Natural Selection and Diversity

Multiple Choice

The opossum, which is native to North

America, and the kangaroo, which is native

to Australia are marsupials.

The fact that both these mammals

incubate their immature offspring in a

pouch provides evidence that they – (if you cannot compare the bones that is not the correct choice)

• belong to the same species

• must range great distances to eat

• have very similar skeletal structures

• are descended from a common ancestor

Multiple Choice

A harmless scarlet king snake and a venomous eastern coral snake have similar band

patterns, as shown below. For the scarlet king snake, the adaptation of having a

banding pattern like the eastern coral snake’s is known as mimicry.

The outcome of this adaptation in the scarlet king snake is to—

• make it easier for the scarlet king snake to attract prey

• make it easier for the scarlet king snake to interbreed with the other snake

• allow the scarlet king snake to blend in with its environment

• protect the scarlet king snake from predators

Natural Selection and Diversity

Ecosystem

​a biological community of interacting organisms and their physical environment.

Ecosystem

Every ecosystem has a __finite____ amount of

resources. There is always a limited amount of

nutrients, water and energy. Because of this

there is a limit to the number of organisms

that can survive.

Carrying Capacity

​The maximum number of a given species that can

survive in a population, based on the amount of

available resources

Multiple Choice

The largest number of individuals that an environment can support long term is...

• carrying capacity

• emigration

• immigration

• population density

Carrying Capacity

When a population exceeds the carrying

capacity, only the organisms with the best

___Adaptations_________ survive and reproduce.

Natural Selection

​The process of the organisms with the

best adaptations surviving and passing

their genes down to their offspring

Multiple Choice

Plants have developed many methods of seed dispersal. The table below shows seeds

of two different plants.

How has the seed dispersal method developed by these plants given them a reproductive

advantage?

• The method ensures that offspring will be dispersed and reduces competition for resources.

• The method reduces the chance that herbivores will consume the seeds.

• The method lengthens the life cycle of each of these plants.

• The method reduces the plants’ need for water and other nutrients.

Natural Selection

Natural selection cannot sense what a

species “needs.” If a population happens to

have the genetic variation that allows some

individuals to survive a particular challenge

better than others, then those individuals

will have more offspring

• Reproductive success

• (How well do your genes fit into your environment)

Fitness

• Term used to describe the variation in our genes

• All of the differences in our DNA (this is why everyone is not exactly the same)

Genetic Variation

Important terms:

Multiple Choice

After examining the fossil record, scientists have determined that scorpions today are

much smaller than their extinct ancestors. For example, Jaekelopterus rhenaniae, a

giant scorpion species that lived 255 million to 460 million years ago, was 2.5 meters

long. Which of the following conclusions is supported by this information?

• Scorpions living today have increased their numbers since they first appeared.

• Scorpions in the fossil record are smaller than their descendants are.

• Scorpions have changed as a result of natural selection.

• Scorpions do not appear in their original state in the fossil record.

Diversity

In order for one organism to be better adapted than

another, there must be ___Diversity______ within the

species. Without ___Variation_______ in the phenotypes of

the organisms, one could not be better adapted

than the other.

Diversity

Differences in the phenotypes (physical appearance)

of organisms like the length of birds’ beaks, the color

of an animal or the shape of a flower are a result of

differences within the ___Genes___ of these organisms.

Allele frequency

​the relative frequency of an allele in a population.

​

(How often we see an allele in a population)​

Ecosystem

This change in the environment allowed the dark

moths to survive and reproduce successfully while

the light moths were eaten. The dark moths were

naturally selected to survive. This caused a change

in the _____population_______, and now in the polluted

forests most moths are dark in color.

Multiple Choice

Genetic variation can aid in the survival of species when the environment changes.

Which of the following is the best example of an organism with a genetic variation that

could improve survival chances over time?

• An ant that is resistant to pesticide

• A wasp that is infected with parasites

• A cactus that has no spines

• A mouse that has learned to avoid mousetraps

Artificial Selection

​an evolutionary process in which humans consciously select for or against particular features in organisms

​Selective Breeding (Artificial Selection)

• Examples: ​Cows with increased levels of milk production, dogs of different sizes, and roses of unique colors are products of selective breeding.

• ​Apples have been selectively bred for many years. Some varieties are sweeter than others while some are bigger and more resistant to disease.

Multiple Choice

Ancient farmers in Mexico took the first steps in domesticating maize when they chose which kernels (seeds) to plant. These farmers noticed that not all plants were the same. Some plants may have grown larger than others, or some kernels tasted better or were easier to grind. The farmers saved the kernels from plants with desirable traits and planted them for the next season's harvest.

This is an example of

• natural selection

• artificial selection

• evolution

• genetic engineering

The alleles in artificial selection

• The alleles must already be present. The DNA does not change.

• Artificial selection causes certain alleles to become more common in the population.

Genetic Engineering

• Changing the actual DNA

• Scientists isolate the DNA strand and then transfer or change it

• Used in research. medicine, agriculture, or industry