- Absolute population size
- Actual abundance. Can be estimated with area-based counts, mark-recapture methods, and niche modeling.
- Abundance
- The number of individuals in a species that are found in a given area.
- Age Structure
- Proportions of the population in each age class.
- Allee Effects
- When population growth rate (r or lambda) decreases as the population density decreases, perhaps due to difficulty finding mates at low population densities.
- Allocation
- Relative amounts of energy or resources that an organism devotes to different tasks
- Allometry
- Differential growth of body parts that results in a change in shape or proportion with size.
- Alternation of generations
- Going from sporophyte to gametophyte and back again.
- Anisogamy
- Different types of gametes that are different sizes.
- Assumptions: Hardy-Weinberg Equilibrium
- Emphasis on Gene Frequencies, Not Individuals
• Random mating
• Infinite population size
• No mutation
• No natural selection
• No gene flow
Allele & genotype frequencies do not vary once
population is at equilibrium - Birth, death, immigration, and emigration equation
- Nt+1 = Nt+B-D+I-E
- Bottom-up Control
- Occurs when the abundance of a population is limited by nutrient supply or by the availability of food organisms.
- C
- Number caught the second time. Ex) A population was marked (M). They went out again and caught 15 more (C), but only 4 were recaptured (R)
- Cohort life table
- The fate of a group of individuals born during the same time period (a cohort) is followed from birth to death.
- Competitive plants
- Under conditions of low stress and disturbance: superior in their ability to acquire light, minerals, water, and space should have a selective advantage.
- Complex life cycle
- Life cycle in which there are at least two distinct stages that differ in their habitat, physiology, or morphology.
- Cooperative breeding
- Younger birds postpone breeding and instead help their parents raise offspring by performing such activities as nest building, feeding the young, defending the territory, and mobbing predators.
- Damped oscillations
- Deviations from the carrying capacity gradually get smaller over time.
- Delayed Density Dependence
- Delays in the effect that density has on population size. Can contribute to population fluctuations.
- demes
- small subpopulations with high probability of
inter-breeding & random mating – panmixia (Hardy-
Weinberg Equilibrium likely) - Demographic Stochasticity
- Chance survival and reproduction of individuals. Can result in outcomes that differ from what we expect.
- Diapause
- State of suspended animation or dormancy in which an organism can survive unfavorable conditions.
- Direct development
- Go directly from fertilized egg to juvenile without passing through a larval stage
- Dispersal limitation
- Prevent species from reaching areas of suitable habitat.
- Distribution
- The geographic area where individuals in a species are present.
- Disturbance
- An event that kills or damages some individuals and thereby creates opportunities for other individuals to grow and reproduce.
- dN/dt
- Represents the rate of change in population size at each instant in time.
- e
- Constant: 2.718. Use e^x on calculators.
- Ecological Niche
- The physical and biological conditions that the species needs to grow, survive, and reproduce.
- Endosperm
- Nutrient-rich material that sustains the developing embryo and often the young seedling.
- Environmental Stochasticity
- Refers to erratic or unpredictable changes in the environment.
- Equation to estimate total number in a population
- N=(M*C)/R
- Exponential Growth
- Population of a species with continuous reproduction changes in size by a constant proportion at each instant in time.
- Exponential Growth Equations
- dn/Dt=rN
N(t)=N(0)ert - Extinction and colonization equation
- dp/dt=cp(c-p)-ep
- Fx
- Fecundity: Average number of offspring produced by a female while she is of age x.
- Gametophyte
- Produces haploid gametes that combine in fertilization to form zygotes that grow into sporophytes.
- Genet
- A grove of genetically identical aspen trees is actually a single individual. Members of a genet are often physiologically independent of one another and may in fact compete for resources.
- Genetic Drift
- The process by which chance events influence which alleles are passed onto the next generation.
- Geographic range
- Entire geographic region over which that species is found.
- Geometric growth
- Population of a species changes in size by a constant proportion from one discrete time period to the next. (hourly, daily, yearly) Forms a J shaped graph.
- Grime's Triangular Model
- Plant success is limited by stress and disturbance. Categorized plant life histories within a triangle whose axes measure the degree of competition, disturbance, and stress.
- Habitat fragmentation
- Cause a species to have a metapopulation structure where it did not have one before.
- Inbreeding
- Mating between related individuals.
- Isogamy
- Equal-sized gametes
- Iteroparous Species
- Capable of reproducing multiple times.
- k-selection
- Slower rates of increase in populations that are at or approaching L, carrying capacity or population size limit for the environment.
- Lambda=e^r or r=ln*lambda
- Compare results of discrete and continuous time growth models.
- Life history
- Record of events and landmarks relating to its growth, development, reproduction, and survival.
- Life History Strategy
- Overall pattern in the timing and nature of life history events averaged across all the individuals in the species.
- Life Table
- Summary of how survival and reproductive rates vary with the age of the organisms.
- Lx
- Proportion of Survivorship: individuals that survive from birth to age x.
Lx=Nx/No - M
- Marked individuals from total population.
- Mark-recapture
- Methods often used to estimate the abundance of mobile organisms.
- Measuring Genetic Variation
- Different measures of genetic variation depend on
level of genetic analysis: phenotypic differences
(polygenic), proteins (amino acids differ), DNA
(nucleotide differences) - Metapopulation dynamics
- Study of conditions in which extinction and establishment are in balance.
- Morphs
- Produces discrete types with few or no intermediates. Polyphenism. (metamorphosis)
- N
- Current population size.
- Natural catastrophes
- Eliminate or reduce size of populations that otherwise would seem large enough to be at little risk.
- Natural Selection
- acts at the level of the individual
(survival and reproduction through differential
reproductive success of phenotypic variants), but
causes changes (evolution) at the level of the
population - Niche Model
- Predictive tool that models the environmental conditions occupied by a species based on the conditions at localities it is known to occupy.
- No*So(Surviving individuals at age x) *Fx(Fecundity at age x)
- The number of newborns those survivors will produce in the next time period.
- No*So=
- Number of individuals that will survive to the next time period
- Nt+1=Lambda*Nt or Nt+Lambda^t*No
- Geometric growth
- Nx
- Number of individuals alive at age x.
- Ontogenetic Niche
- A size or state specific ecological role. Coined by Wener and Gilliam.
- p
- Proportion of habitat patches that are occupied at time t.
- Phenotypic Plasticity
- A single genotype may produce different phenotypes for a particular trait under different environmental conditions.
- Polyphenism
- A single genotype produces multiple, discrete phenotypes. (Morphs)
- Population
- All individuals of the same species
occupying the same space at the same time - Population Cycles
- Alternating periods of high and low abundance occur nearly constant intervals of time.
- Population Fluctuations
- The size rises and falls over time. Fluctuations can occur as increases or decreases in abundance from an overall mean value.
- Population limitation
- Any ecological force that affects abundance (density-independent as well as density-dependent)
- Population regulation
- Density-dependent ecological forces that keep population abundances within upper and lower limits.
- Quadrat
- Sampling area (or volume) of any size or shape, such as a 1 m^2 circular plot to count small plants.
- r
- A constant rate. Provides a measure of how rapidly a population can grow. Also known as exponential population growth rate or intrinsic rate of increase.
- r-selection
- Refers to selection for high population growth rates. Occurs in environments where population density is low.
- Ramets
- Actually or potentially independent members of a genet.
- Randomly Mating Population Equation
- p2 + 2pq + q2 = 1
– p2 represents A1A1
– 2pq represents A1A2
– q2 represents A2A2 - Relaxing Assumptions of
Hardy-Weinberg Equilibrium - • Small population -- chance events & genetic drift,
inbreeding more likely
• Natural selection -- bias in genotype/ phenotype that
reproduces
• Mutation -- introducing significant new alleles?
• Non-random mating -- sexual selection & mate
choice
• Gene flow -- new alleles or altered genotype
frequencies from new individuals - Ruderals
- Best in high disturbance and low stress. Short life spans, rapid growth rates, heavy investment in seed production, and seeds that can survive in the ground for long periods until conditions are right for rapid germination and growth.
- Semelparous Species
- Reproduce only once in a lifetime.
- Senescence
- A decline in the fitness of an organism with age as result of physiological deterioration.
- Sequential hermaphroditism
- Changes sex during the course of life cycle.
- Sporophyte
- produces haploid spores that disperse and grow into gametophytes.
- Stable age distribution
- When the age structure of a population does not change from one year to the next.
- Stable limit cycle
- The population exhibits a cycle in which it fluctuates indefinitely about the carrying capacity (K)
