Natural vs Artificial Selection Worksheet

Theory of Evolution: different species have developed over time from other life forms
Natural Selection: the natural process by which characteristics of a population change over many generations as organisms with heritable traits survive and reproduce, passing their traits to offspring.
Selective Pressure: biotic or abiotic conditions that select for certain characteristics and against other characteristics in individuals of a species.
Artificial Selection: humans choose which individuals in a population will survive and reproduce future generations - also called selective breeding
Gene Pool: all the genes and their different alleles, found within a population
Monoculture: the same varieties of species are planted over large areas of land
Gene Banks: an area where the genome (whole genetic make-up) of artificially selected species have been stored, in case genes that have been selected against wish to be brought back into a population that has been cultured using selective breeding.

Describe the process of natural selection.

Individuals in a species show a wide range of variation and this variation is because of differences in their genes.
Individuals with characteristics most suited to their environment are more likely to survive and reproduce. The genes that allow these individuals to be successful are passed to their offspring.
Those that are poorly adapted to their environment are less likely to survive and reproduce. This means that their genes are less likely to be passed on to the next generation.
Given time, a species will gradually evolve.
Both genes and the environment can cause variation, but only genetic variation can be passed on to the next generation.

Give two examples of biotic factors and two examples of abiotic factors that may cause selective pressure on a population of deer in a forest.

Biotic: the amount of food available in the area - e.g. the abundance of grass; the number of predators like wolves living in the area

Abiotic: the availability of water, the temperature

Will natural selection always allow a species to survive in a certain environment? Explain why or why not.

No because as the environment changes over time, certain traits may mean the species adaptations are no longer suitable for the new environment. This may result in the individuals with those traits disappearing over time as they are replaced with new individuals who have mutations that create variations that are better suited to the new environment.

Compare one similarity and one difference between natural and artificial selection.

Similarity - certain traits are selected for either by nature, or by humans

Difference - nature does the choosing in natural selection and humans do the choosing of traits in artificial selection

List three reasons why humans use artificial selection to breed certain species.

They may want an animal to produce more meat or milk (more robust product from animals)

They may want a plant to be more drought resistant

They may want a plant to be more resistant to pests like insects.

Artificial selection can often provide better quality products with increased nutritional value or taste, and/or allow farmers to make more money off of their products

Explain why artificial selection is not always a good idea. Support your answer with two specific examples of how artificial selection has disadvantaged a species.

Artificial selection can mean a population contains individuals that are all the same. As a result if they are affected by disease, they may all die off.

There is also a loss of alleles as a population is artificially selected, which can mean certain traits are lost forever.

E.g. English bulldogs have respiratory problems which could be a side effect of artificial selection for certain facial features; chickens have become much larger due to selective breeding which has led to heart problems