chapter 5 Flashcards
Exponental growth model
Exponential growth
dN/dt=rN
Key:
N = population density
T = time
R = per capita growth rate
logistic growth model
dN/dt=rN(K-N)/K
N = population density
T = time
R = per capita growth rate
K = carrying capacity
Populations
A group of individuals of one species in an area
Unitary organisms
Those that proceed by a determinate pathway of development of a tightly canalized adult form.
Modular organisms
Those that grows by the repeated iteration of parts
Genet
Genetic individual - The organism developed from a zygote.
Module
An offshoot formed by vegetative growth in modular organisms that is actually or potentially independent physiologically
Abundance
The number of individuals in a population may be obtained by
Census: counting all individuals
Complete
Sample plots
Sampling: counting an known fraction to arrive at an estimate of total number
census examples
aerial photography
thermography
radar
Line transects/quadrat sampling: Involves observing (both sight and sound) individuals within an area of known or estimated size
Mark-recapture method
On a first visit to a population of unknown total size N, a representative sample is caught (r individuals) and given a harmless mark
These are released back into the population, where they remix with the unknown number of unmarked individuals
On a second visit, a further representative sample (n) is caught, and the number of marked individuals (m) is counted
r/N=m/n, therefore N=r*n/m
Life cycles
juvenile phase dominated by growth, onset of reproduction, end of reproduction/death or after that the postreproductive phase e.g. orcas then death
Iteroparous species
repeated breeding cycles / continuous breeding.
resources are set aside for survival to further breeding episodes
e.g.
humans
birds
crickets
Semelparous species
single reproductive episode after which they die.
All resources are devoted to breeding and none to survival
e.g
salmon
Cohort life table, Monitoring birth and death
data are collected by following a cohort throughout its life
Static life table, Monitoring birth and death
age-distribution data are collected from a cross-section of the population at one particular time
Spatial distribution of organisms
Perception of pattern depends on the spatial scale
The density perception of individual organisms determines behaviour
e.g.
Urban white-tail deer in Illinois often reach extreme population levels
Reproduction in these deer is density-dependent (low density -> high reproduction)
Intraspecific competition
Competition between individuals of the same species
Intraspecific competition reduces birth rate and increases mortality per individual
These effects are density-dependent
When birth rate = mortality, the population remains stable
Interspecific competition
Competition between individuals of different species
Carrying capacity (K), Intraspecific competition
The maximum population size that can be supported indefinitely by a given environment, at which intraspecific competition has reduced the per capita net rate of increase to zero.
Life history patterns
For most organisms, there is a trade-off between growth and reproduction
e.g. butterflies females put energy/resources into parenting and males into mating
Trade-off #1, life history patterns
Trade-off #1: An organism has to divide its energy between growth and reproduction
Trade-off #2, life history patterns
Trade-off #2: Fitness of offspring is generally inversely related to number of offspring
r-strategy, Life history patterns
resources assigned to reproduction
produce as much offspring as fast as possible
Most usefull in uncertain environment
Population far below carrying capacity
high mortality rate. Resources assigned to fast reproduction rate, without investing too much energy in developing a long-lived body that will in practice be killed long before the limit age
K-strategy, Life history patterns
invest resources in a long term development and long life
Most usefull in stable environment
Population near carrying capacity
Competition and resource limitation
low mortality rate. Resources assigned to a defense mechanism (shell) and efficient repair mechanisms that allow it to live long
Photoperiod
Length of the period of daylight each day
Unitary
Unitary organisms are organisms that proceed by a determinate pathway of development of a tightly canalized adult form, e.g. all arthropods and vertebrates. The contrast is with modular organisms in which growth occurs by the indeterminate iteration of repeated units of structure (modules).
Static
A static life table is a life table that is constructed from the age structure of a population at a single moment in time
Ephemeral
Ephemeral organisms are organisms with a short life cycle, especially plants whose seeds germinate, grow to produce new seeds, and then die all in a short period, often less than 8 weeks.
Ramet
An offshoot formed by vegetative growth in modular organisms that is actually or potentially physiologically independent.
Stoloniferous
Stoloniferous organisms are modular organisms in which colonies spread laterally and remain joined by “stolons.”
Annual
A species with a life cycle which takes approximately 12 months or rather less to complete, whose life cycle is therefore directly related to the annual cycle of weather, and whose generations are therefore discrete.
Survivorship curve
A survivorship curve is a plot of the declining size of a cohort, or presumed cohort, as the individuals die, usually with time on the horizontal axis and log₁₀ lₓ on the vertical axis (where lₓ is the proportion of the original cohort still alive)
Cohort
All individuals born within a particular period
Genet
The organism developed from a zygote. The term is used especially for modular organisms and members of a clone to define the genetic individual and to contrast with ‘ramet,’ the potentially physiologically independent part that may arise from the iterative process by which modular organisms grow
Fledgling
A young bird which has just developed its flight feathers and is about to leave the nest.
Perennial
An organism that lives for several years
Intraspecific
Intraspecific competition is competition between members of the same species.
Iteroparous
Iteroparous species are species that breed repeatedly, devoting some of their resources during a breeding period not to breeding itself, but to survival to further breeding episodes.
Modular
Modular organisms are organisms that grow by the repeated production of “modules” such as leaves, coral polyps, etc.
Dispersal
The spreading of individuals away from each other, e.g., of offspring from their parents and from regions of high density to regions of lower density.
