Factbites
 Where results make sense
About us   |   Why use us?   |   Reviews   |   PR   |   Contact us  

Topic: Sexual reproduction


Related Topics
Sex

  
  Stayin' Alive
Understanding why sexual reproduction is so strongly maintained, and is so nearly ubiquitous among the eukaryotes and particularly the metazoa, is actually very helpful in thinking about how it got started, so let me begin with the easier question.
It seems, at first, that sexual reproduction is a big disadvantage.
Sexual selection pressure can drive evolution in odd directions, such as making big showy tails that attract predators and slow you down, or investing a lot in unproductive behaviors.
healthvsmedicine.blogspot.com   (9139 words)

  
  Sexual Reproduction: A Continuing Mystery to Evolutionists
Scientific explanations that could account for the maintenance of sexual reproduction in some species usually have no influence on asexual organisms from which their sexual descendents were supposed to have evolved.
The process of sexual reproduction involves the formation of gametes (eggs and sperm) that involves the halving of chromosomal pairs.
Evolutionists have traditionally explained the existence of sexual reproduction as a means to promote genetic variability and, therefore, increase the rate of evolution.
www.godandscience.org /evolution/reproduction.html   (1663 words)

  
 Search Results for "Sexual reproduction"
sexual reproduction The production of a new living thing by two parent organisms, with each parent contributing half the material in the DNA of the offspring.
...of the reproductive process vary tremendously, two fundamental types may be distinguished; asexual reproduction, in which a single organism separates into two or...
...breeding, in agriculture and animal husbandry, propagation of plants and animals by sexual reproduction; usually based on selection of parents with desirable traits...
www.bartleby.com /cgi-bin/texis/webinator/sitesearch?FILTER=&query=Sexual+reproduction   (251 words)

  
 Genetic segregation and the maintenance of sexual reproduction
SEXUAL reproduction confronts evolutionary biology with a paradox: other things being equal, an asexual (all-female) population will have twice the reproductive potential of a competing sexual population and therefore should rapidly drive the sexual population to extinction
Segregation in a diploid sexual population allows selection to carry a single advantageous mutation to a homozygous state, whereas two separate mutations are required in a parthenogenetic population.
Calculation of the selective load incurred suggests that it may offset the intrinsic twofold reproductive advantage of asexual reproduction and maintain sexual reproduction in diploid populations.
www.nature.com /nature/journal/v339/n6222/abs/339300a0.html   (263 words)

  
 Evolution: Library: The Red Queen
Vrijenhoek found that the genetic diversity produced by sexual reproduction allowed the sexual fish to survive a parasite more successfully than the asexual fish.
Invoking the Red Queen hypothesis, Vrijenhoek suggests the sexual populations are able to keep up or adapt to new selective challenges, while the asexual populations, essentially clonal, are not.
When reproduction is sexual, half of the genes handed on to the next generation are those of the other parent.
www.pbs.org /wgbh/evolution/library/01/5/l_015_03.html   (496 words)

  
 Sexual Reproduction
Sexual reproduction is the formation of a new individual following the union of two gametes.
The responsibility of the female mammal for successful reproduction is considerably greater than that of the male.
Physiological changes occur in the female as well as the male in response to sexual excitement, although these are not as readily apparent.
users.rcn.com /jkimball.ma.ultranet/BiologyPages/S/Sexual_Reproduction.html   (3512 words)

  
 Evolution and Sex
Asexual reproduction is the formation of new individuals from cells of only one parent, without gamete formation or fertilization by another member of the species.
In certain lower forms of animals (e.g., hydra), and in yeasts, budding is a common form of asexual reproduction as a small protuberance on the surface of the parent cell increases in size until a wall forms to separate the new individual (the bud) from the parent.
Sexual reproduction, on the other hand, would be like purchasing a small number of tickets, but giving each of them a different number.
www.trueorigin.org /sex01.asp   (5451 words)

  
 sexual reproduction - OneLook Dictionary Search
Sexual reproduction : InfoVisual Visual Dictionary [home, info]
Sexual reproduction : Biological Sciences Dictionary [home, info]
noun: reproduction involving the union or fusion of a male and a female gamete
www.onelook.com /?w=sexual+reproduction&ls=a   (211 words)

  
  ThinkQuest : Library : Sexual Reproduction
Genetics is followed by the physiology of reproduction, from the production of gametes to the birth of the baby.
The SR2000 (Sexual Reproduction 2000) web-site was created to provide you with a better understanding of human reproduction from a clinical aspect.
You can explore the anatomy of the human sexual organs and the development of a foetus within the womb from fertilisation to birth.
www.thinkquest.org /library/cat_show.html?cat_id=464   (200 words)

  
  Reproduction - MSN Encarta
Reproduction is one of the essential functions of plants, animals, and single celled organisms, as necessary for the preservation of the species as eating is for the preservation of the individual.
The typical male reproductive cell, which is known as a sperm, spermatozoon, or spermatozoan, is a motile cell with a head containing the nucleus and a whiplike tail with which it swims.
Plant reproductive cells are roughly similar to animal cells, the male cell being known as the sperm or microgamete and the female cell as the ovum or macrogamete.
encarta.msn.com /encyclopedia_761572784/Reproduction.html   (697 words)

  
  Sexual reproduction - Wikipedia, the free encyclopedia
Sexual reproduction is a type of reproduction that results in increasing genetic diversity of the offspring.
Sexual reproduction is the primary method of reproduction for the vast majority of visible organisms, including almost all animals and plants.
Sexual reproduction may persist because of selection pressure on the clade itself- the ability for a population to radiate more rapidly due to a changing environment through sexual recombination than parthenogenesis allows.
en.wikipedia.org /wiki/Sexual_reproduction   (1282 words)

  
 Biological reproduction - Wikipedia, the free encyclopedia
Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction.
Sexual reproduction is a biological process by which organisms create descendants that have a combination of genetic material contributed from two (usually) different members of the species.
In addition, sexual reproduction usually results in the formation of a life stage that is able to endure the conditions that threaten the offspring of an asexual parent.
en.wikipedia.org /wiki/Reproduction   (1499 words)

  
 reproduction - Encyclopedia.com
Although the methods and complexity of the reproductive process vary tremendously, two fundamental types may be distinguished; asexual reproduction, in which a single organism separates into two or more equal or unequal parts; and sexual reproduction, in which a pair of specialized reproductive (sex) cells fuse.
Sexual reproduction is essentially cellular in nature, i.e., it involves the fertilization of one sex cell (gamete) by another, producing a new cell (called a zygote), which develops into a new organism.
Sexual reproduction is of great significance in that, because of the fusion of two separate parental nuclei, the offspring inherit endlessly varied combinations of characteristics that provide a vast testing ground for new variations that may not only improve the species but ensure its survival.
www.encyclopedia.com /doc/1E1-reproduc.html   (1310 words)

  
 Reproduction - ninemsn Encarta
Reproduction is one of the essential functions of living organisms, as necessary for the preservation of the species as food getting is for the preservation of the individual.
The typical male reproductive cell, which is known as a sperm, spermatozoon, or spermatozoan, is a motile cell with a head containing the nucleus and a whip-like tail with which it swims.
Plant reproductive cells are roughly similar to animal cells, the male cell being known as the sperm or microgamete and the female cell as the ovum or macrogamete.
au.encarta.msn.com /encyclopedia_761572784/Reproduction.html   (643 words)

  
 Asexual reproduction Summary   (Site not responding. Last check: )
The technical term for asexual reproduction in plants is apomixis, derived from apo meaning "without," and mixis meaning "mingling." Apomixis thus refers to the fact that asexual reproduction lacks the mixing of genes that occurs in sexual reproduction.
In normal sexual reproduction, offspring are genetically different from either of the parents, and as a result new traits may be introduced into the population.
Sexual reproduction involves the fusion of two gamete cells (the sperm and ova) which each have half the normal number of chromosomes, a result of reduction division known as meiosis.
www.bookrags.com /Asexual_reproduction   (2189 words)

  
 Sexual Reproduction
Furthermore, the sexually reproducing female contributes only 50% of her genes to the egg, and this contribution is "diluted" in its influence by the male contribution to the offspring.
It is not surprising, therefore, that he saw one advantage of sexual reproduction in terms of its effect on the "load of mutations" in a population.
The reason is that sexual reproduction is a basic fact of life on this planet, and it is almost impossible to conduct either controlled experiments or systematic observations where the only factor is sexual vs. asexual reproduction.
www.towson.edu /~scully/sex.html   (3130 words)

  
 Sexual reproduction - EvoWiki   (Site not responding. Last check: )
Sexual reproduction is a reproductive strategy used by some organisms in which genetic material from two different individuals contribute DNA to offspring.
This reproductive strategy can be compared to reproduction in which all of the DNA of new individual members of a species is derived from a single parental organism.
The evolutionary advantage from sexual reproduction is largely due to special alterations in chromosomes that happen during meiosis.
wiki.cotch.net /index.php/Sexual_reproduction   (233 words)

  
 Sexual intercourse help – Wiki at Help.com   (Site not responding. Last check: )
Sexual intercourse typically plays a powerful bonding role; in many societies it is normal for couples to have frequent intercourse while using birth control, sharing pleasure and strengthening their emotional bond through sex even though they are deliberately avoiding pregnancy.
Sexual intercourse is also defined as referring to any form of insertive sexual behavior, including oral sex, as well as anal intercourse.
Coitus may be preceded by foreplay, which leads to sexual arousal of the partners, resulting in the erection of the penis and natural lubrication of the vagina.
www.help.com /wiki/Sexual_intercourse   (334 words)

  
 Reproduction in Aquarium Corals by Eric Borneman - Reefkeeping.com
First, for some events, it is reproduction of a species that has never been witnessed, documented, or known in the wild and serves as an important observation for general understanding of the nature of sexual reproduction in that species.
Sexual reproduction requires the fusion of male and female gametes (sperm and egg) that form a zygote which grows into an embryo that develops into a free-swimming larva called a planula.
Sexual and asexual reproduction of the tropical Corallimorpharian Rhodactis (=Discosoma) indosinensis (Cnidaria: Corallimorpharia) in Taiwan.
www.reefkeeping.com /issues/2003-05/eb/index.php   (4956 words)

  
 Biological reproduction Summary   (Site not responding. Last check: )
Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction by an antecedent.
Sexual reproduction is a biological process by which organisms create descendants that have a combination of genetic material contributed from two (usually) different members of the species.
In addition, sexual reproduction usually results in the formation of a life stage that is able to endure the conditions that threaten the offspring of an asexual parent.
www.bookrags.com /Biological_reproduction   (4174 words)

  
 The Evolution of Sexual Reproduction
First let's note that what we mean by sexual reproduction is reproduction in which different individuals combine genetic material to produce offspring so that offspring are not genetically identical to their parents, and not all of a parent's genes get passed on to an offspring.
So since sexual individuals have the alleles that code for sexual reproduction and asexual individuals have the alleles that code for asexual reproduction, the allele for sex gets passed from generation to generation at half the rate of the allele for asexual reproduction.
Since sexual reproduction is generally subject to the two-fold cost to sex, and is sometimes subject to additional costs, we would predict asexual reproduction to evolve through individual selection too fast for group selection to cause sexual reproduction to evolve.
www.utm.edu /departments/cens/biology/rirwin/391/391SexEvol.htm   (1201 words)

  
 Sexual Reproduction
Furthermore, the sexually reproducing female contributes only 50% of her genes to the egg, and this contribution is "diluted" in its influence by the male contribution to the offspring.
It is not surprising, therefore, that he saw one advantage of sexual reproduction in terms of its effect on the "load of mutations" in a population.
The reason is that sexual reproduction is a basic fact of life on this planet, and it is almost impossible to conduct either controlled experiments or systematic observations where the only factor is sexual vs. asexual reproduction.
pages.towson.edu /scully/sex.html   (3130 words)

  
 Mycology - Reproduction and Dispersal - Sexual Structures
Sexual reproduction in the Euascomycetes is basically similar across all groups.
Sexual reproduction is suggested to provide a mechanism to remove unwanted mutations during the meiotic process.
By utilising asexual reproduction, fungi increase chances of dispersing, with the reduction in mutations associated with sex irrelevant because so many propagules are dispersed, and selection is immediate because the genome is haploid.
bugs.bio.usyd.edu.au /Mycology/Reprodn_Dispersal/sexualStructures.shtml   (1314 words)

  
 Sexual reproduction
In Malthusian Relativity the evolution of sexual reproduction is given by the evolution of the interacting, reproducing, and sexual units.
To allow for the evolution of larger sexual units Malthusian Relativity applies a model where the sexual unit with three individuals is a unit with a single female and two males with each of the three individuals allocating one third of their heritable code to the offspring.
Sexual units with more than two individuals are not expected to evolve for the case of sexually produced offspring workers because the interactive quality of the male is transferred to the sexually produced offspring workers.
www.peregrine.dk /subjects/SEXRE.HTM   (1920 words)

  
 CiteULike: Sexual selection and the maintenance of sexual reproduction.   (Site not responding. Last check: )
The maintenance of sexual reproduction is a problem in evolutionary theory because, all else being equal, asexual populations have a twofold fitness advantage over their sexual counterparts and should rapidly outnumber a sexual population because every individual has the potential to reproduce.
The continued prevalence of sexual reproduction indicates that the 'all else being equal' assumption is incorrect.
The fitness of sexual females is higher than asexuals because there is no difference in the fecundity of sexual females and asexuals of the same genotype, but the equilibrium frequency of deleterious mutations is lower in sexual populations.
www.citeulike.org /user/stevanspringer/article/547060   (541 words)

Try your search on: Qwika (all wikis)

Factbites
  About us   |   Why use us?   |   Reviews   |   Press   |   Contact us  
Copyright © 2005-2007 www.factbites.com Usage implies agreement with terms.