Grade 8: Diversity of Life

What occurs through gradual processes over many generations?

Diversity of species

What provides evidence that changes have occurred in number and type of species?

Fossil records

3 results of mutations

1. beneficial for the organism

2. harmful for the organism

3. no effect on the organism

evolution

the process by which populations change over time

4 parts of Darwin's theory of natural selection

1. Overpopulation

2. Inherited Variation

3. Selection (Struggle to Survive)

4. Reproduction

Overpopulation

more offspring are produced than will survive

Inherited Variation

offspring have different traits from each other and the parents

Selection (struggle to survive)

offspring that are best suited to the environment survive to adulthood

Reproduction

offspring that survive to reproduce and pass on their adapted traits

Charles Darwin

a naturalist who proposed that most evolution happens through the natural selection of advantageous traits

extinction

-occurs when all members of a species have died

-99% of species in Earth's history have become extinct

species

a group of organisms that can mate with one another to produce fertile offspring

mass extinction

periods of time in which the extinction rate rises abruptly (such as sudden global climate change, global catastrophic events like meteorite impact)

fossil record

-timeline of life provided by the remains or imprints of dead organisms

-provides evidence that changes have occurred in number and type of species

transitional form

term used to describe parts of the fossil record that are incomplete for an animal's ancestry

What has been analyzed to provide evidence that all animals share a common ancestor?

DNA, fossil records, comparing inherited traits

selective breeding

-mating animals so their offspring will inherit desired traits

-process used to change a plant's characteristics to be more productive

adaptation

-change in behavior or physical appearance in response to changes in the environment

-an inherited trait that helps an organism survive and reproduce

What did Darwin not know about when he came up with his theory of natural selection?

genetics; Modern evolutionary theory includes ideas of natural selection and genetics.

What increases the likelihood that some individuals will have the characteristics necessary to survive environment changes?

genetic diversity

antibiotic resistant bacteria

due to increased use of antibiotics in the past, natural selection has caused bacteria that undergo mutation to become resistant to an antibiotic and then survive to increase in number

"The Great Dying"

refers to a large extinction event that took place 250 million years ago causing 90-96% of all animals to go extinct during a short period