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61.
Lindsey Swierk Sean P. Graham Tracy Langkilde 《Behavioral ecology and sociobiology》2014,68(11):1761-1768
Iteroparous species maximize lifetime reproductive fitness by balancing current and future reproductive investments. In order to maximize fitness in the face of social or environmental heterogeneity, individuals of the same species may vary in whether they prioritize current reproductive opportunity or sacrifice immediate reproduction in order to prioritize survival and future reproductive potential. Glucocorticoid (GC) secretion plays an important role in mediating this trade-off by promoting behavioral and physiological responses associated with survival, often at the expense of nonessential (e.g., reproductive) functions. We used wood frogs (Lithobates sylvaticus [Rana sylvatica]) to test whether males and females differed in their (a) physiological response (plasma corticosterone [CORT] concentration) to standardized handling stress—a proxy for predation threat—and (b) performance of reproductive behaviors that may enhance their conspicuousness to predators. We also tested whether levels of male competition influenced sex differences in these factors, as more intense competition may require males to devote more time to risky reproductive behaviors. We found that females had lower baseline CORT but exhibited a significantly greater CORT response to a stressor and spent less time performing potentially risky behavior (surface floating) than did males. These sex differences were consistent across different levels of male mating competition. Our results reveal that during breeding, males and females may differentially respond to stressors and perform risk-prone behaviors, despite facing the same extreme breeding constraints, providing new insight into the survival-reproduction trade-off of explosively breeding species. 相似文献
62.
The current model for larval release in subtidal crustaceans suggests that hatching time is controlled by the embryos, which
release a pheromone that stimulates the parent female to undergo behaviors that synchronize larval release. Alternatively,
hatching could be controlled by the females. Ovigerous spiny lobsters Panulirus argus (Latreille) exhibit stereotypic behaviors during larval release, including rapid abdominal extensions and pleopod-pumping
activity. Ovigerous P. argus were collected from coral reefs in the Florida Keys, USA during the summers of 2005 and 2006. Pleopod-pumping activity was
quantified to determine if a female’s pumping activity correlates with the developmental state of the embryos. The role of
pheromones released by developing and hatching embryos in controlling pumping behaviors was tested by measuring the pumping
response of ovigerous lobsters to (1) hatch water, (2) homogenized embryo water, (3) embryo-conditioned water (unhatched late-stage
embryos soaked for 20 h), and (4) water containing homogenized post-hatch embryo cases. Bioassays were conducted under constant
conditions (dim-red light) in the laboratory at random times during the day to control for any possible rhythm in pumping
activity. Spontaneous pleopod-pumping activity increased significantly with increasing embryo development. Upon exposure to
hatch water, ovigerous lobsters with late-stage embryos displayed increased pleopod pumping with increased treatment concentration.
Water individually conditioned with homogenized late-stage embryos, intact late-stage embryos, and homogenized post-hatch
embryo cases all induced larval release behaviors in females with late-stage embryos. Ovigerous females with early-stage embryos
did not respond to water conditioned with homogenized early- or late-stage embryos. These results suggest that active substances
are released by embryos at the time of hatching and induce the stereotypical pumping behaviors of the female that synchronizes
larval release. The results support the model that larval release in subtidal crustaceans is controlled by pheromones released
from hatching embryos. 相似文献
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Airam Rodríguez Nick D. Holmes Peter G. Ryan Kerry‐Jayne Wilson Lucie Faulquier Yovana Murillo André F. Raine Jay F. Penniman Verónica Neves Beneharo Rodríguez Juan J. Negro André Chiaradia Peter Dann Tracy Anderson Benjamin Metzger Masaki Shirai Lorna Deppe Jennifer Wheeler Peter Hodum Catia Gouveia Vanda Carmo Gilberto P. Carreira Luis Delgado‐Alburqueque Carlos Guerra‐Correa François‐Xavier Couzi Marc Travers Matthieu Le Corre 《Conservation biology》2017,31(5):986-1001
Artificial lights at night cause high mortality of seabirds, one of the most endangered groups of birds globally. Fledglings of burrow‐nesting seabirds, and to a lesser extent adults, are attracted to and then grounded (i.e., forced to land) by lights when they fly at night. We reviewed the current state of knowledge of seabird attraction to light to identify information gaps and propose measures to address the problem. Although species in families such as Alcidae and Anatidae can be grounded by artificial light, the most affected seabirds are petrels and shearwaters (Procellariiformes). At least 56 species of Procellariiformes, more than one‐third of them (24) threatened, are subject to grounding by lights. Seabirds grounded by lights have been found worldwide, mainly on oceanic islands but also at some continental locations. Petrel breeding grounds confined to formerly uninhabited islands are particularly at risk from light pollution due to tourism and urban sprawl. Where it is impractical to ban external lights, rescue programs of grounded birds offer the most immediate and employed mitigation to reduce the rate of light‐induced mortality and save thousands of birds every year. These programs also provide useful information for seabird management. However, these data are typically fragmentary, biased, and uncertain and can lead to inaccurate impact estimates and poor understanding of the phenomenon of seabird attraction to lights. We believe the most urgently needed actions to mitigate and understand light‐induced mortality of seabirds are estimation of mortality and effects on populations; determination of threshold light levels and safe distances from light sources; documentation of the fate of rescued birds; improvement of rescue campaigns, particularly in terms of increasing recovery rates and level of care; and research on seabird‐friendly lights to reduce attraction. 相似文献
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We analyzed the past and current distribution and abundance of vegetation and wildlife to develop a wildlife habitat restoration
plan for the Sweetwater Regional Park, San Diego County, California. Overall, there has been a substantial loss of native
amphibians and reptiles, including four amphibians, three lizards, and 11 snake species. The small-mammal community was depauperate
and dominated by the exotic house mouse (Mus musculus) and the native western harvest mouse (Reithrodontomys megalotis). It appeared that either house mice are exerting a negative influence on most native species or that they are responding
positively to habitat degradation. There has apparently been a net loss of 13 mammal species, including nine insectivores
and rodents, a rabbit, and three large mammals. Willow (Salix) cover and density and cottonwoods (Populus fremontii) had the highest number of positive correlations with bird abundance. There has been an overall net loss of 12 breeding bird
species; this includes an absolute loss of 18 species and a gain of six species. A restoration plan is described that provides
for creation and maintenance of willow riparian, riparian woodland, and coastal sage scrub vegetation types; guides for separation
of human activities and wildlife habitats; and management of feral and exotic species of plants and animals. 相似文献
69.
Self-insurance against natural disasters 总被引:1,自引:0,他引:1
Expenditures on self-insurance to mitigate the effects of natural disasters on the value of private assets are examined in a model where individuals are partially insured against financial loss by a public relief program and where private insurance is unavailable. The model predicts that optimal private expenditures on self-insurance will be excessive or insufficient according to the nature of the technology by which individuals protect their assets. The comparative static effects of variations in the level of public compensation, individual wealth, and attitudes toward risk and the degree of environmental uncertainty on self-insurance expenditures and on the magnitude and frequency of public compensation are also characterized and their implications for remedial government policies are examined. 相似文献
70.
The objective of this project was to assess the efficacy of fluorescence in situ hybridization (FISH) with chromosome-specific DNA probes to identify chromosome number in formalin-fixed, paraffin-embedded placental specimens. Using this approach, 75 per cent of the karyotypes in 20 formalin-fixed placental samples (comprising aneuploids, triploids, and normals) were correctly identified. As this technology improves, the ability to obtain information regarding chromosomal abnormalities in formalin-fixed, paraffin-embedded placental tissue should improve as well. This technology can potentially provide important cytogenetic information even when fresh tissue is not available for standard karyotypic analysis. 相似文献