Self-study
P1
Mechanisms for recognizing kin are found throughout the plant and animal kingdoms, regardless of an organism's social or mental complexity. ████████████ ██ ███ ███████ █████████████ ██ █████ ██████████ ████ ██████ ████ ███████████ █████████ ██ ███ ████████ ██ ███ ███ ███████████ ██████ ██ ████ ███
Phenomenon ·
Many plants and animals can recognize "kin" (relatives)
Inclusive fitness hypothesis ·
Organisms transmit genetic material through relatives (not just offspring)
Contrast inclusive fitness with traditional view of evolution. Under traditional view, natural selection favors those with the most offspring. Inclusive fitness suggests natural selection also favors organisms who help their relatives (because this helps spread the organism's own genes).
Inclusive fitness applied ·
Helps to explain why social insects like bees evolved
P2
█████████ ███████ ██████ ███ ████ ████ ███████ ████████ ██ ███ ████████ ██████████ ███████████ ██████ ██████ ████████ █████ ██ ███ ███████ █████████ ██████ ████ ███████ ██ █████ ██████ █████ ███ ███ ███████ ██ ███ ███████ ███████ █████ ██ ████ █ █████████ ███
Inclusive fitness applied ·
Theory predicts that cannibals will avoid eating their own relatives
Example of theory applied to cannibals ·
Spadefood toad tadpoles
Some tadpoles eat their own species. But they nip at other tadpoles before eating, and end up eating only nonsiblings. Suggests they're trying to avoid eating their kin. But, they're more likely to eat kin when they're very hungry.
P3
███ █████ ███ ██ █████ ███████ ███ █████████ █████████ ████ ███
Other explanations for kin recognition ·
Inclusive fitness theory isn't the only explanation
Example showing other explanation ·
Tiger salamander larva
Some larva are cannibals. The bacteria are more deadly to close relatives, because the relatives have a similar immune system to the infected larva. So, when tiger salamanders avoid eating their close relatives, it could be because they just don't want to die from the bacteria in their relatives. This is about the organism's individual self-interest, not about trying to increase overall genetic representation.
Passage Style
Phenomenon-hypothesis (RC)
Single position
15.
Which one of the following ██████ ██ █████ ████ ████ ██ █████████ ███ ████████ ██████████ ██
a
Many tiger salamander ██████ ████████ ██ ███ ██████ █████████ ███ ███ ██████████████
This is consistent with the author’s interpretation. We already know tiger salamander larvae are “plagued by a deadly bacterium.” The author never assumes that the bacterium infects mainly cannibalistic tadpoles. So pointing out that many non-cannibals are infected has no impact on the author’s argument.
b
The factor that ██████████ █████ █████ ██████████ ██████ ███ ███████████ ███ █████ ███ ██████████ ██ ███ █████████ ██ ███ ███████ ██████ ██ ███ ███████
The author’s discussion of the tiger salamander doesn’t require any belief about what causes some larvae to be carnivores and some to be omnivores. We’re simply examining the behavior of carnivores — why do they avoid eating kin? What causes the carnivores to be carnivores doesn’t impact the reasoning.
c
Kin recognition helps █████ ███████████ █████ ██████████ ████ ███ ██ ████████████████ ██ █████ ██████████
This undermines the author’s interpretation in the last sentence by providing another potential explanation for the carnivorous tiger salamanders’ behavior. Maybe they avoid eating kin because it’s a way to help increase the chances their own offspring survive. If so, the tiger salamanders aren’t necessarily trying to preserve their “own life” — they’re still concerned about their relatives. (One’s offspring are part of one’s relatives.)
d
Noncannibalistic tiger salamanders ████ ██ ███████ █████ █████████ ████ █████████████ █████ ████████████
This doesn’t undermine the author’s reasoning, which is based only on the behavior of cannibal tiger salamanders. Whether noncannibals produce more or fewer offspring doesn’t suggest any explanation for why cannibals avoid eating their kin or otherwise suggest the author’s interpretation might be wrong.
e
Cannibalistic tiger salamanders ███ ██████ ██ ███████ ████████ ██ █████ ████████████████ ███████████ ███ ████
This doesn’t undermine the author’s reasoning, which is based only on the behavior of cannibal tiger salamanders. Whether cannibals are immune to some diseases that noncannibals are not doesn’t suggest any explanation for why cannibals avoid eating their own kin. (E) might be tempting if you assume that the cannibals are immune to the bacterium described, but we have no reason to think that’s true.