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    Author(s): D. Carl Freeman; E. Durant McArthur; Kathleen J. Miglia; Michelle J. Nilson; Michelle L. Brown
    Date: 2007
    Source: Western North American Naturalist. 67(1): 137-141.
    Publication Series: Scientific Journal (JRNL)
    Station: Rocky Mountain Research Station
    PDF: Download Publication  (462.27 KB)


    In principle, natural selection should have endowed species with the ability to assess their normal surroundings and respond to changes that enhance, or at least do not diminish, their fitness (Emlen et al. 1998). Hence, the chameleon changes colors to match its background to avoid being eaten, or a sweet pea's tendrils wrap around supporting structures. Buffalo gourds assess the level of phosphorus in determining their floral sex ratios (Pendleton 2000), and animals use photoperiod to precisely time the onset and termination of breeding activities for successful reproduction under appropriate environmental conditions (see Nelson 2004 for references). In addition to assessing physical aspects of the environment, animals can also assess biotic aspects, such as the density of conspecific individuals, as evidenced by the different morphs of locusts that can be induced by changes in density, with the best dispersing morphs being produced when densities are highest (Wilson et al. 2002). Parasitic wasps respond to the relative size of prey to determine the sex ratio of their offspring, and thereby maximize the number of grandchildren (Charnov 1982). Plants, too, can assess their physical environments. For example, arctic plants turn their flowers to track the sun, a response that increases the rate of pollen tube growth (Galen and Stanton 2003); and many aquatic plants are heterophyllous. Minorsky (2003) argued, "Heterophylly may increase the fitness of aquatic plants by decreasing leaf damage from mechanical forces or herbivores by decreasing water loss or by enhancing photosynthesis." Can plants also assess the density of conspecifics? More precisely, do plants alter their floral structure and the sex ratio of their progeny in response to their immediate surroundings?

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    Freeman, D. Carl; McArthur, E. Durant; Miglia, Kathleen J.; Nilson, Michelle J.; Brown, Michelle L. 2007. Sex and the lonely Atriplex. Western North American Naturalist. 67(1): 137-141.


    Atriplex, sex ratio, delayed pollination, Fisher

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