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251.
Male dung beetles, Onthophagus taurus, are dimorphic for a secondary sexual trait, head horns. Horned males participate in the production of brood masses while
hornless male do not. Here we examine the reproductive performance of females mated with males exhibiting alternative horn
morphologies. We found that exposure to males may be costly for females in that it reduced the total number of brood masses
produced. However, females paired with horned males produced significantly larger brood masses than females paired with hornless
males or females producing broods alone. We discuss the possible selection pressures that may underly horn evolution in this
genus.
Received: 22 August 1997 / Accepted after revision: 19 January 1998 相似文献
252.
Anthony R. Olsen Joseph Sedransk Don Edwards Carol A. Gotway Walter Liggett Stephen Rathbun Kenneth H. Reckhow Linda J. Yyoung 《Environmental monitoring and assessment》1999,54(1):1-45
The United States funds a number of national monitoring programs to measure the status and trends of ecological and natural resources. Each of these programs has a unique focus; the scientific objectives are different as are the sample designs. However, individuals and committees, all well aware of the cost of ecological monitoring, have called for more effective monitoring programs. The objective of this paper is to summarize existing programs' statistical designs and discuss potential alternatives for improvement in national monitoring. Can we improve the current situation by providing an overall framework for the design or analysis of data from these disparate surveys? First, the paper summarizes the objectives of these surveys, compares and contrasts their survey designs as currently implemented, and determines what variables they collect. Through this process we identify commonalities and issues that impact our ability to combine information across one or more of the surveys. Three potential alternatives are presented, leading to comprehensive monitoring in the United States. 相似文献
253.
Senavirathna Mudalige Don Hiranya Jayasanka Zhaozhi Liu Fujino Takeshi 《Environmental science and pollution research international》2022,29(23):34475-34485
Environmental Science and Pollution Research - Microplastics are one of the most widely discussed environmental issues worldwide. Several studies have shown the effect of microplastic exposure on... 相似文献