population ecology Flashcards
monarch butterfly longest migration (lifespan)
goes from canada to mexico, lives 6-8 months
where do the monarch butterflies hibernate?
oyamel fir forests
how long do the 3 generations of monarch butterflies live that don’t migrate?
2-6 weeks
3 ways absolute density is measured?
1) total counts
- photographic
2) quadrat sampling
3) mark, release, recapture
peterson lincoln calculation for determining population size
M = number of marked individuals in pop N = population size m = number of marked individuals that you pulled out when resampled n = number of individuals in resample
M/N=m/n
assumptions for reliable population estimates in mark-recapture studies
1) population is constant
- no immigration, no emmigration, no births, no deaths
- this is only really possible in short time frame
2) marked individuals have the same chance of getting caught as unmarked individuals
3) marked individual`s do not incur greater mortality
- stress related mortality
- mark-associated mortality
4) marked individuals don’t lose their marks
5) equal dispersal
methods for calculating size
- hair collection
- camera trapping
- drones
mark and recapture using genetic markers
- identify individual genotypes
- eg. hair, feathers, faeces, scales
- identify individual genotypes
- resample at future time
- estimate population size
what are the 4 primary population parameters
births, death, immigration, emigration
how can u estimate numbers of individuals in the future??
Nt+1 = Nt + B + I -D - E
what is K
carrying capacity
-total # of individuals that can be sustained in a habitat in the long term
How is K estimated
the average population numbers of the species observed over multiple years
what happens when there is exponential growth of population past K
if it goes past K it cannot continue much longer
calculation for determining K (manipulate to find K)
dN/dt = rN ((1-N)/K))
what happens when the population reaches K
should plateau
what is environmental resistance
sum of environmental factors (drought, mineral deficiencies, competition) restricts the biotic potential (ability of population to increase) stabilizes at K…
–> GOOD
what is biotic potential
the ability of a population of living species to increase under ideal environmental conditions. i.e sufficient food supply, no predators, lack of disease
name the variations in logistic growth graphs… (carrying capacity)
- Ideal logistic (smooth response)
- Damped oscillations
- Stable limit cycle
- Chaotic
Damped oscillations
oscillates around carrying capacity but as the time goes on oscillations lessen
Stable limit cycle
oscillates around carrying capacity.. constant oscillations
Chaotic
overshoots carrying capacity a lot and then huge downfall… probably when reproduction is high strong density regulating population size.
K in human species
we are growing exponentially
-where is our carrying capacity when will we downfall?
what is the K of the habitat influenced by?
- the most limiting resource
What are intrinsic factors limiting K
population numbers (birth rate, death rate, foraging activity, over-grazing, habitat degradation, disease transmission)
What are ways of population regulation
–> before population exceed K
- regulation by increased mortality
- regulation by decreased births
- regulation by decreased births and increased mortality
where is the K on these graphs?
where the birth and death lines intersect
what are ways of population regulation when populations exceed K? DENSITY DEPENDENT
- Intraspecific Competition
- Delayed breeding or reduced offspring production
- Increase territoriality
- Dispersal
- Parasites/disease
- Predators
intraspecific competition
occurs when resources (food, space, mates) in limited supply
a) interference competition: individuals directly compete with eachother for resources
b) differential ability to secure resources (water, nutrients, sunlight)
law of constant final yield
biomass increases, levels off, and then remains constant as density increases further
delayed breeding or reduced offspring production
regression
- as population increases, calf recruitment decreases
- as number of breeding pairs increase, average clutch size decreases
general mechanisms for birth rate reduction and population regulation (7 steps?? ISH?)
- increased aggressive/submissive encounters
- increased stress among sub-dominant individuals
- increased stress leads to hyper activation of the HPA, alters secretion of growth and sex hormones
- leads to suppression in body growth, suppression in reproduction, suppression in immune system
- in pregnant females this leads to inflammation of kidneys, enlarged adrenal glands, uterine mortality, decreased lactation
- young born to stressed mothers: low body weight, poor survival, delayed puberty, low reproductive rate
- odour of urine from females delays puberty in juveniles during periods of high population density
Increased territoriality
- territorial defence by dominant individuals leads to reduced access to resources by sub-dominant individuals
- reduced reproduction in non-territorial individuals
Dispersal
members of a population disperse to regulate the number of individuals
- if you put voles and predators (or just voles) in an enclosed cage (no dispersal) bad for carrying capacity
Parasites/disease
- gastrointestinal nematodes regulate population of reindeer
how do parasite density vary with host
- trees have most (95)
- fish have least (1)
Predators
- major source of mortality
- more prey (allows predators to expand, more predation)
overall predator/prey graphs
- predators will spend more time where prey is abundant
- positive slope…. if there are more mealworms in an area…. graph will be exponential
- graph will plateau if the prey runs out
Who has the most density dependent parasites and disease
Insects
Who has the most predators
- Insects
- Small mammals/birds
- large mammals
who has the most mortality from limited food
- large mammals
- insects
- small mammals/birds
who has the most mortality from limited space or overcrowding
- small mammals and birds
- insects
- large mammals
DENSITY INDEPENDENT POPULATION REGULATION
- independent of N
- reduces the carrying capacity
predator/prey rises and falls (hair and lynx)
-predating is key limiting factor of fluctuations
- predators kill the prey directly
- this indirectly causes stress in the prey
- stress reduces the reproductive rates of prey… transmitted to their offspring who also suffer reduced reproductive rates
- time lag in the response of hair reproductive rate to density (causes this rise and falls)
IS THIS RIGHT?
What else could this predation/prey rise and fall be because of
SUNSPOTS
- sunspots = reduced heat but greater solar output
- also lines up with these rises and falls
how long was each rise and fall
10 years (peak to peak)
another reason for this predation rise/fall
- 9.3 year nodal half-cycle of the moon
- night without darkness
- moon rises before sunset and sets before sun rises
don’t understand - could affect stress, temp, cloudiness, ultrab radiation, food plant quality… causes prey to decrease
age-specific cohort analysis
- group of individuals in the same age class.. follow specific cohort from life to death
- useful in short lived species
50 eggs, 8 eggs lost. What is mortality and survivorship percentages.
Mortality: 16%
Survivorship: 18%
time-specific life table
- age structure at a single point in time
- long-lived animals
- requires age distribution of a population
What doe potential rapid population growth look like
pyramid. ..
- lots of young ppl
- fair amount of reproductive ppl
- and small amount of old ppl
Population stable or decreasing
fair amount of reproductive and old ppl. Not much young ppl
why to males often have a lower ex?
- trophy hunting
- things that influence population structure
age specific fecundity rate
average number of offspring produced per human female for each age group
total fecundity rate
average number of offspring produced per female over her lifetime
what do you need to know to determine the population after reproduction if you have the TFR
you need to know the ratio of males to females
If Ro = 1.87 for a population of 400, what will the population grow per generation
will grow 748 females per generation
how many daughters are produced in 4 years when Ro = 1.5 and there are 100 females in the habitat that breed at 1 y then die after they breed
507
semelparous
species breeds once then dies
what has a huge affect in population size
Ro….graph between an Ro of 1.2 and 1.05… 1.2 grows exponentially, Ro of 1.05 looks linear, not steep slope
geometric growth
if the population grows without constraints
iteroparous
species breeds more tan once
what kind of species have pulsed reproduction
semelparous species
what kind of species have nonpulsed reproduction
iteroparous species
