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Natural Selection

Natural selection refers to the varying frequency of genes in a population because of the differential success in reproduction and survival of different genotypes. The traits which are the most common in a population are the traits originating from the predecessors which left the most descendants. This is the result of natural selection in action.   

Natural selection is the primary driving force of evolution. It is a mechanism which causes diversity in different environments.  Although the concept was first introduced by Charles Darwin in 1859, it wasn’t until around the 1930s that biologists begun to accept this theory.  

The ability of natural selection to drive evolution depends on their being variation between individuals and this variation needs to be heritable. There is variation in the behavioural, morphological and physiological traits of organisms and these are traits which all affect survival. Thus, natural selection can act on all of these traits.

Evidently natural selection acts on traits, not on individuals or the population at large. Natural selection favours the traits which are advantageous and promote an individual’s ability to survive and reproduce. It is these traits which get selected for and passed on through natural selection. Although genetic variation comes from mutations, sexual reproduction and the interaction between genes and the environment, it is natural selection promoting which genes become the most common over subsequent generations.

Furthermore, natural selection is also an observable phenomenon. Bacterial resistance to antibiotics is an example. Bacterial infections are fought with antibiotics, but sometimes, especially when the duration of the drug is short, some bacteria will have randomly obtained mutations making them less susceptible to the drug. Once the drug is stopped, if these bacteria survive, natural selection will favour these new traits increasing microbial resistance for that drug. 

The process of natural selection as defined by Darwin

Discuss the process of natural selection as defined by Darwin. How did Darwin's theories differ from those of his predecessors? In your opinion, have his theories proved to be correct? Why and why not? Discuss how the various "agents" of change can lead to a new species.

Natural Selection Problems

In a population of 1,500 wild rabbits found along the coast of Oregon, dark brown fur (B) is dominant to tan fur (b). Genetic analysis of the population revealed the following genotypic frequencies: 750 BB, 450 Bb, 300 bb 1) Suppose that the tan rabbits fitness is 9% less that dark brown rabbits. What is the selection co

Put in proper order to reflect how natural selection works

Which of the following shows events in the proper order to reflect how natural selection works? Permethrin is used to kill lice; individual lice change in order to survive; most lice become resistant to permethrin. A louse population evolved resistance to permethrin; permethrin is is used to kill lice; lice become mo

Dobzhansky's Experiments and Natural Selection

1. Briefly explain what is meant by the terms directional selection, stabilizing selection, and disruptive selection. Give an example of each. 2. Dobzhansky's laboratory experiments studying mating behavior evolution in the fruit fly Drosophila subobscura provided a striking example of how natural selection operates. Describe t

Animal Behavior: natural selection, proximate/ultimate causes, types of learning

(1) Explain the process of natural selection that has resulted in large antlers. Mention the three requirements for natural selection. (2) Differentiate proximate and ultimate causes of behavior. (3) Which of the various types of learning is occurring in my dog [see attachment for the example]. See attached file for fu

Natural selection

1. Who were a three scientist whose work was fundamental to Darwin's theory? How did their thinking influence his? 2.Vestigial Organs and Embryology are types of evidence that support the theory of natural selection. How each support the theory of natural selection?

Problem Set

1. A population of Madagascar hissing cockroaches lives in a woodpile. It suffers heavy predation from lizards, which pull the roaches out of their hiding places. The largest adults are not able to fit into most of the cracks in the wood, and are hunted down mercilessly, and the smallest adults are easily pried out of their crev