Final Exam Readings Flashcards
what is the most impact variable in the environment
temperature
what is the intertropical convergence zone
a region near the equator where trade winds from the northern and southern hemispheres meet
- rising warm air
what is abiotic and biotic factors
abiotic = non-living
biotic = living
what are conditions
states that cannot be depleted they are not resources but they are factors such as temperature, salinity
what are the big two
water availability and temperature
what is the environmental gradient
changes in habitat factor
illustrated by moisture gradient moving from lakes inward to land
- gradual change in environmental conditions or factors over a large scale of area
what is transect sampling
sampling along a gradient - soil moisture to see how species vary along environmental factors
what does it mean by “range of tolerance”
each species is limited to a portion of a gradient based on tolerance for certain factors - this forms parts of their ecological niche
- bell curve that peaks representing the optimal conditions in the centre
what are death zones
beyond the tolerance limits or peaks
a species cannot survive In these conditions
what are enzymes
essential for biological reactions
- very sensitive to temperature - can denature proteins at high temperatures
what is osmosis
osmotic balance and takes place in almost all chemical reactions
Too much or too little water can = dehydration, dilute, or denaturing of protein
what does it mean to be environmentally at equilibrium
organisms tend to reach their desired temperatures and moisture of their surrounding
Organisms are vulnerable all the time - cannot control the environment
homeostasis
Organisms must maintain a stable internal environment - importantly with thermoregulation and osmoregulation (temperature and salinity)
what does having a high SA/V ratio mean
small organisms, more susceptible to environmental changes
- based on high or low = how much thermoregulation or osmoregulation
paramecium = high SA/V ratio
Ectotherms
organisms that rely on external sources of heat to regulate their body temperatures
their body temp fluctuates with the environment
- they don’t need to eat as much to maintain internal heat
endotherms
organisms that generate their own body heat through the metabolic process, they maintain an OK range of stable body temps
- birds, mammals
- wider range of comfortable temps
poikilotherms
organisms whose body temperature varies with the temperature of the environment
- most poikilotherms are ectothermic but this term refers to specifically the body temp in their body
homeotherms
organisms that maintain a small window of constant body temperatures regardless of environmental temperature changes
conduction
Direct heat transfer between two bodies in contact
convection
Heat transfer from moving fluids (air, water)
evaporation
on water
effective cooling method when it evaporates from a moist surface such as skin to water vapour
what is radiative heat transfer
all bodies emit thermal raditation
- transferring heat without constant
- heat can either radiate outwards or inwards from the surroundings
Bergmann’s rule
Larger body sizes are more common in colder habitats as they retain heat better due to a SA/V ratio
B - Body sizes
Allens Rule
Animals in warmer climates tend to have longer appendages (ears, tails, legs)
This is to increase heat loss, maximizing SA/V ratio
A - appendages
how does insulation help maintain heat
Using body fat, fur, and feathers for heat insulation - traps air - creates a temperature gradient that reduces heat loss
Feathers and fur can be adjusted in thickness with seasonal shedding - the warmer seasons = more shedding
what is countercurrent circulation
To retain heat - animals with extremities like whale flippers use this circulation method
Arterial and venous blood vessels are close together
This allows warm blood to transfer heat to the cooler returning blood
veins bring cold blood back to the core
arteries brings warm blood to appendages
what are some desert adaptations
using ADH, kidneys minimize water loss
- nocturnal habits - burrow under dirt to avoid extreme daytime heat
- water storage in plants - shallow roots
- micropyle in perennial plants - small leaves to reduce heat load instead of big ones - also causes turbulent airflow which keeps them cool
why do plants have large SA (most of them)
to increase photosynthesis, more stomata, more gas exchange
- but a lot of sunlight = risk = tradeoff
laminary flow
smooth lead surfaces create smooth flow off of the leave or object
what is an xerophytic adaptation
adaptations in dry areas - deserts
- leaves dropping, to conserve water, the photosynthetic parts become the bark, stems
- leaves = modified thrones to help water storage and defense from predators
what are age-structured models for population growth
mathematical models that divide the population into different age classes to better understand how age species birth and death rates influence overall population dynamics
why do age-structured models tend to focus on females
tracking females for simplicity
- they put a lot of cost and resources and invest a lot of time into children
- males are treated as abundant cheap resources - this does not affect the overall reproduction potential
what are survivorship schedules
represented by lx
it is the probability of an individual surviving to age x
- ranging from 0 to 1
newborns have a survivorship of 1 and it decreases over
- a survivorship curve only declines as time goes on - only when the offspring are born at first then there is high mortality, then stabilizes
what is a fecundity schedule
Bx = average number of daughters produced by a female at age x
Bx is usually zero until reproductive maturity
what is the net reproductive rate
R0
it means the lifetime reproductive output of the average female
- if R0 = 1 then the population remains stable
- if R0 is above 1 then the population grows
if R0 is below 1 then the population declines
what is the Leslie matrix
a matrix approach by using Bx and survivorship values to project future population age structure
- useful for stimulating stable age distribution or population growth under constant conditions
what are key trade-offs in evolutionary ecology
- Size-number tradeoff
The balance between offspring size and quantity based on resource allocation - larger offspring have a survival advantage but require more resource - Early Vs Late Reproduction
Early reproduction is often favoured for faster population growth
But may trade off with individual survival or future reproduction
Species reproducing early tend to have shorter lifespans - delayed reproduction may be longer-lived - Cost of Reproduction
Energy spent on offspring can reduce parental survival and future reproductive success
what is the reproductive value
Vx it is the expected future offspring of an individual at age x
- Calculated by combining age specific fecundity and survivorship
- High reproductive value individuals contribute more to the future generations - protecting these individuals is key for conservation
what is semelparity
one-time reproduction followed by death = annual plants
what is synchronized flowering
Many long-lived perennials synchronize blooming to maximize reproductive success
Ex:
Asian Bamboo - they may flower and seed in cycles spanning decades
what is predator satiation
When plants produce massive seed crops - they can overwhelm seed predators - ensuring that enough seeds survive to germinate
Masting in Trees
Nut-bearing trees like oaks exhibit periodic heavy seed production - reducing seed predation through predator satiation
what are R selected species
Adapted for rapid growth in less stable environments with high fecundity, short life spans, low survival rates
Weedy species with numerous small-seeds
K related species
Adapted for competitive environments with slower growth, less offspring, high survival
Typical traits include large seeds and longer development times
Some ecologists argue this model is overly simplistic and propose alternatives
what is the C-S-R model
by J.P Grime
C = competitors
S = stress tolerators
R = ruderals
- adapted to disturbed environments - growing quickly to exploit available resources
what is the deterministic model
uses fixed birth and death rates - giving a single and predictable outcome
- lack of realisms and they don’t account for natural variability
what is the stochastic model
introduce random variation in birth, death and other parameters
- reflecting the unpredictability of natural populations
- Stochastic models are more effective for conservation, allowing simulations of extinction risk by generating distributions of outcomes
what is an ecological community
All of the organisms or the biotic entities in some spatially defined locality
If we were to be adding all the abiotic parts of the area then = ecosystem
what is a subset
When biologists make a community study it is mostly just a subset - which can be taxonomically defined or functionally defined (birds in Arizona or soil decomposers in Arizona)
what is species richness
the number of species present
- the amount of distribution of abundance and rarity determines the species diversity of the species assemblage
- A community with 10 equally abundant birds = more diverse
A community with 1 common bird and 9 rare = less diverse
what is the logistic model
A logistic equation effectively models an environment in which resources for population growth are supplies at a certain rate - and organisms used them up
The logistic equation modifies exponential growth by adding a braking term that slows down growth as more individuals of the species use up resources
what does the first braking term in the logistic model mean
Braking term = intraspecific competition = from the first species
what does the second braking term in the logistic model mean
Second braking term = interspecific competition from the second species
what is the alpha constant used for in the logistic model
We need to add this coefficient because there is no reason to expect that the 2 species use resources in the exact same way
**it is the competitive effect on species 1 exerted by species 2 = &12
**competitive effect on species 2 exerted by species 1 = &21
If & = LARGE then = interspecific competition is important
If & = small then there is not much effect from interspecific compeition
what are the 4 possible outcomes between 2 species interactions
- species 1 always outcompetes species 2 - if K1 is bigger than K2
- species 2 always outcompete species 1 - if K2 is bigger than K2
- species 1 and 2 will stably coexist - both of them remaining below their K values at a steady state
- the competition is unstable, but the winner depends on the initial number of the population - whichever species has a larger initial population will outcompete the other
T/F Intraspecific competition needs to be stronger than interspecific
true
What G.F Gause prove with competition in beetles
showed that competitive exclusion was a rule
2 species that compete for the same resources cannot coexist for long
One species will be slightly better at growing with shared resources and the most efficient species will be able to increase its population at the expense of the less efficient competitor
he showed this by examining beetles and seeing that abiotic conditions are important to beetles bc one always outcompete the other
how was the niche concept formulated
by Grinell
It is unlikely that 2 species would occupy the same niche
One of them must be better than the other
Although - there are plenty of situations in nature where organisms do seem to be filling the same functional niche and still manage to coexsit
what was Robert MacArthur’s research
how many species of warbler were able to coexist
The habitat of the northern coniferous forest = not much diversity of trees or food
The birds would not seem to have much-specialized niche
He looked for differences in how these species used their habitats
**the most common warbler species were usually feeding in different zones of the coniferous trees - gave a partial explanation of what species were doing differently - they were engaging in finer-scale niche partitioning
1. the data was quantitative
2. measures of niche overlap should = competition coefficient in LV model
niche partitioning
refers to the process by which competing species or individuals within a species divide or share resources in an ecosystem to reduce direct competition. This occurs when species with overlapping ecological niches evolve to exploit different aspects of the environment, such as food sources, habitat preferences, or time of activity
what is the role of predation in competitive exclusion
Predators reduce pop sizes, keeping species below their carrying capacity
Prevents competitive exclusion by allowing inferior competitors to coexist with superior ones
Robert Paine’s Starfish Experiment
removal of starfish in rocky zones caused the prey of single mussels to become dominate, and not let others grow, taking up space
- this limits species diversity
- this shows that predators keep control over diversity and lower trophic levels
what is a metapopulation
a collection of subpopulations across habitat patches
Patches vary in quality and are separated by unsuitable matrix habitats
Dispersal connects subpopulations = able to recolonize the empty patches
Colonization vs extinction rates determine patch occupancy
Equilibrium proportion: p = 1 - e/c
E = extinction rate
C = colonization rate
source patches
high quality patch with species that are suitable to disperse to other patches and migrate
sink patches
low quality patches that rely on immigration to sustain their population - migrates from the source patches
explain the experiment behind the origin of the symbiosis study
Paul Buchner
- established that bacteria is essential for the survival of many insects
Helps aphids overcome nutrient deficiencies in plant sap (lacks AA)
Giant tube worms → doesn’t have a gut but has a sack of bacteria
The bacteria = chemosynthesis that process H2S into food
It is different from photosynthesis because worms = live in darkness
explain the diversity of microbes
Gut bacteria = bears, rhinos, pandas, lemurs, hippos
Herbivores have the most diverse gut microbes = plant-based diet
Carnivores have the least diversity
Omnivores = middle
explain the hare and lynx predator and prey cycle
coyotes are the hare’s general predator
coyotes thrive in shallow snow and it’s becoming more common for hares who also favour shallow snow
this makes coyotes not a good predator
lynx are not affected by the depth of the snow
- when the pop of hares increase = more food for lynx - hares decrease, lynx increase
- when there is no more hares, lynx decrease and hares increase
climate change is affecting the snow patterns and will effect the population dynamics
autotrophs
species that make food for themselves
- green plants that photosynthesize to create high energy carbon bonds
- at the bottom of the pyramid
heterotrophs
organisms that consume primary producers
eat both plants and animals
primary consumer
herbivores
eat primary PRODUCERS
secondary consumers
eat primary consumers - herbivours
omnivores
feed at multiple trophic levels
decomposers
detritivores
fungi and bacteria that break down dead organic material
what is Hutchinson’s contribution
the study of energy flow in ecosystems
Energy comes to the earth via solar radiation → the organisms use it before it goes back into space as heat
Matter is recycled - involves biogeochemical cycles - some elements spend long periods of time in inactive forms before being used again (phosphorus remains as ocean sediment)
HSS Hypothesis
Most terrestrial ecosystems appear green = abundant plant material
Because herbivores are limited by predators (top-down control)
Plants are not entirely consumed
Criticisms argue that the theory oversimplifies ecosystem dynamics
Some plants may = inedible = alternative explanation for greenness
indirect effects
predators eat herbivores which benefits the primary producer - plants
- u can test the effects of this by removing a top predator and seeing how abundance changes - overgrazing and vegetation loss
T/F Removing predators and observing = cascading effects on lower levels
true
how do plants defend themselves
structurally = thrones, tough leaves
chemically = toxic compounds released when a plant is damaged, alkaloids (caffeine, cocaine)
what are some specialized adaptations that insects have to overcome for plants
plants = sessile = need defenses = toxic
insects will evolve especially to be tolerated to the toxins = milkweed + monarch butterflies
this = coevolutionary arms race with plants and insects that makes them so abundant and why the earth is so green
