Ecology Exam 4

Species richness

The number of different species present in a community; simple count, does not consider abundance differences (not number of individuals)

Equitability (evenness)

How individuals are distributed among the species present

Low

If one species makes up 90% of individuals, evenness is ____

High

If all species have roughly the same number, evenness is ____

High diversity

Many species; grow in roughly equal abundance

Shannon index

Rages from 0 to infinity

Simpsons D index

Ranges from 0 to 1

Shannon index

H’= -sum of (p_ilnp_i)

Pi

Shannon index: Proportion of individuals in x species

~0.5

Shannon index: low diversity

~1.5-2.5

Shannon index: Moderate diversity

>2.5

Shannon index: High diversity

Simpsons D index

D=sum of (p_i²)

Low diversity

Simpsons D index: If one species dominates (90%) D will be close to 1 (___ ___)

High values

Simpsons D index: Low diversity

Low values

Simpsons D index: High diversity

Habitat diversity

More types of habitat, more niches (mountains have different zones of temps and moisture creating microhabitats and niches)

Tropical regions

Over half of all species occurs in ~1% of Earth’s land

Time; area; large; less; larger

Tropical diversity (___ and ___): long-term stability and ____ continuous areas promote speciation; Great tropical areas allows large species ranges and ___ extinction; ___ areas= more individuals, and greater genetic variation

Conservatism

Tropical diversity (____): Many species originated in the tropics, and never left; adaptations to warm, wet climates makes it hard to colonize temperate regions; Most lineages still live near their evolutionary origins

Productivity

Tropical diversity (____): More sunlight and more rainfall in tropical areas allow for more plant biomass; increased photosynthesis; high primary productivity supports more complex food webs; abundant food means less extinction risk

Spatial heterogeneity

Tropical diversity (___): Variation in habitat (light, temperatures, moisture) provides many niches; variation prevents one species from dominating

Evolutionary time

Tropical diversity (___ ___): tropics are extremely old; allows for more time to evolve and diversify

Evolutionary speed

Tropical diversity (___ ___): Evolution occurs faster in warm climates; mutation increases with temperature; faster reproduction=more generations per time unit (faster evolutionary change)

Climate stability

Tropical diversity (___ ___): Tropical climates vary less then temperate climates; decreases extinction and allows niche specialization

Disturbance timing

Tropical diversity (___ ___): How often disturbance happens

Too little

Disturbance timing: Competitive exclusion (one species dominates)

Too much

Disturbance timing: Species cannot establish

Intermediate

Disturbance timing: Mix of colonizers (pioneers) and specialists coexisting

Weather

Current state of the atmosphere at any given time

Climate

Long-term weather conditions; includes variability

Climate change

Directional change in climate over a period of time

3 decades

Climate change has a directional change over a period of time of at least # ____

1.1

Average global surface temperature increased by ___ C between 1880 and 2020

Glacier; sea; extreme; shift; insecurity

Current climate change: ___ loss; ___ levels rise; ___ weather; ecosystem ___; food and water ____

Dryer

Climate change: Deserts are getting ___

Wetter

Climate change: Temperate areas are getting ____

Anthropogenic

Cause of climate change through fossil fuels, deforestation, and agricultural processes (humans)

Fossil fuel burning

Coal, oil, natural gas

Agricultural processes

Changes the amount of sunlight that is absorbed/reradiated back into space; greenhouse gasses (trap heat on Earth)

Food chain impacts

Impacts of climate change: Polar bears hunt seals, but now seals surface in open ocean instead of holes in ice

Ocean acidification

Impacts of climate change: Increases carbon dioxide levels; coral bleaching

Terrestrial organisms

6% of insects, 8% of plants and 4% of vertebrates will loose at least ½ of their geographic range with 1.5C increase

Range shifts

Species have to move to more tolerable climates

Shifts threaten species

Cannot move fast enough; have nowhere to move; paths are blocked by human structures

Surface; water vapor; growing; sea; temperature

Climate change: increased ____ temperature; increased __ __ in atmosphere; increased ___ season; increased ___ level; increased sea ____

Snow; ice sheets; sea

Climate change: Decreased ___ cover; decreased ___ ___ and glaciers; decreased ___ ice

1.5; fossil fuels

Current goal: limit warming to ___ C; reduce use of ___ ___

Extinction

Permanent loss of a species

Mass extinctions

Needs timing, multiple ecosystems, and numbers to classify as this

5

Earth has had __ mass extinctions

Natural

Extinction is a ___ part of Earth’s history

Scale; time

Extinction becomes concerning when ___ increases and ___ decreases

10-100

Normal rate (extinction): roughly __-__ species per year

Background extinction

Normal, ongoing loss of species over geological time

Mass extinction

Widespread, rapid loss of biodiversity; numerous groups and numerous ecosystems

Fossil records

Usually across strata in rocks (geological boundaries)

Geochemical; volcano; impact

Identification of extinction “cause”: Changes in ____ makeup; presence of ___ deposits, ___ sites

Large scale volcanism

Mass extinctions: Release greenhouse gases and other compounds; rapid warming or cooling, acid rain, ocean acidification

Asteroid impacts

Mass extinctions: Shockwaves, fire, dust, aerosols, rapid cooling, food-web collapse

Climate change

Mass extinctions: Alters habitats faster than many species can adapt

Ocean anoxia

Mass extinctions: Decreased oxygen content

Niche vacancies

After extinction: Survivors may occupy habitats left empty

Adaptive radiation

After extinction: Surviving lineages diversify into multiple new species

Recovery period

After extinction: Long term recovery to approach previous levels of diversity and primary productivity; changes in abundance and diversity

~444mya

5 mass extinctions: End-Ordovician

~359-372mya

5 mass extinctions: Late Devonian

~252mya

5 mass extinctions: End-Permian

~201mya

5 mass extinctions: End-Triassic

~65mya

5 mass extinctions: End-Cretaceous

End Ordovician

Loss of majority of marine organisms; formation of massive ice sheets; sea levels dropped; followed by rapid warming

Global cooling

End Ordovician mass extinction happened due to rapid ___ ___

Double pulse extinction

The rapid global warming following the end Ordovician mass extinction caused a ___ ___ ___

Late Devonian

~75% species loss; marine life; armored fishes; expansion of land plants increased runoff

Ocean oxygen; plants; volcanism

Late Devonian mass extinction caused due to reduction in ___ ___; expansion of land ___ (increased chemical weathering; increased nutrient in waterways; increased algae content decreased carbon dioxide and oxygen levels); potential ____

End Permian

Lasted 50,000 years; the great dying; ~96% marine, 70% terrestrial; 50% of families went extinct

Lava flows; atmosphere; ozone; warming; acid; acidification; hurricanes

End Permian mass extinction caused by huge __ __ from Russia (released massive amounts of CO2); toxic ___ (from CO2 and volcanic gas); loss of ___ layer; global ___; ___ rain; ocean ___; Mega ____

End Triassic

~75%; large amphibians, marine reptiles

Pangea; warming

End Triassic mass extinction caused by CO2 released from ____ splitting; global ___

End Cretaceous

~75%; non-avian dinosaurs; plesiosaurs; marine plankton; marine reptiles; non-seed plants; Survivors: Deep sea organisms

Outcompete; glaciation; volcanic

End Cretaceous mass extinction theories: Mammals ___ dinosaurs; ____; ____ activity

Asteroid impact

End Cretaceous mass extinction caused by ___ ___

Before; diversify; marine; partial

Mammals outcompete: Mammals existed ____ extinctions; mammals ____ after dinosaurs went extinct; Doesn’t explain ___ extinctions (___ explanation, but not primary cause)

Mobile; globally

Glaciation/climate cooling: BUT dinosaurs are ___ and could leave cooling areas; Extinction affected organisms ___, not just in areas that cooled

CO2; acid; decline; contributed

Volcanic eruptions: increased ___; lead to ___ rain; stress systems and cause ecosystem ___; BUT too ___ to explain sudden extinction peak (___, but not sole cause)

Seeded; crater; large

Asteroid impact: ___ plants survived (can go dormant in the dark); ___ matches size and age of event; Global extinction pattern: must have been something ___

Time 0

After asteroid: Instant firestorms; Ejected materials re-entering atmosphere; mega-tsunamis over km tall near crash site; massive earthquakes

Minutes/days later

After asteroid: Dust/soot/ aerosols block sunlight; photosynthesis halts; rapid global cooling

Weeks/years later

After asteroid: Food web collapse; plankton crash led to marine die-off; herbivores starve, carnivores crash; fungi and detritivores thrive; ferns=pioneer species

Competition; predation; disease; environmental change; cataclysms

Mass extinctions aren’t always dramatic; ____ (invasive species; early mammals); ___ (cats); ___ (brought by humans); ___ ___ (long term shifts); ____ (asteroids, volcanic eruptions, floods, ocean anoxia)

Dutch elm disease

Extinction event (disease): fungal pathogen; spread by beetles; destroyed native elms in Europe and north America

Terminal Pleistocene extinction

Is a major extinction even NOT a mass extinction

Terminal Pleistocene extinction

~65-70% of large animals in north america; ~50,000-10,000 ya; primarily affected larger megafauna (>100lb) [mammoth, mastodon, sabretooth, giant ground sloth, giant birds, horse, camels, dire wolves]

Human hunting; climate change; recent

Terminal Pleistocene extinction caused by ___ ___ pressure (new hunting tools and techniques; lack of fear in organisms); ____ ___ led to rapid warming; Most ___ large-scale extinction