According to Foster's rule, large mammal species isolated on islands often undergo dwarfism, evolving much smaller body sizes than their mainland counterparts. While researchers traditionally attribute this change to restricted resource availability on islands, evolutionary biologist Dr. Marcus Vance hypothesized that the primary driver of island dwarfism in large herbivores is actually the absence of large terrestrial predators, which relaxes the evolutionary pressure to maintain a large body size for defense.
Which finding, if true, would most directly support Vance's hypothesis?
- Island populations of a deer species coexisting with large predators showed no reduction in body size, whereas populations of the same species on islands with similar food resources but no predators grew significantly smaller over generations.Cevap
- BFossil evidence indicates that mainland populations of large herbivores experienced rapid declines in overall abundance when new carnivorous predators entered their habitats.
- CSmall rodent species on predator-free islands evolved to be significantly larger than their mainland ancestors to better defend themselves against avian predators.
- DLarge herbivore species residing on islands with abundant foliage and vegetation consistently maintained larger population sizes than those on resource-poor islands.
Cevap
The finding that island populations of a deer species coexisting with large predators showed no reduction in body size, whereas populations of the same species on islands with similar food resources but no predators grew significantly smaller over generations.
The hypothesis suggests that the lack of predators, not food scarcity, is the main driver of island dwarfism in large herbivores. The finding comparing deer populations on islands with similar food resources demonstrates that dwarfism only occurs when predators are absent, which directly isolates predator presence as the key variable.
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Textual evidence evaluation and hypothesis testing
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