Question

can you answer these
Charles Darwin hypothesized that some individuals would be better equipped for survival than others, and that those that were less equipped would not survive. Darwin formulated this hypothesis based on the work of which scholar?
John Gould, who compared mainland and island finches
Thomas Malthus, who studied population growth
Sir Isaac Newton, who formulated the laws of motion
Gregor Mendel, who determined genetic inheritance of traits

A male cardinal’s red color is an example of a trait affected by natural selection. The females of the species choose mates based on the vibrant colors of the males’ feathers. If females begin using different criteria than feather color when they choose mates, what would most likely happen to the color of the male cardinals over time?
increased variation in the shades of red because there is no advantage in one specific color
increased variation in the shades of red because the cardinals try different ways to impress the females
decreased variation in the shades of red over time because no form of the trait is advantageous
decreased variation in the shades of red after a single generation

Evolution is change in a population over time and includes the gene pools of that population. How does biogeographic isolation allow for the change of gene pools over time?
Biogeographic isolation affects the random changes that take place within gene pools.
Biogeographic isolation causes changes in gene pools that result from populations being separated.
Biogeographic isolation determines who will win competition for mates.
Biogeographic isolation determines the time that populations will breed.

Consider the generalized cladogram of fish.

A cladogram is shown. At point B, the organism shares jaws but not bones.

A fossilized fish is found that has jaws but no true bones. Where does this fossil belong on the cladogram?
A
B
C
D

Thylacosmilus is a marsupial, and Smilodon is a mammal. Thylacosmilus and Smilodon both have saber teeth, but they do not share an ancestor that had saber teeth. What are saber teeth for these organisms?
analogous structures
homologous structures
vestigial structures
mutated structures

Answer 1

1) Thomas Malthus, who studied population growth.
- Darwin was influenced by Malthus’s ideas about population pressure and struggle for existence.

2) increased variation in the shades of red because there is no advantage in one specific color.
- If females stop selecting by color, sexual selection is relaxed and different shades can persist or drift, increasing variation.

3) Biogeographic isolation causes changes in gene pools that result from populations being separated.
- Geographic separation prevents gene flow, allowing populations’ gene pools to diverge over time.

4) B.
- A fish with jaws but no true bones fits the branch at point B (jaws present, bones absent).

5) analogous structures.
- Saber teeth evolved independently in the two lineages (convergent evolution), so they are analogous rather than homologous.