Biology Chapter 45

What is a species life history? What influences it?

A species' life history is a series of events over its lifetime, that shows how resources are allocated for growth, maintenance, and reproduction. An organism's life history will often affect their life table.

What is exponential growth? Give an example. How would you identify this type of growth on a graph?

Exponential growth is referred to as a accelerating pattern of increasing population size. The best example of exponential growth is seen in bacteria. Bacteria reproduce by prokaryotic fission. This division takes about an hour for many bacterial species. When populations exhibit exponential growth, it results in a J-shaped curve on a graph.

What are the three types of survivorship?

Humans and most primates most often have a Type I survivorship curve because a high percentage of offspring survive their early and middle years and death occurs mainly in older individuals. Birds are an example of a Type II survivorship curve because birds die more or less equally at each age interval. . Trees, marine invertebrates, and most fishes exhibit a Type III survivorship curve because very few of these organisms survive their younger years; however, those that make it to an old age are more likely to survive for a relatively long period of time.

Describe the general strategies of an iteroparous species in terms of fecundity, timing of reproduction, and parental care.

Iteroparity describes species that reproduce repeatedly during their lives. Some animals are able to mate only once per year but survive multiple mating seasons. Females of these species mate only during the estrus phase of the cycle.

What are the three types of species dispersion pattern?

The three types of species dispersion are uniform, random, and clumped. An example of uniform is when penguins are huddled together. An example of random dispersion is wildflowers in a field. An example of clumped dispersion is a herd of elephants traveling in a pack.

population density

number of population members divided by the area or volume being measured.

Differentiate between a foundation species and a keystone species. Give an example of each.

· A keystone species is one whose presence is key to maintaining biodiversity within an ecosystem and to upholding an ecological community's structure. The intertidal sea star, Pisaster ochraceus, of the northwestern United States is a keystone species. Whereas foundation species are species that have a strong role in structuring a community.

Explain how humans have expanded the carrying capacity of their habitat. Is the overall effect to the environment positive or negative?

· Although humans have increased the carrying capacity of their environment, the technologies used to achieve this transformation have caused unprecedented changes to Earth's environment, altering ecosystems to the point where some may be in danger of collapse.

What are the long-term consequences of exponential human population growth? What are possible solutions?

· At some point the food supply may run out. Another result of population growth is the endangerment of the natural environment. Many countries have attempted to reduce the human impact on climate change by reducing their emission of the greenhouse gas carbon dioxide. However, these treaties have not been ratified by every country.

What is carrying capacity?

· Carrying capacity refers to the maximum population size that a particular environment can support.

Compare density-dependent growth regulation and density-independent growth regulation, giving examples of each.

· Density-dependent factors, in which the density of the population at a given time affects growth rate and mortality, whereas density-independent factors are factors that influence mortality in a population regardless of population density. Roundworms are an density dependent organism.

What is a pioneer species, and under what circumstances are these species important?

· Hearty plants and lichens with few soil requirements, are known as pioneer species. They are important because these species help to further break down the mineral rich lava into soil where other, less hardy species will grow and eventually replace the pioneer species.

What is an invasive species? Give an example.

· Invasive species are nonnative organisms that, when introduced to an area out of their native range, threaten the ecosystem balance of that habitat. The purple loosestrife is an example of this.

Differentiate between a K-selected and an r-selected species based on reproductive strategies, habitat, behavior, and the way they obtain resources and care for their young.

· K-selected species are species selected by stable, predictable environments. K-selected populations species tend to exist close to their carrying capacity where intraspecific competition is high. K-selected species also are known to have a few large offspring over their lifetime. In contrast, r-selected species have a large number of small offspring.

What is logistic growth? Give an example. How would you identify this type of growth on a graph?

· Logistic growth is the leveling off of exponential growth due to limiting resources. On a graph you would see this as a large decrease in resources.

What factors influence density-dependent growth? What factors influence density-independent growth?

· Many factors influence the mortality of a population regardless of its density including weather, natural disasters, and pollution.

How do we calculate mortality rate?

Mortality rate is calculated by dividing the number of individuals dying by the number of individuals surviving and the multiplying that result by 1000.

Describe the energy trade-off in organisms with early vs. late reproduction.

Organisms that reproduce at an early age have a greater chance of producing offspring, but this is usually at the expense of their growth and the maintenance of their health. Organisms that start reproducing later in life often have greater fecundity or are better able to provide parental care, but they risk that they will not survive to reproductive age.

Describe the energy trade-off in organisms with high fecundity vs. low fecundity.

Plants with low fecundity produce few energy-rich seeds with each having a good chance to germinate into a new organism whereas plants with high fecundity usually have many small, energy-poor seeds that have a relatively poor chance of surviving.

Describe the general strategies of a semelparous species in terms of fecundity, timing of reproduction, and parental care.

Some life history traits, such as fecundity, timing of reproduction, and parental care, can be grouped together into general strategies that are used by multiple species. Semelparity occurs when a species reproduces only once during its lifetime and then dies. Such species use most of their resource budget during a single reproductive event, sacrificing their health to the point that they do not survive.

Population

The number of organisms of the same species that live in a particular geographic area at the same time, with the capability of interbreeding

Demography

The statistical study of changes in populations over time.

How would you calculate the population size of a species of plant? How would you calculate the population size of a species of mice?

To calculate the population size of a plant you would use a quadrat. To measure population size for mice you would use the technique referred to as mark and recapture.

Life table

a table showing the life expectancy of a population member based on its age