Bio 1B Midterm 2

Biotic factor

living things w/in ecosystem

Abiotic factor

non-living components ecosystem

Abiotic factors influence on terrestrial organisms

Temperature + precipitation

Abiotic factors influence on aquatic organisms

Light + nutrients

Why are temperatures at lower latitudes higher?

Receive more solar radiation

-> Equator (0) warmer > N + S pole (90)

What causes seasons?

Earth's tilt

Why is there less precipitation at mid latitudes

- Air circulation patterns

- Descending dry air absorbs moisture

- Ascending air releases

- Warm air rises

What are climatic zones?

Regions earth defined patterns temperature + precipitation

Describe trophics

Warm, wet, weakly seasonal

Temperate zone

Highly seasonal, cold winters + hot summers

Polar

Year round low temps, 24h darkness/ light @ solstices

Curvature earth = low angle incoming sunlight

What are environmental gradients

- Steady change environmental variable through space

Latitudinal gradients

- Steady change environment across latitude

- Steeper land + N hemisphere

- Becoming more shallow cut world warming

- Temp increase as approach equator

Elevational gradients

- Oxygen availability decrease w/increase elevation as less atm pressure

- Lower pressure @ higher elevations

- Atm pressure decrease w/alt

- Limit animal dist

- Lower pressure = lower temp

Precipitation and elevations

- ppt increases higher elevations windward side mountains

1) cool air flows

2) Ppt

3) Rain shadow

- Higher ppt up windward side mountain range

- Air cools = Water vapour condenses = falls rainfall

- Descending air + reduced moisture = rain shadow leeward side = sheltered from prevailing winds

What are rain shadows?

Region little rainfall bcus shelters prevailing rain-bearing winds by mountain range

3 types Biodiversity

Genetic d in pop = diverse genome

Species d ecosystem = many species + interacting

Community + ecosystem d landscape entire region = many ecosystems

Biodiversity Scales

Alpha d = species d community/local scale (1 eco)

Beta d = species d between 2 communities/ ecosystems

-> Bio d (S1-S2) = (S1-C) + (S2-C)

Gamma d = total species d across landscape

Interactions species + ecosystem limit species distribution

Dist organisms set by eco facts + eco history = vicariance

Dispersal = organism new place

Abiotic tolerances requires species intra determine survive + reproduce

Biome

Major life zone characterised characteristic plant communities

Average conditions + pattern seasonal variation determines

Large, naturally occurring community organisms occupying major habitat

Primary productivity

Determines by temp + ppt

= Rate energy sun converted in2 biomass by photosynthetic producers

Tropical rainforest

High ppt, wet + dry seasons, temp high, highest animal + plant diversity

Desert

low ppt, temp highly variable seasonally + daily

adapt heat + desiccation tolerance

Coniferous forests

Cold winters, warm summers, cone-bearing trees, fire dependent, migratory birds + mammals

Tundra

Cold winters, cool summers, herbaceous, permafrost restricts plant growth, migratory birds

Chaparral

Seasonal, cool fall + winter + spring, hot summer temp, high diversity + endemism, small mammals

Fire + drought adapt

Elevation + Latitude + Biomes

Air temp decreases w/increasing lat

Biomes high latitudes = high elevations

Latitudinal gradient equator -> poles = tropical forest, desert, coniferous forests tundra

Niche

Combination biotic + abiotic factors species needs reproduce

Compare + contrast Chaparral and tundra biomes

- Both = low-growing herbaceous shrubs, drier

- Different ppt, climate, biodiversity

- Tundra organisms adapted cold = more fur density + fat stores, slower metabolism

- Chaparral = drought adapt = waxy cuticle, large ears release heat

Pros biodiversity

- Increased primary productivity

- Diverse pollinators = supports plant reproduction

- Soil health + nutrient cycling

- Resilience environ change

- Genetic d future

- Food security

Cultural, aesthetic, rural value

- Bio d increases NPP + resilience stress

NPP

= Net primary productivity

Total amount biomass produced by plants

Resilience

= Ability bounce back after stress

Life history

= suite traits related species' lifespan + timing + pattern reproduction

E.g. size birth, growth pattern, age + size maturity, life length, size + number sex ration, offspring, duration, investment parental care

Semelparous

Reproduces once = short adult lifespan

Interoparous

Reproduces multiple x throughout life

Survival adults high = survival juveniles

r =

rate pop increase

k =

carrying capacity = how many indies given area hold

R-selection

Selects life history maximises reproduction + ability pop increase rapidly @ low density

K- selection

Density-dependent selection

Selects LH traits enhance indies fitness when pop high (close carrying capacity) + stable

Cohort

Group Indies same age birth -> death

Life table

Age specific summary survival + reproductive rates w/in pop

Survivorship curve

Plot proportion/cohort number still alive each age + pattern survivorship pop

- Straight line = constant rate death

- log scale

Types survivorship curve

1) Low death rate early + middle life, sharp decrease later life

-> large animals, few offspring

2) Constant

-> Rodents + invertebrates

3) High dr, drdeclines survivors early period die off

-> Large number offspring b little parental care

Allocation tradeoffs

Trade off long life + diversity

Principe allocation

- Limited resources invest different activities + functions

- Growth, survival, reproduction

- Animals allocate time + energy different activities

- Plants biomass + nutrients different parts + parts carry functions

Tradeoffs

- Current reproduction + survival

- Current + future reproduction

- Number + size offspring

- Somatic maintenance = energy spent maintain body

Explain why mice often abandon their young

- carrying young substantial time, energy, resources

- food shortages = less resources allocated

- less resources available survival + reproduction = trade off

- Survival + future reproduction over current

- Interparous = invest more somantic maintenance

Reasons modelling population growth

Conservation, resource needs, policy, max harvests, biological invasions, disease spread

Calculating population size

Nt+1 = Nt + I - D - E

Nt = number indies pop @ 1x

Calculating population size of closed population

Nt = Nt + B - D

Assume no immigration/emigration

Rate population growth

^N/ ^t = B - D = R

Exponential pop growth

- Geometric growth

- intrinsic rate increase (r) = % change pop size per capita

- r constant = pop grow exponentially

- Assumes time intervals infinitely small, continuous demography

- r>0 = pop size grow

- r = 0 same

- r < 0 = decline

- looks linear log-scale

Causes exponential growth

- Pop introduced new environment

- Catastrophic disturbance

- Important predator removed

Density-dependent population growth

- Changed br + dr w/density pop

- Exponential growth = brings + dr assumed constant regardless pop density

- Denser pop = decrease br + increase dr

- Less resources indivs

- More competition, disease, predation risk

-Logistic (S-shaped) pop growth curve

S-shaped growth curves

Density-dependent pop

- Pop low density = growth exponential

- Pop size increase = d-d factors decrease birth/decrease death

- Pop growth slows until carrying capacity

Density Independent pop growth

= Rate growth pop @ any instant limited something unrelated size pop

- External environ aspects = cold winters, droughts, storms, volcanic eruptions

- Erratic pop growth patterns

Logistic Growth Equation

dN/dt = rN (k-N/K)

rn= exponential growth model

() = linear decrease towards carrying capacity

r = intrinsic rate increase

k = carrying capacity

Competition

Occurs 2 indivs share resource + consumption 1 reduces availability others = reduced growth, survival,/ fecundity

Intraspecific competition

between indivs same species

Mechanism behind density-dependent pop growth

Interspecific competition

between indivs different species

Food, mates, pollinator, space, nests water

Exploitative competition

= comp mediated by consumption/shared resource

- Indivs/species not physically encounter

- indirect use shared resource

- 1 competitor consume = reduce supply

Inference competition

involves direct, physical interaction

1 competitor expend energy inhibit access resource other

Scarcity

no resource unlimited quantity = competition

Parasites

Derive nourishment from host = damaged/killed

Parasitoids

Lay eggs + larvae consume prey

Can herbivores be considered predators

Eat seeds + embryonic plant fully eaten

Mutualistic if seeds not digested + dispersed

Ectoparasites

live outside body

endoparasites

live inside body

Mutualism

= Both interacting species benefit increased fitness

- Direct/indirect

- conservation = seed dispersal, mycorrhizae, pollination

- increase reproductive revival, rate pop growth/size

Commensalism

1 species benefits, other unaffected

E.g. birds eat insects off buffalo

Symbiosis

Organism living in/on another organism regardless outcome

Ecological effects species interactions

Ecological processes = determine abundance, range/distribution, timing + activity interacting partners

(+) increase abundance. extend range, select synchronised activity partners

(-) oppo, select altered timings

Cycle ecological change

Ecological change -> Alters selective pressures pop -> evo change -> alters outcome eco interactions

Co-evolution

= Reciprocal evolution 2 interacting species

- Change traits indivs 1 pop response trait indivs other pop

- From competition, exploitative mutualistic intrxs

Population cyclic

- Pred overexploit prey = cyclic fluctuations

- Lag prep pop decline + red response

- Fred alters selective pressure prey = evo change

Consequences cyclic populations

- Competition decreases fitness both interacting species = competitive exclusion weaker species

- Evo act reduce competition = niche partitioning + character displacement

Competitive exclusion

= Species compete 1/+ species extinct

- Species exhibits logistic (s-shaped) growth flask w/other species

- Failure co-exist = competition same resources

Gause's principle

= 2 species competing same limited resource, species uses resource more efficiently eventually eliminate other locally

- slight advantages built into species over time

- only valid if single resource + vary time/space

Selective sweep

= Allele fixed population

Niche

= Range abiotic + biotic factors species needs survive

When does competitive exclusion occur?

Competition asymmetric + niches completely overlap

Sympatric

= species/populations overlapping ranges

Allopatric

= species/populations separated by barrier

Character displacement

= tendency characteristics (physiology, behaviour, morphology) diverge more sympatric (geographically overlapping) compared allopatric populations reduce competition

- decreases competition

Fundamental niche

Resources used/conditions tolerated absence competitors

Realised niche

Resources used/conditions tolerated when competition occurs

Niche overlap not complete

Weaker competitor uses non-overlapping resource

Niche differentiation/resource partitioning

= Evolutionary change use by competition over generations

- decrease niche overlap + amount comp = coexistence more likely

Outcomes exploitative interactions

- Boom + bust pop cycles

- decrease abundance + range prey/host

- Defensive + offensive adaptations morph, physiology, behaviour

Defensive adaptations

- Eco selection pressure = adaptation

- Evo response = m/p/b adaptations = prevent detection + eaten

- Plants = mechanical + chemical

- Host = immune system, sequester toxins, behavioural

Offensive adaptations

m/p/b = eat + find prey

Parasite adaptations

- Disrupt immunity

- Manipulate host chem

- Physical structures stay in/on host

- Manipulate host behaviour = facilitate transmission + increase survival

-> ants climb blades grass = eaten sheep = next host

Outcome mutualistic interactions

Increase abundance + range interacting partners

Adaptations promote interactions

Outcome species interactions

(-) Decrease br + increase dr

(+) opposite

- Impacts pop demography + species range limits

- Natural selection enhances traits = decrease -ve itrxs = co-evolution interacting partners

What limits primary productivity?

Water, energy, nutrients (N, P, iron, salt)

What drives productivity gradients?

solar radiation

Main stages water cycle

Evaporation, precipitation, runoff

Stocks

Stores/pools matter

10^3km^3

Fluxes

Movements between pools

km^3/yr

Nitrogen containing molecules

DNA, ATP, RNA, nucleic acids, proteins

Chlorophyll, rubisco