Artificial Selection and Natural Selection

INSTRUCTIONS:

Read the information below and summarize what you learned/important concepts/ideas!

Types of Selection

There are two types of Selection relating to the Theory of Evolution:

Artificial Selection

Natural Selection

Artificial Selection

Artificial Selection – selective pressure exerted by humans on populations in order to improve on or modify particular desirable traits.

Artificial Selection can be used for both plant and animal species.

Artificial Selection is a type of Biotechnology.

Biotechnology – the use of technology and organisms to produce useful products

Like all technologies, there are Pros and Cons to Artificial Selection:

Pros:

Can improve/modify desired traits to produce a superior breed

Eliminate/control diseases

Can result to an increase in production/yield

Cons:

Lack of genetic diversity can result

Unanticipated consequences of encouraging a specific trait

Quality of life is often reduced

Natural Selection

Natural Selection – the process by which characteristics of a population change over many generations as organisms with heritable traits survive and reproduce, passing their traits to offspring

The way in which the environment (nature), favours the reproductive success of certain individuals over others.

Who Came Up With the Theory of Natural Selection?

Charles Darwin is credited with the Theory of Natural Selection! 

In 1859, Darwin published his book, “The Origin of Species”.

Key Points from The Origin of Species Individuals within a species vary in many Populations of a species tend to remain "SAEM stable (in numbers). 2 Some of this variability can be inherited. 5 Members of the same species compete with each other for survival. Every generation produces far more offspring Individuals with more favourable variations than can survive and pass on this variability. are more likely to survive and pass these traits on – survival is not random! With succeeding generations, these favourable variations will become more common in the population.

Natural Selection

While humans are the ones who control Artificial Selection, Natural Selection is instead controlled by the biotic and abiotic environmental conditions/factors.

In Natural Selection, the environment exerts selective pressure on a population.

Natural Selection is situational – there is no will, purpose, or direction to it!

A trait that at one time in one situation seems to have no apparent relevance to survival may be the trait that, at a different time and situation, helps individuals in a population survive and reproduce!

The Allele for the trait will then be inherited, resulting in more individuals who possess that trait!

Selective Pressure

Selective Pressure – the environmental conditions that select for certain characteristics of individuals and select against other characteristics.

Fitness:

When talking about Natural Selection, you may hear the term “Fitness” being used.

Fitness – contribution an individual makes to the next generation by producing offspring that survive long enough to reproduce.

When talking about Natural Selection, you may hear the term “Fitness” being used.

Fitness – contribution an individual makes to the next generation by producing offspring that survive long enough to reproduce.

An organism with many viable offspring is considered to have a “high fitness”.

An organism with few or no viable offspring is considered to have a “low fitness”.