Ecology Quiz: Population Reguation And Density Dependent Factors!

R-selected organisms typically have short life spans and little parental care of offspring. This means that they have a high reproductive rate and produce a large number of offspring, but provide minimal care or protection for their young. This strategy is advantageous in unpredictable or unstable environments where survival rates are low and resources are limited. By producing many offspring and investing minimal energy in their care, r-selected organisms increase their chances of passing on their genes to the next generation.

An r-selected organism is characterized by having a high reproductive rate, short lifespan, and little parental care for offspring. A mouse fits this description as it reproduces quickly, has a short lifespan, and provides minimal parental care. On the other hand, a K-selected organism has a low reproductive rate, long lifespan, and significant parental care. An elephant fits this description as it has a low reproductive rate, long lifespan, and provides extensive parental care for its young.

The survivorship curve that is typical of organisms like deciduous trees is type III. Type III survivorship curves show a high early mortality rate, meaning that many individuals die at a young age. However, for the few individuals that do survive, their chances of dying decrease significantly, allowing them to live a long time. This pattern is similar to deciduous trees, which often experience high mortality rates in their early stages but can live for many years once they are established.

The statement "Carrying capacity can not be dynamic" is false. Carrying capacity refers to the maximum number of individuals of a species that an environment can sustainably support. It is influenced by various factors such as resource availability, competition, predation, and environmental conditions. These factors can change over time, causing the carrying capacity to fluctuate. For example, if a population's resources become scarce, the carrying capacity may decrease. Therefore, carrying capacity is not a fixed value and can indeed be dynamic.

Organisms such as oysters or fish that produce millions of eggs per year and have a type III survivorship curve are characterized as r-selected. R-selected species typically have a high reproductive rate, produce many offspring, and have a low survival rate. The type III survivorship curve indicates that the mortality rate is highest in the early stages of life, with a sharp decline in survivorship. This pattern is commonly seen in species with large numbers of offspring, where only a small fraction of individuals survive to adulthood.

All of the listed factors can contribute to density-dependent regulation of populations. The accumulation of toxic wastes can limit population growth as it increases with population density. Intraspecific competition for nutrients occurs when individuals of the same species compete for limited resources, which can regulate population size. Predation can also regulate population density as it acts as a natural control mechanism by reducing the number of individuals in a population. Therefore, all three factors mentioned can contribute to density-dependent regulation of populations.

Earthquakes are a density-independent factor that can limit human population growth because they occur randomly and are not influenced by population size. Unlike social pressure for birth control, plagues, and famines, earthquakes do not directly affect population growth based on the number of individuals. Earthquakes can cause widespread destruction, loss of life, and displacement of populations, which can hinder population growth by disrupting infrastructure, causing economic setbacks, and creating unfavorable living conditions. Therefore, earthquakes can limit human population growth regardless of population density.

Competition and predation are examples of density-dependent factors that can influence the size of a population. Competition occurs when individuals within a population compete for limited resources such as food, water, or shelter. This can lead to a decrease in population size as individuals struggle to survive and reproduce. Predation occurs when one organism hunts and consumes another organism. As the population size of prey increases, so does the availability of food for predators, leading to an increase in predation rates and a decrease in prey population size. Therefore, both competition and predation can have a significant impact on the size of a population.

Pest or weedy species are typically r-selected, which means they have a high reproductive rate and produce many offspring. These species also tend to have a short lifespan and reach sexual maturity quickly. The survivorship curve for r-selected species is typically Type III, which means that there is a high mortality rate among the offspring, but those that do survive have a higher chance of living longer. This is because r-selected species invest less energy into individual offspring and instead focus on producing a large number of offspring in the hopes that some will survive.

Natural selection involves energetic trade-offs between or among life history traits such as the number of offspring per reproductive episode, the number of reproductive episodes per lifetime, and the age at first reproduction. This means that individuals need to allocate their limited resources, such as energy and time, in a way that maximizes their reproductive success. For example, investing more energy into producing a larger number of offspring per reproductive episode may come at the cost of reducing the number of reproductive episodes per lifetime or delaying the age at first reproduction. Therefore, all of the options A, B, and C are correct as they represent different aspects of the trade-offs involved in natural selection.

In a population characterized by type III survivorship, the probability of survival with age increases. This means that individuals in this population are more likely to die at a younger age, resulting in a higher mortality rate. As individuals age and reach a certain threshold, their chances of survival increase, as they have already surpassed the period of highest mortality. Therefore, the probability of survival with age increases in a population with type III survivorship.

Species that show a type I survivorship curve would be expected to have high mortality late in life and be K-selected. Type I survivorship curves indicate that individuals have a high probability of surviving to old age, but once they reach a certain age, mortality rates increase rapidly. This pattern is often seen in species that invest heavily in parental care and have low reproductive rates, known as K-selected species. These species prioritize the survival and longevity of individuals over high reproductive output.

These three curves represent idealized situations. What occurred in human history, and still probably occurs in impoverished underdeveloped countries, is a high juvenile mortality, such as the initial portion of a type III curve, followed by a steady decline throughout middle age, as is found with the mid-portion of a type II curve. Once old age is attained, the individual is likely to survive until physiological aging leads to death, as is typical of the end of the type I curve.