Ecology Flashcards
What is ecology as a study?
- the study of organism-environment relationships
- one of the most divers and interdisciplinary sciences
What may occur when one organism is destroyed? Why?
Ecology indicates the links between everything, nothing is isolated, everything is interconnected
- the destruction of one organism can lead to the destruction of other organisms
What are 3 reasons why ecology is important?
- provides information about the benefits of ecosystems and sustainable uses of the earth’s resources (for farming, construction, sustainability, etc)
- allows us to predict the consequences of human activity
- helps find solutions to burning issues ie: habitat destruction
What is an ecosystem? What is the biosphere?
Ecosystem: Includes all organisms in an area and the physical environment in which they interact
Biosphere: Highest level of ecological organization, can be viewed as the global ecosystem (includes all living things on planet : bacteria, animals, plants, etc)
How does one distinguish a biome?
Biomes distinguished primarily by their predominant plants and are associated with particular climates
Describe the ecology of warblers case study
Prediction: 2 species with identical ecological requirements cannot coexist due to competition, cannot live together indefinitely
- 5 warblers in spruce forest found to coexist via resource partitioning: eat on different sections of the tree
- suggested that aggression between species maintains feeding zones
Describe a large scale case study of ecology
- Lakes turning green (eutrophication)
-Algae was growing due to excess nutrients but which nutrients - lab experiments were inconclusive, needed a whole lake
- lake 226: part of lake with added Phosphorus turned green coming from household detergents - communication allows ban, water quality improved
What is eutrophication?
Process by which excess algae grows due to extra nutrients (typically phosphorus) residing in the water
What did Darwin discover on his trips to the Galapagos?
- every island had related species and each species traits varied among islands
Describe evolution
process that changes populations of organisms over time
- descent with modification
What is Darwin’s theory of natural selection?
- more offspring are produced each generation that can survive
- heritable variation in traits among individuals in population
- some individuals have greater fitness, which become more common in the population over subsequent generations
What is fitness?
Ability to survive and reproduce
- greater fitness traits more common and frequent
Who is Gregor Mendel?
- monk who studied garden peas
- discovered characteristics pass to offspring in genes
What is the basic unit of heredity?
Genes.
Describe genes
- portion of a DNA molecule and the basic unit of heredity
- exist in different forms called alleles
- dominant and recessive
What is the modern synthesis theory
- Darwin and Mendel’s theories complemented each other perfectly, revolutionized biology
What is the cause of phenotypic variation?
- combined effects of genes and environments causes variation
–> Phenotype = genotype + environment + (G x E interaction)
What is phenotypic plasticity ?
variation among individuals in form, function, or physiology ad a result of environmental influence
What are distinctive ecotypes?
- distinct form or race of a plant or animal species occupying a particular habitat
Why might plant species differ dramatically in one elevation to another?
Clausen found evidence of adaptation by ecotypes to local environmental conditions
Describe the Potentilla Glandulosa variation?
- 3 main gardens of plant clones at different elevations
- garden experiment revealed potential genetic differences among populations
- ecotypes present, plant’s variation increases based on environment
What is an ecotype?
a population (or subspecies or race) that is adapted to local environmental conditions.
- - unique plants adapted to a local environment
- specific traits made for unique environment
Review the genetic variation and heritability equation
What are two processes by which evolution may occur
- natural selection or random processes (genetic drift)
What can genetic drifts cause?
- gene variations to disappear completely / reduce genetic variation
- rare alleles to become more frequent
What is the Hardy Weinberg principles?
If strict conditions true (e.g., no selection, random mating, infinitely large populations) allelic variation in a gene will be maitnained
What are the major forms of selection?
- stabilizing, directional, disruptive
What is stabilizing selection?
- impedes changes in a population by acting against extreme phenotypes and favouring average phenotypes
- small and greater fitness becomes low, phenotype remains the most common
What is an example of stabilizing selection?
- ural owl hatching success: lowered fitness in individuals who lay small and large eggs
What is directional selection?
- directional selection leads to changes in phenotypes by favouring an extreme phenotype over others
What is an example of directional selection?
Soapberry bugs : soapberry bugs in FL have shorter beak, in central US longer
- beaks correlated with fruit size
What is disruptive selection?
- Creates bimodal distributions by favouring two or more extreme phenotypes over the average phenotype in a population
- phenotypically diverse,
What is speciation?
- natural selection and genetic drift change gene frequencies: in combo with physical and ecological processes and over time evolution of new species may occur
What is a species?
- multiple definitions
- most commonly defines using Mayr’s concept: a group of actually or potentially interbreeding populations which are reproductively isolated from other such groups
(must be able to breed together)
What is hybridization driven extinction?
- introduced species interbreed with native species leading to the lost of the native species’ distinct genetic identity
What is the morphological species concept?
- classification of organisms belonging to the same species based on conserved morphological features
- this concept may be useful when organisms do not reproduce or are extinct/only know by fossils
-a concept that characterizes a species based on its structural features, like body shape.
What is the biological species concept?
- when populations of organisms are able to interbreed and produce viable, fertile offspring are classified as belonging to the same biological species
What is the phylogenetic species concept?
- defines species based upon evolutionary history and phylogenetic similarity
what may cause new species?
Physical and ecological processes interact with selection and drift to produce new species
- ie: environment and genes can cause phenotypic variation - leading to new species
What is allopatric speciation?
- occurs when a single population becomes spatially subdivided into multiple subpopulations
- exchanging genes stops because of distance/isolation
What is parapatric speciation?
Occurs when a population expands into a new habitat within the range of its parent species
- extreme change in habitat followed by interbreeding
What is sympatric speciation?
- Occurs when a single population forms genetically distinct subpopulations with no spatial isolation
- new species evolves from a single ancestral species while inhabiting the same geographic region
Label/describe the images for allopatric, parapatric, and sympatric speciation
Do sympatric speciation new species breed with the former species?
No!
Why would a bee sting someone even if it will die?
- worker bees wish to ensure their genes are passed on by protecting the hive: a form of altruism, natural selection favours
What is behaviour? What causes it?
- Behaviour is the observable response of organisms to internal or external stimuli
- causes focus on genetic and physiological mechanics
- real reason is to improve reproductive success
What causes behaviour? What is its primary focus?
- based on genetic and physiological mechanics
- focus on its effects on reproductive success
What is behavioural ecology?
The study of social relations (the interactions between organisms and the environment are mediated by behaviour)
What mediates the relationship between organisms and the environment?
Behaviour
What is sociobiology?
Branch of biology concerned about the study of social relations
What is the scientific study of behaviour called?
Ethology
Can natural selection act on behaviour?
- yes! Natural selection selects for behaviour to promote reproductive success
- natural selection can work on all aspects of an organism (behaviour, phenotype)
Give an example of natural selection working on behaviour
- a single gene alters the role of a honey bee: the value fo foraging and hive building conditions depend on local conditions
- bees that are active foragers are likely less fit than bees that don’t forage until later
- another example may be prides of lions who have social benefits
What is inclusive fitness? Who introduced the concept?
- Hamilton introduced
- individuals overall fitness is determined by its survival and reproduction plus the survival and reproduction of its relative (who the individual shares genes with)
Why might an animal be less interested in protecting a baby unrelated to them?
- not genetically related, wish to preserve their genes
- that being said, animals are still likely to protect young of others, but infanticide may also occur as an act of selfishness
What is the selection for helping relatives called? What is it?
Kin selection
–> An evolutionary strategy that favours the reproductive success of an organism’s relatives, even at a cost of the organisms own survival and reproduction
-> ensure the survival of genes!
Why might an organism sacrifice itself to preserve its relatives?
- to ensure the survival of genes they both share
What is inclusive fitness a combination of?
- combination of direct and indirect fitness
inclusive fitness works to preserve actor’s personal reproductive success as well as kin
What is direct and indirect fitness?
- direct fitness affect: actor’s own reproductive success
- indirect fitness effect: the impact on the reproductive success of social partners, weighted by the relatedness of the actor to the recipient
What are the 4 main classes of social interaction? Who are they between?
Between donor and recipient, can have positive or negative impacts for those involved
- cooperation, selfishness, altruism, spite
Provide an example of spite please.
- parasitoid wasp
- sterile soldier wasps attack relatively unrelated brother larvae so the genetically identical sisters have more access to food
Which social interactions might natural selection select against? Which ones might it select for?
- spite and altruism have negative fitness consequences for the donor
- cooperation and selfishness have positive donor fitness consequences
What is altruism? Provide and example
- an act that benefits the recipient but harms the donor
- the red squirrel adopts offspring of another squirrel (expends energy for the donor, the recipient is benefitted)
What is the goal of most altruistic acts?
- to benefit the individual’s close relatives or kin
Why might an organism take care of its young if it costs energy?
- an act of altruism: offspring have copies of their parent’s gene so when parents take care of their young they are helping the survival of their own genes
- these genes continue on, and are therefore favoured by natural selection
What is group selection?
- individual acts counter to own interest for betterment of group
- criticized as inconsistent with evolutionary understanding
Why is group selection criticized as a theory?
- Because it goes against evolutionary understanding: why would an individual reduce its own well being, natural selection might be expected to go against that
Does altruism present in all situations?
no, altruisms role is actually debated - but known to occur in some circumstances
- some ecologists accept that individual gain is more likely to be selected for than group selection (resulting in behaviour like infanticide)
Why might altruism be a point of contention for some?
- natural selections leads us to expect animals to behave in ways that increase their own chances of survival and reproduction, not of others
- altruism puts animals at a select disadvantage than those who act selfishly
What is the reasoning for why altruism has not been eliminated by natural selection?
May have evolved by a progress between group selection
What is Hamilton’s rule?
- rB>C
- study the coefficients and the math plz
What is sociality?
- the fundamental change in relationships among individuals that comes with group living
- generally positive relationships, ‘worth it’
What is sociality generally accompanied by?
- cooperative feeding, defence of the social group, restricted reproductive opportunities
- cooperation generally involves exchanges of resources or other forms of assistance
What is eusociality? What are the 3 major characteristics?
- more complex level of sociality
- 3 major characteristics :
- individuals of more than on generation living together
- cooperative care of young
- division of individuals into non-reproductive and reproductive castes
What are the two forms of castes? What are they a result of?
Reproductive and non-reproductive castes found in eusocial groups
What are cooperative breeders?
- groups of adults cooperate in producing/rearing offspring including not their own
What are the benefits for helpers associated with cooperative breeding?
- inclusive fitness
- inherited territory
-kin selection
Describe the example of African Lions and sociality
–
How did eusociality evolve?
- kin selection may play role: in leaf cutters workers may be more related to other workers than to their own offspring
- ecological constrains: work required may demand more complex social behaviour, limited resources/mating prospects, etc
What behaviour does natural selection favour?
- behaviours that increase the inclusive fitness of individuals
What are trade-offs? What term is associated?
- If organisms use energy for one function, energy for other function is reduced = the principle of allocation
What are life histories?
- the sequence of events related to survival and reproduction that occurs from birth to death
What is the principle of allocation?
- how an organisms allocated energy within a segment of its overall energy budget
- leads to trade-offs between functions such as number and size of offspring
What is allometry?
The study of scaling between body size and various biological functions
Which animal shows more variation in life history than any other group?
- fish show the most variation in life history!
What does fecundicity mean?
- the number of offspring produced by an organism to produce viable, fertile offspring
Describe the darter population study in relation to gene variance
- Turner and treadler found darter populations that produced many small eggs showed less difference in allelic frequencies than populations producing few, large eggs
- proposed larvae from larger eggs hatch earlier: do not drift as far, and don’t disperse as greatly
- results in greater gene isolation and rapid gene differentiation
- smaller larvae lead to greater gene flow
Which size darter has greater gene flow? What does this represent?
The smaller larvae
- these are the consequences of life history trade-offs in darters
- more incubation time = more gene flow ??
Which two factors influence seed size and population?
Seed dispersal mode and plant growth form
What are the 4 recognized plant forms?
( Westoby )
- Graminoids: grass and grass-like plants
- Forbs - herbaceous non-graminoids (little or no woody tissue and persisting for a single growing season)
- Woody plants: woody thickening of tissues
- climbers : Climbing plants and vines
**Woody plants and climbers produce 10x mass of seeds
Which plants produce greater seed mass?
Plant forms Climbers and woodyplants: produce 10x the seed mass of forbs
What are the 6 seed dispersal strategies?
- unassisted: no specialized strucutres
-adhesion: hooks, spines, barbs - wind: wings, hair, resistance structures
- ant: Oil surface coating (elaisome-oil which sticks to ants)
- vertebrate: fleshy coating (aril)
- scatter-hoarded: gathered, stored in caches
What is the relationship between seed mass and number?
Negative relationship: greater mass, smaller number
What is the conclusion about seed size in areas of high disturbance and high stress?
- small plants producing large number of small seeds appear to have an advantage in areas of high disturbance
- large plants with large seeds produce fewer seedling but more capable of surviving environmental hazards due to deep rooting (more nutrients/grounding)
Which plants would do best in areas of high stress?
Small plants (forbs, graminoids) that produce smaller seeds tend to do better in high stress areas
Why might larger plants do better in areas of high disturbance?
- climbers and woody plants produce large, but limited number, of seeds = allows for deep rooting and more nutrient access so they are less impacted by disturbance
How does adult survival and reproductive allocation describe tradeoffs?
- shine and charnov pointed out that vertebrate energy budgets are different before and after sexual maturity
- before energy is dedicated to maintenance or growth, whereas after its maintenance, growth, and reproduction
- individuals delaying reproduction will grow faster and reach a larger size
Why might an individual who matures later have greater success?
- ‘trade-off’ they can dedicate more energy to maintenance and growth and reach a bigger size - THEN they can reproduce = greater chances of survival,
Who has a greater chance of survival? Organism who has delayed or early reproduction age
Delayed!
What relationship might be found with higher mortality rates in fish?
- higher mortality = higher production rates
Name the scientists associated with experiments
- shine and charnov: adult survival and reproduction allocation
- bertschy and fox: pumpkinseed fish
- westoby: plant size and seed dispersal
What were the findings of Bertschy and Fox’s experiment on pumpkinseed fish?
- supported theory that when adult survival is lower relative to juvenile survival, natural selection allocates greater resources to reproduction/increased reproductive efforts
- likewise, life history theory suggests that high adult survival relative to juvenile survival favours, delayed maturity and reduced reproductive effort is favoured (corroborates what we know!)
What is being favoured by natural selection when the adult fish have greater mortality than the juveniles?
- NS is favouring reproduction, allow them to reproduce quicker
What are the two conclusions researchers reached from Pumpkinseed fish experiment?
- populations with higher adult survival mature at an older age
- if females survive to greater ages reproductive effort decrease
- higher rates of adult mortality can favour greater allocation of resources to reproduction
What are the 2 life history classifications?
r selection and K selection
What is r selection?
- r: measure of population growth rate
- larger values: rapidly growing population
- r selected species good colonizers, found in habitats with high levels of disturbance (dandelion = small, rapid growth, short life span, small seeds w/good dispersal)
What is K selection?
K: max sustainable size of population
- larger values: habitat that can support larger population size
- k selected species have traits favouring efficient use of resources: found in habitats where populations always near carrying capacity
ex: Oak: large, slow growth, long life span, few seeds, poor seed dispersal
what is true of r and k selection?
most organisms are in between!
What is semelparity?
semelparity: if the environment is stable, then selection favours a single act of reproduction because ether organism can devote all its energy to making offspring and not maintaining its own body
- ie: bugs have short lifespan so will reproduce just once, can dedicate energy to babies and ensuring their survival
- common in insects and other invertebrates and some plants
What is iteroparity?
- if survival of juveniles is poor and unpredictable selection favours repeated reproduction and long reproductive life to increase chance that juveniles will survive some years
- common in vertebrates and perennial plants such as trees
What are the organisms of r selected species?
- r-selected traits include organisms ranging from bacteria and diatoms, to insects and grasses, to various mammals and small rodents
What are some k selected organisms?
- k selected traits include large organisms such as elephants humans and whales but also smaller long lived organisms (arctic terns)
Which species, k or r, are at risk of extinction? Why?
- In a human-dominated world, k selected species are at risk of extinction
- limited habitat, fewer offspring so opulations cannot recover as quickly, generation times are long + breed at a later age
What are the two variables exerting the most selective pressure in plants?
Intensity of disturbance: any process limiting plants by destroying biomass
Intensity of stress: external constraints limiting rate of dry matter reproduction
In the context of ecosystems, what is the difference between stress and disturbance?
Disturbance: short term, natural disasters ie: tornadoes, storms, disease, volcanic eruptions
Stress: long term, impacts the functioning of the ecosystem ie: limited water, increasing temperatures
What are the four environmental extremes?
- Low disturbance: low stress
- low disturbance:high stress
- High disturbance: low stress
- high disturbance: high stress
What are ruderals?
Highly disturbed habitats, low stress
- grow rapidly and produce seed quickly, comparable to r selection
What form of selection are ruderals most comparable to?
- r selection: grow rapidly and produce seeds quickly in areas of high disturbance
What are the types of plants that exist in the environmental extremes?
ruderals, stress-tolerant, competitive
What are stress tolerant plants?
- areas of high stress, no distrubance
- grow slowly to conserve resources, comparable to k selection
What selection type are stress tolerant plants most comparable to?
K - selection, slow growing to conserve resources
What are competitive species?
- found in areas of low disturbance and low stress
- grow well but eventually compete with others for resources
What is a fundamental niche?
- reflects environmental requirement of species in a ‘perfect world’
What is the realized niche?
- involves the interactions with other species
What ecology studies does population ecology bridge?
-physiological and community ecology
What are some real world applications of population ecology?
- at the centre of many studies of species at risk with recovery plans often constructed using information learned
- provides valuable insight in understanding and control of populations and invasive species
What is a population? What are some define characteristics of a population?
a group of individuals of a single species inhabiting a specific area
- characterized by distribution, number of individuals, growth rates, etc.
What is population density?
- concentration of individuals within a species in a specific geographic locale
What can influence the distribution of a species?
- influenced by the occurrence of suitable environmental conditions
What is spatial structure?
- the pattern of density and spacing of individuals in a population
- no single species can tolerate full earth’s environment
What is a geographic range of a population?
- the area that encompasses all individuals of a species
- a measure of the total area covered by a population
What might limit the distribution of a population and restrict its ability to colonize other suitable areas?
- competition and predation can limit distribution
What is a niche? What are the types?
An abstract concept representing the multidimensional conditions necessary for a species to persist
- fundamental and realized niche
Describe the difference between a realized and fundamental niche
fundamental: the range of abiotic conditions under which a species can exist (conditions a species might live in if not for other species ) = potentially survive
Realized: the range of biotic and abiotic conditions under which a species actually persists: more rested conditions (smaller than fundamental niche)
What are some limits to the fundamental niche? Why can’t a species live in its ideal conditions in the real world?
- competitors, predators and pathogens may prevent a species from persisting in an area
What are distribution limits?
Physical environment limits geographic distribution of a species as no species can tolerate all environment - can only handle so much variation in environment
Describe the case study of Arctic terns and their distribution. how do they compensate for environmental variation?
- arctic birds have annual migration from arctic ocean to Antartica - follow two summers
- reasons related to the drop in temperature over winter
Migration: breeding reasons: breed in norther parts oc arctic ocean
feeding: travel to take advantage of food available in particular seasons
What are the two reasons arctic terns may migrate?
Breeding areas and feeding areas
Describe the migratory behaviour of case study : muskox populations
- have traits that allows them to withstand extremely cold temperatures
- fur coat with thick guard hair help protect insulating properties of the undercoat
- remains in the arctic all year through migrate to higher elevations in the winter to avoid deep snow
- this is how they compensate for environmental variation
Describe the compensation strategies for environmental variation in the arctic tern and muskox populations
arctic tern: migrates in winter
muskox: develop thick fur to help them withstand cold
Describe the compensation strategies for environmental conditions in blue whales
Winter: warm low tropical waters, breed/birth
Summer: cooler high polar waters (feeding)
- migratory - during which they eat nothing for 4 months living on body reserves
Describe kangaroo distribution strategies
- three largest kangaroo species in Australia have different distributions that are closely tied to climate
What are some way climate can indirectly impact species distribution?
influences species distributions via food, water, habitat, parasites, pathogens, competitors
BALANUS and CTHAMALUS
- review case study: key point: competitive interaction with balanus is what excludes cthalamus from its fundamental niche
What are the two types of distribution patterns?
- small scale and large scale
What are small scale distribution patterns?
Distance of no more than a few hundred meters over which there is little environmental change significant to organism
What are large scale distribution patterns?
- area over which substantial environmental change (and can change conditions of organism as well)
What are the small scale patterns?
- random, regular, clumped
What are random patterns?
- equal chance of being anywhere, uniform distribution of resources
What are regular patterns?
- uniformly spaced, exclusive use of areas, individuals avoid one another
- due to antagonistic interactions
What are clumped patterns?
- unequal chance of being anywhere, mutual attraction between individuals (eg; wolf packs)
- patchy resource distribution
Why is the movement of individuals in a population important?
Moving between patches of habitats ensure the persistence of populations: they can adapt to resource availability etc.
What does the population distribution refer to?
The size, shape, and location of the area it occupies
Which conditions play a major role in geographic range?
Environmental conditions
- eg: maple trees
What is the size of the fundamental niche and realized niche?
Fundamental niche: larger, realized niche: smaller
When do species find their realized niche?
when their fundamental niche is exposed to abiotic and biotic interactions
Is climate always the direct cause of distribution patterns?
- no, climate often influences species disruption indirectly
What is dispersion?
The spacing of individuals with respect to one another within the geographic range of a population
- random, regular, clumped
What is dispersal?
The movement of individuals from one area to another
- dispersal allows species to colonize areas outside geographic range
- a way to avoid high competition or predation risk
Why is it important to study ecology at a population level?
- serves as a bridge between physiological and community ecology
- At the centre of many studies of species at risk: recovery plants constructed
- Provides valuable insight into the understanding and control of harmful invasive species
Why are populations divided into local or subpopulations?
- due to environmental heterogeneity
- individuals can only occupy areas that can meet their requirements
Why aren’t individuals distrusted evenly throughout the geographic range of a population?
- because they can only occupy ares that meet their requirements
What are subpopulations connected by? What is this?
Dispersal : Mechanisms by which individuals can move between suitable habitats
What is a meta population?
- a collection of local subpopulations as one linked population
- a series of small separate populations in individual habitat patches that mutually affect one another
Describe metapopulations
- fragmented landscapes create fragmented populations many of which may exchange individuals via dispersal creating metapopulations
- develop due to interactions between biology go the species and landscape upon which it lives
- a series of small separate populations in individual patches that mutually affect on another
What is one potential cause of fragmented landscapes?
- human activity such as logging can lead to habitat fragmentation and can change population structure
What are populations that persist in a balance between local extinction and colonization?
- metapopulations:
- local extinction of individuals can be recolonized from other patches
Describe the basic information for the meta population of an alpine butterfly
The Rocky Mountain Parnassian butterfly
- extends from northern New Mexico to southwest Alaska
- host plant of caterpillars is sedum : found in alpine meadows
- tie to a narrow range of host plants –> populations are often distorted among habitat patches (form metapopulations)
Describe the study on alpine butterflies AND the results please
- a study focused on a series of 20 alpine meadows in rockies
- meadows ranged from 0l8 to 20 ha (some adjacent, other separated)
- Mark recapture techniques were used to estimate the size of subpopulations and dispersal behaviour
- studies showed: average butterfly populations were more likely to leave small populations and disperse to larger populations
- with forest encroachment into alpine meadows populations will likely decline
IE: Larger meadows tend to support larger populations
What was the result of the alpine butterfly experiment?
- larger meadows tend to support larger populations
- butterflies were more likely to leave small populations and disperse to large populations
What 3 factors are the classification of commonness and rarity based on?
- geographic range of species: extreme vs. restricted
- Habitat tolerance: broad vs. narrow
- local population size: large vs. small
- these 3 factors lead to 8 possible combinations: 7 include some attribute of rarity (I, II, III)
what are the forms of rarity?
Rarity I, II, III
What is rarity I?
- extensive range, broad habitat tolerance, small local population
–> e.g., peregrine falcon: broad geographic range but small density, driven to brink of extinction by DDT, saved by ban of DDT
–> Eg., tiger: many small local populations, driven to extinction by hunting - now only series of small, fragmented populations
Provide 2 examples of rarity 1?
tigers and peregrine falcons
What it the relationship between extirpation and recolonization?
- meta populations are populations persisting in a balance between extirpation (local extinction) and recolonization
What are the 4 key points about meta populations?
- Metapopulations are a population of subpopulations
- the subpopulations are connected by movement of individuals from one subpopulation to another
- any subpopulation can go extinct and be re-colonized over time
- The risk of subpopulation extinction is generally greatest for small subpopulations which usually occur in small patches on the landscape
What kinds of subpopulations have the greatest risk of extinction?
- small subpopulations in small patches on landscape
What are the 3 characteristics of a population least likely to go extinct?
- extensive geographic range, broad habitat tolerance and some large local populations
What is rarity II?
extensive - medium range, narrow habitat tolerance, large populations
eg; passenger pigeon: nested in large aggressions in virgin forests, logging of forests and hunting led to decline and last died in 1914
- harelip sucker: common fish found n streams with rocks bottoms
- habitats eliminated by silting of rivers and erosion following deforestation: last individual collected 1893
What are the two examples used for rarity II?
- passenger pigeon and harelip sucker
What are the characteristics of Rarity III?
- restricted range, narrow habitat tolerance, small populations (all 3 factors = extreme rarity)
- eg; california condor, mountain gorilla, giant panda
- many island species have these attributes: go extinct
What is the relationship between population density and organism size?
- population density declines as organisms size increases
- ie: bacterial populations have 109 individual per cm^3, whereas large mammals and birds may be less than 1 individuals per km^2
Do mammals or birds live at higher population densities?
- mammals (weird)
What are the 3 main methods of estimation?
–> Cohort life table: identify individuals born at same time and keep record from birth
–> Static life table: record age at death of individuals
–> Age distribution:
Calculate difference in proportion of individuals in each age class
- assumes differences in numbers form one age class to next due to mortality
- assumes population stable In size
What is considered a fundamental descriptor of a population?
- the pattern of survival and mortality among individuals in a population
What is a survivorship curve?
- summarises pattern of survival in a population
What does population growth mean?
- refers to how the number of individuals in a population increases or decreases with time
- individuals added via birth and immigration
- individuals removed via death and emigration
What kind of population does immigration and emigration occur in?
- open populations - does not occur in closed populations
What is the relationship between growth rate and time?
- the faster a populations growth rate the faster the population grows
What does it mean when a population is growing geometrically? Exponentially? What shapes are their curves?
- geometrically: when a population breeds seasonally (often once a year)
- exponentially: species reproduce almost continuously and generations overlap
- both have J shaped population growth curves
Which model is used to describe how a population grows under limited resource conditions?
- such growth is called logistic growth (s-shaped curve) - has carrying capacity
What are BIDE dynamics?
- population size changes as function of birth, death, emigration and immigration
- Born, Immigrated, Died, Emigrated
Describe the BIDE equation
What are the limits to population growth?
- environment limits population growth by altering birth and death rates
- density dependant factors: disease, resource competition
- density indépendant factors: natural disasters, weather
Describe the environment, birth and death among Galapagos finches
- medium ground finch was numerically domiannt
- after drought population fell, food plants failed to produce seed crop
- 10x normal rainfall led epilation to grow due to abundance of seed and cetrepillas
- during heavy year of rainfall large abundance of seeds and caterpillars allows increased reproduction
Describe the populations and precipitation of the Large Cactus Finch
During 1980s rosemary and Peter grants tracked larger cactus finch populations on the Galapagos island
- population numbers were correlated with precipitation
-rainfall impacted food supply, in turn impacted finch population number
What are life tables used for?
- used to track age-specific mortality rates and birth rates
What is the fecundicity schedule?
- birthrates for females of different ages
fecundity: the ability to procure abundant healthy growth or offspring
What is the net reproductive rate (R0) ?
Average number of offsetting produced by an individual in a population per generation
What is the geometric and exponential population growth?
- population growing at maximum rate produce J-shaped curve
- due to density dependance / some population grow geometrically, other exponentially
What is geometric growth?
- growth by population with pulsed reproduction can be model as geometric population growth (non-overlapping generation)
- successive generations differ in size by constant ratio
- applies to organisms such as annual plants and insects with single generation per year
How can growth be modelled when the generations do not overlap?
- growth can be modelled geometrically
- Nt = NoAlphat
What is exponential growth?
- populations with overlapping generations have continuous growth: can be modelled as exponential population growth
- represents populations growth as continuous process
- intrinsic rate of increase : per capita rate of increase under ideal environmental conditions
What is the formula for exponential growth?
rate of population change = change in number / change in time
For an exponential growth population, size and time can be calculated:
Describe exponential growth in nature
- pollen accumulation rate
- whooping cranes: hunting and habitat destruction reduced to a single natural population - protection and intensive management of the population has left to dramatic recovery
What are the two assumptions made about exponential growth?
- essential resources are limited
2 environment is constant
- under these assumptions birth and death rates are constant
- the intrinsic rate of increased r is fully realized
Why don’t the assumptions of exponential growth hold in the real world?
- resources are limited and environments are variable
- as population densities increase, demand for resources also increase
- if the rate of consumption exceeds the rate at which resources are supplied, then resources will shrink (decreases fecundicity rate and increases mortality rate)
Which factors change population size?
- birth rates, death rates, immigration, emigration
Which factors cause speciation?
- ecological and physical processes combined with natural selection and genetic drift produce new species
Why are K selected species often near their carrying capacity in the environment?
- reproduce based on resources available: a lot = reproduce enough to use those resources, not enough: stop reproduction so there is enough
= always near carrying capacity
What kind of growth does an annual plant introduced to a new environment exhibit?
- geometric growth
Why is competition essential to natural systems?
Natural selection, niche specialization, population limitations, evolution
What kind of competition was present in the white pine tree experiments?
- interspecific and infraspecific: demonstrated by young white pines growing better and the vegetation in the experimental plots growing better
- there was competition between trees and between trees and vegetation
What is the difference between exploration and interference?
- exploitation: Organisms compete indirectly through consumption of a limited resource ie: plants compete
Interference: individuals interact directly though physical force or intimation
- ritualized with aggressive behaviour associated with territoriality
- strong survive and take best territory and the weaker ones perish or take suboptimal territory
What are the warning signs of a sparrows defence of territory?
- matches intruders song
- flaps wings : ‘flipping off’
- if nothing else works attack!
Which sparrows are more likely to have their territory encroached on by floaters?
- juveniles and older males
What was grimes theory on plant competition and productivity?
- as productivity increases competition increases
What was Newman and Tilmans theory ?
argued competition is generally constant, however competition for light increases and competition for soil resources decrease as productivity increases
What is the relationship between biomass and plant density?
- competition plays a role
- more abundance.= self thinning, individual biomass decreases as overall biomass increases
- less abundance: fewer plants, larger biomass
What are the 4 kinds of competition?
- interspecific, infraspecific, interference, exploitative
What is the base equation for infraspecific and interspecific competition modelling?
- the logistic model equation (dn/dt = rN (1-N/K)
- modified for both
What is the difference between the infraspecific mathematical model and the interspecific model?
- infraspecific modifies the logistic equation to reflect only infraspecific competition and its impacts
- interspecific takes into account the effect of species 2 on species 1 (and vice versa)
How can you tell predict whether coexistence can occur?
- using the single species logistic equation and the multiple species equation: whichever value is lower is favoured
- if interspecific is lower then coexistence can occur!
What affects a populations growth size in a single species logistic equation?
- affected by the population size relative to its carrying capacity
- K-N quantifies how far below carrying capacity the population is
What decreases carrying capacity in the interspecific model ?
- population size of species 1 and the competitive effect of species 2 on 1 time the population size
When is coexistence possible according to isocline lines?
- when the lines cross
Which conditions permit stable coexistence?
K1 < K2 / effect of species 1on 2
and
K2 < K1 / effect of species 2 on 1
- to hold, the competitive effect of each species on the other must be small
- stable coexistence occurs when each species is more limited by its own carrying capacity compared to interspecific competition
What was the results of the experiment with paramecia on competition?
- grown alone carrying capacity determine by infraspecific competition
- grown alone Aurelia and cautetum survives at low and high resource availability
- grown together cautetum dies off
How many graphs of isoclines are there? Know them and describe them
4 graphs
What is the competitive exclusion principle?
- two species with identical niches cannot coexist indefinitely
How can coexistence occur despite the competitive exclusion principle?
- mechanisms:
- spatial heterogeneity in strength of competition
- variation in competitive ability within species
- competitive equivalence
Describe spatial heterogeneity’s impact on competition:
– competitive ability can be influenced by the abiotic environment
eg: flour beetles: one type survives better in dry conditions while the other survives better in moist conditions
- flour beetle completely excludes other in certain environments
What does interspecific competition do to niches?
- interspecific competition restricts the realized niches of both species to fewer environmental conditions
-
What can the heterogeneity in an environment do to competition?
- heterogeneity in environment can change competitive ability
What are some potential impacts on niches due to competition?
Short term: can impact species distributions by restricting realized niches
- long term: strong and pervasive competition may lead to evolutionary response by changing fundamental niches
Can a species be introduced without being invasive? what are the forms of reintroduction?
- yes: if they are reintroduced species or if they do not have the qualities of an invasive species
forms of introduction:
- natural range expansion: potentially climate change induced, new species appear as species move north
- human mediated introduction across natural barriers and vast distances: humans act as vectors
- eg; asian carp, honey bees (introduced species breed with native species also counts!)
What is the subject of Allison’s research?
-Codium fragile ssp. Tomentosoides
→ green algae
- tolerates a wide range of environmental conditions
- sexual and asexual reproduction (advantage over sexual)
- at a time one of the most invasive species in the world
How were the green algae introduced into the tide pools?
- originally form Japan and arrived from Europe via aquaculture (packed mussels with seaweed to keep moist and then discard into waters)
- asexual reproduction: buds off and grows
Why are the sodium algae a problem?
- used to have kelp forests that would switch between sea urchin barrens and kelp beds ( mass mortality)
- codium cannot grow if kelp is not there: sweeps surface of the rocks
- kelp no longer present: codium meadows grow
Describe the graph trends for the lowland, midland, and high pools
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