The results propose that the balance between natural selection for inconspicuousness and sexual selection for conspicuousness may vary among the lizard populations. At SL, the habitat consists primarily of gray rocks, so the SL collared lizard population has a small chance to hide. Because of this, the male SL lizards are a dull greenish-brown color that is similar to the females and rocks. At GM, the background is more complicated, so the male lizards are more conspicuous compared to the rocks and females (Macedonia et al. 2004). More than double the number of models was preyed upon at SL than at GM, which shows that natural selection restricts sexual selection for colorful males more efficiently at SL than GM. This reveals why the males at SL are duller than those collared lizards at GM. This seems to be different for the WM population.
These male WM populations are more conspicuous than the GM and SL males; however, WM has the greatest predation pressure among the three sites. The investigators suggested that the WM males may look conspicuous outside of its environment, but may actually be cryptic in its complex environment (Baird et al. 1997; McCoy et al. 1997). When this idea was tested, mixed support for it was found. They found that some areas of the site caused the WM lizards to be conspicuous (flowers, lichens, and vegetation) and other areas caused the lizards to be more inconspicuous (rocks and other vegetation) (Macedonia et al. 2004).
Another reason why male WM lizards may be more conspicuous even though the population experiences great predation pressure is the tall grass area in WM. These tall grasses offer great concealment from visually hunting snakes, like the coachwhip. Because the WM collared lizards may se...
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...J. M., Husak, J. F., Brandt, Y. M., Lappin, A. K. & Baird, T. A. 2004: Sexual dichromatism and color conspicuousness in three populations of collared lizards (Crotaphytus collaris) from Oklahoma, USA. J. Herpetol. 38, 343—357.
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In his peer-reviewed article, “Sexing fossils: a boy named Lucy?,” James Shreeve discusses, in detail, a study on sexual dimorphism and possible speciation in Australopithecines in Hadar, Ethiopia, based on the famous A. afarensis specimen, “Lucy.” In the article, “Lucy’s kind takes humanlike turn,” the author addresses sexual dimorphism and speculates on sex-based differences in behaviors in A. afarensis. The two articles have differences and commonalities with each other in content and both present research methods and conclusions on topics including sexual dimorphism, sex-based behaviors, and speciation in Australopithecines, which receive critical analysis.
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Females like to choose mates who have very bright colors as it is a sign of the male’s good health and vigor. The natural and sexual selection can affect populations in three ways: directional (environmental conditions change in a consistent direction; one extreme of phenotypes is favored), stabilizing (environmental conditions are relatively constant; intermediate phenotype is favored), and disruptive selection (environment has more than one type of useful resource; both extremes of phenotypes are favored). An example of directional selection is pesticide resistance since only the insects with a resistance are favored; an example of stabilizing selection is that the smallest lizards have a difficulty defending their territory whereas the largest lizards are most likely to be eaten by owls; an example of disruptive selection are the black-bellied seedcrackers since they either have a large beak (which they can use to eat had seeds), or a small beak (which allows them to eat soft seeds). Disruptive selection shows a balanced polymorphism, which is when two or more phenotypes are maintained in a
The reason I am writing this paper is to share the information I attained about human sexuality by learning about sexuality in a college setting and by exploring my sexuality through personal experiences. I do not consider myself to have experienced much exposure to sexual behavior but I do have a cultural bias to what I consider a heavy amount of exposure because the North American culture is considered more promiscuous and sexually active than other cultures.
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Belkin, Lisa. “The Sex Life.” NYTimes.com The New York Times. 09 Feb. 2011. Web. 01 April 2014.
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Reptiles, one the most widely spread animal group throughout the world. They can live almost everywhere because they adapt so well. Reptiles also come in a lot of shapes, sizes and colors. So let's explore the wonder of these scaly creatures.
The 'Standard' of the 'Standard'. 1,500 Animal Species Practice Homosexuality. News - Medical - Medical. N.p., n.d. Web. The Web.
The platypus is sexually dimorphic in that males of the species are larger in size than females. Size variation within populations from different regions is also evident, with smaller platypuses in general being found in north Queensland compared to Tasmania. Additionally, each male bears a horny spur on the ankle of the hind leg reaching roughly 1.5 cm in length. This spur is connected to a venom glad and is used to fight for females and ensures spatial separation.
A pair of equal sized birds of prey might overhunt an area and compete for food. However the Ecological theory shows validity in the idea that a territory is not overhunted because a small male will eat small prey while the large female hunts larger prey. However, it does not adequately explain why it is the female who would eat the larger prey or the bigger portion and be the bigger mate. It also does not explain why some species have smaller RSD than others such as the Screech Owl for