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Topic: Sexual dimorphism

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	Theoretical Background
		Rice (1984), came to a different conclusion and, in a theoretical analysis of the effect of X-linkage on the evolution of sexual dimorphism, stated that "sex chromosomes facilitate the evolution of sexual dimorphism and that X-linked genes have a predominant role in coding for sexually dimorphic traits".
		Sexual selection is thought to operate on males characters in two main ways: male competition where the winning male gains access to more matings, and female choice where the female chooses the male she deems more fit.
		Ely, J. and Kurland, J. Spatial autocorrelation, phylogenetic constraints, and the causes of sexual dimorphism in primates.
	www.zoologi.su.se /research/dimorphism/Doktoranduppsats.htm (12841 words)

	Sexual dimorphism - Wikipedia, the free encyclopedia (via CobWeb/3.1 planetlab2.cs.unc.edu) (Site not responding. Last check: 2007-10-11)
		Sexual dimorphism is the systematic difference in form between individuals of different sex in the same species.
		Species with the highest sexual dimorphism, such as the pheasant, tend to be those species in which the care and raising of offspring is done only by the mother, with no involvement of the father (low degree of paternal investment).
		Sexual dimorphism is sometimes quantified by biologists through the dimorphism index, which is usually the ratio between the average adult male mass and average adult female mass (see for a thorough review sexual dimorphism measures).
	en.wikipedia.org.cob-web.org:8888 /wiki/Sexual_dimorphism (1692 words)

	Female Sexual Selection
		Enhancing the sexual dimorphism of human faces should raise attractiveness by enhancing sex-hormone-related cues to youth and fertility in females, and to dominance and immunocompetence in males.
		Sexual selection (differing criteria in females and males in choosing a mate) acting on this genetic innovation has generated a dimension of competence in social interaction in relation to which there has been a progressive increase in cerebral size by delayed maturation (neoteny).
		A sexual dimorphism in cerebral asymmetry and the sex difference in age of onset of psychosis can be parsimoniously explained if a gene regulating the relative growth of the two hemispheres is X-Y homologous." (Crow TJ (1995) A Darwinian approach to the origins of psychosis.
	www.neoteny.org /a/femalesexualselection.html (10771 words)

	RedOrbit - Science - Sexual Segregation in Ruminants: Definitions, Hypotheses, and Implications for Conservation and ... (Site not responding. Last check: 2007-10-11)
		Sexual segregation has been defined traditionally as the differential use of space (and often habitat and forage) by sexes outside the mating season, but other hypotheses related to activity patterns of sexes recently have been forwarded.
		Sexual segregation should be considered in a niche framework wherein overlap on 1 niche axis is accompanied by avoidance on another, including space, diet, and habitat.
		The basic tenet that polygyny resulted in increased sexual dimorphism among ruminants, which in turn effected sexual segregation, is the foundation of current hypotheses for why sexes tend to live separately for much of the year.
	www.redorbit.com /news/display/?id=117355 (8024 words)

	Sexual Dimorphism and Heterochronic Theory
		They are not strikingly dimorphic for size as are the other two species (Fig 2), but male chimpanzees have enormous scrotal testes, proportionately about 5 and 10 times larger than Pongo and Gorilla, respectively, and a specialized penis more than twice as long as that on the much larger gorilla.
		Quite possibly, then, A. afarensis had already undergone some reduction of sexual dimorphism, and its descendants were to undergo even more.
		The reduction and effective loss of canine dimorphism in early hominids therefore serves as primary evidence in favor of the proposed behavioral model (86)." (Lovejoy, C.O. (1981) The o rigin of man. Science 211: pp.
	www.neoteny.org /a/sexualdimorphism.html (1373 words)

	Sexual Dimorphism of the Leopard Lizards (Site not responding. Last check: 2007-10-11)
		Sexual dimorphism is a phenomenon that occurs among a variety of animal taxa, and its occurrence can reflect and\or influence crucial aspects of the natural history of organisms.
		Sexual selection can be defined as the directional selection of certain characteristics (e.g., large body size) associated with an increase in reproductive fitness.
		Sexual dimorphism has been the focus of investigation in a variety of animal taxa.
	www-mcnair.berkeley.edu /97journal/Swinney.html (2970 words)

	Sexual Dimorphism of Song Learning in Birds (Site not responding. Last check: 2007-10-11)
		Study of sexual dimorphism in song birds was pioneered through the study of this species and has lead to fascinating new discoveries that help to understand other song bird species as well.
		Zebra finches are sexually dimorphic in their plumage and song behavior.
		Although the sexual dimorphism in plumage and in song behavior is striking, the roles of the two sexes in raising young are relatively equal.
	instruct1.cit.cornell.edu /courses/bionb424/students/av54 (397 words)

	Ex Astris Scientia - Sexual Dimorphism of Star Trek Aliens
		This kind of sexual dimorphism is tacitly assumed to be a common trait in the following.
		This may be a considerable sexual dimorphism, but she could also have been an offworlder who came to Tiburon for her despicable experiments.
		But their women are taller on average than their men, a dimorphism which is mirrored in the matriarchal society on the planet.
	www.ex-astris-scientia.org /inconsistencies/dimorphism.htm (1535 words)

	REVERSED SEXUAL SIZE DIMORPHISM: EFFECT ON RESOURCE DEFENSE AND FORAGING BEHAVIORS OF NONBREEDING NORTHERN HARRIERS (Site not responding. Last check: 2007-10-11)
		Extreme sexual size dimorphism also facilitated sex- ing harriers of all ages, especially on occasions when a bird was seen flying with a member of the opposite sex.
		Sexual differences in foraging behaviors.--Sexual differences in flight speeds and foraging be- haviors were observed only in high-vegetation areas, where female harriers hunted by slow quartering whereas male harriers hunted by fast, straight flight.
		Sexual differences in resource defense and foraging behaviors during the non-breeding season are detailed for Northern Harriers (Circus cyaneus) in California.
	elibrary.unm.edu /sora/Auk/v103n01/p0070-p0078.html (6565 words)

	Evolution - A-Z - Sexual dimorphism (Site not responding. Last check: 2007-10-11)
		Sexual dimorphism is the existence of physical differences between the sexes, other than differences in the sex organs.
		Darwin contended that sexual dimorphism evolved by means of sexual selection.
		Darwin's main argument for the importance of sexual selection was comparative: his principal evidence came from looking at a large number of species.
	www.blackwellpublishing.com /ridley/a-z/Sexual_dimorphism.asp (210 words)

	"Sexual Dimorphism in Femora: An Indian Study, Forensic Science Communications, July 2002
		This study is an attempt to examine the sexual dimorphism in femora of Indian origin.
		This study on sexual dimorphism is based on the principle that the axial skeleton weight of the male is relatively and absolutely heavier than that of the female (William et al.
		Trancho, G. J., Robledo, B., Lopez-Bueis, I., and Sanchez, A. Sexual determination of femur using discriminant function analysis of a Spanish population of known sex and age, Journal of Forensic Sciences (1997) 42:181-185.
	www.fbi.gov /hq/lab/fsc/backissu/july2002/purkait.htm (3041 words)

	Sexual Dimorphism and sexual selection: Monkeys, Apes and Humans-Anth 1500
		Darwin proposed that sexually dimorphic characteristics are related to a critical hostile force: mate shortages.
		Sexual selection is a form of natural selection.
		Sexual dimorphism is greater in uni-male societies than in multi-male societies.
	www.missouri.edu /~anthmark/courses/mah/lectures/sexdim.htm (894 words)

	Gender and Sexual Dimorphism in Flowering Plants
		Gender dimorphism is found in approximately 10% of flowering plant species and has been an active topic of research.
		The second section deals with the evolution of secondary sexual characters, including the theory related to the evolution of sexual dimorphism and its empirical patterns.
		Gender and sexual dimorphism in flowering plants: review of terminology, biogeographic patterns, ecological correlates, and phylogenetic approaches.
	www.cplbookshop.com /contents/C336.htm (210 words)

	[No title]
		We conclude that the transition between alternative states is not difficult, and that the evolution of sexual dimorphism, given appropriate selection pressures, is unlikely to be constrained.
		When sexually dimorphic structures mediate learning, and when such learning ability is necessary to compete for mates, then such differences are best understood within the framework of sexual selection.
		We investigated the adaptive significance of a distinctive pattern of sexual dimorphism in a south-eastern Australian frog, Adelotus brevis.
	www.largocanyon.org /science/species/dimorphic.htm (2442 words)

	Shoot morphology and reproduction in jojoba: advantages of sexual dimorphism Ecology - Find Articles (Site not responding. Last check: 2007-10-11)
		Dioecious plant species may also be sexually dimorphic, in the sense that sexes differ in vegetative morphological characteristics or other secondary sexual characteristics (Lloyd and Webb 1977).
		The mechanisms for the evolution and maintenance of this vegetative dimorphism have been little explored, but may be attributable to sexual differences in selection regimes resulting from sex-specific modes of reproduction.
		In a dioecious species with secondary sex characters, the relationship between morphology and reproduction may be explored by determining whether those individuals at the morphological extremes of the dimorphism differ in their reproductive success, and whether morphological variation contributes, specifically and differentially, to success as a male or as a female.
	www.findarticles.com /p/articles/mi_m2120/is_n8_v75/ai_16541438 (825 words)

	Sexual Dimorphism in a Hummingbird
		dimorphism in size and morphology is widespread in the animal kingdom.
		Although empirical studies demonstrate that the first two mechanisms operate in natural populations, unambiguous examples of ecological causation of sexual dimorphism have been hard to find, because in many animal species, sexual differences in the size of feeding structures scale positively with body size.
		Further evidence for ecological causation of sexual dimorphism (and plant-pollinator coevolution) was provided by a geographic replacement of H.
	www.amherst.edu /~ejtemeles/hummingbirds.html (726 words)

	Effects of sexual dimorphism on facial attractiveness Testosterone
		Testosterone-dependent secondary sexual characteristics in males may signal immunological competence and are sexually selected for in several species.
		In many species, competition between males for the eye of females has resulted in profound sexual dimorphism, the most famous example being the difference between the ostentatious peacock and the drab peahen.
		Because such nurturing traits are associated with femaleness and juvenileness, the appeal of the feminine, youthful look became pansexual, and helped to counter such standard engines of sexual dimorphism as competition between males.
	www.unl.edu /rhames/courses/male_facial_beauty.htm (2023 words)

	[No title]
		Once you push sexual dimorphism out of the picture, it becomes much more difficult to demonstrate that sexual selection has been an operative factor in human evolution.
		True, sexual selection does not increase sexual dimorphism in all the physical characteristics it acts upon.
		Sexual dimorphism will not increase if the physical characteristic has no sex-linked genetic variability and if not enough evolutionary time has elapsed for such variability to build up (through mutations).
	www.arthurhu.com /99/05/asfem.txt (4661 words)

	Flower Bud Abortion Influences Clonal Growth and Sexual Dimorphism in the Understorey Dioecious Shrub Aucuba japonica ... (Site not responding. Last check: 2007-10-11)
		Sexual dimorphisms of the mean number of inflorescences in A.
		Sexual dimorphism and ecological differentiation of male and female plants.
		Sexual dimorphism and resource allocation in male and female shrubs of Simmondsia chinensis.
	aob.oxfordjournals.org /cgi/content/full/89/6/675 (3137 words)

	Sexual dimorphism in diverse metazoans is regulated by a novel class of intertwined zinc fingers -- Zhu et al. 14 (14): ... (Site not responding. Last check: 2007-10-11)
		Sexual dimorphism in diverse metazoans is regulated by a novel class of intertwined zinc fingers -- Zhu et al.
		Sexual dimorphism in diverse metazoans is regulated by a novel class of intertwined zinc fingers
		Sexual dimorphism exhibits a diversity of molecular mechanisms.
	www.genesdev.org /cgi/content/full/14/14/1750 (6950 words)

	Sexual Dimorphism and Mating System: Monkeys, Apes and Humans-Anth 1500
		Sexual dimorphism in body size (as well as canine size) is related to mating system.
		Generally, terrestrial polygynous species (e.g., baboons) are more sexually dimorphic than arboreal polygynous species (e.g., fl and white colobus).
		Frugivores, for reasons that are not clear, are slightly more sexually dimorphic than folivores.
	www.missouri.edu /~anthmark/courses/mah/lectures/sd.htm (202 words)

	[No title]
		I demonstrated that sexual dimorphism in both body size and body shape are also strongly correlated with habitat type.
		Patterns of interspecific divergence are almost always described in terms of one sex only, despite the fact that sexual dimorphism is known from such classic examples of adaptive radiation such as East African cichlid fishes and Hawaiian honey creepers.
		Losos J.B., Butler M.A., and Schoener, T.W. (2002) Sexual dimorphism in size and shape in relation to habitat use in Caribbean Anolis lizards.in Stanley F. Fox, J. Kelly McCoy, and Troy A. Baird (eds.), Lizard Social Behavior.
	web.utk.edu /~mhiga (1065 words)

	Architectural effects mimic floral sexual dimorphism in Solanum (Solanaceae) -- Diggle and Miller 91 (12): 2030 -- ...
		Plants are assigned to one of two treatments; either a treatment in which no flowers are pollinated and fruit are not allowed to mature (no-fruit), or a treatment in which all flowers within inflorescences are pollinated and allowed to mature fruit (plus-fruit).
		is a measure of floral sexual dimorphism (Fig.
		Miller J. Venable 2003 Floral morphometrics and the evolution of sexual dimorphism in Lycium (Solanaceae).
	www.amjbot.org /cgi/content/full/91/12/2030 (5576 words)

	Canine sexual dimorphism in Egyptian Eocene anthropoid primates: Catopithecus and Proteopithecus -- Simons et al. 96 ...
		Canine sexual dimorphism in Egyptian Eocene anthropoid primates: Catopithecus and Proteopithecus -- Simons et al.
		Canine sexual dimorphism in Egyptian Eocene anthropoid primates: Catopithecus and Proteopithecus
		of canine dimorphism and polygyny in anthropoids was not associated
	www.pnas.org /cgi/content/abstract/96/5/2559 (209 words)

	November: Development of the Cerebral Cortex 11. Sexual Dimorphism in the Brain
		In fact, the evidence for sexual dimorphism in the brain is compelling.
		This is a small population of motor neurons located in the lumbar spinal cord that innervates some of the penile musculature in males and is reduced in size or absent in females.
		Moreover, the only reported sex difference in cell death within area X is extremely modest compared with the huge dimorphism in the size of this brain region in adulthood.
	info.med.yale.edu /chldstdy/plomdevelop/development/november.html (1452 words)

	Interaction between the X chromosome and an autosome regulates size sexual dimorphism in Portuguese Water Dogs -- Chase ...
		Interaction between the X chromosome and an autosome regulates size sexual dimorphism in Portuguese Water Dogs -- Chase et al.
		Size sexual dimorphism occurs in almost all mammals.
		Sexual dimorphism is evident as a shift in population
	www.genome.org /cgi/content/full/15/12/1820 (3111 words)

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