exam 3 BIO

Which will evolve faster: a bacterial population whose cells divide every 20 minutes, or a deer population whose females give birth to 2 fawns once a year? Why?

Bacteria. Each generation has a chance to have evolved. The faster you reproduce, the faster you could evolve.

A small population of vignacious lizards (completely fictional) lives only on the southern coast of Aruba. A devastating hurricane wipes out 95% of these lizards. The surviving population no longer carries the allele that codes for rough skin. This genetic change in the population is due to which of the following mechanisms?

Bottleneck Effect

A population of grasshoppers in the Kansas prairie has two color phenotypes, green and brown. Typically the prairie receives adequate water to maintain healthy green grass. Assume a bird that eats grasshoppers moves into the prairie. How will this affect the natural selection of grasshoppers? How might this change in a drought year?

Brown will be eaten more often, so they will not reproduce with as great a frequency. In a drought, the grass is brown and green grasshoppers will be eaten more often.

Why is the survival of small populations more difficult than that of larger populations?

Changes in the population can easily cause alleles to disappear from the gene pool because there are so few individuals that carry each allele.

How has our ability to sequence DNA influenced the field of Evolutionary Biology? How has isotope chemistry influenced it? What role does Geology play in Evolutionary Biology? What other disciplines are important to study evolution?

DNA is the basis for the traits we have that allow our survival and reproduction. So, knowing how organisms have changed genetically allows us to study evolution from its root. DNA sequence homology has helped us verify what we already knew from fossil and comparative evidence. It has also helped us solve some of the puzzles that comparative evidence couldn't sort out for us.

Salamanders living on the northeast shore of South America and the southwest coast of Africa share 92% DNA sequences, but are considered different species. What can you hypothesize about this information?

a) These two species of salamander used to be members of the same population. b) When the continents of South America and Africa separated and drifted apart, two groups of the same species of salamander evolved independently from one another. c) One species of salamander became two species due to geographical separation.

Modern whales lack hindlimbs (legs), but have structural remnants of pelvic and leg bones. Which of the following statements is true regarding this information?

a) modern whales most likely had an ancestor that possessed hindlimbs. b) The remnants of pelvic and leg bones in whales suggests that while whales don't use these bones, they are present due to evolution of this species from an ancestor that had legs. c) This comparative anatomy evidence suggests that in evolution, organisms evolve from species that already exist. d) Species that have a common ancestor have similar anatomical structures that are used for different functions.

If, within a large population no mutations occur, no migration occurs, all matings are random and there is no change in the environment, what will happen?

no evolution will occur in that population

Assume that it is possible to remove cores of rock from the earth 6 inches in diameter and 3000 feet deep into the earth. Evolution would predict what about the fossils in such cores as they are examined from the top soil layer to bottom?

Fossils further down into the earth are older, from organisms that lived a longer time ago.

Why don't we have a complete fossil record?

Fossils only form under specific circumstances - usually when an organism is buried quickly.

Explain what Evolution is in your own words. Be specific and careful with your terminology.

Genetic change in populations

Two species of garter snakes live in the same geographic area. One mainly lives in water and the other mainly on land so that they rarely encounter each other and do not interbreed. This is an example of what type of Macroevolutionary separation?

Geographic - Environmental or habitat separation

There are currently many similar but different species on either side of the isthmus of panama. They probably resulted from what type of evolutionary processes?

Geographic separation

What is the only mechanism of evolution that introduces entirely new alleles into a population? Why is this mechanism different from the others?

Mutation. Entirely random introduction of brand new alleles. All other mechanisms just change the frequency of already existing alleles.

Which process of evolution occurs in response to the environment?

Natural Selection

A population of deer was threatened with overpopulation until cheetahs were imported. After a couple of years there were fewer deer but the average running speed of the deer had increased. This is an example of which of the following: mutation, genetic drift, gene flow, natural selection?

Natural selection

The Theory of Natural Selection states that:

The best adapted individuals in a population survive and reproduce contributing the most genes to the next generation

We know that it is possible to take a gene from a human being, put it into bacteria, and have those bacteria produce the human protein. The human protein produced by the bacteria is indistinguishable from the protein produced in human cells. From this observation we can conclude:

The way proteins are produced from genes must be the same in humans and bacteria.

Why might some species have very few changes in their populations, even over a large span of a million years?

They have a wide range of environments they can live in. They aren't as specific in what they eat or the temperature they can take, etc.

A dog that lives in Florida is moved to Alaska. It grows a thicker coat now than it did in Florida. Is this an example of evolution? Explain.

Individuals do not evolve. Populations do.

Diverse organisms such as insects and mammals have very different body plans. For instance, fruit flies have mouth parts and antennae toward their anterior end (head end) and wings and specialized structures called halteres more toward their posterior end (tail end). Although humans have anterior and posterior ends of their body that are different from one another, they possess different structures on these ends than fruit flies. A group of genes called the Hox genes are necessary to set up the body plan of flies. Hox genes, with very similar sequences to those found in fruit flies, have been found in all multicellular organisms, including humans. The fruit fly Hox gene, called Hox-1, is important for development of the anterior end of fruit flies. Based on what you have learned about DNA evidence and how nature does not tend to reinvent the wheel, what would you predict about the human Hox-1 gene?

It is likely required for development of the anterior end of humans, even though the specific structures are different.

Almost no modern species (species alive today) are found as fossils in rocks below the glacial till (the sediment left from the last ice age). What does this have to do with our discussions of evolution?

Many of the species we see today evolved as a result of that environmental change. Many organisms died, and new species evolved to recolonize those habitats.

Describe the process of Natural Selection. Give an example.

Populations are genetically diverse. If the environment changes, some will live and reproduce. Those who reproduce will pass their genes to the next generation. If the frequency of alleles is different in the new generations, evolution by natural selection has occurred.