Week 2: Biodiversity, the Biosphere, and Soils & Nutrient Cycling

geographic isolation caused by...

-destroyed portions of forest -movement of glacial ice -new areas created and colonized (islands)

types of biodiversity

-genetic diversity -species diversity -ecosystem diversity (variety of habitat types --> promotes the other two types)

species coexistence

-neither competitor fully excludes the other (one species may adjust to minimize competition) - ex: many birds foraging for insects on tree trunks, but use different portions of trunk/ seek different food in different ways

introduced species

-non-native species, introduced to community by people

herbivores

-primary consumers -eat primary producers

specialists

species w narrow tolerances, specific niche requirements - ex: Hawaiian honeycreeper --> its bill is specifically adapted for eating grubs that tunnel into trees

generalists

species with broad tolerances, general niche requirements - ex: myna bird, unremarkable bill lets it eat many types of food from many types of areas

habitat

specific environment in which an organism lives; living and non-living elements

LECTURE 1

BIODIVERSITY

adaptation - 2 defs

- (verb) characteristics passed from one gen to another--> lead to better reproductive success in given environment --> evolve in pop - (noun) trait that promotes success

Who discovered natural selection? Where? How?

- Charles Darwin while on the ship the Beagle - Galapagos islands: each supported its own form of tortoise, mockingbird, and finch --> various forms closely related, but with different structure and eating habits

History of Biodiversity on Earth

- Earth ~ 4.6 billion yrs old - life arose ~3.5 billion yrs ago - microscopic life for 2 billion yrs --> CO2 and H2O --> Photosynthesis--> oxygen --> made evolution of animals possible - evolution led to high genetic and species diversity

Breakdown of species described

- LOTS of insects - a lot of arachnids

ecological restoration

- actual on the ground efforts to carry out visions + restore communities - ex restoring US prarie by planting native prarie vegetation and weeding out invaders and competitors

Producers - another name for them - what they do

- autotrophs - plants, cyanobacteria, algea... capture soalr energy and use photosynthesis to turn it into sugars

intra-specific competition

- btwn members of same species

phase shift/ regime shift

- character of community fundamentally changes - can be due to climate threshold being passed, keystone species lost, etc - ex: coral reef undergoing phase shift of becoming dominated by algea bc humans are over harvesting fish that eat algea

resilience

- community changes in response to disturbance, later returns to original state

resistance

- community resists change and remains stable despite disturbance - ex:

character displacement

- competing species diverge in physical characteristics bc of evolution of traits best suited to range of resources they use - ex: bird example, beak evolves to be bigger

***Species interactions - both harmed

- competition - ex: gray and red squirrels in England - competitive exclusion principle = two species cannot occupy the same exact niche - niche partitioning = specialization allows many species to co-exist and avoid competition

how to respond to invasive species

- control, eradication, prevention - ex: ships must dump freshwater balast at sea and exchange it with salt water before entering great lakes

secondary succession

- disturbance drastically alters community, but doesn't destroy all living things/ all organic soil matter - ex post forest fire, most vegetation gone, but perhaps a little survived & soil still has organic matter

what three things decrease at higher trophic levels?

- energy - biomass - numbers

how does energy move

- energy passes down among trophic levels - producers --> primary consumers --> secondary consumers --> tertiary consumers

Geographic isolation

- evolution via natural selection produces different adaptations in different places - geographic speciation: isolated populations become different, can no longer interbreed --> different species - ex squirrels on different sides of grand canyon

mass extinction events

- extinctions at staggering proportions; killing off massive amounts of species at once - ex: the extinction of many of the dinosaurs due to asteroid hitting earth

mutation

- genes = unit of heredity, consist of DNA - DNA replication usually produces exact copies - mutations = errors in DNA replication - mutations = source of genetic diversity

Human influence on biodiversity

- habitat modification: ex deforestation, land use for agriculture, urbanization - pollution: global climate change, particular matter in water/air - natural selection takes long time --> we are changing the environment faster then species can adapt --> extinction hurting biodiversity - short life span species (mosquitoes) ale to adapt, long life span (100yr old oaks) less likely to survive

keystone species

- have strong/wide reaching impact far out of proportion to its abundance (often secondary or tertiary consumers) - ie wolves and mountain lions --> keep deer populations at bay --> prevent overgrazing of forest floor vegetation

coevolution

- long term reciprocal process in which two (or more) types of orgs repeatedly respond by natural selection to the other's adaptations (evolutionary arms race btwn parasites and host)

food web

- more accurate representation - map of energy flow using arrows as orgs consume one another

***Species interactions - both benefit

- mutualism (symbiosis) -ex:

Species diversity - # named so far - estimated total

- named so far = ~1.9 million - estimated total = 3-100 million - 2010 study suggest: 7-10 million

invasive species

- non-native species that spread widely, coming to dominate communities - ex: zebra and quagga mussels in Great Lakes

why are island species often vulnerable?

- only a few species reach islands--> not same pressures of competition and predation - if new predators arrive (ie by humans bringing dogs - INTRODUCED SPECIES), the species are not prepared - ex: Hawaii --> humans have brought cattle, goats, etc that eat native vegetation --> endanger plant populations

***Species interactions - one benefits, one harmed

- predation (one species kills and consumes another), parasitism (one org depends on another for benefit while harming its host), herbivory - ex: owl hunting mouse (predation) - ex: wasps use caterpillars as host for their larva --> larva hatch and eat caterpillar (parasitism)

trophic cascade

- predators at high trophic levels indirectly promote populations of orgs at low trophic levels by keeping species at intermediate levels in check - ex: wolves and mountain lions in scenario described above --> if killed off, deer pop grows exponentially --> overgrazes grass, kills off tree seedlings--> changes forest structure and starves

***Natural Selection

- process by which inherited characteristics that increase chance of survival/reproduction are passed on more frequently to future generations 1st result: origin of new adaptations 2nd: origin of new species

genetic drift

- random events, independent of ability to survive and reproduce - can substantially change small pops - ex: northern elephant seals hunted down to small pop --> built back up, but genetic diversity limited --> easily wiped out by disease, change in environment, etc

resource partitioning

- species divide resources they use in common by specializing in different ways - ex: two species eat same size seed, indiv of one species that eats larger seeds doesnt have to compete as much --> better chance of survival & passing on large seed preference --> species shifts to eating larger seeds

restoration ecology

- study history, devise ways to restore altered areas to their pre-industrial civilization state

climax community

- succession leads to this - given region reaches maximum life its able to support (determined by climate) --> remains this way until next disturbance

issue with "protected areas" as effective way to help endangered species

- tempatures changing, rainfall shifting --> areas turn unsuitable for the species they're meant to protect - ex: honeycreepers in Hawaii --> warming temp rising area up mountains that mosquitos go --> into protected honeycreeper land and infecting more of them

convergent evolution

- unrelated species acquire similar traits as they adapt to selective pressures from similar environments

novel/no-analog communities

- wholly new communities (new mix of plants and animals), never before existed on earth --> caused by human disturbance

which extinction are we on now? who is causing it?

-6th -human impact

Breakdown of species identified

-LOTS of insects - a lot of plants - fewest mammals

Ecosystem Diversity

earth's biomes - review quizlet

Natural Selection - Darwin's thinking

Darwin's Thinking - orgs struggle to survive and reproduce - too many progeny, not all can survive - variation among individuals and species - traits inherited --> if fittest survive in certain environment, then their traits will be passed on to progeny - Origin of Species

READING

EVOLUTION, BIODIVERSITY, & POPULATION ECOLOGY

endemic

species occur nowhere else on the planet than this region -more vulnerable to extinction bc all members belong to same (sometimes small) pop

how to measure biodiversity?

species richness = total # of species in given area

READING CH4

SPECIES INTERACTIONS AND COMMUNITY ECOLOGY

levels ecology studied at

biosphere ecosystem community population organism molecules

decomposers

break down leaf litter (& other non-living things) into simpler constituents that can be used by plants --> enhance soil - fungi, bacteria

***Species

a group of individuals capable of interbreeding to produce fertile offspring - scientific name: /Genus species/ - can be multiple related species, share common genus

community

assemblage of populations of interacting species that live in the same area

explain why energy decreases as you go up trophic levels

at each trophic level, orgs use energy in cellular respiration to grow/maintain themselves + most of energy given off as heat --> only small amount transferred to next trophic level - each trophic level has ~10% of the energy of the level below it

evolution def

change over time; change in populations across generations

ecosystem

communities + abiotic environment + forces with which community members interact (matter cycles and energy flows)

fossil record

cumulative body of fossils world wide, teach us about life's long history

Encyclopedia of life

database, attempting to have a page for every species

organism ecology

describes relationship between organism and its physical environment

extinction

disappearance of a species from earth

omnivores

eat plants and animals - ex: humans

disturbance

event that affects environmental conditions rapidly & drastically, resulting in changes to community & ecosystem - ex: can range from tree falling in forest, creating a gap in the canopy to a hurricane

population ecology

examines dynamics of pop change + factors that affect distribution and abundance of members of pop

pioneer species

first to arrive and colonize new lifeless surface

community ecology

focuses on patterns of species diversity and on interactions among species

primary succession

follows disturbance so sever that no vegetation or soil life remains - ex: post volcano exploding --> starting life on hardened lava flow

fundamental niche

full niche of a species

Survival of the Fittest

genes that produce better fitness come to dominate population

recombination

genetic variation generated as organisms mix genetic material during sexual reproduction

population

group of individuals interbreeding and separated from other such groups

why is genetic variation helpful to pop?

helps protect pop against novel changes - ex: birds in Hawaii surviving malaria onset

selective breeding

human choices re breeding to promote particular traits --> artificial selection

Fossil

imprint in stone of a dead organism

realized niche

individual only plays part of its role/ uses only some resources due to competition or other species interactions - ie quagga mussel reducing zebra mussel's realized niche by displacing the zebra mussel in many areas

food chain

linear series of feeding relationships; energy passed up this

inter-specific competition

members of different species

Mechanisms of evolution

mutation natural selection geographic isolation genetic drift

parasitoids

one org parasites another in a way that kills it eventually - ex: wasps lay eggs on caterpillar

competitive exclusion

one species = effective competitor, excludes other species from resource entirely - ex: zebra mussels displaced natives in Great Lakes (invasive species also)

fitness

organisms with different genes have different survival or reproductive abilities

pathogens

parasites that cause disease in their hosts

ecotourism

place's wildlife and natural reserves draw tourism (ie grand canyon)

allopatric speciation

pops physically separated by geographic distance --> isolated pops evolve separately, form separate pops - ex: hawaiian fruit fly populations separated when volcano explodes and lava destruction creates isolated patches of forest--> evolve separately

succession

predictable series of changes following disturbance that eliminates all species in a community

to human's advantage to maintain diversity bc

provides medicine and food

biodiversity def

range of different types of organisms and biological systems in a given area

background extinction rate

rate of gradual, single species at a time extinction - 1 species extinction/year

niche

reflects species use of resources and its functional role in the community (consumption of certain foods, role in flow of energy + matter, interactions with other orgs)

ecosystem ecology

reveals patterns (ie flow of energy & nutrients) by studying living and non-living components of systems in conjunction

detritivores

scavenge waste products or dead bodies of other community members - ex: millipedes, soil insects (worms)

***ecology

scientific study of interactions between organisms and their environment... 1) distribution are abundance of organisms 2) interactions among organisms 3) relationships between organisms & their environments

biosphere

total sum of all living things on earth + the areas they inhabit

humans have reduced diversity by

urbanification and agriculture

taxonomists

use org's physical appearance & genetic makeup to determine its species, then group species by similarity into hierarchy categories meant to reflect evolutionary relationship - Domain, Kingdom, phylum, class, order, family, genus, species

phylogenetic trees

used to represent history of divergence using branching, tree-like diagrams - map traits on tree --> trace when they evolved