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Natural
 In A Nutshell |
(cough, preservation, cough)
I do find some people have misunderstandings of Darwin's theory due the term "Natural Selection". Darwin chose this from an analogy to "Artificial Selection" as seen in farming which everyone at the time understood and could relate to. The "Natural" part is fine. It's "Selection" that is misleading. It really isn't a selection at all. Selection connotes or implies a conscious, observing, selector with intent. However, in nature, as Darwin was describing it is more a kin to "preservation by circumstance" rather than an active selection process. And contingency plays a big role.
Ok. I'm done with my rant now,
on to...
THE 5 CONDITIONS IN WHICH NATURAL SELECTION TAKES PLACE  |
1. Life is not easy.
No matter the means to survive, you have to hustle to live.
Clearly, all the resources for living are not of infinite availability or supply. This creates a condition that Darwin called a struggle for existence. One must struggle in varying degrees with the conditions of the environment, such as heat, cold and the weather, as well as in varying degrees there are situations where one struggles in competition with other beings. However, there can be advantages in cooperating as well.
You must put forth some effort in order to live, eat and reproduce.
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| 2. Bad Stuff happens.
In order to maintain continuity of the lineage there must be an excess of offspring produced to offset natural and unexpected loss.
Life is a struggle and not everybody survives this struggle with enough offspring to continue their line.
Death, it happens. Predators, competition, old age and illness are vulnerabilities that could be more immediately fatal to the mal-adapted. And death comes not only to the ones unsuitable to the conditions. Sometimes it happens through no fault or defect or deficiency. Natural disasters like volcanoes, don't always seem to be so fussy who's in the way. There are no guarantees that even those in harmony or suitable to the living conditions are going to avoid failure to reproduce into the future due to stochastic events. Asteroids and dinosaurs.
Therefore, those that reproduce in greater number than needed solely to replace the individuals will likely have better chances of having offspring surviving into the future.
Life is not a sure thing but death is. No one survives forever.
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3. Variation happens.
Whether reproduction is asexual or sexual, variation inevitably exists in the population.
The offspring from reproduction have a constitution and appearance that is similar but not identical in every way to the parent. Variation in asexual organisms that produce clones and sexual organisms can be the result of copy error, point mutations, environmental mutagens and more.
In sexual creatures, the offspring are a new recombination of genes from both parents. Variation in genetic composition and/or phenotype can occur by factors in the environment before (developmental), before/after birth of the offspring (epigenetics) and of course during (lifetime conditions).
Variation exists in the offspring, they are not exact copies.
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| 4. Stuff gets handed down.
Offspring get their genes and the recombined traits of those genes from their parents.
Whether sexual or asexual, parents contribute to the genes of their progeny. In sexual reproduction, a mix or recombination of the parental genes are present in the descendants and are passed then passed on, recombined, passed on. Genes that make certain traits possible can and may be there in the offspring in a dominant state that is always expressed or a recessive state where expression depends being diploid with another recessive allele. Mind you, they will in some measure be present in the offspring of their relatives and in the population. A type of fitness that is known as inclusive fitness.
Offspring traits and variations are inherited from the parent(s). |
5. Good stuff happens.
Some traits will be adaptive and enhance the individual's ability to survive and reproduce.
All things being even, sooner or later, a small advantage improves the individual's chances of contributing to posterity. Some of the variations will have a quality that assists in the struggle of life, others assist in covert ways. Nonetheless if there is any opportunity which gives even the most minute advantage in reproduction of the individual's traits, that's an "evolutionary" good thing.
Inherited variation will sometimes be better suited to ecology.
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Science and Rigor
Have fun, play safe
MU-Peter Science
© 2016 MU - Peter Shimon
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