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81.
Valve activity rhythm of the oyster Crassostrea gigas is mainly driven by tides in the field, but in the laboratory, only a circadian clock mechanism has been demonstrated. In an attempt to reconcile these results, the mechanisms underlying the circatidal rhythm were studied in the laboratory under different entrainment or free-running regimes and in the field at Arcachon (44°39′N/1°09′W) in February–April 2011). Results confirm the existence of a circadian clock in C. gigas. Under entrainment regimes (12-h dark/12-h light photoperiod and tidal cycles simulated by a reversing current flow), oysters exhibited both circadian and circatidal cycles. Under free-running conditions (e.g., continuous darkness), the endogenous rhythm appeared to be circadian. There was no experimental evidence for an endogenous circatidal rhythm, even in oysters just transferred from the field, where a clear tidal cycle was expressed. There are two possible mechanisms to explain tidal behavior in C. gigas: an exogenous tidal cue that drives tidal activity and masks the circadian rhythm and an endogenous circatidal clock that is sensitive to tidal zeitgebers and runs at tidal frequency. 相似文献
82.
Andréanne Lessard Audrey Bourret Marc Bélisle Fanie Pelletier Dany Garant 《Behavioral ecology and sociobiology》2014,68(5):733-742
Evaluating the contribution of individual and environmental determinants of reproductive success is essential to improve our understanding of sexual selection. In socially monogamous bird species with high rates of extrapair paternity, traits or environmental contexts affecting the number of within-pair young (WPY) produced by males can differ from those affecting the number of extrapair young fathered (EPY). Here, we use a 4-year dataset collected in contrasted environments to assess the factors affecting male reproductive success in tree swallows (Tachycineta bicolor), a species showing high levels of extrapair paternity. Our analyses revealed that the number of WPY was higher under better environmental conditions, while the number of EPY was mainly related to male characteristics. Males nesting in more intensive agricultural areas had fewer WPY produced and a lower reproductive success. Also, males breeding earlier in the season had more WPY. The presence of parasites reduced males’ reproductive success, mainly by reducing the number of EPY. The influence of male phenotype varied according to population density: Tarsus length variation had a greater effect on reproductive success at low population density than at high density, while wing length was also positively related to the number of EPY, more so at high than at low density. Altogether, our results suggest a complex interplay between individual and environmental determinants of reproductive success and imply that sexual selection dynamics varies depending on environmental contexts. 相似文献
83.
84.
The authors look at Britain's post‐war response to the challenge of the Inner Cities and attempts to account for this response's more obvious failings. The paper considers the challenge facing the planners and considers the nature of their response, concluding that the future of planning as a weapon in the armoury of public policy is assured. 相似文献
85.
A fundamental property of most animals is the ability to see whether an object is approaching on a direct collision course
and, if so, when it will collide. Using high-density electroencephalography in 5- to 11-month-old infants and a looming stimulus
approaching under three different accelerations, we investigated how the young human nervous system extracts and processes
information for impending collision. Here, we show that infants’ looming related brain activity is characterised by theta
oscillations. Source analyses reveal clear localised activity in the visual cortex. Analysing the temporal dynamics of the
source waveform, we provide evidence that the temporal structure of different looming stimuli is sustained during processing
in the more mature infant brain, providing infants with increasingly veridical time-to-collision information about looming
danger as they grow older and become more mobile. 相似文献
86.
87.
The U.S. Clean Water Act requires compensatory mitigation for wetland and stream damage through restoration of damaged aquatic
ecosystems. We evaluate the North Carolina’s Ecosystem Enhancement Program (EEP), a state agency responsible for compensatory
mitigation. We compare communities gaining and losing aquatic resources during mitigation, finding new types of socioeconomic
disparities that contradict previous studies of mitigation program behavior. We find average distances between impact and
mitigation sites for streams (43.53 km) and wetlands (50.3 km) to be larger in North Carolina than in off-site mitigation
programs in other regions previously studied. We also find that aquatic resources in the State are lost from urbanized areas
that are more affluent, white, and highly educated, and mitigated at sites in rural areas that are less affluent, less well
educated, and have a higher percentage of minorities. We also analyze the relationship between urban growth indicators and
EEP accumulation of compensation sites. Growth indicators and long-term population projections are uncorrelated with both
projected transportation impacts and advance mitigation acquired by the EEP, suggesting that growth considerations can be
more effectively incorporated into the EEP’s planning process. We explore the possibility that spatial mismatches could develop
between watersheds that are rapidly growing and those that are gaining mitigation. We make recommendations for ways that regulators
incorporate growth indicators into the mitigation planning process. 相似文献
88.
Ian C. Simcock Audrey Lamouroux Neil J. Sebire Susan C. Shelmerdine Owen J. Arthurs 《黑龙江环境通报》2023,43(7):937-949
Autopsy investigations provide valuable information regarding fetal death that can assist in the parental bereavement process, and influence future pregnancies, but conventional autopsy is often declined by parents because of its invasive approach. This has led to the development of less-invasive autopsy investigations based on imaging technology to provide a more accessible and acceptable choice for parents when investigating their loss. Whilst the development and use of more conventional clinical imaging techniques (radiographs, CT, MRI, US) are well described in the literature for fetuses over 20 weeks of gestational age, these investigations have limited diagnostic accuracy in imaging smaller fetuses. Techniques such as ultra-high-field MRI (>3T) and micro-focus computed tomography have been shown to have higher diagnostic accuracy whilst still being acceptable to parents. By further developing and increasing the availability of these more innovative imaging techniques, parents will be provided with a greater choice of acceptable options to investigate their loss, which may in turn increase their uptake. We provide a narrative review focussing on the development of high-resolution, non-invasive imaging techniques to evaluate early gestational pregnancy loss. 相似文献