Exam 55: Species Interactions

A biologist is studying an established plant-insect interaction, in which the insect feeds on several closely related plants.She discovers that, over the past 10 years, the amount of plant tissue harvested by the insect herbivore has doubled.This doubling coincides with rising summer temperatures in the region.Population genetics studies show a very slight increase in a plant species with a more rapid reproduction rate due to greater seed production.The biologist concludes that the genetic change in the plant was likely not related to evolutionary pressure from the insect herbivores.On what does she most likely base this conclusion?

Bombardier beetles defend themselves by means of

Which type of animal has most likely evolved specialized detoxification systems?

A survey of predator-prey relationships shows that the fastest predators are usually found in regions where the fastest prey are found.The most likely explanation for this is

Rock nuthatches are small Eurasian birds that forage for insects and spiders on bare, rocky ground, and species occur either separately or in a common habitat.When two species exist separately, with no interspecies competition, their beaks are similar in length.But when they exist in the same habitat, one species has a longer-than-average beak and the other has a shorter-than-average beak.The latter situation is an example of _______ competition that has resulted in character displacement.

In a plant-frugivore interaction, which factor is most likely to benefit the plant by helping to ensure that the frugivore carries out successful seed dispersal?

Many highly specific adaptations are actually the result of reciprocal adaptations, or _______, between partners of an interaction.

Butterfly species A is a Batesian mimic of butterfly species B.If species B were eradicated from a region, what would be the most likely effect on the population of species A?

The best characterization of pathogenic organisms is that all

Two species of barnacles, stellate and rock barnacles, occupy the rocky intertidal zone of the Scottish coast and illustrate factors that can determine species distribution in a community.Larvae of both species settle throughout the intertidal zone, but adult barnacles occupy specific zones.The smaller stellate barnacle lives only in higher zones, where the environment dries out between high tides.The larger, faster-reproducing rock barnacle lives only at lower zones.In general, the intertidal zonation seen in the barnacles is due to

Monarch and viceroy butterflies are both toxic, and they resemble each other.They provide an example of _______ mimicry.

In both crypsis and mimicry, prey defend themselves by trying to make predators not see them as prey.What is a major difference between crypsis and mimicry?

American toads are prey for a number of vertebrate predators.The toads themselves also prey on a variety of insects.Which characteristic most benefits toads in their role as potential prey, rather than as potential predators?

The relationship between a zebra and the lion that eats it is an example of

Eastern tent caterpillars are social nesters that spin weblike nests, or tents, to which they keep adding layers as they molt and grow.The caterpillars leave the tent several times each day to feed on the leaves of their host tree.Many predators attack caterpillars feeding outside the tent.Which caterpillar behavior would be least advantageous in minimizing predation while the caterpillars are feeding?

Two birds in the American eastern deciduous forest, the nuthatch and the brown creeper, both feed on insects living on tree trunks.As the nuthatch forages, it moves down the trunk.As the brown creeper forages, it moves up the trunk.In this way, the two birds feed on different groups of insects.Which type of competition are the birds exhibiting?

Plants and mycorrhizae (fungi that grow in association with plant roots) are usually mutualistic.The fungus absorbs water and minerals, such as phosphorus, from the soil, which the plant uses.The plant provides the fungus with carbohydrates.In soils where phosphorus is low, nutrient transfer from fungus to plant may increase plant fitness.But in very fertile soils, the net benefit of the interaction may become negative, with the fungus acting more as a parasite than a mutualist.Which is the best description of the change in this interaction?

After the European rabbit was introduced into Australia in 1859, it quickly became a devastating invasive species, causing extinction or decline of many native animals and plants, major damage to crops, and soil erosion.To control the exponential growth of the population (which had grown from 24 animals to an estimated 600 million), biologists infected rabbits with the myxoma virus in 1950.In the first years after introduction of the virus, up to 99 percent of infected rabbits died.Over later years, however, both the average life span of infected rabbits and the percentage of rabbits surviving infection increased.How can these changes be explained?

Which factor might best explain why a pathogen infecting a host population often undergoes an initial rapid increase, followed by a decrease?

Some plant species produce, on the same plant, two types of flowers: ones that open and attract pollinators and ones that never open but instead self-pollinate.Which is not a reason that the two reproductive strategies would benefit the plant species?