post midterm env s 60
L10: Nov 1, 2024
Niche
Fundamental Niche
The entire range of environmental conditions under which a species can survive and reproduce
What do organisms need to survive and reproduce
Plants
Water
Light
Soil and or water nutrients
Physical space
Animals
Food (nutrients, water)
Territory
Mating partners
Organisms need to compete for limited resources
EX)
Can two species with the same fundamental niche coexist?
Single-celled paramecium (protozoans
Two species
Each species, grew in a culture by themselves
Looked at growth in population over time
Both grew and then levled out
Then put them together
P aurelia increased
P caudatum eventually decreases
SHOWS: competitive exclusion principle
ANSWER:
No-they compete for shared resources and one species will out compete the other one
Thus at least one species will not be able to exist in its entire fundamental niche
Realized Niche
The fundamental niche, but restricted by species interactions
The subset of the fundamental niche describing the conditions under which an organism actually lives
Exceptions to the competitive exclusion
Paradox of the plankton
How can hundreds of species of phytoplankton exist within a small sample of ocean water? Why doesn’t competitive exclusion occur
They are all interacting together and living with each other
Repercussion of Competition
Both organisms completing with each other are negatively impacted
EX)
Decrease growth rated
Increased mortality
Reduced reproductive capacity
Types of Competition
Interference
Individuals or populations behave in a way that reduces exploitation efficiency or another individual or population
Allelopathy
Use of secondary chemicals by one species of individuals that inhibit the growth, survival or education of another
Territoriality
The establishment of an area by one or more organism from which others are at leat partly exclude
Only animals = must be mobile to protect territory
Preemption
Individuals prevent other individuals from occupying a location by occupying the space first
Scramble or Exploitation
Individuals or populations depress one another through use of a shared resource
Allelopathy
Week 6
L11: Nov 6, 2024
Intraspecific
Between individuals of the same species
Interspecific
Between individuals of other populations
Demographic pattern
Growth rate = birth rate
Per Capita Population Growth Rate (r)
Exponential growth
dN/dt = rN
R = per capita growth rate aka intrinsic growth rate
Does not change over time
EX)
r>0: population is increasing
r<0: population is decreasing
r=0: population is stable
dN/dt = population growth rate (instantaneous)
Does change over time
EX)
dN/dt >0: increasing
dN/dt<0: decreasing
dN/dt=0: stable
Intrinstic Growth rate ®
KEy points
Unlimited resources
No competition
Populations can grow exponentially at their intrinsic rate of growth
Limited resources
As population density increase, intraspecific competition increases
Reduced fitness for individuals
Size, survival birth
Population exhibit logistic growth where their
Lotka -Volterra Equations- competition coefficients
A12
The effect ON species 1 by species 2
How species 2 affects species 1
A21
The effect ON species 2 by species 1
How species 1 affects species 2
Phase Plane Diagram
Zero growth isoclines
Week 7
L13: Nov 13, 2024
Community Dynamics
Food Chains and Indirect Effects
Top-Down Control:
Community structure is determined by consumers
Bottom-Up Control:
Community stricture is determined by resource availability
TopDown Trophic Cascades:
Specific type of top down effect where the addition or removal of a top carnivore has an effect that cascades down to primary producers at the bottom of the chain
When are primary producers abundant?
Top-Down Hypothesis
If the world looks green…
Plants not limited by herbivory
Herbivores are limited by predations
Food chain length determines whether or not herbivores limit plants
EX)
If the world looks green, what is true?
Herbivores are not limiting the plants
Predators are limiting herbivores
Sea otter→urchin→kelp:
High kelp biomass
Orca→sea otter→urchin→ kelp:
Low kelp biomass
Bottom-Up Control Hypothesis
Communities that aren’t green lack certain nutrients (nitrogen, phosphorus)
Where the world is green (has high net primary productivity) is driven by climate (temperature and precipitation)
Organisms at each trophic level are resource-limited
Food-chain length increases as resource availability increases
How should we describe the world?
Top-Down: deserts are brown because predators are rare and herbivores limit primary production
Bottom-Up: Deserts are brown because resources are scarce and net primary production is low
BOTH WORK!
False Dichotomy? Role of Distrubrance
Need the base of the food web to be established/reestablished post-disturbance before top-down forces could impact community structure
Yellowstone
Wolves reintroduced
Elk eat the aspen
Ecosystem Engineers
Must alter the availability of environmental resources
Light, water, heat, temperature
Autogenic Engineers
Alter the environment through their own physical structures
Trees provide shade
Corals buffer waves
Allogenic Engineers
Alter the environment through building structures
Beavers build dams that modify water availability
What determines food-chain length
Producvitivy Hypothesis
Productivity increases → food chain length increases
Ecosystem-size hypothesis
About physical size of ecosystem
Small lake can only support a few level of trophic levels
Big lake can support a larger amount of trophic levels
Productivity has no effect
Productive-Space Hypothesis
Both size of ecosystem and productivity affects what can be support
As size increases, can have more food chains
As productivity increases, can have more food chains
Community stability questions
How big of a change did the disturbance cause
Resistance
How quickly did the community recover from this change
Return time
How closely did the post-recovery community resemble the pre-disturbance community
resilience
Too much disturbance can lead too:
Alternative stable states
When different types of communities can exist in a particular environment
Same lake with different conditions
Coral reef systems
Healthy coral reef vs reef affected by storms and hurricanes not allowing it to recover, stays in alternative state
What promotes stability
Diversity
Allows it to be more stable, resilient, + quicker return times
Connectance
Keystone and Dominant species
Dominant species have lots of biomass (trees, corals, kelp) + high impact
Keystone species have high impact and low proportional biomass
Non-Endemic / Introduced Species
Not endemic to a community
Spread /transported to a new community
Many of not2 disrupt communities
Those that do are considered nuisance species
Change communities impact local economies
L14: Nov 15, 2024
Ecological Levels of Organization
Everything above level is included
Biosphere includes biome, landscape, ecosystem, community, population and individual
Species Interactions
Exploitations:
Positive effect on one species
Negative effect on another species
Parasitism
What is a parasite
An organism that live on or in another organism
Uses the host for energy
Consuming host tissue or body fluids
Not killing it at all, or at least for a really long time
Active:
Parasites moves on its own
EX) swimming lamprey
Passive:
Parasites lurking for host
EX) tick sitting on a leaf waiting for host to walk by
Endoparasites:
Parasites live in its host
EX) tapeworm
Ectoparasites:
Parasite lives outsides or on top of its host
EX) cordyceps fungus on ants
FINAL QUESTION:
Mosquitos are what type of parasite
Ecto with active transmission
Herbivory
Grazers
Eat grasses
EX) zebra
Browers
Eat leaves bark twigs
EX) deer
Granivores
Eats seeds
EX) small birds, rodents
Frugivores
Eat fruits
EX) toucans, monkey
Some fall into multipole or all
EX) Microtus californicus
EX) humans
Plant Defenses Against Herbivory
Chemical:
noxious/poisonous chemicals to herbivores
EX) chili pepper
Mechanical:
Physical structural deterrents
EX) spikes on cactus
EX) thorns on rose bush
Nutritional:
Low P and N content
Low nutritional content, so animal would gain minimal/ no benefits from consuming it
Tolerant:
Regrow quickly
Herbivore Effects on Communities through Top-Down Controls
Predation
Chemical:
Chemicals that are noxious, poisonous or disruptive to predators
Physical:
Physical barriers to predation
EX) spines and shells
Aposematism:
Warning colors, smells, etc. signaling “i taste bad”
EX) monarch butterflies, colorful amphibians
Crypsis:
the ability of an organism to conceal itself especially from a predator by having a color, pattern, and shape that allows it to blend into the surrounding environment.
Mimicry:
Looking, sounding, or seeming like other pieces that predators do not like
Bastesian vs Mullerian mimicry
Mullerian:
Mimicking something else that is like you and is gross and tastes bad
Perpetuating idea that things like them don’t taste good, so avoid things like them
EX) monarch butterfly
Bastesian
Prey tricking the predators that they are a poisonous animal
EX) king snake vs coral snake
They go hand in hand
Mimicry and Crypsis
Often doing both
Animals often mimic their environment in order to camouflage
Most crypsis is mimicry
Mimicry is not likely to be crypsis
Combo Package
Sea urchin: physical and behavioral
Mackerel: crypsis and behavioral
Countershading
Schooling
Horned lizard:
Behavior: squirts blood
Chemical: blood is toxic to dogs
Crypsis: looks like dirt/docks
Behavior: inflate their bodies
Predation Strategies
Stalking:
Follow prey and then strike
Pursuit:
Chase via flying, running swimming
Ambush:
Wait for prey to come to you
Random Encounter:
Randomly find something you want to eat
Lokta & Vikterr:
Interspecific COmpetition
Predator and prey
How fast a growth rate is changing in the presence of one another
How fast is the prey population changing because of predators
How fast is the predator population changing because of prey
When we assume:
The predator species is totally dependent on a single prey species as its only food supply
The prey species ahs an unlimited supply of food
There is no threat to the prey other than the specific predator
When do we use equations?
When we want to calculator prey/predator population growth rates in the presence of one another
Conversion rate:
How efficient
Week 10
L17: Dec 4, 2024
Final
December 11 @ 8 AM
Climate Change
Terminology
Weather
Short term changes in atmospheric conditions (temperature, wind, precipitation)
Occurs over shorter time scales (minutes to months)
Climate
Mean weather conditions over longer time scales
Typically multiple decades
Climate change
Persistent change in climate
General term includes many different phenomena
Natural vs anthropogenic
Natural: cycles that happen with or without human interferences
Fluctuations in solar, plate tectonics
El nino vs la niña
Anthropogenic: climate change due to human activity
Comes from release of carbon and greenhouse gases
Global warming
Anthropogenic increases in mean surface temperature
More narrow than climate change
Symptom of climate change
Due to greenhouse effect
Greenhouse effect
Causes global warming
Greenhouse gasses trapped and creates global warming
Anomalies
Difference between observed value and mean value
How much does my value differ from the mean value?
Signal
Meaningful information
The trend
What is the data actually showing?
What is the conclusion?
Noise
The variability, or the error, around the trend
Part of the data that may be obscuring the trends of obscuring the conclusion
Anomalies and Noise are related
Anomaly as measure of how much one data point may be contributing to the noise
The lower the anomalies, the less the noise
Types of Thermy
Endothermy: relies on internal heat production
Ectothermy: relies on external heat production
Homeothermy: constant body temperature
Poikilothermy: variable body temperature
Thermal Performance Curve
pMax: top line
Topt: optimal temperature
CTmin:
CTmax:
EX)
Surf clam vs bay scallop
Population Level
Ladybugs
Measures population size growth rate at 6 different temperatures
r= slope of growth rate curve
Spatial Variation in Temperature Changes
Land absorbs more heat than water
Why?
Specific heat capacity
Water SHC > Air SHC
Air temperature increases faster
Heat Distribution
Oceans spread heat to deeper depths
Positive feedback mechanisms
Land has albedo effects
Meting ice/snow albedo (heat reflectivity) and increases heat absorption because ice/snow is white (more white = more reflectivity) and underlying ocean water is dark (more dark = more absolution)
This amplifies warming over land
Negative Feedback Loop
The cause (warming is NOT the same as the effect
The end result (cooling is the opposite of the initial trigger (warming)
Warming → increased evaporation → increased cloud cover → less heat is absorbed → less heat is absorbed → cooling
Which areas warm the most
High latitudes of the northern hemisphere
More ice/snow = more albedo effects
Atmospheric circulation patterns
Air moves from the equator towards the poles = more warming at the poles
Lower baseline
Northern hemisphere warming > southern hemisphere warming
More water in south hemisphere (more land in the northern hemisphere) and water has a higher SHC
Assessing Historical Temperature trends
Proxies
Tree growth rings
During winter, trees stop growing, this creates the dark lines
When they start growing again, the space between the dark lines starting forming
Warmer years = more space between annual growth rings
Ocean Quahogs
Produce growth rings like trees
Can be used as proxies for temperature
Ice Cores
Ration of Oxygen (and Hydrogen) isotopes in water change with temperature
Natural Climate cycles
Milankovitch Cycles
Changes in earth’s orbit, tilt and wobble
Degree of wobble affects how much heat we receive, the temperature
Other planets
This gravitational tug of war between earth and mars drives a 2.4 million year cycle of global warming and cooling
Effects our place in the solar system
Effects how close we are to the sun
Effects how much heat we get
Regional pressure differences
Cycle in air pressure affect regional wind patterns and therefore temperature and precipitation
La nina/ el nino, north pacific oscillation, atlantic multidecadal oscillation
L18: December 8, 2024
Final
15 multiple choice questions (30 points)
10 true false questions (10 questions)
10 fill in the bank questions (10 points)
Remaining 50 points = short answer and scenario questions
Reel Solutions
Exploring the impact of eco-labels on fishery + aquaculture practices & consumer behavior
Seafood provides essential nutrients to over 3 billion people worldwide
We harvest over 179 tons of seafood
The USA imports 88% of seafood annually
How do consumers know what sustainable
Certifications and ratings
Key insights
Consumer findings:
Gap between intentions and purchases
Guided by health benefits and prices
Communication + education gap
Traceability
Challenging to pinpoint where seafood originates
Larger issues internationally
Difficult monitoring catch data
FINAL: ASK about recruitment, how are larvae related
Fishiers and Ecology
Fisheries
A fishing ground of area where fish are caught
The occupation or industry of catching fish
The act of removing fish
The specific type of fish being caught
Not just fish
Includes shellfish]
NOT fisheries:
Corporation, partnerships and their products
They support fisheries, but they themselves are not fisheries
Growth
Growth leads to healthy, sustainable fisheries and stocks
Individual level:
Affected by many things such as temperatures and density dependent factors
ex) food
Population level:
Affected by many things such as temperature, density dependent factors, predation, fishing pressure and recruitment
Recruitment
Recruitment leads to population growth
The process by which new individuals enter a population and become part of the fishable stock
The amount of new individuals that enter the population
The fate of earlier life stages
Without recruitment, without new individuals entering the population, the population cannot grow
You can think of it in terms of year class strength
“ 2021 was a good recruitment year”
Means a lot of new individuals population that year
Tracking what happens to larvae through their life time
Broadcast spawning
External
Final Review
Population level:
Multiple organisms of the same species
Community Level:
Multipole populations, multiple individuals of different species
Ecosystem:
Multiple populations including abiotic factors
Pelagic Trophic Cascade:
Circle size represents population size
Density Dependence
Clam size/ growth rate and 5 density class
A is low density class
E is high density class (has a lot more individuals per area)
A reaches higher numbers
E doesn’t
Do we have evidence of density dependent growth?
Yes, we see differences in growth rate
DISREGARD: connectance, community importance, and total impact,
THEY GIVE EVERY MATH EQUATION BUT WE NEED TO KNOW HOW TO USE IT
Questions
Which of the following biological levels of organization typically include multiple individuals of the same species?
All the above: population, community, ecosystem
Which of the following biological levels of organization only include multiple individuals of the same species?
Population
Intraspecific competition primarily occurs at which biological level of organization?
Population