Chapter 9 Online Study Guide

The cockroach would be considered an r-selected species because it exhibits characteristics typically associated with r-selection. R-selected species are known for their high reproductive rate, short lifespan, and ability to produce a large number of offspring. Cockroaches have a short lifespan, reproduce quickly, and can produce a large number of offspring in a short period of time, making them a good example of an r-selected species.

The correct answer is logistic. Logistic growth involves exponential population growth when the population is small, but as the population encounters environmental resistance and approaches the carrying capacity of its environment, the population growth rate decreases steadily. This type of growth is often observed in natural populations where resources become limited, causing the population to stabilize and reach a balance with its environment.

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Giraffes would be considered a k-selected species because they have a low reproductive rate, long gestation period, and provide extensive parental care to their offspring. K-selected species typically have a longer lifespan, slower growth rate, and invest more resources into each individual offspring, ensuring their survival and success.

An early loss survivorship curve indicates that the mortality rate of a species is highest early in life. Fish typically have a large number of offspring, and many of them die at a young age due to predation, disease, or other factors. This results in a steep decline in the number of individuals surviving to older ages. Therefore, fish would have an early loss survivorship curve.

Sea urchins are known to feed on kelp, making it one of their favorite foods. Kelp is a type of large brown seaweed that grows in underwater forests. It provides a rich source of nutrients for sea urchins, and they are adapted to graze on the kelp blades. This relationship is important for the ecosystem as sea urchins help control the growth of kelp, preventing it from overgrowing and maintaining a healthy balance in the marine environment.

Environmental resistance refers to all the factors that act together to limit the growth of a population. These factors can include availability of resources, predation, competition, disease, and other environmental conditions. These factors create a balance between birth and death rates in a population, preventing it from exceeding the carrying capacity of its environment. Intrinsic rate of increase, carrying capacity, and population dynamics are related concepts but do not encompass the full range of factors that make up environmental resistance.

Fire is considered a density-independent control because it affects populations regardless of their size or density. Unlike predation, parasitism, and disease, which tend to have a greater impact on larger, more densely populated areas, fire can spread and impact populations regardless of their density. Fire can quickly consume vegetation, destroy habitats, and disrupt ecosystems, affecting all organisms within the affected area. Therefore, fire is not influenced by population density and can act as a density-independent control.

Dandelions exemplify a random pattern of dispersion. This means that they are distributed in a way that is not clumped or uniform, but rather scattered randomly throughout their habitat. This could be due to factors such as wind dispersal of their seeds or the presence of suitable conditions for growth in various areas.