APES - Unit 2: The Living World: Biodiversity

biodiversity

diversity of life forms in an ecosystem

• 3 levels: ecosystem, species, & genetic

ecosystem diversity

number of different habitats available in a given area

species diversity

number of different species in ecosystem and balance/evenness of population sizes of all species in an ecosystem

• involves richness and evenness

genetic diversity

how different the genomes (set of genes) are of individuals within a population

How does diversity relate to ecosystem/population health?

higher biodiversity = higher ecosystem/population heat

richness

r; total number of different species in an ecosystem

• part of species diversity

evenness

measure of how all the organisms in an ecosystem are balanced between different species

Why is genetic diversity within a species beneficial?

population can respond better to environmental stressors (drought, disease, famine, etc.) b/c not as many may be susceptible

bottleneck event

environmental disturbance (natural disaster or human habitat destruction) that drastically decreases population size, killing organisms regardless of genome

• individuals die randomly, so survivors don’t represent genetic diversity of population

• reduces genetic diversity - new population begins with fewer founders, who remain isolated - when they reproduce, the lost genomes remain lost

inbreeding depression

when organisms mate with close relations - more chance of offspring having harmful genetic mutations b/c get similar genotypes from both parents

• more likey with smaller populations b/c harder to find nonrelated mate

ecosystem resilience

ecosystem’s ability to return to original conditions after a major disturbance (ex. wind storm, fire, flood, clear-cutting, etc.)

How does biodiversity relate to ecosystem resilience?

higher biodiversity = higher ecosystem resilience

ecosystem services

goods that come from natural resources or ecosystem services/functions that have measurable economic/financial value to humans

• provisioning, regulating, supporting, cultural

provisioning

goods taken directly from ecosystems or made from natural resources

• ex. fish, hunting animals, lumber naturally grown foods (berries, seeds, natural grains, honey)

• ex. paper, medicine, rubber

What disrupts provisioning services?

overharvesting, water pollution, clearing land for agriculture/cities

regulating

natural ecosystems regulate natural conditions like climate/air quality + storm damage, healthcare costs

• ex. trees sequester (store) CO₂ through photosynthesis - reduces climate change, damage from rising sea level, crop failure from drought

• ex. trees filter air by absorbing air pollutants - reduces healthcare costs (asthma, bronchitis, etc.)

What disrupts regulating services?

deforestation

supporting

natural ecosystems support processes we do ourselves, making them cheaper/easier OR “life support” - essential for ecosystem function

• ex. wetland plant roots filter pollutants - cleaner groundwater so not as costly to purify with water treatment plants

• ex. bees/pollinators pollinate crops - more crop production, higher profits

What disrupts supporting services?

pollinator habitat loss & filling in wetlands for development

cultural

money generated by recreation or scientific knowledge

• ex. beautiful landscapes draw tourists who pay to enter parks, spend $ at local stores/restaurants, or camping fees

• ex. pay for fishing licenses to fish in clean rivers

• ex. scientists learn about plant compounds - new medicines created & sold for profit

What disrupts cultural services?

deforestation, pollution, & urbanization

What is the result of humans disrupting ecosystem functions?

decreases value of ecosystem services - ecological and economic consequences

• ex. clearing land for ag/cities removes trees that sequester CO₂ → more atmospheric CO₂ → more climate change → more storm damage and crop failure

• ex. overfishing → fish population collapse → lost fishing jobs and lower future fish sales

What causes acid rain?

the burning of fossil fuels

island biogeography

study of ecological relationships and community structure on islands

• applies to actual islands or figurative habitat islands (natural habitats surrounded by human development - Central Park, National Parks, NC campus, etc.)

What are the 2 basic “rules”/observations of island biogeography?

1. Larger islands support more total species

   • b/c bigger → more ecosystem diversity → more food/habitat resources → more niches/roles organisms can play

2. Closer to mainland supports more species

   • b/c easier for mainland colonizing organisms to get to island → more genetic diversity

Explain 1. Larger islands support more total species

positive correlation between island size and species richness

• higher ecosystem diversity

• more available niches/roles - ex. many different food sources available to birds on Galapagos

• higher population sizes - more genetically diverse, so resistant to environmental disturbances

• lower extinction rate (less likely to die off)

Explain 2. Islands closer to mainland support more species

inverse relationship between island distance from mainland and species richness (father away = fewer species)

• closer = higher species richness

• easier to migrate (swim/fly) from mainland

• more continual migration to island → brings more genetic diversity and increases population size

evolution on islands

single colonizing species from mainland quickly evolves to many slightly different species to adapt to new island conditions

• ex. different beaks quickly evolve to fit various food sources

ecological range of tolerance

range of conditions (e.g. temp, salinity, pH) organisms can endure before injury or death results

• species & individual organisms both have range for all different environmental conditions of habitat

  • Ex. Salmon have basic range of temp tolerance from 6-22 degrees C, but some individual salmon have adaptations for larger range of tolerance

• 3 zones: optimal range, zone of physiological stress, & zone of intolerance

optimal range

range where organisms survive, grow, or reproduce

zone of physiological stress

range where organisms survive, but experience some stress like infertility, lack of growth, decreased activity, etc.

zone of intolerance

range where organism dies (ex. thermal shock, suffocation, lack of food/water/oxygen)

natural disturbances

natural events that disrupt structure/function of ecosystem; can be even greater than human disruptions

• ex. tornados, hurricanes, asteroids, forest fires, droughts

periodic disturbances

regular frequency

• ex. dry-wet seasons

episodic disturbances

occasional with irregular frequency - know general when they’ll happen (e.g. hurricane season) but not exactly when

• ex. hurricanes, droughts, fires

random disturbances

no regular frequency

• ex. volcanos, earthquakes, asteroids

natural climate change

climate has varied over geological time for various reasons - ex. slight changes in earth’s orbit and tilt cause it to shift slightly closer/further from Sun - cause mini ice ages & warmer periods

• so sea level has varied over geological time as glacial ice melts & forms

What do major environmental disturbances result in?

• widespread habitat changes &/or loss

  • ex. rising sea level floods coastal & estuary habitats, so underwater plants get less sunlight

• migration to new habitats

  • ex. wildebeests migrate to follow African savanna rain patterns (cyclical)

  • ex. ocean species move farther north as water temp warms (not cyclical)

  • ex. bird migration and breeding shift earlier as insect hatching shifts earlier with warming climate (not cyclical)

ecological succession

series of predictable stages of growth that a forest goes through

• 2 types: primary succession and secondary succession

primary succession

starts from bare rock in area w/o previous soil formation/plants

• ex. from volcanic rock or rock exposed after glacial retreat

• pioneer species = moss & lichen (spores dispersed by wind) - grow directly on rock by secreting acids that break down rock & release minerals with needed nutrients (N/P/K)

  • initial shallow soil is formed by chemical weathering of rocks by moss/lichen + organic matter from dead moss/lichen

secondary succession

starts from already established soil in area where disturbance (ex. fire, tornado, human land clearing) cleared out most plants

• pioneer species are still wind-dispersed seeds of sun-tolerant and fast-growing plants, but are grasses/wildflowers/weeds instead of moss/lichen

• soil is already established and sometimes enriched by nutrient-rich ash from fire, so is quicker than primary succession

What are the stages of succession characterized by?

which types of plant species dominate the ecosystem - b/c different species are adapted to conditions of different stages

pioneer/early succession species

appear first, when ground is bare rock or bare soil after disturbance

• characteristics: seeds spread by wind/animals, fast-growing, tolerant of shallow soil & full sunlight

• what they do: increase water/nutrients/shade/biodiversity, fix nitrogen, form new soil or improve it (through nutrient from growth/death cycles), alter environmental conditions for later plant growth

• ex. moss, lichen, wildflowers, raspberries, grasses/sedges

mid-successional species

appear after pioneer species have developed deeper soil

• characteristics: relatively fast-growing, larger plants that need deeper soils w/ more nutrients than pioneers need, sun tolerant

• continue to deepen/enrich soil with nutrients from growth/death cycles

• ex. shrubs, bushes, fast-growing trees (aspen, cherry, pine)

late successional species OR climax community species

appear last, after soil is deepened/enriched with nutrients by early & mid-successional species

• “oldest” stage b/c is latest stage & has had most time to develop

• characteristics: large, slow-growing trees, shade-tolerant, require deep soils for large root networks

• ex. maples, oaks, other large trees

Do all populations have some genetic diversity?

yes

Why does genetic diversity exist?

1. random mutations create new traits when DNA is copied

2. crossing over in parent chromosomes creates new combos of genes & therefore traits

adaptation

new trait that increases an organism’s fitness

fitness

ability to survive and reproduce

natural selection

organisms better adapted to environment survive & reproduce more offspring

• so individuals with adaptations pass them to offspring & individuals w/o adaptations die off → over time, entire population has adaptation (evolution)

selective/pressure force

environmental condition that kills individuals w/o the adaptation

• ex. predation

What determines which traits are adaptations? Explain.

the environment - as environment changes, different traits become adaptations & old traits become disadvantages

• ex. drought kills of finches with smaller beaks, making larger beaks for cracking nuts an adaptation

What happens when the environment changes rapidly?

it’s less likely that a species can adapt - if too rapid, species migrate out or die off completely

• ex. ocean warms too quickly → fish species might not be able to migrate before they run out of O₂ & suffocate

How does genetic diversity relate to adaptations? Explain.

more genetic diversity = adapt better to environmental changes b/c higher chance some individuals have good mutations

What determines a species’s evolution rate? Explain.

an individual’s lifespan - ex. longer lifespan = slower evolution rate

What factors cause species to become endangered?

poaching, special food/habitat needs, invasives, climate change

poaching

• poachers hunt exotic species for fur, tusks, & horns

• hunted for food

• sold as pets

can be overharvested

special food/habitat needs (how it relates to endangerment)

niche specialists are more prone to endangerment less tolerant of changing climate, habitat loss, wildfires, deforestation, urbanization, etc.

How do invasives cause endangerment?

can outcompete natives for resources life food, water, sun, and space

• both natural & human threat

How does climate change cause endangerment?

shifts species’s habitats/biomes, and migration to a new habitat is harder with fragmentation/loss

• changes in temp/precipitation can be too quick for a species to migrate/adapt

• both natural & human threat

poaching prevention

hiring armed guards to monitor populations & prevent poaching; laws punish poachers with stiff fines or jail

CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora)

international agreement for countries to set up agencies to monitor import/export of endangered species (as specified by IUCN Red List)

Endangered Species Act

US law giving USFWS (US Fish & Wildlife Service) the power to designate a species as endangered or threatened, monitor trade, & purchase land critical to those species’ habitats

How can habitats be protected, and why does that work?

designate them as National Parks, wildlife preserves, or animal sanctuaries

• to prevent hunting, development, fragmentation, & deforestation

• allows species to breed and reestablish population size

endangerment of amphibians, mammals, birds, warm water coral, and conifers

• amphibians - 41% b/c especially vulnerable to climate change b/c they’re biphasic life (rely on water & land) & have highly permeable skin

• mammals - 25%

• birds - 13%

• warm water coral - 33% b/c threatened by changing ocean temp & pH

• conifers - 34% b/c threatened by disease & warming temperatures expanding insect pest ranges

  • bad b/c coniferous forests sequester 3x as much CO₂ as temperate or tropical forests

What causes ocean acidification?

increasing atmospheric CO₂ levels

specialists

most likely to be endangered/extinct b/c:

1. are less likely to more to new habitat and adapt to new conditions

2. disadvantaged by rapidly changing habitat conditions

generalists

least likely to be endangered/extinct b/c:

1. more likely to move to new habitat & adapt to new conditions

2. advantaged by rapidly changing habitat conditions

interspecific competition

competition for resources (food, nest sites, water) between different species

• can cause species to be threatened, especially when combines with habitat fragmentation/loss due to human land use

• can further threaten species already vulnerable to habitat disruption due to climate change

• ex. Shenandoah salamander is endangered b/c limited to ranges on 3 specific mountains b/c of the fiercely territorial red-backed salamander (least concern, guard their rock habitats from other species, preventing range expansion)

HIPPCO

the 6 humans threats to biodiversity:

• Habitat fragmentation/loss

• Invasive species

• Population growth

• Pollution

• Climate change

• Overexploitation

population growth (HIPPCO)

• human population growth drives habitat loss

• urbanization & ag expansion are needed to feed more ppl

• ppl remove/fragment habitats

pollution/pollutants (HIPPCO)

• oil spills reduce organism population size

• pesticides (glyphosate, atrazine) kill non-target species

overexploitation (HIPPCO)

excessive hunting/poaching (faster than reproduction rate) → population decline & potential extinction

habitat fragmentation/loss (HIPPCO)

breaking of larger, continuous habitats into smaller, isolated patches; disrupts breeding, hunting, & migration

• roads & oil/gas pipelines disrupt movement & cause collisions with vehicles

• clear forests & grasslands for agricultural fields & lumber

• urbanization fragments habitats

• wetland draining (for ag/cities)

• river water level decrease (by dams)

Why are some species more disrupted by fragmentation that others?

• big predators need big hunting spaces

• smaller populations of large k-selected animals struggle to find mates

What does habitat fragmentation cause with regards to populations?

creates smaller, isolated subpopulations - less genetically diverse, more inbreeding depression, less resilient to environmental disturbances/disease

metapopulations

mostly isolated subpopulations connected by habitat corridors, which allows gene flow (mating between populations), improving genetic diversity

edge habitat

where 2 ecosystems meet; has different characteristics than the middle of each ecosystem

• some species thrive there

• biodiversity is often higher b/c diversity of food, shelter, and nutrient resources

• ex. forest-grassland, ocean-river (estuary)

How can edge habitats cause disruption?

can expand range of potentially disruptive species

• ex. brown-headed cowbird - brood parasite that leaves eggs in songbird nests for them to unknowingly raise

How does temperature change (as a part of climate change) cause disruption?

shifts biomes

• ex. warming temps shift boreal & temperate coniferous forests north, tundra decreases

How does precipitation change (as a part of climate change) cause disruption?

• warming glocal temp decreases precipitation in some areas - causes soil desiccation and desertification

  • precipitation increases in other areas - expands tropical ecosystems

How does sea level rise (as a part of climate change) cause disruption?

estuary habitats (salt marshes, mangrove swamps) become fully submerged & more saline, and coastal ecosystems are flooded

Relationship between domestication of species of agriculture and genetic/species biodiversity + explanation for crops & livestock

general decreases genetic/species biodiversity

• crops: less species are grown as selective breeding & GM results in only highest yield species (cause less genetic diversity, making crops vulnerable to disease or environmental disruptions)

• livestock: more than 8000 breeds of 11 species most commonly eating by humans - breeds are uniquely adapted to local climate, but many extinct or at risk b/c selected for only highest productivity

invasive species

species not native to area - introduced by human transport

• have no natural predators to control population

• highly competitive for resources (aggressive feeders or fast growers)

• generalists - can thrive in non-native habitats b/c adaptable and have diverse food/habitat needs

• many offspring - lay eggs or disperse many seeds

zebra mussel

• local to US rivers

• transported by ship ballast water

• aggressive filter feeders (eat algae other species rely on)

• 1 million eggs per year

• clog intake pipes in water systems

kudzu vine

• was planted to limit soil erosion in US

• grows fast

• outcompetes natives for sunlight (grows over them)

• has no herbivore control in US

Asian carp

• brought to US to control algae in aquatic farms, escaped to Mississippi River

• outcompetes native fish for food & space

• decrease fishery production & value

Emerald Ash Borer

• local to US

• spread by wood packing materials of ships/planes & firewood

• larvae are laid in bark and eat their way into phloem (plant tissue that moves glucose from photosynthesis to other parts of plant)

• disrupt tree nutrient transport, killing them

• global warming expands their range

Cane toad

• introduced to Australia to eat cane beetles that were causing sugarcane crop loss

• huge appetite

• drove decrease in amphibians and small reptiles

Python

• brought as pets to Florida and released into wild by owners when too big

• decimate mammal populations in Everglades: ~90-90%

• aggressive hunters w/o natural predators

Spotted lanternfly

• local to US

• eats native species’ plant sap (grapevines, maples, black walnut), damaging trees/ag

• outcompetes other species

How much do invasives cost the US per year and why?

about $120 billion per year (in 2005) b/c of lost agricultural productivity, tourism, property value, fish; & control/removal costs

control/removal methods for invasive species

• laws preventing their transport (ex. firewood for emerald ash borer)

• removing hosts to reduce spread (ex. dead ash trees for emerald ash borer)

• careful boat cleaning/inspection (for zebra mussels)

• introducing natural predators - biological control (ex. Chinese wasps for emerald ash borer)

• physical removal (ex. hunting pythons, detaching zebra mussels, pulling out plants, cutting down trees)