Test 1 Flashcards
Ecology
The scientific study of the relationships between organisms and the environment
Population
A group of (Interbreeding) individuals found in the same space or area at the same time
Demography
The study of the age structure and growth rate of populations
Density
The number of individuals in relation to the space or volume in which they occur
Distribution
The geographic and ecological range of a population
Dispersion
The spacing of individuals with respect to one another
b
Probability of an individual having offspring during some time interval (Per capita Birth Rate)
d
Probability of individual dying during some time interval (Per Capita Death rate)
bN
The population birth rate during some time interval
dN
The population death rate during some time interval
rN
The population growth rate
Immigration
Number of individuals that join the population per unit of time
Emigration
Number of individuals that leave the population per unit of time
Exponential growth
The growth rate when per capita rate
(r) remains constant
Open population
Any population with immigration and emigration
Closed population
Any population with no immigration or emigration
John Graunt
- Population demography
- London records of birth and death
- Doubling time
The 2 laws of population growth
- Populations have the potential to rapidly grow
- They usually don’t. Population growth has to be regulated so that there is only a brief period where there is rapid growth
Nt=NOert
Population Size
DN/Dt = RN
Population growth rate
DN/Dt= bN-dN = DN/Dt = (b-d)N
(b-d) = R (Intrinsic Growth Rate)
1/N DN/Dt =rn
Per capital or individual rate
Rate of population change per individual (Per capita) is affect by what 4 things ?
- Birth rate
- Death rate
- Immigration
- Emigration
r= (births - deaths) + (immigration - emigration)
r=b-d when immigration is equal to emigration
Ronald Ross
Used linked equations to study malaria
-dH/dt
-dM/dt
Alexander Von Humboldt
- Early catalogers of vegetation
Logistic Growth
Growth that occurs when a population’s growth rate (not the population itself) decreases towards zero as the population size approaches at maximum level
Continuous Growth
Population growth that occurs when individuals are constantly reproducing and dying
Discrete Growth
Population growth that occurs when individuals are constrained to specific seasons or times
R0
Multiplicative or per-generation growth rate, generally used for discrete growth.
Density Independent growth
Growth when per capita growth rate is uncorrelated with population density
Density Dependent growth
Growth when the per-capita growth rate is correlated with population density
Genetic Bottleneck
Occurs when a population is greatly reduced in size, limiting the genetic diversity of the species and resulting in a potentially reduced growth rate
Malthus
- Studied population growth in England and the United States
- As population density increases, the quality of conditions decreases because of competition for resources
- Drew a connection between population growth, resources, and behavior
Case study about wolfs
- Genetic Bottleneck
-Population Growth
- Wolves were thought to be extinct in Northern Europe. An unknown pack was discovered and the population started to quickly increase.
- Russian wolf came in and restored the genetic diversity
Heinz vin Foerster
- Determined that the population growth rate was greater than exponential - R is increasing.
- Predicted that the population size would go to infinity 11-13-2026
R and K are affected by ?
Temperature
Nt+1 =NtxR0
Multiplicative Growth Rate
R0
- Growth rate
- Multiplicative growth rate
- Used for populations with discrete growth patterns
Discrete exponential population growth
Nt=N0xR0t
Continuous exponential growth rate
Nt= Noert or dN/dt=rN
Logistic equation
dN/dt =rN x (k-n)k
Growth Slows down when ?
Population density gets higher (Density-dependent)
K (Carrying capacity)
the number of living organisms that a region can support in
a stable manor
competition
a reduction in resource acquisition rate due to the action or presence
of another individual that seeks to acquire the same resources (intra and inter)
alee effects
pattern of a lower than expected per-individual success at low
densities
minimum viable population (MVP) size
an estimate of the number of individuals required
for a high probability of survival of a population over a given period of time
environmental stochasticity
random environmental fluctuations that affect birth
and/or death rates, in turn causing variation in population growth rates
time lags
when population growth rates are determined not by the density at the
present time, but by the density at some other time, often leading to oscillations
demographic stochasticity
variation in population growth rates arising from
differences among individuals in survival and reproduction
Chaos
erratic variation in population size due to the effects of time lags on
population growth, generally at high population growth rates.
Intraspecific
Within species
Interspecific
Between species
Competition can be ?
Intraspecific or Interspecific
Key traits of density-dependent populations
There is a relationship between per capita rate and density. (Usually Negative). Demonstrates competition
Benkwitt Case Study
- Lionfish were grown at different densities with artificial coral
- Density independence
MVP Bighorn Sheep Case Study
- Smallest population that can be predicted to have some probability chance of continuing for some years
Drosophila Graph Case Study
- Genetic bottleneck and environment can have an effect on competition and carrying capacity.
Density-dependent growth generally involves what?
Intraspecific Competition
What factors affect logistic growth ?
- Carrying capacity is not constant
- Birth and Death rates don’t change in a linear way
- Time lags between when the population grows to when density effects are experienced
- Population is not a stable age distribution. Ages are disproportionate
Density Vagueness
-There is some average population level around which a regulated population fluctuates
-The concept that density dependence is strongest away from the carrying capacity or equilibrium but very weak when near the carrying capacity or equilibrium
Age Specific Survival
The probability of surviving from one age class x to the next age class x+1
Age Specific Survivorship Ix
The probability of surviving from BIRTH to the BEGINNING of any given age class
Age specific reproduction Mx
The number of offspring per individual produced during age class x
Static life table
A life table created by following individuals of all ages or age classes during one single time interval
Cohort life table
A life table created by following a single even-aged group of individuals from birth until they all have all died
Eisenberg’s snails as classic test of density dependence
- First experimental tests of Density dependence and Independence.
- Experimented to see if snails in a pond exhibited density-dependent growth and to determine what factors might limit the snail population growth
Erickson Dinosaur Case study
The survivorship curve was a type 1 curve
Sensitivity Analyses
A method to evaluate the importance of different life-history transitions (lx and mx values) for determining population growth rate
Life History
The pattern of survival and reproduction events at different ages that are typical for a population
Emperor Geese
- Sensitivity Analysis
- Used bird breeds and saw declines. We can use life tables to estimate sensitive growth rate in different parts of life history
Sea Turtles, Sensitivity
- Inform management decisions about this endangered species
- Used loggerheads; found that because sex is determined by temperature, climate change may be causing female-skewed sex ratios
-Used little r instead of RO in their finding graphs
Sink Population
A local population that could not be maintained by itself and is maintained only through migration from other local populations
Immigration > Emigration
Source Population
A local population that has net dispersal away to other local populations
Emigration > Immigration
Rescue effect
When a local sink population avoids extinction because of the dispersal of individuals from other local populations
Regional Population
All the local populations that can potentially exchange individuals
Metapopulation
a group of spatially separated “local” populations of the same species which interact through dispersal
Local Population
A spatially separated population within a larger metapopulation
Hanski Butterfly Case Study
-Example of metapopulation
- Some populations may increase in size, while others decline. Some populations may go extinct, while others are being colonized
-Studied butterfly populations in dry meadows on islands near finland
Sparrows on 4 islands Case Study
- Demonstrating Sources and Sinks
- Graph demonstrated that some of the islands are more productive then others, acting as sources in good years. but in several years, all populations sink
Beetles in Netherlands Case Study
- Rescue Effects
- One beetle graph showed asynchronously, There were no extinctions over 21 years
- The other beetle graph showed synchronously, leading to local extinctions
Robert’s study of coral reef Case Study-
Special case of metapopulation, in which populations are arranged circularly
- Circular nature will link all populations so that the extinction of any one would lead to problems in all of them
- Island with large upstream sides should be more stable in the short term
Demographic Transition
The historical shift from high birth rates and high death rates in societies with minimal technology, education (especially of women) and economic development, to low birth rates and low death rates in societies with advanced technology, education and economic development, as well as the stages between these two scenarios
Replacement Rate
The number of offspring per individual or per female necessary to have a stable population (R0=1)
Zero population growth
R = 0
R0 =1
Green revolution
The large increase in global food production in the 1960s and 1970s caused by the use of modern methods and fertilizers in tropical agriculture
Paul Erlich Human Population case study
Population Bomb
- Populations will outstrip resources
-Population bomb can lead to problems however, increase in population might not be the only factor
Soma
The non-reproductive body tissue of an organism ; Tissue general related to survival and growth
Iteroparous
Species that have more than 1 reproductive bouts during their lifetime
Semelparous
“Big Bang” species that have one reproductive bouts during their lifetime
