Innate behavior is known as inflexible behavior, in which learning plays no role in the behavior. Communicating, courtship, and decision making all rely on learned behavior from the environment.

With regard to evolution and natural selection, fitness refers only to the ability of an organism to contribute to the next generation of its species. In other words, if an organism has a large number of viable offspring, its fitness is high, regardless of other factors like strength, size, and longevity.

Of these answer choices, the only organism with an above-average number of healthy, surviving offspring is the prairie dog. The mule and the dog have below-average fitness because they cannot give birth. The turtle also has below-average fitness because it produces an unusually low number of healthy offspring. The human male has average to below-average fitness; certain traits made him choose not to produce offspring, though he may have been able to produce numerous offspring.

In evolutionary terms, “fitness” refers to the reproductive success or reproductive potential of an organism—its contribution to its species' gene pool.

Initially, the population of bacteria was composed of mostly bacteria vulnerable to methicillin and a small number of resistant bacteria. Treatment with methicillin destroyed all of the vulnerable bacteria. leaving only the resistant alive to reproduce. Over time, the resistant bacteria became the majority.

Although it's possible a new patient could have introduced the first resistant bacteria, it's unlikely to have occurred in such a short time frame.

It's also unlikely the bacteria possessed the ability to resist the bacteria from the start, as methicillin treatment wouldn't have worked on any of them.

Bacteria do not possess a mechanism by which they can build up immunity to antibiotics over time.

According to Darwin's theory, the survival and reproduction of individuals is not random. Survival and reproduction is tied to the variations among individuals. Those with the most favorable variations are more fit; therefore, they are naturally selected.

A sharp decrease in population size caused by environmental or human impact is known as the bottleneck effect, where the bottlenecking occurs in the relative population diversity. This is mainly due to the fact that the individuals who survived rarely represent the genetic makeup of the initial population as a whole. The effect size is a statistical measurement of the strength of a phenomenon, which can be applied in the study of population dynamics, but is not a type of genetic drift. Artificial selection is the deliberate selection of mating preferences by humans in order to alter the proportion of traits in the offspring. However, this type of selection is not caused by a dramatic event, nor does it result in a severe decrease in population size. The founder effect does pertain to small populations but specifically on how genetic variation is lost in a small population that comes from a larger population due to misrepresentation.

The most biologically fit organism is one that produces the most fertile offspring. Lifespan can correlate to the number of offspring produced, but is not a direct factor in determining fitness.

Since the organism that lives 36 years produced the most offspring (6), it is the most biologically fit.

Homeostasis is the tendency of the body to maintain stable, constant states. Homeostasis is often mediated by negative feedback systems, which prevent the measure from getting too high or too low. Regulation of body temperature within a narrow range would be an example of homeostatic regulation. Other examples include blood glucose concentration and blood calcium concentration.

Metabolism refers to the chemical processes of the body. These processes can help maintain homeostasis, but are not directly responsible for body regulation.

Biological fitness is directly related to the ability of an organism to survive and produce future progeny. There are a lot of factors that will play into an organism's fitness, especially in a harsh place like the tundra. Small size can be beneficial, as smaller animals require less food and can survive better in harsh environments, but large size can be beneficial to help preserve body heat. The color of an animal will help it to hide from predators; many tundra animals are white to help them blend in to the snow. Thermoregulation is extremely important in a cold environment; endotherms are able to regulate their own internal temperature, and will survive better than exotherms, which would be affected by the cold temperature of the air. Finally, fur and feathers help to trap body heat close to the skin and would enhance the fitness of animals in a cold environment.

Size, color, mode of thermoregulation, and fur all impact an animal's ability to survive in the tundra. Nocturnal activity, however, would not necessarily be favored over diurnal activity, as there is no clear advantage of one over the other in this specific environment.

Breeding with genetically different individuals tends to "scramble" the alleles of a population. When genetically similar individuals breed, they tend to produce homozygous genotypes in their offspring, so potentially dangerous recessive alleles appear more frequently and beneficial alleles are not as efficiently selected for. Thus, inbred populations have a lower survival rate over time. This is called inbreeding depression.