Exam 3 Flashcards
How do u calculate alpha diversity
Alpha diversity is the number of species within a specific habitat
Beta diversity
The number of distinct species between 2 habitats.
Gamma diversity
The total number of species across the community
How do u calculate jaccard similarity value between 2 habitats
J = X/A+B+X
X = number of shared species between habitats
A = number of distinct species in habitat A
B = number of distinct species in habitat B
Difference between demographic and environmental stochasticity?
Demographic stochasiticty is when random variation in death and birth rates is based off differences in inidividuald in the population rather than environmental changes. Environmental stochasticity is when random variation in death and birth rates is based off environmental changes.
How did Clements and Gleason views of communities differ? Would they favor facilitation or inhibition?
Clements believed that communities function as a super organism where species depend on each other to exist, favoring facilitation. Gleason believed that species in communities function independently, and live in the same area due to similar adaptation and habitat requirements. Gleason would favor inhibition.
Describe the ecological succession in Glacier bay
Vegetation started with mosses, lichens, herbs, low shrubs. 35-45 years of exposure contained talk species of willow and black Cottonwood trees. 100 years of exposure contained spruce trees.
Examples of facilitation and inhibition in glacier bay.
Facilitation: alder shrubs that grew develop mutualistic relationship with nitrogen-fixing bacteria, releasing more nitrogen into the soil. This paved way for spruce trees to grow since they are nitrogen limited.
Inhibition: tall spruce trees start to grow and shade the floor, creating unfavorable environment for any shrubs to continue to grow there.
Standard equation for species-area relationship?
S = cA^Z
S = number of species
c = y-intercept
A = area associated
z = slope of graph (normally 0.20-0.35)
What is turnover in the Island Biogeograohy theory?
Turnover occurs when a new species colonized an island and others go extinct because of it. This would continuously occur on an island in species equilibrium.
Describe an actual experiment or study testing whether turnover occurs
In the islands of the Florida keys, species richness reached equilibrium and the composition of species on the island changed. As more intervertebrages inhabited the island, some species went extinct.
Are communities controlled from the top-down or bottom-up? Provide examples
Communities are most commonly controlled from the top-down, meaning abundance of trophic groups is determined by the existence of predators at the top of the food chain. In ecosystems with large abundances of grass, it suggests that predators limit the number of herbivores in the community, showing why there is excess vegetation. However, on rare occasions, some communities could be bottom-up, such as small ponds with phyloplankton and zooplankton.
Does an ecosystem “improve” after an ecological succession? Provide evidence
Over the course of an ecological succession, the ecosystem constantly does improve over time. Different communities and species gradually succeed each other until it reaches a climax community where all communities can thrive. An example would be when a succession on land starts with grasslands and shrubs and eventually becomes an area of tall trees and moist soil.
What is the relationship of productivity and biodiversity?
The most buodiverse communities tend to have the highest productivity. Plant communities with high biodiversity assimilate and release nutrients and solar energy in its community.
Relationship between biodiversity-disturbance
Disturbance of an ecosystem, for the most part, tends to increase biodiversity. Although species can be harmed, it provides opportunities for new species who did not have a place in the community. New species tend to move in after disturbance.
