culturales y la deforestación están entre algunas de las principales amenazas para los xenartros en Honduras.Fil: Turcios Casco, Manfredo A.. Instituto Nacional de Conservación y Desarrollo Foresta; HondurasFil: Ávila Palma, Hefer D.. Universidad Nacional Autónoma de Honduras; HondurasFil: Martínez, Marcio. Instituto Nacional de Conservación y Desarrollo Foresta; HondurasFil: Trejo Ordoñez, Eduardo J.. Universidad Nacional Autónoma de Honduras; HondurasFil: Meza Flores, David E.. Asociación de Investigación para el Desarrollo Ecológico y Socioeconómico; HondurasFil: Castañeda, Franklin. Panthera; HondurasFil: King, Travis. Washington State University; Estados UnidosFil: Thornton, Daniel. Washington State University; Estados UnidosFil: Superina, Mariella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentin