Natural Selection

Populations of interbreeding organisms have the ability to change over time and space. This means that the populations living today have different traits with the population that live in the recent past. Moreover, the populations occupying a specific geographical region differ either in behavior or form. Actually, organisms share common ancestors, but over time the populations divide to form different species, though maintaining the common ancestry.

In evolution, natural selection involve species adapting to their environment and subsequent evolutionary change as the individuals with the specific character trait stands a grater reproductive and survival rate than other individuals without the trait in the same population. Species genes can pool and adapt to enhance long term survival through their off-springs. This paper presents finches to explain natural selection.

Galapagos finches

Finches can feed in various ecological niches as a result of adaptation. Over timed, the beaks of finches have evolved to suit their functions most. The beaks of finches who feed on grubs are usually thin and extended in order to poke into the ground effectively to extract the grub. For finches who feed on fruits and buds such beaks would not be effective rather, they have parrot-like beaks that are capable of grinding down food. (Darwin, 1959). This means that in an environment where the fruits and buds are the only available sources of food, they stand a better selective advantage than the finches with thin extended beaks. Some finches have slender beaks that enable them to feed also on small insects especially insect larvae found in the woods just like the woodpeckers. Every Galapagos island has a different type of the fourteen types of finches. The finches are specific habitants of the islands as they are not found in any other part of the world. Though the finches that occupy the Galapagos are a mixture of tree finches and ground dwellers, they have diversified into different ecological niches to ensure coexistence of multiple species. Basing this on the natural selection, the Galapagos finches underwent adaptive radiation which modified them from the original colony that lives in South America, about 600 miles way. This means that the Galapagos finches moved to the island to escape the competition for resources, and after settling in the island probably because there was little or no competition, they continually adapted in order to benefit from the resources available in the island. (Darwin, 1959). This trait is passed from one generation to another as the adaptation encourages reproduction within the population and subsequent competition for the available resources.

Finches with parrot-like beaks are favored   along generations in the struggle for resources- in this case food, there by changing the frequency of the traits in finches population.  Natural selection operates in finches beaks as they have heritable variation giving the finches with the claws advantage over the ones with thin and extended beaks in the competition for food.  As the finches compete for food, they adapt inhabitants of every ecological region in relation to their associates perfection.

 Natural selection is predictable and antithesis of chance. It therefore means that in an environment with plenty fruits and buds and no seeds, insects or grubs, finches with parrot like beaks are better placed as they can feed on the fruits and buds effectively unlike other finches in the same population.  (Futuyma, 1986).


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