Tuesday, December 20, 2011

SEX and proliferation



Sex is a very intriguing subject. Sex has become an advantageous means of procreation; combining two genomes so that the offspring has the best possible combination of alleles that will be beneficial for their survival and reproduction. Darwin introduced descent with modification, and modern science has revealed DNA to be the physical means of heredity. Armed with this knowledge, one might suspect sex to be the shiznit of strategies, and I believe it is one of the best certainly. But species have existed and remain in existence today who do not participate in this activity.. how is that possible?  

A-sexual species produce genetically identical copies of themselves, clones, and if they have all the alleles in their DNA that they need to perform physical processes they're set. Archaea bacteria are a great example, the little guys survive in 150 degree + hot springs and chug along doing what there doing like they have for millions of years.  

Hermaphrodites have the ability to produce both types of gametes needed for fertilization, sperm and eggs, fish are often hermaphroditic. They are born as males and develop testes, store the sperm, and if the environment is right for reproduction they will devote their energy to forming ovaries and eggs, which they then self fertilize.  

So these strategies, each fascinating and unique, have been developed to propagate ones genes in the big scheme of evolution. I love evolution, sex is pretty interesting, and this article below is awesome. It discusses each of the means of procreation in the context of Darwin's theories combined with advances in modern science, check it out!

Clones, hermaphrodites and pregnancies: nature's oddities offer evolutionary lessons on reproduction

J.C. Avise. Article first published online: 11 OCT 2011. DOI: 10.1111/j.1469-7998.2011.00869.x. 2011 The Author. Journal of Zoology. 2011 The Zoological Society of London

Abstract:
I love the term ‘natural history’ because it encapsulates the sentiment that nature's operations have evolutionary etiologies. Charles Darwin was a natural historian par excellence and his elucidation of natural selection, artificial selection, and sexual selection fundamentally changed how scientists interpret the origins of biological features previously ascribed to sentient craftsmanship by supernatural agents. Darwin's insights on evolutionary forces grew from his exceptional knowledge of natural history, yet two key topics steeped in natural history – sex and reproductive genetics – remained poorly understood (and probably even shunned) in Darwin's Victorian era. That situation changed dramatically in the latter half of the 20th century with societal awakenings about sexuality that also happened to coincide with the introduction of molecular parentage analyses that unveiled a plethora of formerly hidden ‘sexcapades’ throughout the biological world. Here I summarize some of the evolutionary revelations that have emerged from selection theory as applied to genetic and phylogenetic information on clonality, hermaphroditism, and pregnancy, three procreative phenomena that are relatively rare in vertebrate animals and thus offer alternative evolutionary perspectives on standard reproductive modes. Collectively, these three peculiarities of nature illustrate how the abnormal in biology can enlighten evolutionary thought about the norm.

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