BIO Ch 19-20 - Lecture notes bio chapter 19-20 PDF

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Ch 19 Population Ecology Population & Population ecology Population a group of individuals of a single species that occupy the same general area. Example we humans are a population. Individuals of the population rely on the same resources and are influenced by the same environmental factors. Population ecology is concerned with changes in population size and the factors that regulate populations over time. this means that a population ecologist focuses on changes in a population and they can describe a population in terms of its size, age, or density which is how the number of individuals per unit area or volume. They also study interactions between biotic (living things) and abiotic (non-living things) factors. Population Density & Age structure Population density is the number of individuals of a species per unit area or volume of the habitat. Population density is not a constant number and may change when individuals are born or die or when new individuals enter the population or leave it. Age Structure is and shows the distribution of individuals in different age-groups. Age structure can provide information on a population’s survival or reproductive success and how it relates to environmental factors. Life history – opportunistic & equilibrial A population’s pattern of survivorship is a key feature of its life history, the set of traits that affect an organism’s schedule of reproduction and survival. Key life history traits include the age at first reproduction, the frequency of reproduction, the number of offspring, and the amount of parental care given. Life history traits are shaped by evolutionary adaption. An opportunistic life history describes those who develop and reach sexual maturity rapidly which means that they have many offspring but give little parental care. This applies to animals and plants. Organisms that have an opportunistic life history take immediate advantage of favorable conditions and they exhibit a Type III survival curve. Equilibrial life history is the opposite of opportunistic life history. Organisms that follow the equilibrial life history tend to develop and reach sexual maturity slowly and have few offspring who are well taken care of. Organisms that have this life history tend to be bigger in size and tend to live longer. Populations with this life history pattern exhibit a type I survivorship curve. Exponential population growth model Exponential population growth describes the expansion of a population in an ideal, unlimited environment, meaning no predators, food scarcity, no disturbances. The exponential population growth model is the current population size multiplied by a constant factor that represents the number of births minus the number of deaths. Logistic population growth model The logistic population growth model is a model that describes population growth that decreases as population size approaches carrying capacity. The growth rate decreases as the population size approaches carrying capacity. Carrying capacity & limiting factors Carrying capacity is the maximum population size that an environment can sustain. For example, there are 7 billion humans and the earth is almost about to reach its carrying capacity for humans.

Limiting factors are environmental factors that restricts the number of individuals that can occupy a habitat, thus holding population growth in check, restricts population growth. Density‐ dependent factors & intraspecific competition Density-dependent factors are limiting factors whose intensity is related to population density. There are many types of density dependent limiting factors such as availability of food, predation, disease, and migration. But the main factor is the availability of food. Some densitydependent factors that limit population growth are food and nutrient limitations, insufficient space for territories or nests, increase in disease and predation, and accumulation of toxins/ toxic waste of animals. Intraspecific competition is competition between individuals of the same species for the same limited resources. Density‐ independent factors Density-independent factors are a population limiting factor whose intensity is unrelated to population density is called a density-independent factor. This means that abiotic factors, nonliving things such as water or the weather among other things. Population cycles Population cycles are cycles that show the increase and decrease of a population. There is a cycle called boom and bust where boom means that there is a rapid exponential growth followed by a bust where the population falls back to a minimal level. In the textbook it shows an example where the snowshoe hare and the lynx seem to match each other on a graph that depicts their population cycle. This happens because the hare is the main food source for the lynx. This shows that when there is a decrease in hares the population of the lynx goes into a bust because their food source is limited. This can be an example of a density dependent factor, availability of food. Endangered species & threatened species As defined in the U.S. Endangered Species Act, a species that is in danger of extinction throughout all or a significant portion of its range. Threatened species are defined as those that are likely to become endangered in their foreseeable future, meaning there is time to save them if we act quickly. Endangered and threatened species are characterized by population sizes that are highly reduced or steadily declining. Invasive species Invasive species is 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. Invasive species tend to exhibit an opportunistic life history pattern. Biological control Biological Control is the intentional release of a natural enemy to attack a pest population in order to eliminate or control invasive species. Integrated pest management Integrated pest management uses a combination of biological, chemical, and cultural methods for sustainable control of agricultural pests. Researchers are investigating IPM approaches to combat invasive species. Biology helps with the knowledge of population ecology of the pest,

its predators, and parasites as well as plant growth dynamics. Chemicals can also be used but not a lot of it, only when there seems to be an abundance of pests. Lastly cultural methods can help with dealing with pests by rotating crops which helps deprive pests of a dependable food source. The big thing to take away from this is that IPM advocates tolerating a low level of pests rather than attempting total eradication. Population momentum Population momentum is a population in which the fertility rate averages two children two children per female (replacement rate), the continuation of populating growth as girls reach their reproductive years. Ecological footprint Ecological footprint is an estimate of the amount of land required to provide the raw materials an individual or a population consumes, including food, fuel, water, housing, and waste disposal.

Ch 20. Communities and Ecosystems Biodiversity: Genetic diversity, species diversity (richness & relative abundance) & ecosystem diversity Biodiversity is the variety of living things; includes genetic diversity, species diversity, and ecosystem diversity. Biodiversity is short for biological diversity. Genetic diversity within a population is the raw material that makes microevolution and adaption to the environment possible. The loss of genetic diversity affects the species and threatens its survival since it won’t have those raw, unique genes. This also affects people since many researchers and biotech people are enthusiastic about the potential that genetic “bioprospecting” holds the future development of new medicines, industrial medicines, and other products. Species diversity is at a low point. The current rate of species extinctions is extremely high compared to the rate of natural extinctions over the past 100,000 years. Researchers say that at the current rate of destruction, over half of all currently living plant and animal species will be long gone by the end of this century. Ecosystem diversity is the destruction of ecosystems that results in the loss of essential ecosystem services. An ecosystem includes both the organisms and the abiotic factors in an area. The loss of one species can have a negative impact on the entire ecosystem. Ecosystem services Ecosystem services are functions performed by an ecosystem that directly or indirectly benefit people. These services include air and water purification, climate regulation, and erosion control. For example, forests absorb and store carbon from the atmosphere, a service that vanishes when forests are destroyed or degraded. Community & ecosystem A community is an assemblage of species living close enough together for potential interaction. All organisms inhabiting and potentially interacting in a area; an assemblage of populations of different species. The lion, zebra, hyenas, vultures, plants, and unseen microbes are all members of an ecological community in Kenya. An ecosystem is all the organisms in a given area, along with the nonliving (abiotic) factors with which they interact; a biological community and its physical environment. Interspecific interactions: Interspecific competition, mutualism, predation, herbivory, parasites & pathogen Interspecific interactions are any interaction between members of different species. Interspecific competition is competition between populations of two or more species that require similar limited resources Mutualisms is an interspecific interaction in which both partners benefit. Predation is an interaction between species in which one species, the predator, kills and eats the other, the prey. Herbivory is the consumption of plant parts or algae by an animal. Parasites are organisms that live in or on another organism (the host ) from which it obtains nourishment; an organism that benefits at the expense of another organism which is harmed in the process. Pathogens are a disease-causing virus or organism.

Ecological niche Competitive exclusion principle Trophic structure Food chain & food web Producers & consumers (herbivores, carnivores & omnivores) Biological magnification Keystone species Ecological succession Primary and secondary succession Biomass & primary production Biogeochemical cycles C cycle & N cycle Conservation Biology & restoration biology Biodiversity hot spots Endemic species Landscapes & landscape ecology Bioremediation Sustainable development...