Natural Selection/ Evolution

8.L.4.1 Summarize the use of evidence drawn from geology, fossils, and comparative anatomy to form the basis for biological classification systems and the theory of evolution.

8.L.4.2 Explain the relationship between genetic variation and an organism’s ability to adapt to its environment.

Populations in a particular environment that have adapted to living conditions in that specific area are therefore better able to meet their survival needs and are more likely to survive and reproduce offspring with those key survival traits.

An adaptation is a trait or behavior that helps an organism survive and reproduce.
- Traits are genetic differences that occur in a species. Traits are developed as a species adapts to its environment.
- Organisms of a species differ from one another in many of their traits.
There can also be variations among species of similar populations. Variations are changes in the genes among members of the same species.
- Variations can occur both randomly and as a result of a trait being more fit for an environment.
Natural selection is the process that explains this survival and shows how species can change over time.
- For example, certain traits or adaptations involving color, camouflage, food gathering (beaks and claws) and other physical traits, sensory abilities, or behaviors enhance the survival of a species.

Physical Adaptations/Traits

Color
Camouflage

(adaptation that allows animals to blend in with certain aspects of their environment.)

Beaks (food gathering)
Claws (food gathering, protection)
Sensory abilities (sight, smell, taste, touch, hearing)
Mimicry (close external resemblance of an animal or plant (or part of one) to another animal, or plant generally to avoid or deter predators)

Behavioral Adaptations

Migration
Hibernation
Traveling in herds
Hunting in packs
Nocturnal (active at night)
Instincts (running, hiding, building nests)
Learned behaviors

Time Tree

TimeTree is a public knowledge-base for information on the evolutionary timescale of life. Data from thousands of published studies are assembled into a searchable tree of life scaled to time.

Bajau people 'evolved bigger spleens' for free-divingIn an example of human natural selection, Asia's Bajau people have evolved bigger spleens for diving.

More humans born with an extra artery as part of ‘microevolution’ phenomenonHumans are undergoing a “microevolution” resulting in babies being born without wisdom teeth and with an extra artery in their arm, according to Australian researchers. The scientists b…

It provides an opportunity for students to analyze amino acid data and draw conclusions about the evolution of coat-color phenotypes in the rock pocket mouse. Students review key concepts and mechanisms of evolution, including mutation, gene flow (or migration), genetic drift, and natural selection

DNA Mutations Are Not Random: New Research Radically Changes Our Understanding of Evolution

New Research changing ideas on Natural Selection as we know it.

Climate Effects on Human Evolution

This article explores the hypothesis that key human adaptations evolved in response to environmental instability. This idea was developed during research conducted by Dr. Rick Potts of the Smithsonian’s Human Origins Program. Natural selection was not always a matter of ‘survival of the fittest’ but also survival of those most adaptable to changing surroundings.