APES unit 2

Question 1

Definition of biodiversity

Answer 1

“the variety of life on earth”
More biodiversity = more resistance to disturbances, which is why it is so important

Question 2

Habitat diversity
what increases it and what decreases it

Answer 2

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

Question 3

specialists vs generalists

Answer 3

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

Question 4

genetic diversity

Answer 4

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

Question 5

Evolution:
Natural Selection:
Fitness:

Answer 5

Evolution: when a species changes overtime based on which individuals are best able to reproduce and continue their genes/mutations
Natural 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

Question 6

mutations and adaptive traits

Answer 6

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

Question 7

phylogeny

Answer 7

a model that shows how species grow into each other, branches out like a tree

Question 8

genetic bottlenecks

Answer 8

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

Question 9

Species diversity
evenness vs richness

Answer 9

The number and abundance of species living in an ecosystem
Species evenness: a measure of the comparative abundance of all species in an organism
Species richness: the number of different species in the ecosystem

Question 10

ecological tolerance (3 zones)

Answer 10

each living thing has a set of ideal conditions to live in.
Three zones: zone of optimum, zone of physiological stress, zone of intolerance

Question 11

ecological disturbances

Answer 11

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.

Question 12

natural climate change

Answer 12

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

Question 13

adaptations (biological or structural, behavioral)

Answer 13

behavioral adaptations can occur within one generation, where a species will behave differently (ex. eat a new food) to survive
biological 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

Question 14

migrations

Answer 14

movement of species from one location to another. Can be seasonal, like bird migration, or permanent

Question 15

extinction

Answer 15

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)

Question 16

functionally extinct species

Answer 16

When a species has a very small population and thus cannot fulfill their niche
Also occurs when the population is no longer viable to reproduce effectively, whether the gene pool is too small or there is not enough organisms

Question 17

indicator species

Answer 17

They tend to be species that are particularly sensitive to change, and will indicate when one is happening
Ecologists monitor “indicator species” populations to determine if and how a change is occurring
Amphibians are usually good indicator species

Question 18

mass extinctions

Answer 18

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

Question 19

island biogeography

Answer 19

the closer an island is to the mainland the higher the biodiversity
the bigger an island is, the higher biodiversity
islands gain species from colonization and speciation, which the two features above help with

Question 20

endemic species

Answer 20

a species that has a very limited range, limited to just a few locations
islands often create these because they are so remote

Question 21

habitat fragmentation

Answer 21

When a contiguous, undisturbed habitat is split up into smaller fragments due to natural or man made events
smaller fragments = lower biodiversity

Question 22

linking fragments

Answer 22

They use this method to improve ecosystems harmed by human activities, by making ecological corridors
can be used by species to “island hop”

Question 23

ecological succession

Answer 23

The process by which an ecosystem recovers from a disturbance
In general, ecosystems with higher biodiversity have an easier time recovering from disturbances
two types of succession: primary and secondary

Question 24

primary succession

Answer 24

Must build the soil to support the plants first, which can take 100s or 1000s of years
lichens and mosses first colonize the area
As 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 soil
This process of growth, decay and regrowth continues and soil depth increases
Eventually, shrubs and small trees grow, followed by larger trees
Finally, a climax community forms made up of large hardwood species like oak and hickory

Question 25

secondary succession

Answer 25

Very similar to primary succession except that soil is already present
Can take less than 100 years to complete
Process starts with grasses and shrubs then moves to a climax community once again

Question 26

types of selection

Answer 26

Directional selection: One extreme trait against the other extreme (moves left or right)
Stabilizing selection: Moderate traits are better than extremes, smaller bell curve
Disruptive selection: Both extremes are fine but moderate traits are bad, creates a dip in the middle

Question 27

causes of extinction

Answer 27

Competition, predation, environmental change

Question 28

adaptive radiation

Answer 28

The diversification of a group of organisms to fill multiple niches
This always occurs after a mass extinction event, because the survivors evolve to fill the niches that have just been vacated.