AP Bio - Chapter 19

What is indicated by the hatch marks?

A homologous characteristic shared by all groups to the right of the mark. Ex. 4 chamber hearts.

Charles Darwin proposed that the mechanism of evolution is natural selection and that it explains how adaptations arise. What are adaptations?

Adaptations are changes in a current trait that evolves in an organism by Natural selection. It is a trait that helps the survival and reproduction of an organisms in its present environment. This will lead to change in a population over generations in a process which Darwin Called Descent with modification.

What is biogeography? How is it affected by continental drift and the presence of endemic species?

Biogeography is the geographic distribution of species. The geographic distribution of organisms is influenced by many factors, including continental drift, the slow movement of Earth's movement over time, and the presence of endemic species, species that are found nowhere else in the world.

evolution

Evolution is an ongoing process where the tenant of life has evolved from a common ancestor. It is a change in the gene pool. It is a mechanism that describe how organisms change over time by natural selection. Takes a long time.

examples of adaptions

Example 1: Turtles with long necks were able to get food and more likely to survive. The next generations had more turtles with long necks. Example 2: Peter and Rosemary Grant and colleagues looked at bird beaks size. During a period with high rainfall there was a decrease of large hard seeds and abundance of small soft seeds. Therefore in the next year there was a greater number of small beak birds who ate small seeds. As conditions improved. There were more large seed and after 1987 more large beak birds were cited. Example 3: The webbed feet of platypuses are an adaptation for swimming. Example 4: The snow leopards' thick fur is an adaptation for living in the cold. Example 5: The cheetahs' fast speed is an adaptation for catching prey.

What is summarized in an evolutionary tree?

For example how modern elephants evolved from Palaeomastodon that lived 30-50 million years ago.

which two inferences did Darwin make?

Inherited traits determine the survival of population. Over production will lead to competition and only the organisms with traits that work best in environment will survive

It is important to remember that differences in heritable traits can lead to differential reproductive success. This means that the individuals who have the necessary traits to promote survival in the current environment will leave the most offspring. What can this differential reproductive success lead to over time?

It can lead to variation in a population.

Explain the process of natural selection.

It is also known as survival of the fittest. It is the reproduction of organisms with favorable traits. This results as organisms that reproduce and survive in the presence of environmental changes. This process leads to evolutionary change.

In an evolutionary tree what is indicated by each branch point?

It represents a common ancestor

James Hutton and Charles Lyell were geologists whose ideas strongly influenced Darwin's thinking. What were the ideas each of them contributed?

James Hutton: geological change occurred gradually over time by the accumulation of small changes. Charles Lyell : Believed earth was older which gave more time for gradual change. Provided room for the analogy of gradual change of species

Species overproduce- example

More organisms are produced than there is food, there is competition. Ex. Large amounts of sea turtles are produced but only few survive. Dandelions produce thousands of seeds.

These variations (traits) are heritable- example

Most characteristics are inherited. Passed from parent to offspring. For example eye color, hair color. Sisters resemble each other.

Analogous structures

Structures that evolve due to two distinct lineages with similar characteristics independent of one another. Ex. Wings in flies and bats both adaptations to flight but from different common ancestor.

Homologous structures

Structures that have the same lay out. For example the similar construction of the appendages of the human, dog and whale indicate that the organisms share a common ancestor. So the human arm has the same three bones that whale, dog arm have even if their function is different.

Although Lamarck's mechanism of evolution does not explain the changes in species over time, his thinking has been influential. What is considered to be the great importance of his ideas?

That changes occur over time.

There is competition for resources; not all offspring survive.- example

There is competition for food not all food. Over reproduction causes that competition. Not all sea turtles survive.

Vestigial structures

These are unused structures without function: Ex. Wings on flightless birds, leaves on cacti and hind legs on whales

Explain the role of fossils in rock strata as a window to life in earlier times.

They provide evidence that organisms from the past are not the same as the organisms from today. The fossil record tell the evolution of form over a millions of years.

How do homologous structures give evidence for evolution?

Throughout evolution there are changes in the shape and size of bones but their maintain the same bones.

Variations in traits exist.- example

Variations in a population are inherited. For example height, beak size. Color variation of moths.

Convergent evolution might be summarized like this: Similar problem, similar solution. Can you give two examples of convergent evolution?

Wings of bats and insects flight as a trait but come from a different ancestor.

BLANK_do not evolve. BLANK evolve.

individuals....populations

Organisms that are only distantly related can resemble each other. Explain convergent evolution, and describe how analogous structures can arise.

similar traits evolve independently in species that do not share common ancestry. Example bats and insects have wings that developed from different organisms. Analogous structures are similarities due to convergent evolution which often is due to environment. Wings of Bats and insects as cited earlier.

Jean-Baptiste de Lamarck proposed a mechanism for how life changes over time. Explain the two principles of his mechanism.

use and disuse: he use or disuse of a structure over time would increase or decrease the structure over time. The famous example is the neck of giraffes. If a giraffe needed to reach branches that were high on a tree over and over again then eventually the offspring with long necks would be more prevelant and giraffes would develop longer necks. Disuse would decrease size (not accepted today) inheritance of acquired characteristics: How modifications of an organism are caused by its environment.