Population Ecology Flashcards
Distribution
The way in which something is spread out over an area
Dynamics
A force that stimulates a change within a system
-branch of mechanics concerned with the motion of bodies under the action of forces
Population dynamics
Changes in population size, density, structure; patterns and causes
Distribution limits are also
Niches
Fundamental population ecology equation
N(t+1)=N(t)+B-S+I-E
Population
Group of organism of the same species that occupy a particular place at a particular time
Demes
Possible subdivision of pop; groups of interbreeding organisms, random mating
Delimitation
Clear
Arbitrary
Processes that affect population density
Births: Natality
Death: mortality
Emigration
Immigration
N or population I linked to ____ and _____
Distribution
Abundance
Life tables
-tool borrowed from actuarial science
-monitoring birth and death
-information to solve our fundamental equation
Styles of life tables information gathering
Cohort: identifier individuals born at the same time and keep records
Static: record age at death of individuals and calculate difference in proportion of individuals in each age class. Assumes differences from mortality
Fundamental niche
The range of abiotic conditions under which species can persist
Realized niche
The range of abiotic and biotic conditions under which a species persists
Ecological niche modeling
The process of determining the suitable habitat conditions for a species
Ecological envelope
The range of ecological conditions that are predicted to be suitable for a species
-prediction of where species could live
Geographic range
A measure of the total area covered by a population
Endemic species
Cosmopolitan species
Species that live in a single, often isolated location
Species with very large geographic ranges that can span several continents
Dispersion
Dispersion of a population describes the spacing of individuals with respect to one another without the geographic range of a population
Can be clustered, evenly spaced or random
Dispersal
The movement of individuals from one area to another
Not migration, they don’t typically return in dispersal
Area and volume based surveys
Surgery’s the define the boundaries of an area or a volume and then count all the individuals in the space
Line transect survey
Surgery’s that count the number of individuals observed as one moves along a line
Mark recapture surveys
A method of population estimation in which researchers capture and mark a subset of a population from an area, return it to the area, and then capture a second sample of the population after some time has passed
Lifetime dispersal distance
The average distance an individual moves from where it was hatched or born to where it reproduces
Dispersal limitation
A substantial barrier that prevents dispersal between suitable habitats
-oceans
-desert
Habitat corridors
A strip of favourable habitat located between two large patches of habitat that facilitates dispersal
Ideal free distribution
When individuals distribute themselves along different habitats in a way that allows them to have the same per capita benefit
Growth rate
In a population, the number of new individuals that are produced in a given amount of time minus the number of individuals that die
Intrinsic growth rate 📈
The highest possible per capita growth rate for a population
Denoted as r
Exponential growth model
A model of population growth in which the population increases continuously at an exponential rate
Applies to those that reproduce through the year
Geometric growth model
A model of population growth that compares population sizes at regular time intervals
Used for species with discrete breeding seasons
Doubling time
The time required for a population to double in size
Can populations growth indefinitely
No, limited by competition, predation and pathogens eventually
Density- independent
Factors that limit population size regardless of the populations density
-natural disaster
-extreme temp
Density-dependent factors and types
Factors that affect population size in relation to the populations density
Negative density dependence: when the rate of population growth decreases as population density increases.
-limited supply of resources (food, habitat)
Positive density dependence: when the rate of population growth increases as population density increases.
-more animals means less inbreeding
-small pop have less males and females
-small pop have higher predation risk
Self thinning curve
A graphical relationship that shows how decreases in population density over time lead to increases in the mass of each individual in the population
Carrying capacity
Maximum population size that can be supported by the environment
Denoted as k
Logistic growth model
Model showing the slowing growth of populations at high densities
Age structure
In a population, the proportion of individuals that occurs in different age classes
Life tables
Tables that contain class-specific survival and fecundity data
-typically based on females and fecundity is defined as the number of female offspring per reproductive female.
Stable age distribution
When the age structure of a population does not change over time
Net reproductive rate for
The total number of female offspring that we expect and average female to produce over the course of her life
If the value is more than 1 then population will grow
Generation time
The average time between the birth of an individual and the birth of its offspring
Cohort life table
A life table that follows a group of individuals born at the same time from birth to the death of the last individual
Static life table
A life table that quantifies the survival and fecundity of all individuals in a population during a single time interval
Important when we can’t outlive organisms
Which directions do you read static and cohort life tables
Static-vertically
Cohort-diagonally up
So cohort and static tables match?
Not necessarily. Show same general pattern but not same units. In static you mix cohorts.
Can’t see previous generations with static.
Age specific survival equation
Sx=n(x+1)/nx
Lx equation
Nx/n0
Calculating R0
Net reproductive rate
R0=sum of lx(mx)
If R0 is more than 1, the population is growing
Survivorship curves
Type 1: steady and then later drop (k selection) -Rotifers, vertebrates
Type 2: steady drop (no particular age of death) - birds
Type 3: initial drop (R selection)
Discrete breeding
Continuous breeding
Annuals
Use integers
No set time to breed
Use any real number
K=
If N is same as K then….
Carrying capacity
Population slope will hault
Inflection point
The point of fastest growth after which growth begins to slow
Survivorship curve types
- Population with low mortality early in life and high mortality late in life. Ex: humans, elephants, whales
- Population experiences constant mortality throughout its life span. Ex: squirrels, corals
- Pop with high mortality early in life and high survival late in life. Ex: insects, plants
Abundance of a population
The total number of individuals that exist within a defined area
Density of a population
The number of individuals in a unit of area of volume
Census
Survey
Counting every individual in a population
Count a subset of the population
Populations with high abundance also have a large ________
Geographical range
The density of a population is ____ correlated to the body mass of an individual
Negatively
Mark recapture equation
N=MxC/R
N is estimated population
M is marked
C is collected after marking
R is recaptured
