APES Unit 2: The Living World - Biodiversity

Mod 8: Intro to Biodiversity

Biodiversity

an ecosystem that includes genetic, species & habitat diversity

• the more genetically diverse a population is, the better it can respond to environmental stressors

Genetic Diversity

measure of the genetic variation among individuals in a population

• large populations tend to have a high amount of variation in their genetic composition

• high GD benefits the long-term persistence of pop bc they’re better able to respond to changes in the env.

Species Diversity

# of species in a region/particular ecosystem

• ex: tundra & taiga vs tropical rainforest biomes

Habitat Diversity

variety of habitats that exist in a given ecosystem

• when a region contains a high diversity of habitats there is an increase in the # of species that live in them

* w/habitats that r diff, diff species will have diff adaptations

Ecosystem Diversity

variety of ecosystems that exist in a given region

Population Bottleneck

larger pops may have higher genetic diversity, but when that pop declines rapidly, the survivors may not have as much genetic diversity as the og group

Consequences of Genetic Diversity

High: disease resistance

Low: disease susceptibility

Consequences of Species Diversity

High: ecosystems respond well to disturbances

Low: decreases in species # can serve as an indicator of ecosystem health

Consequences of Habitat Diversity

High: higher species #’s

Low: specialists decline, generalists succeed

Consequences of Ecosystem Diversity

High: greater diversity of ecosystems can lead to more species

Low: decreases in ecosystem types reduce species & GD available

Species Richness

# of diff species in a given area

• gives a sense of the biodiversity in an area of an ecosystem

Species Evenness

relative proportion of individuals w/in the diff species in a given area

• tells whether a particular ecosystem is dominated by 1 species/whether all species have similar abundance

* high evenness indicates higher diversity

Mod 9: Ecosystem Services

Ecosystem Services

include:

• provisional

• regulating

• supporting

• cultural

* each ecosystem service can have a monetary value applied

* HUMAN IMPACTS: other services have also been affected by human overuse

• water availability has decreased

• pollinators have been affected by disease & pesticides

Provisional

goods humans can directly use

• furs

• trees

• natural pharmaceuticals 70% of drugs sold in the US come from plant sources

* disrupted by: overharvesting, water pollution, clearing land for agriculture/urbanization

Regulating

benefit provided by ecosystem processes that moderate natural conditions like climate, air quality, biodiversity, soil quality

• removal of CO2 by plants

• flood control

• temp control in forested areas

* disrupted by deforestation, pollinator hab. loss, filling in wetlands

* AP classroom + the UN Food & Agricultural Org classify pollination as regulating, bc it assists plant reproduction, fruit production, fostering biodiversity. They both classify water purification/treatment as regulating, since ecosystems like wetlands regulate water quality by removing pollutants

Supporting

natural processes that sustain ecosystems, allowing them to support life + all of the other ecosystem services

• photosynthesis

• soil creation

• nutrient cycling

• habitat + food creation for plants + animals (all of these processes support ecosystem function, allowing them to support life)

* disrupted by habitat loss due to deforestation, agriculture, urbanization

* friedland 4th ed. classifies pollination as supporting since it aids human agriculture & makes it more reproductive. It also classifies water filtration by ecosystems as supporting, since they reduce the cost humans need to pay to purify water

Cultural

income generating recreational activities (hunting/fishing licenses, park fees, tourism-related spending) & profits from scientific discoveries made in ecosystems (health/agriculture/educational knowledge)

• natural beauty to draw visitors

• religious/cultural value

* disrupted by deforestation, pollution, urbanizatio n

Replacement Value

cost to replace natural ecosystems

Property Value

nearness to natural ecosystems & services

Time & Service Fees

amount of time + money ppl r willing to spend visiting natural areas (like nationa parks)

Mod 10: Island Biogeography

Island Biogeography

study of how species r distributed + interact on islands

• typically, larger islands have more species due to the resources available

• islands that r closer to the mainland also have more species diversity

• size of the island affects # of species + ecological relationships

* need of producers will affect ecological efficiency

• smaller islands can’t support larger #’s of predators, so producers don’t last

* islands of similar size, but closer proximity to the mainland will have higher species diversity

* larger, closer islands have higher species #’s

Specialists

species that evolve on islands, due to the limited/variable scenarios:

• some species may lack predators

• food sources may be specialized to the island

• adaptations can occur rapidly

Generalists

can quickly be invasive on islands

• mice + rats have a history of wreaking havoc on island species, bc they:

  • are able to consume the native food sources

  • can also be predators to native species

• other orgs, such as snakes, can also invade + affect island specialists

* roughly 50% of extinctions in the last 400 yrs have been island species

Mod 11: Ecological Tolerance

Ecological Tolerance

optimal env. (abiotic conditions) where individuals + species perform particularly well

• also known as the fundamental niche

IMPORTANT INFO:

• habitats have changed over time + species have been forced to adapt to these diff envs.

• changes in pollen records have shown that changes in climate have changed ranges of tree types over time

* knowing a species ecological tolerance, combined w/the fact that environmental change causes species to move, can help identify which species r vulnerable to extinction

* 5 major extinctions in Earth’s hist. (99% of species that have lived on the planet r extinct)

Fundamental Niche

where the species can survive, grow + reproduce successfully

• these ranges can be measured for sev abiotic factors

Zone of Intolerance

range where the org will die

ex: thermal shock, suffocation, lack of water/food/oxygen

Realized Niche

though species have a range they can survive + thrive in, some biotic + abiotic factors can limit that range

• this can occur through compt. even if abiotic factors for a species r ideal, another species may occupy an area, limiting where the 1st species will be found

• ex: red winged blackbird

Reasons for Species Extinction

• their current env may no longer be favorable

• newly favorable envs may alr be occupied by competing species

• newly favorable envs may have predators that would prevent a successful move

* the difference in this mass extinction is the cause; rather than being caused by climate/external factors, this extinction is currently being caused by humans.

Mod 12: Natural Disruptions to Ecosystems

Periodic Disruptions

occurring at regular intervals (night & day)

Episodic Disruptions

somewhat regularly (drought + rain intervals) 

Random Disruptions

no regular pattern (natural disasters)

Disruptions

• those that have small special extent tend to occur in short durations

• some can be beneficial, such as a fire removing non-adapted species

* can cause large habitat changes + animal migrations

• when some changes happen infrequently + rapidly, resistance + resilience can allow an ecosystem to bounce back quickly

• long/rare ones can lead to bigger changes 

Resistance

when a species is unaffected by a disruption

Resilience

the rate it takes for a species to return to its og state after being affected by a disruption

Climate + Sea Levels

Methods of measuring their changes:

• species compositions

• gas bubbles in ancient ice

• measuring melt of ice sheets

- measuring #’s of species through fossils/build up of sediments gives us a clue to these lvls

- when snow falls + freezes through compression, it carries gases that freeze - ice cores can measure these gases to see how climate + gases have changed over time

Intermediate Disturbance Hypothesis

explains that having intermediate lvls of disturbance will help an ecosystem due to the build up of resistance + resilience

• not all disruptions to ecosystems have negative impacts on the ecosystem

Natural Disruptions

a seasonal change can lead to species choosing to migrate, rather than adapt overall

• migrations can lead species to where resources r more abundant, predators r less common, or conditions r more in their range of tolerance

Mod 13: Adaptations 

Genetic Diversity

* all pops have some of this, or variability in genomes of individuals; it exists bc of: 

• Random mutations while DNA is being copied to create new traits

• Crossing over in parent chromosomes creates new combos of genes (+ therefore traits)

Gene

physical location in chromosomes in the DNA that code for a particular trait (ex: body size)

Alleles

when many traits have multiple variations

Adaptation

* when a mutation is beneficial it can become this

• a new trait that increases an organism’s fitness (ability to survive + reproduce) 

  • when that …. can be passed on to subsequent generations, this lead to evolution

Evolution

change in the genetic composition in pops

Microevolution

when the pop level evolves

• small-scale changes in the genetic makeup of a pop over a relatively short pd. These changes can be due to processes such as mutation, natural selection, gene flow + genetic drift

Macroevolution

when larger categories of organisms change

• large-scale evolutionary changes that occur over long pds of time, leading to the formation of new species + higher-lvl taxonomic groups

Evolution by Artificial Selection

when humans select certain traits

• exs of this are found in many food crops + domesticated animals

Darwin’s Theory of Natural Selection

* Natural selection is evolution through natural mechanisms, often termed “survival of the fittest”

• individuals produce an excess amount of offspring

• not all offspring survive

• diff traits get passed from parent to offspring

• those that have the ability to survive + reproduce pass on their traits

Random processes

* evolution occurs through this

• changes that alter genetic composition of a pop over time 

Fitness

ability to survive + reproduce, is improved, leading to an adaptation

* higher lvl, increased chances of survival 

* these can occur as: mutations, gene flow, genetic drift, bottleneck effect + founder effect (can lead to microevolution)

Mutations

changes to the genetic variation of a pop

Gene Flow

individuals moving from 1 pop to another

Genetic Drift

simple change in genes over time due to random mating

Bottleneck Effect

reduction in the size of a pop’s genetic variation

Founder Effect

a few individuals begin a new pop w/genotypes not representative of the larger group

Allopatric Speciation

geographic separation in a pop, leading to a new species

Sympatric Speciation

genetic isolation w/o geographic separation in a pop, leading to a new species

Genetically Modified Organism (GMO)

a plant, animal or microorganism whose DNA has been altered using genetic engineering tech to achieve a specific purpose, such as increasing nutritional value/resistance to pests.

Mod 14: Ecological Succession

Ecological Succession

* terrestrial ecosystems experience this change

• a predictable replacement of 1 group of species by another group over time

  • begins by increasing species richness, biomass + productivity

  • as there r few species to begin w/, resources start high. as more species show up, biomass + productivity increase

  • after species have been in an area for a long pd of time, resources tend to get used up + compt increases, leading to a slight drop in biomass + productivity

Primary Succession

succession that occurs where there was bare rock + no soil to begin with

* as soil begins to develop, the og species r replaced w/more advanced species, eventually leading to a forest ecosystem

Pioneer Species

the 1st species to show up

• ex: algae, lichens, mosses

Climax Community

once succession reaches its final stage, the resulting ecosystem can be considered the ….

Secondary Succession

happens in areas that alr have soil + have experienced a disruption like a forest fire/hurricane

• doesn’t take long to occur, but the process is similar

Aquatic Succession

occur through small changes, such as overturned/exposed rocks in a rocky intertidal shore, or as water dries up in shallow bodies of water

Keystone Species

species whose activities have a particularly significant role in determining community structure

• some species are not abundant have a disproportionately large impact on a community

ex:

• beavers

  • sea stars: predators of mussels + allow for a diverse ecosystem

  • sea otters: also predators that consume sea urchins which helps in controllling their pops + preserving kelp forests

* tend to create/change habitat or can serve as a pop control on other species

Indicator Species 

a plant/animal that, by its presence, abundance, scarcity or chemical composition, demonstrates that some distinctive aspect of the character/quality of an ecosystem is present 

• typically used to determine if there is a negative impact on that ecosystem

ex: 

• lichens present on trees (sensitivity to pollution)

• amphibians (sensitivity to disease, habitat loss + pollution)

• larval mayflies (sensitivity to pollution)