Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Gen Comp Endocrinol ; 250: 95-103, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28619288

RESUMO

Animals living in temperate climates respond to environmental cues that signal current and future resource availability to ensure that energy resources are available to support reproduction. Siberian hamsters (Phodopus sungorus) undergo robust gonadal regression in short, winter-like photoperiods as well as in response to mild food restriction in intermediate photoperiods. The goal of the present study was to investigate whether leptin is a relevant metabolic signal in regulating gonadal regression in response to diminishing food availability. Adult female hamsters housed in short-day (winter-like) or intermediate (fall-like) photoperiods received either ad libitum access to food or mild food restriction (90% of ad libitum intake) and were treated with either leptin or a vehicle for five weeks in order to determine the ability of leptin to inhibit gonadal regression. At the end of five weeks, vehicle-treated hamsters showed physiological signs associated with ongoing gonadal regression, such as decreases in body mass and food intake, cessation of estrous cycling, and small decreases in reproductive tissue mass. Leptin did not modify changes in body mass, food intake, hormone concentration, or tissue mass, but showed a tendency to support estrous cycling, particularly in response to food restriction in the intermediate photoperiod treatment. Overall, leptin appears to play a minor role in coordinating reproductive responses to multiple environmental cues, at least in the early stages of gonadal regression.


Assuntos
Sinais (Psicologia) , Meio Ambiente , Leptina/farmacologia , Phodopus/fisiologia , Reprodução/efeitos dos fármacos , Estações do Ano , Animais , Peso Corporal/efeitos dos fármacos , Cricetinae , Ingestão de Alimentos/fisiologia , Ciclo Estral/efeitos dos fármacos , Feminino , Hormônio Luteinizante/sangue , Phodopus/sangue , Fotoperíodo , Reprodução/fisiologia
2.
Conserv Biol ; 28(5): 1415-27, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24724940

RESUMO

The U.S. National Wildlife Refuge System has nearly completed its first round of unit-level, comprehensive conservation plans (CCPs) and will soon begin required revisions. Laws and policies governing refuge planning emphasize ecological integrity, landscape-scale conservation, and adaptive management. We evaluated 185 CCPs completed during 2005-2011, which cover 324 of 555 national wildlife refuges. We reviewed CCP prescriptions addressing 5 common conservation issues (habitat and game, nongame, imperiled, and invasive species) and 3 specialized topics (landscape-scale conservation, climate change, and environmental quality). Common conservation issues received prescriptions in >90% of CCPs. Specialized topics received more variable treatment. Prescriptions for aquatic connectivity, water quantity, and climate-change impacts increased over the study period. Except for climate change, direct actions were the most common type of management prescription, followed by plans or studies. Most CCPs stated a commitment to adaptive management and prescribed monitoring for common conservation objectives; other aspects of planning for adaptive management were often lacking, despite strong support for adaptive management in the conservation planning literature. To better address refuge-specific threats, we recommend that revised plans explicitly match identified refuge issues with prescriptions, particularly for under-represented concerns such as novel pests and pathogens. We recommend incorporating triggers into monitoring frameworks and specifying actions that will occur when threshold values are reached to improve support for adaptive management. Revised CCPs should better reflect work that refuges already undertake to extend conservation objectives beyond their borders and better engage with regional conservation efforts to continue this work. More thorough landscape-scale threat assessments and explicit prioritization of planned actions would further improve conservation effectiveness. Excellent examples of all recommended practices exist within the CCPs we examined; sharing best planning practices would improve planning efficiency within the refuge system.


Assuntos
Conservação dos Recursos Naturais/legislação & jurisprudência , Conservação dos Recursos Naturais/métodos , Tomada de Decisões , Animais , Mudança Climática , Meio Ambiente , Espécies Introduzidas , Técnicas de Planejamento , Plantas , Estados Unidos
4.
Ambio ; 51(1): 84-92, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34008095

RESUMO

The Convention on Biological Diversity is defining the goals that will frame future global biodiversity policy in a context of rapid biodiversity decline and under pressure to make transformative change. Drawing on the work of Indigenous and non-Indigenous scholars, we argue that transformative change requires the foregrounding of Indigenous peoples' and local communities' rights and agency in biodiversity policy. We support this argument with four key points. First, Indigenous peoples and local communities hold knowledge essential for setting realistic and effective biodiversity targets that simultaneously improve local livelihoods. Second, Indigenous peoples' conceptualizations of nature sustain and manifest CBD's 2050 vision of "Living in harmony with nature." Third, Indigenous peoples' and local communities' participation in biodiversity policy contributes to the recognition of human and Indigenous peoples' rights. And fourth, engagement in biodiversity policy is essential for Indigenous peoples and local communities to be able to exercise their recognized rights to territories and resources.


Assuntos
Biodiversidade , Povos Indígenas , Humanos
5.
Conserv Biol ; 25(4): 827-34, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21535148

RESUMO

The use of conservation easements as a conservation mechanism for private land has increased greatly in the past decade; conservation easements now protect over 15 million ha across the United States from residential and commercial development. We used a mailed survey and in-depth telephone interviews to determine factors that motivate private landowners in Iowa, Illinois, Michigan, Ohio, and Wisconsin (U.S.A.) to place conservation easements on their properties. The mailed survey asked about characteristics of landowners, their properties, and their opinions on 9 factors related to the decision to place an easement. A follow-up telephone interview was completed with 19 mail-survey participants to gain an in-depth understanding of the action and to triangulate the results with the questionnaire. Place attachment, which is a measure of personal connection to a location or property, was the greatest motivation for implementation of an easement. Results of a principal components analysis suggested contributing to the public good underlaid several of the strong motivational factors for participation. Financial reasons were the lowest ranked motivational factor; however, financial concerns may facilitate placement of an easement that would otherwise not be realized. We believe that our results may be transferable to places where land protected by easements is not dominated by traditional farming (row crops, pastures, and hay), timber harvesting, or nonextractive uses (e.g., habitat for wild animals, recreation, and protection of ecosystem services).


Assuntos
Conservação dos Recursos Naturais , Motivação , Humanos , Entrevistas como Assunto , Meio-Oeste dos Estados Unidos , Inquéritos e Questionários
7.
Environ Law ; 41(2): 447-534, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-29332970

RESUMO

Migratory animals provide unique spectacles of cultural, ecological, and economic importance. However, the process of migration is a source of risk for migratory species as human actions increasingly destroy and fragment habitat, create obstacles to migration, and increase mortality along the migration corridor. As a result, many migratory species are declining in numbers. In the United States, the Endangered Species Act provides some protection against extinction for such species, but no protection until numbers are severely reduced, and no guarantee of recovery to population levels associated with cultural, ecological, or economic significance. Although groups of species receive some protection from statutes such as the Migratory Bird Treaty Act and Marine Mammal Protection Act, there is no coordinated system for conservation of migratory species. In addition, information needed to protect migratory species is often lacking, limiting options for land and wildlife managers who seek to support these species. In this Article, we outline the existing scientific, legal, and management information and approaches to migratory species. Our objective is to assess present capacity to protect the species and the phenomenon of migration, and we argue that al three disciplines are necessary for effective conservation. We find significant capacity to support conservation in all three disciplines, but no organization around conservation of migration within any discipline or among the three disciplines. Areas of synergy exist among the disciplines but not as a result of any attempt for coordination. As a result, significant gaps in information and capacity exist that must be addressed if effective conservation of migratory species is to be undertaken. We suggest that all three disciplines cooperate to identify the most pressing research needs, so that these can become targets for relevant funding sources. We identify areas of current risk to migratory species that represent gaps in current legal protections: protective legislation that provides no guidelines for desirable population sizes or best management practices for migratory species, taxonomic groups, particularly those including long-distance migrants, for which no agency has oversight, and gaps in policies to address impacts of fragmentation and obstacles such as power lines and wind turbines that curtail migration or cause mortality. Finally, we suggest that state-level programs provide either a foundation to augment with, or a model on which to build, conservation efforts targeting migratory species. Problems will arise due to lack of funds, difficulties in securing a landscape that will support abundant migrations, lack of adequate standards and best management practices, and an insufficient culture of collaboration among the three main relevant disciplines. However, we view these problems as entirely soluble and see evidence of support in society at large for conservation of migratory species.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA