unit 2 Flashcards
Definition of biodiversity
“the variety of life on earth”More biodiversity = more resistance to disturbances, which is why it is so important
Habitat diversitywhat increases it and what decreases it
the diversity of habitats (ex forests, oceans, wetlands, deserts, etc.)the more productive an ecosystem is, the more diversity it can support since there are more niches
specialists vs generalists
Specialists: species with narrow niches and specific living requirements. Really good at what it does where it does, but is vulnerable to change and disturbances Generalists: not super good at one thing, but can really just survive anywhere. Often have a broad range of tolerance, and are adaptable in terms of their habitats and niches
genetic diversity
The variety of genes found in a population or species. Once again, the more genetic diversity a species has, the better chance of survival it has against disturbances
Evolution:Natural Selection:Fitness:
Evolution: when a species changes overtime based on which individuals are best able to reproduce and continue their genes/mutationsNatural selection: The process by which traits that enhance survival and reproduction are passed on more frequently to future generations than those that do not. (drives evolution)Fitness: The likelihood that an individual will reproduce
mutations and adaptive traits
mutations: accidental changes in DNA that may be passed on to the next generation. Non-lethal mutations provide the genetic variation on which natural selection acts.Adaptive traits: A trait that promotes reproductive success, but it must be heritable
phylogeny
a model that shows how species grow into each other, branches out like a tree
genetic bottlenecks
A drastic decrease in genetic diversity for a population or species due to a sudden decrease in population, making the gene pool much smaller. This can lead to inbreeding, difficulty dealing with disturbances, or population collapse
Species diversityevenness vs richness
The number and abundance of species living in an ecosystemSpecies evenness: a measure of the comparative abundance of all species in an organismSpecies richness: the number of different species in the ecosystem
ecological tolerance (3 zones)
each living thing has a set of ideal conditions to live in. Three zones: zone of optimum, zone of physiological stress, zone of intolerance
ecological disturbances
Disturbances change the conditions in an ecosystem. They aren’t inherently bad, and build biodiversity in the long run. However, for species that aren’t prepared, they can be damaging. They can be short term or long term, natural or manmade. Also periodic, episodic, or random.
natural climate change
Earth has NATURALLY occurring climate change all the time, it’s just on a much longer time frame. this leads to significant changes in the biosphere since species must adapt to the new climates. When faced with habitat change, species can adapt, move, or die
adaptations (biological or structural, behavioral)
behavioral adaptations can occur within one generation, where a species will behave differently (ex. eat a new food) to survivebiological or structural adaptations often take generations to form, and can never occur within one individual. Changes the actual make of an organism that may or may not be passed on
migrations
movement of species from one location to another. Can be seasonal, like bird migration, or permanent
extinction
when the last member of a species dies, meaning the species is gone forever. It is not necessarily bad though, and is a natural extension of natural selection. There is a background extinction rate but it is veryyy slow (has sped up quite a bit with climate change)
functionally extinct species
When a species has a very small population and thus cannot fulfill their nicheAlso occurs when the population is no longer viable to reproduce effectively, whether the gene pool is too small or there is not enough organisms
indicator species
They tend to be species that are particularly sensitive to change, and will indicate when one is happeningEcologists monitor “indicator species” populations to determine if and how a change is occurringAmphibians are usually good indicator species
mass extinctions
when at least 50% of all species on earth die out in a short period of time (usually happens after largescale climate change)There have been 5 throughout history, we are now in a 6th.Creates a sudden and significant drop in biodiversity. This takes time to recover, but massive drops in biodiversity are often followed by an explosion of evolution and return of biodiversity
island biogeography
the closer an island is to the mainland the higher the biodiversitythe bigger an island is, the higher biodiversityislands gain species from colonization and speciation, which the two features above help with
endemic species
a species that has a very limited range, limited to just a few locationsislands often create these because they are so remote
habitat fragmentation
When a contiguous, undisturbed habitat is split up into smaller fragments due to natural or man made eventssmaller fragments = lower biodiversity
linking fragments
They use this method to improve ecosystems harmed by human activities, by making ecological corridorscan be used by species to “island hop”
ecological succession
The process by which an ecosystem recovers from a disturbanceIn general, ecosystems with higher biodiversity have an easier time recovering from disturbancestwo types of succession: primary and secondary
primary succession
Must build the soil to support the plants first, which can take 100s or 1000s of years lichens and mosses first colonize the areaAs they die/decompose, small amounts of soil are created which allows more complex plants to grow (weeds and grasses)- the roots of these plants break up rock to form deeper soilThis process of growth, decay and regrowth continues and soil depth increasesEventually, shrubs and small trees grow, followed by larger treesFinally, a climax community forms made up of large hardwood species like oak and hickory
secondary succession
Very similar to primary succession except that soil is already presentCan take less than 100 years to completeProcess starts with grasses and shrubs then moves to a climax community once again
types of selection
Directional selection: One extreme trait against the other extreme (moves left or right)Stabilizing selection: Moderate traits are better than extremes, smaller bell curveDisruptive selection: Both extremes are fine but moderate traits are bad, creates a dip in the middle
causes of extinction
Competition, predation, environmental change
adaptive radiation
The diversification of a group of organisms to fill multiple nichesThis always occurs after a mass extinction event, because the survivors evolve to fill the niches that have just been vacated.
