Solution-Example of the principle of fitness

1) What is the trait that distinguishes primates, rodents/ rabbits, crocodiles, and dinosaurs/ birds from amphibians and earlier lineages? Look in “Patterns- The family tree”

2) In the following phylogenetic tree, which of the following are in the clade that has a therian mammal ancestor?

139_Characteristic of therian mammals.png

monotremes and eutherians

lepidosaurs and archosaurs

monotremes and marsupials

marsupials and eutherians

3. In the following phylogenetic tree, the unique lineage of archosaurs is represented by:

a red line

a green line

a blue line

a black line

4) In the following phylogenetic tree, which of the following is not a shared derived characteristic of therian mammals?


holoblastic cleavage



5)Would you expect a bird wing and a butterfly wing to be homologous or analogous structures? Explain.

6) Hint: look in “Mechanisms- Descent with modification”)

In a population of beetles which can be either green or brown in color, the gene (allele) frequency of green beetles in 2009 was measured to be 36% and increased to 52% in 2010. The gene (allele) frequency of brown beetles in 2009 was measured to be 64% and decreased to 48% in 2010.

True of False? This population of beetles is evolving.



7)In your own words, list and describe the four mechanisms of evolution.

8) (Hint: Look in “Mechanisms- Natural selection”)

In your own words, give an example in nature of how natural selection works.

9) Which of the following is the best example of the principle of “fitness”?

a white rabbit living on a forested hill side compared to a brown rabbit living there gorilla males with large testicles consistently producing more offspring than gorilla males with small testicles the most dominant chimpanzee male in the group eating more often than less dominant males a giraffe having thicker,spottier fur than another giraffe


1. Which of the following statements is TRUE?

mutation are non-random

only germline mutations can affect evolution

natural selection is random

mutation always affect the phenotype to the same extent

11)When female pea hens choose a peacock to mate with based on how many colorful feathers he has in his tail, this is an example of __________ selection.

12) The process of breeding new types of dogs is an example of ____________ selection.

13)Hummingbirds feed on flower nectar and often have a beak whose shape is adapted specifically to only one flower shape, fitting in no other flower species. As a result, this hummingbird may only feed on that particular flower and is its only pollinator, creating a mutual dependency between the two species.

This is an example of ___________.

14)A field biologist discovers a population of pocket mice in Nebraska which has a very different phenotype of the other populations of pocket mice in the area. Which of the following is the best strategy the biologist should use in order to establish whether or not she has found a new species?

compare the color, size, shape, and any other physical traits between the various populations to the newly discovered one and if they look at least 95% the same, consider them the same species.

check to see what kind of habitat they live in, and if it is the same, consider them the same species

check to see what they eat, at what time of the year they breed, how many offspring they generally produce, and what their social structure is, and if it is the same, consider them the same species

check to see if they would produce viable and fertile offspring when brought together to mate. If yes, then consider them the same species

1. 15)The fact that a mule (hybrid offspring of a horse and a donkey) is sterile is an example of:

reduction of gene flow

genetic drift

reproductive isolation

geographic isolation

16) In your own words, describe the difference between microevolution and macroevolution.

1. 17)True or False. The mechanisms causing microevolution are different from those of macroevolution.



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