Parallelism can describe a type of evolution, but does not represent a type of species interaction. On the other had the other choices—interspecific competition, predation, parasitism, and mutualism—are types of species interactions. Interspecific competition occurs when members of species compete for the same resource or niche. Predation happens when one species (predator) feeds on another species (prey). Parasitism takes place when one organism lives off the body of another. This organism is a parasite and usually lives inside or on the host. Mutualism refers to interaction between multiple species for the benefit of all species members.

Coevolution is a process by which two or more species evolve in response to one another, and generally describes competing species. While the hummingbird and the flower may evolve due to this relationship, coevolution more freqeucntly describes the evolution of defense mechanisms in response to a predator-prey relationship. Parasitism is the relationship in which one species benefits at the expense of the host. This can sometimes lead to coevolution, depending on how the host reacts. Neither species is being harmed in the given scenario, so this is incorrect. Commensalism is when one species benefits, but the other species is not impacted. In this case, both the hummingbird and the flower are benefiting, so this is not our answer. Resource partitioning is when species evolve together to share resources in a sustainable way. The hummingbird is using a resource that the flower provides, but they are not "sharing" in the sense of the definition of resource partitioning. Competitive exclusion describes the phenomenon when two species share the same niche, and the stronger one forces out the weaker competitor.

Mutualism, the correct answer, describes a relationship wherein species exploit each other mutually. In this case, the hummingbird gains nutrition from the flower, and the flower gains a reproductive advantage from the hummingbird.

Species evenness is a measure of diversity that takes into account the relative proportion of different species in a given area. Richness can also be classified as a measure of diversity; however, it refers to the number of different species in an area rather than proportion. Last, phylogeny refers to the construction of branched models that illustrate evolutionary pathways.

Sharks have been shown to be very resistant to infection when they have been wounded. It is also notable how low cancer rates are in sharks—in fact, researchers from MIT have isolated a potential anti-tumor agent in sharks' skeletons that could further cancer research with regard to human patients.

The question describes a mutualistic relationship in which both the bee and the flower benefit. Mutualistic relationships can be described as win-win interactions between species. Facilitative relationships occur when one species benefits and the other species is not impacted in any way. Competitive relationships are win-lose interactions where one species benefits and the other species is detrimentally impacted.

Batesian mimicry and Mullerian mimicry are easily confused. Batesian mimicry involves one organism taking on physical characteristics of a commonly known, dangerous organism. Mullerian mimicry happens when multiple poisonous species resemble each other.

Camouflage helps prey avoid predators by blending into their surroundings. Warning coloration is similar to Batesian mimicry. Since many poisonous organisms exhibit colorful exteriors, some non poisonous organisms can also be brightly colored and are still avoided.

In relationships based upon commensalism, one of the species benefits greatly, while the other is neither harmed nor helped. This is different from mutualism, where both species are benefited, and parasitism, where one species is benefited and the other is hindered. "Endosymbiosis" is the theory used to describe how mitochondria developed, and "predation" describes a situation where one organism feeds on another.

Bottleneck effect occurs after a drastic reduction in population size due to events such as a natural disaster, or widespread disease. The remaining population lacks genetic diversity because there are fewer individuals and fewer genes present within the population. This is the correct answer. The founder effect is not correct because it is defined as the loss of genetic variation as a result of a few numbers of individuals establishing a population. Geographic isolation occurs when a population is isolated from others due to geographic boundaries such as mountains, cliffs, or large bodies of water; therefore, it is not the correct choice. Last, genetic drift refers to the change in frequency of gene variation due to random sampling and does not correctly answer the question.

Species interact in many ways:

Predation - one species (predator) preys on another species (prey).

Parasitism - symbiotic relationship between species where one species benefits at the expense of the other.

Mutualism - a positive symbiotic relationship where both species benefit.

Commensalism - a relationship between species where one benefits and the other remains unaffected.

Somewhere between 40% and 75% of all species are indigenous to rainforests, meaning that they are found nowhere else on earth. They contain half of the extant animal and plant species currently on earth, with a large majority of all flowering plants found there. Many of the world's natural medicines have been found in tropical rainforests, and with thousands of undiscovered species still lurking within them, it is likely that there are many more medicines waiting to be discovered.