Question

directions: read each description, determine which type of natural selection is being described, and write ns for natural selection, as for artificial selection, and ss for sexual selection.

1. female peacocks select the male with the most spots on the males tail to breed with. males with fewer spots dont reproduce with females as much as males with many spots.
2. methicillin is an antibiotic used to kill bacteria in humans. humans create environments in which bacteria frequently come into contact with methicillin. this lead to the rise of methicillin - resistant staphylococcus aureus (mrsa) which is a huge problem for humans.
3. chinese fishermen catch crabs in their nets and bring them to shore to eat. when the chinese fishermen see a crab with marks on the back of the crabs shell that looks like a human face, they believe the face is that of an ancestor. the fishermen throw these crabs back into the water out of respect to their ancestors.
4. ddt was once considered a \silver bullet\ that would permanently eradicate insect pests. today, insects are resistant against ddt. this is because ddt is largely useless against many insects today. insects today are resistant against ddt because some insects had some resistance to ddt when ddt was first used. ddt killed most of the bugs. unknowingly to humans, some were left behind because they had some resistance to ddt.
5. humans and dogs have coexisted for thousands of years. in the middle ages, humans used bloodhounds to find and hunt prey. through choosing the best - smelling dogs, the bloodhound is now used in police and detective agencies.
6. farmers select only the largest chickens that have the most amount of muscle. the subsequent next generation is larger than the last generation. the farmer profits more from his chickens because they weigh more. the farmer then earns more money per chicken.
7. in the case of the firefly (lampyrid beetles), males fly at night while emitting a particular pattern of light flashes that receptive females respond to by perching. the flashes color and temporal variety aid in their ability to draw in females.
8. male walruses compete with each other in elaborate and fierce battles where one walrus either dies or retreats. females then select from the winners who to mate with.
9. the modern commercial strawberry is derived from hybridization of the virginia strawberry and the beach strawberry.
10. during the industrial revolution, many of the light - colored birch trees in england were covered with pollution which turned them a darker black color. subsequently moth populations that were light in color were easily eaten by birds. after several generations, moths with darker wings started to become more frequent in the population because they blended in with the polluted trees.
11. male frogs assemble in great numbers first near the waters edge and use a variety of vocalizations to entice females. frog ladies choose their partners in part depending on the depth of the croak, with the little males having the deepest croaks and the best territories.
12. nebraskas sand hills is home to a deer mouse which are normally dark brown, which is a good color for mice living in the woods and surrounding areas, since it allows them to hide better and avoid predators. the deer mouse that lives in the sand hills, however, has evolved into a much lighter, sand - like color. without this change, the deer mouse would be easily spotted by predators against the areas light terrain.
13. since nylon wasnt invented until the 1940s, bacteria that can eat nylon can be nothing but new. the bacterium pseudomonas is able to metabolize nylon thanks to certain enzymes it has. however, a surprising thing happens when you take a non - nylon eating variety of this bacterium and place it in an environment where the only type of food available is nylon. every single time the experiment was tried, the bacteria would evolve until it was able to consume nylon.
14. yeasts are fungi that compete with other fungis males to produce fertile eggs. female gametes use pheromone communication, which implies male preference in these circumstances. the significantly faster evolution of female - biased good genes in fungi suggests that female - female rivalry may possibly take place.
15. plants like cauliflower, broccoli, cabbage, kale, and kohlrabi bear little superficial resemblance to their mustard relatives. and yet, through many generations of humans selecting for certain traits, these five crops were intentionally evolved from a wild, weedy ancestor.

Explanation:

1. Female peacocks selecting males with more spots is sexual selection as it involves mate - choice based on a trait.
2. The rise of methicillin - resistant Staphylococcus aureus due to human - introduced methicillin is natural selection as bacteria adapt to the new selective pressure.
3. Chinese fishermen's action of releasing crabs with human - face - like marks is not a form of natural, artificial, or sexual selection in the evolutionary sense described in the question context.
4. Insects developing resistance to DDT is natural selection as they adapt to the presence of the pesticide.
5. Selecting bloodhounds for their sense of smell is artificial selection as humans are choosing specific traits.
6. Farmers selecting larger, more muscular chickens is artificial selection for economic gain.
7. Firefly males using light patterns to attract females is sexual selection through mate - attraction signals.
8. Male walruses competing and females selecting winners is sexual selection involving male - male competition and female choice.
9. Hybridization of strawberries by humans is artificial selection.
10. Moths evolving darker wings due to industrial pollution is natural selection as they adapt to the changed environment.
11. Female frogs choosing mates based on croak depth is sexual selection.
12. Deer mice evolving a lighter color in the Sand Hills is natural selection to match the environment.
13. Bacteria evolving to eat nylon is natural selection as they adapt to a new food source.
14. Yeasts' mating and gene evolution related to pheromone communication is sexual selection.
15. Humans selecting traits in plants like cauliflower is artificial selection.

Answer:

1. SS
2. NS
3. None
4. NS
5. AS
6. AS
7. SS
8. SS
9. AS
10. NS
11. SS
12. NS
13. NS
14. SS
15. AS