BIO FINAL EXAM Flashcards
Ecology is the study
- How organisms interact with each other and environment
- Distribution and abundance of species
- Structure of function of ecosystems
- Science of biodiversity
Ecology vs Enviornmentalism
Environmentalism: social and political movement
(people being more ecoally aware)
Model organisms
stand in for all animals and plants
Mice: for vertebrates
Fruit fly: insects
Arabidopsis thaliana: plants
Population
Community
Ecosystem
individuals of the same species in one place at the same time
species living together at one time
all the species plus nonliving environment
Species Ranges: what is it?
We don’t know more than 85% of species and bacteria have the most species.
Knowing species range tell us where plants and animals grow
Good cuz they give us food, clothing, medicine
Predict how biodiversity will react to different things like
Habitat destruction, pollution, invasive species, climate change
For microbes and infectious disease agent: to determine disease risk
Determining specice’s range
Dispersal
Climatic and other inexhaustible conditions (unlimited ie temp, salinity)
Food or other exhaustible resources (limited ie space, nutrients)
Species interactions e.g competition, predation, or mutualism
These factors vary across space and time: gradients of conditions
Organisms perform best at certain portions of gradient
Determining abundance
Example: THE SIXTH EXTINCTION
Ongoing mass extinction due to mostly human actively
32% of known vertebrate species are decreasing in population size or range.
Important people to know:
Lynn Margulis: Created theory of symbiogenesis, arguing that modern plant cells are the result of the merging of separate ancestors (symbiosis).
Thomas Malthus: Has a theory stating the food supply can’t keep up with the growth of human population, resulting in disease, famine, war, etc.
Spieces tolerance
Climate and other niche axes
Species have ranges of tolerance along environmental gradient
The ecological niche
combination of physiological tolerances and resource requirements of a species
A species place in the world (what climate it lives in what it eats etc)
The Hutchinsonian Niche
Considers the niche as an n-dimensional hypervolume where each axis is an ecological factor important to the species we are talking about.
Outside of the blue area (ellipses) a species cannot survive
Temperature: mostly a function of latitude - How does it affect latitudes
Warmer at equator closer towards pole
Higher latitude colder: seasonality is a function of temperature (winter summer)
Lower latitude is warm: seasonality stays the same year round
Reasoning: at higher latitudes, light strikes the earth’s surface at a lower angle and is spread over a greater area: photon density not as high
The tilt causes seasonality - winter the tilt is shaper meaning less light hits it
What are hadley sells and how do they work
The hottest air is at the equator and hot air rises (think of hot air balloon)
Hot air rises up from the earth’s surface and into the upper atmosphere at the equator where they eventually start drifting south and north of the equator and fall back down around 30 degrees north and south in latitude
As air rises, it start to cool down at adiabatic lapse rate - 5-10 celsius/km
As air cools, water vapor condenses causing rain to fall near equator and air warms as it falls
Resulting in dry high pressure agrees at 30 degree latitude
Ferrel cells - 30-60 & Polar cells - 60-90
Coriolis effect
the earth’s rotation deflects winds
Air masses near earth’s surface are spinning together with earth as earth spins around its axis
Objects spin at diff speeds depending on latitude
Near equator it moves fast cuz it has has to move equal to earth’s circumference in 24 hours - around 40000 km/24hr north pole you have smaller circumference so they don’t move as fast
Because the storm is moving faster than the points on the ground beneath it are moving eastwards it overshoots its points
Intertropical convergence zone
shows a rain clouds across the planet at the equator
Not exactly above 0 degree in latitude but moves around
Moves 23 degrees north Tropic of cancer and 23 degrees south capricon
It’s at the location of ascending branches of the hadley cells
The convergence zone moves more in Asia because there is more landmass in asia VS in the Americas, there is more thermal inertia than land masses which mean they resists changes
Land heats and cools faster than water therefore greater swings in temp therefore move movement of intertropical convergence zone
Movement of intertropical convergence zone causes seasonality in rainfall in the tropics
Monsoon season in asia’s vs dry seasons COMPARED to america that is rainy
Coriolos effect (general definition):
objects appear to be deflected eastwards as they move away from the equator and deflected westwards as they move towards the equator
Coupled cells + coriolis effect
prevailing wind patterns
0-30 degrees towards equator air deflected westwards
Easterly winds: blow to the west and originate to the east
Westerly winds: blow winds to the east and originate in the west
30-60 degrees away deflecting east
60-90 degree deflecting to the west
weak winds
Right at the equator and 30 degrees winds blow straight up to upper atmosphere - weak winds
The affect of land mass
More land mass at northern hemisphere affects wind speeds
At 44 degrees north we get moderate westerly winds cuz landmass breaks wind speed
At 44 degrees south lost of wind cuz theres mainly ocean
Vegetation growth (primary production) increases w moisture and temp
Biomes - regions w certain computations of moisture and temp
Similar latitudes tend to have similar biomes
Desserts occurs at 30 degrees north and south
Additional climate patchiness overlaid on basic latitudinal belts
Oceans provide thermal inertia
Precipitation
Evaporations high from warm bodies of water
Orographic precipitation: air forced up mountainsides undergoes cooling, precipitates on upper windward slopes which lead to rain shadows created on leeward slopes of mount ranges
Animals and biomes
Animals geographical ranges often correspond to biomes ie climate or vegetation
But transient biomones (ecological versatility), recent history eg limited dispersal, and being limited by other organisms (enemies, friends) are exceptions
Ecological niche modeling use data from a species present distribution to predict where they can leave
Physiological ecology
the study of physiology in the context of an organism’s ecology
Ranges of tolerances: limit distribution
Organism: complex chemical reactions
Enzymes function best at optimum temp and osmotic condition: fitness is maximized
Mechanisms for homeostasis: evolved to challenge hostile environment
Maintenance of homeostasis: requires energy and is limited by constraints and trade off
What do orgaisms physiology reflect
the climate and other conditions its adapted to
Diff environment lead to different physiologies
Similar environment lead to similar adaptation (convergent evolution)
Heat Balence + why is important
especially important to homeotherms (birds, mammals)
Poikilotherms
(most reptiles, amphibians, fish, invertebrates) lack physiological means to deviate from environmental temperature: their temperatures fluctuate
Poikilotherms have lower energy requirements than similarly sized homeotherms because it maintaining constant temperature requires energy
Homeotherms
must regulate heat balance to keep internal temperature within a narrow range: many traits contribute
Modes of heat gain and loss
Radiation: heat transfer by electromagnetic radiation
Conduction: direct contact w substrat
Convection: moving fluid (air or water)
Evaporation: cooling from wet surfaces
Redistribution: circulatory system redistributes head among body parts
SA VOL
Size matters to heat balance because of surface area to volume ratio
Surface area determines equilibration rate - big SA:Vol equilibrates quickly
Volume provides the inertia
Bergmann’s Rule
Homeotherms tend to be larger at higher latitudes to conserve heat
Shape matters:
SA is needed for function - particular shapes
Therefore the shape is a trade off and adaptive compromises
Allen’s rule
Homeotherms tend to have smaller appendages at higher,colder latitude
Ways to counteract heating up + allens rule tie in
Insultion: more important than size and shape
Fur, blubber, feathers
Animals spend a lot of resources for insulation
Convective cooling is enhanced by vascularization
- Desert hares ears blood vessels
Countercurrent circulation to limbs conserves heat: Arteries and veins should appressed (close together) in appendages to conserve heat
Separated in appendages designed to shed heat
Countercurrent flow maintains gradient so head is always flowing from outgoing blood to incoming blood
Evaporative cooling
Behavioral thermoregulation: seek out cooler places on a hot day
Trade offs and example of weseal
cause animals to not be perfectly adapted
Being good at x may necessarily imply being bad y
Weasels are the shape they are to be able to hunt for gophers
Constrains
Natural selection builds on what’s already there
Plany ecophysiology
Plants cant evade stress by moving
- But they make their own food - autotrophs
- Photosynthesis light, co2, and water
- Leaf stem and roots reflect adaptation
Angiosperm flowering plant
Hermaphrodites: have both and male and female parts
- Anthers: pollen - male, stigma - women
- Depend on animals to move pollen
Plants are sessile
they have little scope for behavior
Are autotrophic and they need the same things to grow: light, Co2, water, soil nutrients
Plants bring CO2, water and light in functioning photosynthetic tissue to create carbohydrates and o2
Enzymes need to be at a good temp
Respiration turning carb and oxygen into co2 and h2o
Carbon balance: for growth plants have to acquire more carbon through photosynthesis than they lose through respiration:
Net primary productivity (NPP)
C gained via photosynthesis - C lost via respiration = NPP
Photosynthetic structures embody adaptation to environment
Example of conserveing water
PALO VERDE
Photosynthetic bark on trunks and branches: can grow without incurring head load and water loss through
Sometimes even sheds all its leaves as an adaptation
Microphyll: super small leaves
PLANT FEATURES THAT MAKE THEM WHAT THEY ARE
Chlorophyll make plants green
Plants take in CO2 through stomata but they also lose water through stomata (transpire)
Leaf size and shape: SA:V ratio important again
Large leaf surface: good for light and gaining CO2
Cost: easily transpire and therefore cause overheating
Coping with overheating/water loss
They use rubisco to carbon fix but it doesn’t work at high temp
Sometimes catches o2 instead of Co2
Plant defence to waterconservation
C4 photosynthesis: enzyme pepe carboxylase accepts CO2
CAM photosynthesis: close stomata during the day avoiding waterloos, open at night to let in CO2 and store that CO2 as maltate to be able to do photosynthesis during the light
Large leaves grow in shady habitats and open and close their stomata by opening stomata cuz stomata releases water for evaporation cooling (hormone ABA is responsible)
Trade off between water conservation and rapid growth
Conserve water vs carry out photosynthesis seen on desert plants
Rainforset adpations
VS TROPICAL
Extensive but shallow because rainforests have a shallow of nutrient rich soil
Root foraging
Going roots into soil patches where nutrients are abundant
Split root experiment to see how roots adapt
Legumes also get nitrogen from nitrogen fixing bacteria
Take Dinitrogen from the air and turn it into a form via nitrogen fixation
Deciduous habit: leaves gone during cold or dry seasons to reduce water stress/ tissue damage
Population ecology
N - Number of individuals in absolute terms (y axis, time on x axis - Time Series)
N/area - population density
Leaf shape influence
Limar vs turbulent flow
Limnar: unimpeded moves like aerodynamic like moving over a car
Cases a stagnant boundary layer of air to build up on the leaf surface: Prevents gas exchange
Turbulent flow: ridges and irregular
Does a better job at promoting gas exchange
Morphological plasticity
Epiphytes have their roots in the air or on trees so they can still be water stressed even in rainforest
Why care about N?
Natural resource management:
Ex size of fish stocks in ocean
Abundance of outbreaking insect pests in forests
How much damage they do to forests
Conservation: Population declines of species
Health: Monintstoring population or bacteria in humans
Understanding and predicting human population growth
Basic science question of what limits population growth
Goal of most population models
Predict the trajectory of population through time ie N as a function of t
How many populations are in the population now? Nt
Time advances by one so t - t +1: How many individuals are in the population one step later: Nt +1
General model: Nt+1 = f(Nt)
Malthus
scientist said Human population cannot grow faster than food production
Time steps
When using differential equation, time steps are infinitesimally small: use concept of limits and calculus growth is smooth and is best suited for species w continuous reproduction
Ex population size of humans
Difference equations: time steps are discrete (days, years), use it iterated recursion equations
Best suited for episodic reproduction
Lambda
Nt+1 = Nt x (lambda)
Lambda: Nt+1/Nt the multipleive factors by which population changes over one unit of time
Lambda > 1 births exceed dead population is growing
Notation
Therefore population growth starts at t = 0 therefore N0 or N(0)
How can N change from Nt to Nt=1 (All happen in one time step)
D = number who die
B = number born
E = emigrate
I = immigration
Nt+1 = Nt - D + B - E + I
Births and immigration are equivalent, Death and immigration are equivocation
Only model births and death and assume no immigration or emigration
Treat birth and deaths during one time step per capita rates that are fixed constant - dont expect birth and death rates to be changing a lot
Consequences
Main consequence of an exponential model growth is that when it increasing it will increase til infinity (exploding in an exponential way)
All species have the potential for positive population growth under good conditions(lambda greater than 1)
All species have the potential for negative population growth under good conditions less than 1
But no species has ever sustained lambda more than one or less than 1 for a long period
Density-dependent regulation (growth depends on N) or Density independent reduction
Geometric growth
Geometric growth
N1 = lambda (N0) N2 = lambda (N1) = N2 = lambda ( lamda (N0) Therefore Nt = N0lambda ^t
Continous time
assumes population growth is instantaneous
Instantaneous, per captivate rate of population change = b-d = r (a constant)
r= intrinsic rate of increase
Differential equation = dN/dT = rN General continuous time: Nt = N0 e ^ rt
Exponential growth if r > 0 Ln (lambda) = r
Logistic growth
S-shaped growth = logistic growth (only happens when populationstarts low)
Same as exponential growth with a new term added for breaks
dn/dt = rN (1-N/k)
K = carrying capacity - the size of the population that the resources in the environment can support
General equation
Nt = (KN0e^rt)/(K+N0 (e^rt - 1))
Pros
Inflection point at K/2 aPros:
Mathematically tractable model of intraspecific competition and simple
Can be expanded to consider multiple species competition
Cons of logistic growth model
too simple
Always a gradual approach to carrying capacity
In reality density dependence is likely to be non linear
Allee effects
negative effects of low density
Arise from social benefits ex mate finding, group living and group defense
Issue of the models
But Fecundity and survivorship depends on age
Species have diff life history strategies
Life story : what age do events occur at
Typical life history
Start life small size
Grow for a period without reproduction- resource accumulation
When they have enough resources and become mature they prediction
Some expend all resources at once some spread it out cuz they have various lifestyles
Need to consider age structure and how birth and death rate depend on age
Age structured population growth
Still single population but now fecundity and survivorship vary w age
Variation is summarized by life tables of age specific rates
Important implication for:
Evolution of life histories
Conservations
Understanding changings structure of human population
Age-sex pyramid
Stable age structure - instead of period it’s gonna be a flat shape - roughly the same number of individuals in the same age
Life tables
Life tables: summarize the life events that statistically expected for the average individual of an specific age in population
Age of death and age of timing of reproduction
Suvivorship schedules
Age classes denoted subscript x
Lx = probability of being alive at age x
L0 = 1.0 cuz when a baby is alive its always 1
“Survivorship curve” graph of lx vs x
Lx necessarily declines with x
If mortality is constant then its gonna have an exceptionally curve: Usually use plot w log(lx)
Type 2 - straight line
Type 1 - survivorship high in early live and then declines rapidly at old age (ex humans)
Type three - early mortality but after middle age survivorship is high
Impact of growth rate
Higher growth rates = higher fitness
Constraints and trade-offs: reproduction is costly. Longe reproductive periods allow for accumulate more resources
Semelparity: ate in life reproduction
Iteroparity: multiple years of their life reproduction
Fecundity schedule
Age defined by x again
Mx = number of daughters birth to a female of age x during the interval of x to x +1
Shape of mx is specific to species
Reproductive period usually preceded by resource accumulation phase
Fecundity - survivorship trade-offs = cost of reproduction
Net production
R0 = average number of daughters a female has in her lifetime
R0 = Sum of lx mx
Unit of one generation
Generation time (Average age at which a female gives birth) T = sum of x lxmx/r0
X = female age
r = ln(R0)/T = ln(lambda)
Plant life history cateorgies
look at doc
Life expectancy
Life expectancy = ex
Reproductive value vx = expected number of future daughters left to an individual age x
Fitness consequences of alternative life history straighteners and trade off between current reproduction and future
Selection generally selects for early prediction so genes can be copied but u need to accumulate resources which can delay reprodction
Specific compeition
Intraspecific competition (conspecifics): same species competition for resources
Interspecific competition: different species
Scramble/exploitative competition: depletion of a shared resource
Ex squirrel eating bird food leaving less food for birds
Contest/interference: direct interactions ex battle over territory
Invasive ants fight harvester ants: Invasive often drive down population of native ants
Possible outcome of lokta model for interspecifc compeititon
dn1/dt = r1n1( 1 - N1/K1 - (a12N2)/K1)
a= alpha aij = per capital effect on specifics one of individuals of species 2
“Competition coefficient”
A is fixed for a pair of species
Convert individuals into an equal number of individuals of species one because species are not equivalent competitors
Possible outcomes
Two species stably coexist
Species 1 may always win (N1 = K1, N2 = 0)
Species 2 may always win ( n2 = K2, N1 = 0)
Indeed of winner may depend on starting N’s
Outcomes depend on values of K’s and a’s
Coexistence requires both species to inhibit their own growth more than they inhibit each other’s
Can expand to consider n species
Equlibrium, stability, coexistence
Equilibrium = N’s no longer changing (dN/dt = 0)
For a community: a community not changing over time meaning that all populations in a community at equilibrium
Generally: constant species composition over time
Stability : ability of a system to return to equilibrium following a disturbance
Coexistence: two or more species have non zero population sizes at equilibrium
Principal competive exclusion
Principal competitive exclusion:
LVM predictions that for two species to co-exist competition between species muscat be weaker than within species (Old idea - 1934 gause said)
Paradox of plankton
Competitive exclusion seems false for plankton (also rainforesets cuz all the trees live together)
WHY? Lotka volterra models too simple and ignores too much relative
Real populations be ne kept below K
Lotka volterra model for predator prey
Lotka-Volterra models for predator-prey interaction tend to cycle
Similar to competition models: two differential equations
Repdicy couple lagged population cycles
These cycles are hard to sustain in a lab -
Most common result: predator and prey do not coexist, interaction is unstable
But cycles in natural are unusual
Additional factors
Heavy browning regulates food available - hares may also be cycling w food
Most natural cycles have complex causes
Antagongistic vs coevolution
Coevolution = reciprocal adaptation
Prey evolves defenses - predators counteract w new adaptations to get over defenses
Life dinner principal
unequal election pressures
Prey should be under stronger selection to make defenses than predator to make counter defenses cuz life vs food
Defences are often inducible + example
Human immune system
Reply morphology, chemistry and behavior
Plant secondary chemical
Predation and community structure
Competition decrease biodiversity = superior competitors exclude inferior
Predators and parasites also influence biological invasions
Invasive species achieve high population size and have a negative effect
Enemy release hypothesis: invaders impacts result from having fewer natural enemies in their new range compared to their native range
Many parasites have complex life cycles
Single host spices = direct life cycle
Many requires two or most host species to complete life cycle = complex life cycle
Vectors are hosts that transport parasites to next host
Zoonotic diseases: diseases transferred between animals and humans
Often refer to other host species as reservoir
Distribution, life history traits, and behaviors of hosts can affect parasite abundance and transmission
Community ecology of disease
Dilution effect: for seieases that infest many host, host diversity can dilute disease risk to humans or animals - conserving host would be good
Amplification effect: most host or vector species can support larger populations of disease causing organisms increasing risk to humans or animals
Latitudinal gradient in species richness:
More species near the tropes at the equator than the poles
Age or time the habitat has had accumulate species = most places near poles were under ice
Maybe climate
Relating back to predation - moew human pathogens are near the tropics and equator
But a good part of this is based on government stuff ie healthcare spending
Mutualisms typically involved reciprocal exchange of goods or services between species
Nutritional mutualism
Legumes and rhizome: exchange fixed c for fixed n
Defensive mutualism
ants and plants exchange protection for food
Dispersal mutualisms
Plants and animal seed dispensers: exchange seed dispersal for food
Plants and animal pollinators: exchange gamete dispersal for food
Mutualism between humans and free living wild animals
EXAMPLE
Yao people in mozambique harvest wild honey so they use honey guides birds to get them to the nests because honey guides only eat the bees waxes
Has been around for at least 500 years
Playback experience: play a series of sounds to see how birds react
Showed that the birds were able to understand and signal humans to where the bees next are
Limits of the population growth of mutualists?
Strong intra-specific competition
A third species or competitor
Diminishing return to mutualism as the population grow
Only mutualists when the population is small but not large
Invasive meltdown
the process which two non-native species facilitate one another’s spread
examples of invasive meltdowns
Spring ephemerals
Produce short-lived carpets of flowers which flow right after snow melts
Seed dispersal between native anit vs invasive red ant
Invasive red ant spreads a lot of seeds in europe so she wanted to see if it did the same
Used a experimental mesocosms
Invasive ant caused the invasive plants to move around more vs native and did more with native plants
Are mutualistic relationships often highly specialized?
But most mutuals are NOT tightly coevolved
Reciprocal adaptation (coevolution) between flowers and insects
and example
Aphids feed on phloem sap that is rich on sugars but poor in essential amino acids
Adapids have intracellular bacteria that provide their hosts w essential amino acids
Buchera are vertically transmitted: passed on from mothers egg to off spring
Vertically transmitted endosymbionts often have tiny genomes
Buchnera has a much smaller genome than free living bacteria
Other endosymbiotic bacteria also have tiny genomes
mitochondria: - 17000 base pairs only codes dor 37 genes vs nuclear genes that have 3 billion
Endosymbiotic bacteria lose genes that they no longer need
Some functions are unnecessary cuz theyre no longer freelivig and are protected
“Outsourced” to host genome
Horizontally transmitted
Partners are anew each generation
Mutualisms are rarely one to interactions - usually many
Current hot area of research:
Understanding networks of interactions among large number of species
Microbiomes: all the microbes living together or those collectives
Most plants have many pollinator species; most pollinators visit many plants species
Meta populations
“population of populations”
DIspersal connects populations
A metapopulation is a collection of spatially distinct populations that are connected via dispersal
We call each spatially distinct population a “patch”
Dispersal is important for…
colonization of new habitats
Postglacial colonization depends on plant and animal dispersal
Metapopulation and population persistence - source-sink
Metapopulation structure can allow population persistence even when individual populations are doomed
Local populations can be re established by colonist by other populations after going extinct
Source-sink dynamics
“Sinks” are populations in a small habitat patches that would go extinct expect
Migrants from”source” population “rescue” these populations
