12 Weeks to TAKSWeek 3

Objective 3 8a-b, 13a

Adaptation and Evolution of Plants and Animals

All animals and plants have adaptations that help them survive in their environment. Examples of Plant Adaptations:

Support/food storage: Above ground (prop) roots, Stiff cell walls in stems and trunks (vascular tissue that also carries water and food), Starch storage in roots.

Prevention of water loss: Waxy cuticle, stomata on leaves, reduced leaf surface area (cactus), seed coats.

Reproduction: Seed dispersal by wind and animals, colors to attract pollinators, pollen, coevolution with insects.

Defense: Toxins, thorns, bark.

Examples of Animal Adaptations:Protection and prevention of dehydration: exoskeletons, armor, scales, skin, kidneys.

Defense/Predation: Claws, teeth, well developed eye lens, sense of smell, speed, camouflage, armor, mimicry.

Reproduction: Eggs, internal fertilization, placentas, care of young, nesting.

Life is very Diverse. Diversity is a measure of how many different types of organisms live in an area. For example, a rainforest is a very diverse habitat (many different species of insects, plants and animals). A desert is not as diverse (lots of the same kind of cactus and a few species of animals). A species is a group of animals that can breed and produce fertile offspring. (Poodles and Dalmatians can make Doodles/Palmations. They are the same species. Lions and tigers are not. There are no ligers/tions)

Populations of animals adapt to their environment by Natural Selection.

1.All species have variations (caused by genetic makeup…Mutations can cause variation).

2. Variation is inherited.

3. More species are produced than will live.

4. Those species that survive to reproduce will pass their characteristics (genes) on to the next generation those that don’t become extinct.

5. Over time, characteristics and behavior that allow the species survive are “selected” for. Unfavorable traits won’t be passed on.

If two populations of organisms become separated by a barrier, each separate group may have different selection pressures on it and change in different ways. Eventually they may not be able to reproduce and become separate species. This process is called speciation.

Phylogenetic Trees are diagrams that show the relatedness (Phylogeny) of organisms based on physical and chemical similarities.

100mya

Present

A

B

C D E F G

A is the common ancestor. B is extinct. E and F are the most closely related.

Scientist look at both physical and biochemical similarities (like DNA and protein comparisons) to see how organisms are related. Which two organisms in this chart are the least related?The silkworm moth and the screwworm fly.

Polar bears and brown bears have the most bands of DNA in common and are the most closely related. Brown and Black bears share 4 bands out of 9 total. (44.4%)