Vocabulary:

• Species: A group of organisms capable of interbreeding, this is a taxonomic representation

• Species richness: The number of different species in a given area

• Species evenness: The relative abundance of rare and common species within a community (are 5 species all 20% or is one 60% and the other 10%?). Typically, the higher the evenness, the more healthy an ecosystem, because one species isn’t dominating all the resources

• Species diversity: A communities species richness and evenness is considered diversity, combines the two metrics

• Simpson’s Index: Measures species diversity in a given community, by dividing the number of total individuals by the summation of individuals in one species. Randomly sampling species twice, this is the chance they are the same species, though this might depend on density of communities.

• Shannon’s-Weiner Index: Measures species diversity, by measuring the uncertainty of diversity. Uncertainty is low is a community is dominated by one species

• Rank abundance curve: Graphical representation of abundances, with respect to one another

• Intermediate disturbance hypothesis: If there is a moderate level or disturbances, diversity will increase. This is because disturbances increase diversity in areas starting with low diversity, and decrease it in areas starting with high diversity. Different species prefer different levels of disturbances, and a moderate level balances everything out.

• Pioneer species: A species that colonizes an area right after a disturbance has occurred in said area

• Late succession species: A species that colonizes an area after it has been established after a disturbance

• Functional diversity: Shows the roles of plants, what their niches are and how they help the ecosystem, the range of niches

• Extinction: Loss of diversity, typical rate is 1 to 5 species a year naturally, has been expedited by humans

• Mass extinction event: 99.99% of species go extinct, 5 have happened on Earth, widespread and rapid decrease in diversity

  • Ordovician: Most sea life gone, caused ice age

  • Devonian: Sea level changes, asteroid impacts, climate change caused

  • Permian: 96% of species lost, asteroid impact, methane gas released and sea levels changed

  • Triassic: 50% lost, primarily due to climate change

  • Cretaceous (K-T): Bye bye dinos, 75 million years ago, massive asteroid on Yucatan caused basalt erruptions and dust and debris to enter the atmosphere and cover the sun. Turtles, snakes, crocodiles, and lizards survived, mammals emerged

  • Holocene: Human driven, under way right now, extinction rate is soaring into 1000 to 10000 a year. Caused by habitat loss, exotic and invasice species introduction, pollution, overexploitation of resources, and global climate change that will likely occur in the future. This can be stopped by not using fossil fuels, preserving half of Earth’s land, ending public subsidies that damage nature, and slowing population growth