Chapter 19- Biology 1010 UVU – Flashcards

Population ecology is concerned with changes in population size and the factors that regulate populations over time, and population density is, the number of individuals of a species per unit area or volume of the habitat.

The three types of survivorship curves are as such; Type I curve, Humans and many other large mammals- usually produce very few offspring but give them good care, increasing the likelihood that they will survive to maturity. Type II curve, indicates low survivorship for the very young, followed by a period when survivorship is high for those few individuals who live to a certain age, which would include fish who lay millions of eggs at the same time, yet many get eaten by predators in the water. Type III curve, is intermediate, with survivorship constant over the life span....individuals are no more vulnerable at one stage of the life cycle than another. The authors give the example of certain invertebrates, lizards and rodents.

In comparing opportunist and equilibrial life histories, I learned that both life histories are a type of parental care that plants or animals give to their offspring. Opportunistic life history, enables the plant or animal to take immediate advantage of favorable conditions, such as a tree that produces well-nurtured seeds that it releases, and then offers it no parental care while the seedlings grow into mature trees. The other, equilibrial life history, is a pattern of developing and reaching sexual maturity slowly and producing few, well-cared-for offspring, such as a mother grizzly bear, who has one or two cubs, and cares for them well before letting them run off on their own as they mature.

The exponential population growth model indicates, the expansion of a population in an ideal, unlimited environment. This model shows population size on the vertical line and time on the horizontal line. This graph also shows the rate of population growth and how it increases with population size. The second chart, called the logistic population growth model, is used when growth is slowed by limiting factors. This chart predicts what a population's growth rate will be when the population size is small or large, or reaching its carrying capacity.

The population rate of population growth must increase with population size in order for it to exhibit exponential growth.

Density dependent factors are different than density-independent factors because density-dependent factors are limiting factors whose intensity is related to population density, and the other is not. Density-independent factors are population limiting factors whose intensity is unrelated to population density. An example of a density dependent factor is when a population's death rate increases while its birth rate depresses. This can be due to overpopulation or when a population has reached its carrying capacity, and the organisms have to compete for space and food. An example of a density-independent factor is when there is exponential growth and then a sudden decline of a population. An example of this can be the hare and the linx, whose rates go up and down at the same time.

Carrying capacity is the maximum population that a particular environment can sustain. Carrying capacity is limited, especially when a certain type of species experiences overpopulation, so with population growth, the environment cannot sustain more than its carrying capacity, or the organisms would have to compete for space, food and shelter.

Some populations of insects, birds, and mammals undergo dramatic fluctuations in density with remarkable regularity. These are known as population cycles. "Bust and boom" cycles that are characterized by rapid exponential growth are followed by 'busts,' during which the population falls back to a minimal level.

Endangered species are defined as those who are in danger of extinction, and threatened species are those that are likely to become endangered in the near future.

Invasive species are a non-native species that has spread far beyond the original point of introduction and causes environmental or economic damage by colonizing and dominating suitable habitats. These invasive species have devastating effects on native species because they spread and destroy native species as they take over in the new area. Weeds such as cheatgrass act like this, taking minerals that native plants would have used to flourish.

Biological control is the intentional release of a natural enemy to attack a pest population. An example of this is when they released mongooses in Hawaii to consume the invasive rat infestations, yet the mongooses took over and are eating endangered state birds in Hawaii also. Sometimes the biological control may work against our plans to eliminate the enemy.

Age structures predict a population's future growth, according to page 418 of our textbook. These diagrams can be informative as they show gaps or increases in births or deaths of certain age groups of males and females in a particular population.

Some of the factors that were responsible for the human growth rate to be high in the 1900s can be blamed on the Baby Boomers, that lasted for about two decades after World War II ended in 1945. Also, the growth and spread of healthcare, doctors and medicines helped more babies to be born and people to live longer.

This chart explains that since all of the baby boomers are reaching the last 10-30 years of their lives, the healthcare and social security systems in the U.S. will be pressured, just as schools were pressured when they were school-aged, and job competition was pressured when the baby boomers were graduate-aged. The authors suggest, The leading edge has reached retirement age, which will place pressure on programs such as Medicare and Social Security.

The average ecological footprint of a U.S. citizen is ranging high at around 9 gha per person, while the average for someone in an underdeveloped country would be around 2.6 gha. This is most likely because Americans have an abundance of possessions, and they over-consume food, fuel and other important but limited resources. The world will likely run out of resources due to Americans' and other developed, rich countries' overuse of these resources, I would think.