BIO 153 P3

• the total genetic information contained within all the individuals of a species
• it is measured as the number and relative frequency of all alleles present in a species

• is based on the variety of species on Earth
• measured by quantifying the number and relative frequency of species in a particular region

the array of biotic communities in a region along with abiotic components, such as soil, water, and nutrients

species that are found in an area and nowhere else

• species that are nonnative competitors, diseases, or predators
• grow to large population size
• disrupt species native to the area

species which are almost certain to go extinct unless effective conservation programs are put in place

• 1. habitat loss - most important factor in terrestrial environments
• 2. invasive species
• 3. overexploitation - dominant problem for marine species
• 4. pollution - dominant problem for freshwater species
• 5. native species interactions
• 6. natural causes

• 1. it can reduce habitats to a size that is too small to support some species
• 2. it reduces the ability of individuals to disperse from one habitat to another
• 3. creates large amounts of "edge" habitat (subject to invasion by weedy species and are exposed to more intense sunlight and wind)
• 4. large drop in biomass or the total amount of fixed Carbon

• 1. sustainability - the managed use of resources at a rate only as fast as the rate at which they are replaced
• 2. stabilizing human population size and resource use
• 3. ex situ conservation - the preservation of species in zoos, aquaria, wildlife ranches, seed banks, or other artificial settings
• 4. ecosystem restoration

the study of how organisms interact with each other and their environment

living things that organisms interact with--all the organisms that are part of the individual's environment

non-living things organisms interact with--all the chemical and physical factors, such as temperature, light, water, and nutrients, that influence the distribution and abundance of organisms

all of the organisms within a given area as well as the abiotic factors with which they interact

• the sum of a species' use of biotic and abiotic resources in its environment (range of resources it can use and range of conditions it can tolerate)
• the presence or absence of a particular species depends on whether its niche requirements are met

the number of different species in an environment

the totality of genes, species, and ecosystems in a region. These three levels describe different aspects of living systems and are measured in different ways

• you manipulate the independent variable and then look for an effect on the dependent variable
• your controls make sure that any effect you observe actually occurs as a result of your manipulation of the independent variable

• you look for naturally occurring differences in the independent variable and then see if the dependent variable changes in relation to the independent variable
• limitation of this kind of study is that it is harder to demonstrate a causal relationship
• use controls to reduce this limitation