The Living World: Biodiversitt

ecosystem diversity

the number of different habitats available in a given area

species diversity

the number of different species in an ecosystem and the evenness of the population sizes of all species in the ecosystem

effects of higher species diversity

allows for a higher ecosystem resilience, as more plant species are available to repopulate disturbed ground, anchor soil, and provide food and habitat for animal species

species richness (r)

the total number of different species found in an ecosystem

a high number indicates a good sign of ecosystem health, with more quality resources like water and soil

species evenness

a measure of how all the individual organisms in an ecosystem are balanced between the different species

indicates whether there are one or two dominant species, or if the population sizes are well-balanced

genetic diversity

how different the genes are of individuals within a population, which occurs as a result of either random mutations in DNA or the recombination of sex cells of parents leading to new genetic combinations

benefits of high genetic diversity

the more genetic diversity in a population, the better the population can respond to environmental stressors, as there is a higher chance of some of the individuals in a population having traits that allow them to survive the environmental stressor

environmental stressors

events or situations that cause overall environmental decline

examples: drought, famine, or disease

bottleneck event

an environmental disturbance that drastically reduces population size and kills organisms regardless of their genome

effects of a bottleneck event

• the surviving population is much smaller, to the extent that it doesn’t represent and reduces the genetic diversity of the original population

• the surviving population is smaller and less genetically diverse, leading to vulnerability in future disturbances

inbreeding

the process of organisms mating with closely-related “family” members

effects of inbreeding

leads to a higher chance of harmful genetic mutations because of the similar genotypes from both parents

inbreeding depression

offspring of inbred generations suffering from extremely harmful mutations, making it both harder to reproduce and any offspring they do have has a harder chance of survival

ecosystem resilience

the ability of an ecosystem to return to its original conditions after a major disturbance

ecosystem services

goods that from natural resources, or the services/functions that ecosystems carry out that have measurable economic value to humans

provisioning services

goods taken directly from ecosystems or made from natural resources

examples: wood, paper, food, fish, hunting animals

human disruption of provisioning services

caused by overharvesting, water pollution, and clearing the land for agriculture or urbanization

regulating services

natural ecosystems regulate climate and air quality, reducing storm damage, and healthcare costs

example:

• trees store carbon dioxide through photosynthesis, which reduces the rate of climate change’s progress and lessens possible crop failures from crops

human disruption of regulating services

caused by deforestation, whether that be for logging or for agriculture and urbanization

supporting services

natural ecosystems support processes we do ourselves, making them cheaper and easier

example:

• wetland plant roots filter pollutants, leading to cleaner groundwater that doesn’t require as much money in order to purify it via water-treatment plants

human disruption of supporting services

caused by destroying pollinator habitats and filling wetlands in for development

cultural services

money generated by recreation in natural ecosystems or scientific discoveries made in ecosystems

examples:

• beautiful landscapes draw in tourists, who pay to enter parks, in order to see the landscape

• scientists learning about plant compounds that could lead to the creation of new medicines, that are sold for profit

human disruption of cultural services

caused by deforestation, pollution, and urbanization

harmful effects of human disruption of ecosystems

• decreases the value of ecosystem services that ecosystems provide, which has both ecological and economic consequences

examples:

• clearing land for agriculture or cities removes trees that store carbon dioxide, eventually leading to more storm damage as a result of climate change

• overfishing leads to fish population collapses, eventually leading to a loss in fishing jobs and lower fish sales

island biogeography

the study of ecological relationships and community structures on islands

islands

a piece of land surrounded by a body of water, or a figurative island such as a natural habitat surrounded by human-developed land

effects of larger islands

supports more total species; greater ecosystem diversity on larger islands, meaning that there will be more food and habitat resources as well as more niches that organisms can fill in the ecosystem\

there is a positive correlation between island size and species richness

effects of an island’s distance from the mainland

the closer an island is to a mainland the more likely it is to support more species; easier for colonizing organisms and migrating organisms to get to the island leading to genetic diversity in the population

there is a negative correlation between an island’s distance from the mainland and the species richness

colonizing organisms

organisms that move from the mainland and take up residence on an island

adaptive radiation

a single species rapidly evolving into several new species to use different resources and reduce competition

example: the Galapagos Finches and their different beaks evolving to fit a variety of different food sources

ecological range of tolerance

the range of conditions, such as temperature, salinity, pH, or sunlight that an organism can endure before injury or death results

the range of tolerance of a species can vary depending on the different environmental conditions of an individual organism’s habitat as a result of genetic biodiversity

optimal range

the range where organisms survive, grow, and reproduce

zone of physiological stress

the range where organisms survive, but experience some stress, such as infertility, lack of growth, and decreased activity

zone of intolerance

range where the organism will die

examples: thermal shock, suffocation, lack of food/water/oxygen

natural disturbances

a natural event that disrupts the structure and/or function of an ecosystem, and can be even greater than human disruptions

examples: tornados, hurricanes, asteroids, forest fires, etc.

period disturbances

natural disturbances that occur with regular frequency

example: dry-wet seasons

episodic disturbances

occasional natural disturbances that occur with irregular frequency

examples: hurricanes, droughts, and fires

random disturbances

natural disturbances that have no regular frequency

examples: volcanic eruptions, earthquakes, and asteroids

natural climate change

the variation of Earth’s climate over geologic time for numerous reasons that aren’t human-caused

effects of natural disturbances

• widespread habitat changes and loss (example: rising sea levels flood coastal and estuary habitats)

• wildlife may migrate to a new habitat as a result, but is largely irregular

adaptation

a new trait that increases an organism’s fitness

fitness

the ability for an organism to survive and reproduce

natural selection

organisms that are better adapted to their environment survive and reproduce more offspring, leading to the entire population having the adaptation over time

selective pressure

the environmental condition that kills individuals without the adaptation

example: predation

traits

characteristics determined by an organism’s environment, thus if the environments change these characteristics can become adaptations and older characteristics may become disadvantages

pace of evolution

the more rapidly that an environment changes, the less likely a species in the environment will be able to adapt to those changes

genetic diversity in evolution

enables a population to adapt to environmental changes as a result of the higher chance that some individuals have beneficial mutations