University of Maine

About: University of Maine is a education organization based out in Orono, Maine, United States. It is known for research contribution in the topics: Population & Ice sheet. The organization has 8637 authors who have published 16932 publications receiving 590124 citations. The organization is also known as: University of Maine at Orono.

Use of a New Reproductive Index to Evaluate Relationship Between Habitat Quality and Breeding Success

Abstract: -A new method of measuring reproductive success is proposed that uses a composite of breeding-behavior observations (for behaviors that reflect different stages in the reproductive cycle) as an index of fitness. This reproductive index does not rely on discovery of nests, but is comprehensive in that it includes information on all monitored territories. The reproductive index was applied to three co-occurring grassland emberizine sparrows, two of which required special care because of their regional rarity. Ranks derived from this reproductive index were used to distinguish territories of birds of known high success (i.e. those that fledged young in at least one brood) from territories of birds with known low success (unpaired males), and were compared with findings for "spot-mapped" territories. Principal-components analyses of habitat measurements for these territory types revealed a similar pattern for all three species: spot-mapped territories overlapped broadly with nonterritory (unoccupied) plots, whereas high-success territories formed a discrete, isolated cluster within the spot-map matrix. Univariate analyses revealed that high-success territories were described by 15 vegetation features that differed (P < 0.01) from nonterritory values, whereas in spot-mapped territories only 8 vegetation measures differed and in lowsuccess territories only 2 differed. The ability to distinguish high-success territories allowed us to identify a greater number of habitat features that were correlated with reproductive success. If we had relied on the spot-mapping method, we would have been unable to identify many of these important habitat features. Yet, the ability to make such discriminations is likely to be critical in the management of threatened species. Received 5 March 1991, accepted 7 April 1992. THE DIFFICULTY of being able to gather detailed reproductive information about a bird 3Present address: Conservation Department, Massachusetts Audubon Society, Lincoln, Massachusetts 01773, USA. 4 Present address: Department of Natural Resources, Field of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853, USA. population or community in a time-efficient manner has frequently limited avian-community research (e.g. Wiens 1973). Techniques for quantifying avian reproductive activity usually fall into two general categories. The simplest method, territory mapping, allows the researcher to define the location of individual male territories for a species or group of co-occurring species (Kendeigh 1944, International Bird Cen-

The Plankton, Aerosol, Cloud, Ocean Ecosystem Mission: Status, Science, Advances

Abstract: The Plankton, Aerosol, Cloud, Ocean Ecosystem (PACE) mission represents the National Aeronautics and Space Administration’s (NASA) next investment in satellite ocean color and the study of ...

The economic and career effects of sexual harassment on working women

Abstract: Many working women will experience sexual harassment at some point in their careers. While some report this harassment, many leave their jobs to escape the harassing environment. This mixed-methods study examines whether sexual harassment and subsequent career disruption affect women’s careers. Using in-depth interviews and longitudinal survey data from the Youth Development Study, we examine the effect of sexual harassment for women in the early career. We find that sexual harassment increases financial stress, largely by precipitating job change, and can significantly alter women’s career attainment.

In situ evaluation of the initiation of the North Atlantic phytoplankton bloom

Abstract: [1] Two years of continuous physical and optical measurements from a profiling float in the western subarctic North Atlantic are used to analyze seasonal phytoplankton dynamics. The observed annual cycle challenges the traditional view that initiation of spring accumulations of phytoplankton in the upper water column requires a critical stratification threshold (known as the ‘Gran effect’ or the ‘Sverdrup Hypothesis’). Instead, we find that biomass accumulation begins in mid-winter when light levels are minimal and near-surface mixing is deepest. These observations are consistent with the recently proposed dilution–recoupling hypothesis which states that deep winter mixing in the North Atlantic is essential for bloom formation as it decouples phytoplankton growth from grazing losses, thereby allowing net biomass accumulation despite low-light conditions.

Disentangling host, pathogen, and environmental determinants of a recently emerged wildlife disease: lessons from the first 15 years of amphibian chytridiomycosis research

Abstract: The amphibian fungal disease chytridiomycosis, which affects species across all continents, recently emerged as one of the greatest threats to biodiversity. Yet, many aspects of the basic biology and epidemiology of the pathogen, Batrachochytrium dendrobatidis (Bd), are still unknown, such as when and from where did Bd emerge and what is its true ecological niche? Here, we review the ecology and evolution of Bd in the Americas and highlight controversies that make this disease so enigmatic. We explore factors associated with variance in severity of epizootics focusing on the disease triangle of host susceptibility, pathogen virulence, and environment. Reevaluating the causes of the panzootic is timely given the wealth of data on Bd prevalence across hosts and communities and the recent discoveries suggesting co-evolutionary potential of hosts and Bd. We generate a new species distribution model for Bd in the Americas based on over 30,000 records and suggest a novel future research agenda. Instead of focusing on pathogen "hot spots," we need to identify pathogen "cold spots" so that we can better understand what limits the pathogen's distribution. Finally, we introduce the concept of "the Ghost of Epizootics Past" to discuss expected patterns in postepizootic host communities.