Variance in male reproductive success is expected to be high in sexually dimorphic mammals, even when it is modulated by the
costs and benefits of group living. Here, we investigate the variance in reproductive success of male western gorillas (Gorilla gorilla), a highly dimorphic primate with long-term male–female associations, using 12.5 years of data collected at Mbeli Bai in
northern Congo. Access to mates and offspring survival were both major sources of variance in male reproductive success. Males
with larger harems had lower offspring mortality with no apparent reduction in female fertility or observed tenure length,
so the size of harems did not seem to be limited by female feeding competition or by the risk of takeovers and infanticide
by outsider males. The lower mortality in larger harems may reflect improved vigilance against predators, and females may
cluster around males that enhance offspring survival. Thus, this study illustrates how a detailed analysis of the components
of male reproductive success can shed light on the interrelated social and ecological aspects that affect it. 相似文献
Biological invasions can change ecosystem function, have tremendous economic costs, and impact human health; understanding the forces that cause and maintain biological invasions is thus of immediate importance. A mechanism by which exotic plants might displace native plants is by increasing the pressure of native consumers on native plants, a form of indirect interaction termed "apparent competition." Using experimental exclosures, seed addition, and monitoring of small mammals in a California grassland, we examined whether exotic Brassica nigra increases the pressure of native consumers on a native bunchgrass, Nassella pulchra. Experimental plots were weeded to focus entirely on indirect effects via consumers. We demonstrate that B. nigra alters the activity of native small-mammal consumers, creating a gradient of consumption that dramatically reduces N. pulchra establishment. Previous work has shown that N. pulchra is a strong competitor, but that it is heavily seed limited. By demonstrating that consumer pressure is sufficient to curtail establishment, our work provides a mechanism for this seed limitation and suggests that, despite being a good competitor, N. pulchra cannot reestablish close to B. nigra within its old habitats because exotic-mediated consumption preempts direct competitive exclusion. Moreover, we find that apparent competition has a spatial extent, suggesting that consumers may dictate the rate of invasion and the area available for restoration, and that nonspatial studies of apparent competition may miss important dynamics. 相似文献
We conducted a literature review on the biology, ecology, fishery, and protection of totoaba ( Totoaba macdonaldi ), an endemic, threatened fish of the Gulf of Calfornia, Mexico. Reinterpretation and integration of published and unpublished information enabled us to confirm and estimate specific biological parameters of the totooba, make hypothetical constructs of its life history, and to propose ideas for its preservation. In specific, we found (1) that the mean age of first reproduction of male and female totoaba are 6 and 7 years, respectively; (2) that the intrinsic rate of natural mortality was estimated as 0.268 per year and (3) that in the mid 1980s an estimated 120,300 juveniles died each year in the shrimp fishery by-catch and 6200 adults (26 kg average weight) died due to poaching. The parameters of an individual growth model for juveniles and adults were also estimated. Decreased spring water input from the Colorado River into the Gulf of California may have caused a contraction of the spawning season and a reduction of the carrying capacity of juvenile totoaba. An increase in annual survival during recent years indicates recovery of the stock that might be related to protection of adults. We argue that habitat restoration, which includes the elimination of growth and recruitment over-fishing, is critical to increasing numbers of totoaba, and thereby lifting the fishing ban, and to the delisting of totoaba. 相似文献
Bacteriophages MS-2 and PRD-1 were used as indicators of human viral behaviour in a series of turf-grass irrigation and washing
machine experiments to provide information about the level of human exposure to potential residual enteric viruses in recycled
water that can affect health. Results provided evidence to support a potential inadvertent exposure volume of 0.01 ml for
recycled water used for machine clothes washing. Results for irrigation experiments showed that a one log reduction in bacteriophage
numbers on turf-grass was not achieved under exposure to high solar conditions after 4 h. Experimentation showed that bacteriophages
may be usefully employed in exposure assessment studies based on the ease of their enumeration and logistical and cost considerations.
In terms of future studies, observed differences in individual bacteriophage characteristics provide a rationale for using
multiple viral indicators. However, limitations on the utility of bacteriophage also need to be considered. 相似文献
Climate change is one of the main challenges faced by mankind in this century. Although developing countries have little historical responsibility for climate change, they are likely to be most affected by it since they lack resources to cope with or to adapt to its effects. Studies show that the semi-arid northeast region of Brazil – where the country's poorest populations are concentrated – is one of the most vulnerable to climate change and thus likely to suffer its impacts more severely. The present paper addresses these problems by presenting a concrete initiative for strengthening adaptive capacity in the rural community of Pintadas as a first step in the development of a comprehensive methodology to help smallholder farmers in the region adapt to climate change. Based on the project results this paper highlights the integration of development, adaptive capacity and adaptation strategies. Furthermore, the necessity of vulnerability studies and concrete local experiences is highlighted in order to develop adaptation strategies that can alleviate poverty and minimize climate change impacts for the poor. 相似文献
Globally, hepatitis A virus (HAV) is one of the most common agents of acute viral hepatitis and causes approximately 1.4 million cases and 90,000 deaths annually despite the existence of an effective vaccine. In 2019, federal, state, and local partners investigated a multi-state outbreak of HAV infections linked to fresh blackberries sourced from multiple suppliers in Michoacán, Mexico. A total of 20 individuals with outbreak-related HAV infection were reported in seven states, including 11 hospitalizations, and no deaths. The Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and Nebraska State and Douglas County Health Departments conducted a traceback investigation for fresh blackberries reportedly purchased by 16 ill persons. These individuals reported purchasing fresh blackberries from 11 points of service from September 16 through 29, 2019 and their clinical isolates assessed through next-generation sequencing and phylogenetic analysis were genetically similar. The traceback investigation did not reveal convergence on a common grower or packing house within Mexico, but all of the blackberries were harvested from growers in Michoacán, Mexico. FDA did not detect the pathogen after analyzing fresh blackberry samples from four distributors, one consumer, and from nine importers at the port of entry as a result of increased screening. Challenges included gaps in traceability practices and the inability to recover the pathogen from sample testing, which prohibited investigators from determining the source of the implicated blackberries. This multi-state outbreak illustrated the importance of food safety practices for fresh produce that may contribute to foodborne illness outbreaks.
Boston Chinatown is a community that grapples with a constant pressure from the downtown area to build new and larger buildings. The effort to preserve the residential aspect of Chinatown has used data analysis in recent years by forming partnerships with academics. This has allowed for more sophisticated studies of traffic injuries, scientific surveys of residents about environmental health, the measurement of noise levels and the construction of physical and electronic mapping of data. While not the only factor contributing to the community's efforts to question the role of development, these data have added useful tools that reduce, but do not eliminate, the disparity between what the community brings to discussions about the environmental impact of development and what the developers have at their disposal. 相似文献