228 research outputs found
Movement and habitat use of headstarted Blandingβs turtles in Michigan
Captive breeding or headstarting is a management option to increase population numbers in threatened and endangered animals. The success of these programs depends on increasing population numbers while maintaining fitness within populations that contain some captiveΓ’ reared individuals. As part of an ongoing conservation project with Shiawassee National Wildlife Refuge (SNWR) in Saginaw, Michigan, USA, the Detroit Zoological Society (DZS) headstarted Blandingβs turtles (Emydoidea blandingii) to 18 months of age. To determine survival, movements, and habitat use of these headstarted Blandingβs turtles, we externally attached radioΓ’ transmitters to 24 turtles and released them at 4 sites in release groups of 6 along a transect in a wetland within SNWR during June 2014. We located turtles weekly during the active season (MayΓ’ Sep) and every 2 weeks during the inactive season (OctΓ’ Apr) for 18 months, starting immediately after release and ending November 2015. We calculated straightΓ’ line distances between release sites and home range centers over the study period. We examined habitat use of the turtles in relation to habitat availability. To predict movement of headstarted Blandingβs turtles away from release sites, we used geographically weighted regression (GWR) with measured habitat factors and release sites as independent variables. There were differences in home range sizes across release groups but not between years. Headstarted juvenile Blandingβs turtles in this study have home range sizes similar to those measured in other studies for wildΓ’ hatched juveniles but smaller home ranges than those measured for wildΓ’ hatched adults. Our study showed that headstarted Blandingβs turtles used habitats with muskrat (Ondatra zibethica) dens and cattails (Typha spp.) more than proportionally available, and used open water, willows (Salix spp.), and lowland forest less than proportionally available. The GWR model was able to predict habitat characteristics (water depth and temperature, duckweed [Lemna minor], cattails, muskrat dens and fields, buttonbush [Cephalanthus occidentalis]) that influenced the movement of turtles away from the release sites. The habitat coefficientβs influence on movement varied in relation to the current location of the turtle and as habitat characteristics increased or decreased. Turtle distance from release sites decreased as water depth, water temperature, and duckweed increased, and increased as cattails, muskrat dens and fields, and buttonbush increased. Habitat in the small spatial extent at release sites may affect movement of headstarted Blandingβs turtles. Furthermore, this study uses novel methodologies for assessing headstart programs that can aid future conservation and management efforts by providing information on habitat use and movement patterns of headstarted Blandingβs turtles after release. ΓΒ© 2018 The Wildlife Society.We aimed to determine survival, movements, habitat use in relation to availability, and impact of release sites on 18Γ’ monthΓ’ old headstarted Blandingβs turtles by releasing them at 4 different sites in Shiawassee National Wildlife Refuge. We showed high survival of the headstarted Blandingβs turtles, reported differences in home range size across release groups, and used geographically weighted regression to explain how turtle distance from release sites varies by measured habitat characteristics; we concluded that habitat characteristics in the small spatial extent at release sites affect movement and space use of headstarted Blandingβs turtles.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145553/1/jwmg21530.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145553/2/jwmg21530_am.pd
Paternal attractiveness and the effects of differential allocation of parental investment
The differential allocation hypothesis (DAH) predicts that an individual should vary its reproductive investment according to the attractiveness of its mate. A recently revised version of the DAH makes explicit that investment can be positive, i.e. higher for the offspring of attractive males which should be of higher quality, or negative, i.e. higher for offspring of unattractive males, for example compensating for inheriting poor paternal genes. Moreover, investment can be made by the father and the mother. Here, we tested whether experimental manipulation of male attractiveness affected parental investment at different reproductive stages and thus influenced fitness-related traits in offspring. In two aviaries, all male zebra finches, Taeniopygia guttata, were given red leg rings to increase attractiveness and in two aviaries all males received green leg rings to decrease attractiveness. This controlled for assortative mating between treatments. Ring colour was merely an experimental manipulation of male attractiveness, not paternal quality, so we might expect additional investment to elevate offspring quality. Eggs were cross-fostered between and within treatments to allow differentiation of effects of investment in eggs and nestlings. Clutch and brood sizes were standardized. Both positive and negative investment were observed: Eggs from red-ringed fathers had higher yolk to albumen ratios than eggs from green-ringed fathers. Nestlings from eggs laid and incubated by parents in the red-ringed group had higher hatching masses than those in the green-ringed group. Both parents in the green-ringed group fed nestlings more frequently than red-ringed parents. Offspring performance was influenced by the treatment of both foster and biological parents, but combined effects of these different investment patterns on fitness-related traits were ambiguous. Male attractiveness appeared to affect patterns of reproductive investment but not consistently across all forms of reproductive investment suggesting that the costs and benefits of differential allocation vary among individuals and across contexts
Ethical Praxis and the Business Case for LGBT Diversity: Political Insights from Judith Butler and Emmanuel Levinas
Β© 2017 John Wiley & Sons Ltd This paper critically reconsiders debates about the business case for workplace diversity as exemplified in lesbian, gay, bisexual and transgender (LGBT) activism. These debates have long suggested that there is an oppositional distinction between justifying diversity on self-interested business grounds and justifying it on the grounds of ethics, equality and social justice. This has led to an impasse between ethically driven diversity theory and activism, and the dominant business case approach commonly deferred to in managerial practice. As a way of mediating this impasse the contribution of this paper is to demonstrate how βethical praxisβ can be deployed both despite and because of non-ethically motivated approaches to ethics in business. Drawing on Judith Butler's and Emmanuel Levinas's considerations of the relationship between ethics and the practice of justice, it is argued that critiques of the business case for diversity rely on a pure ethics that does not adequately recognize its connection to lived politics. Conversely, support for the business case evinces a politics that has failed to remember its origin in ethics. The paper positions ethical praxis as a political intervention undertaken in the name of ethics and uses this to suggest that the business case, despite its ethical poverty, holds potential to create real opportunities for justice in organizations
Ethical Praxis and the Business Case for LGBT Diversity: Political Insights from Judith Butler and Emmanuel Levinas
Ecological impacts of non-native Pacific oysters (Crassostrea gigas) and management measures for protected areas in Europe
Pacific oysters are now one of the most βglobalisedβ marine invertebrates. They dominate bivalve aquaculture production in many regions and wild populations are increasingly becoming established, with potential to displace native species and modify habitats and ecosystems. While some fishing communities may benefit from wild populations, there is now a tension between the continued production of Pacific oysters and risk to biodiversity, which is of particular concern within protected sites. The issue of the Pacific oyster therefore locates at the intersection between two policy areas: one concerning the conservation of protected habitats, the other relating to livelihoods and the socio-economics of coastal aquaculture and fishing communities. To help provide an informed basis for management decisions, we first summarise evidence for ecological impacts of wild Pacific oysters in representative coastal habitats. At local scales, it is clear that establishment of Pacific oysters can significantly alter diversity, community structure and ecosystem processes, with effects varying among habitats and locations and with the density of oysters. Less evidence is available to evaluate regional-scale impacts. A range of management measures have been applied to mitigate negative impacts of wild Pacific oysters and we develop recommendations which are consistent with the scientific evidence and believe compatible with multiple interests. We conclude that all stakeholders must engage in regional decision making to help minimise negative environmental impacts, and promote sustainable industry development
Epidemiology of a Daphnia-Multiparasite System and Its Implications for the Red Queen
The Red Queen hypothesis can explain the maintenance of host and parasite diversity. However, the Red Queen requires genetic specificity for infection risk (i.e., that infection depends on the exact combination of host and parasite genotypes) and strongly virulent effects of infection on host fitness. A European crustacean (Daphnia magna) - bacterium (Pasteuria ramosa) system typifies such specificity and high virulence. We studied the North American host Daphnia dentifera and its natural parasite Pasteuria ramosa, and also found strong genetic specificity for infection success and high virulence. These results suggest that Pasteuria could promote Red Queen dynamics with D. dentifera populations as well. However, the Red Queen might be undermined in this system by selection from a more common yeast parasite (Metschnikowia bicuspidata). Resistance to the yeast did not correlate with resistance to Pasteuria among host genotypes, suggesting that selection by Metschnikowia should proceed relatively independently of selection by Pasteuria
Toxin-Based Therapeutic Approaches
Protein toxins confer a defense against predation/grazing or a superior pathogenic competence upon the producing organism. Such toxins have been perfected through evolution in poisonous animals/plants and pathogenic bacteria. Over the past five decades, a lot of effort has been invested in studying their mechanism of action, the way they contribute to pathogenicity and in the development of antidotes that neutralize their action. In parallel, many research groups turned to explore the pharmaceutical potential of such toxins when they are used to efficiently impair essential cellular processes and/or damage the integrity of their target cells. The following review summarizes major advances in the field of toxin based therapeutics and offers a comprehensive description of the mode of action of each applied toxin
How a songbird with a continuous singing style modulates its song when territorially challenged
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