Population Dynamics Flashcards
Population size/abundance
Number of individuals
Population density
Number of individuals per unit area
Population distribution
Where individuals live in an environment
Clumped - fish
Uniform - penguins
Random - plants
Population composition
Characteristics of populations
Eg age structure, sex ratio, fertility rate
Information on composition helps develop strategies to protest endangered species and their ecosystems
Population size equation
No. Individuals in quadrats
————————————— X no. Quadrats
No. Selected quadrats
No. Marked in population x sample population
———————————————————————
No. Marked in sample
Population density equation
Population size
———————— x no. Quadrats
Total area
Factors affecting population size and density
Density-dependent factors- biotic factors that have an impact on increasing population densities, the bigger the population the bigger the impact ( disease, parasites
Density-independent factors- abiotic factors that affect populations regardless of their size ( a flood wiping out all animals )
Factors affecting population distribution and abundance
Characteristics of environment - availability of food and water, sunlight availability, soil type, temperature
Characteristics of organisms - ways organisms find food, methods of reproduction
Relationships between organisms - prey- predator relationship, competition
Exponential growth
- number of individuals increases at a constant and continuous acceleration
- occurs when a species is introduces into a new unoccupied habitat and the resources are unlimited so birth rates exceed death rates
Logistic growth
- Rate of population growth slows as the population size reaches its carrying capacity
Population growth equation
(B+I) - (D+E)
Carrying capacity
The maximum number of individuals of a population an environment can sustain with its amount of available resources
R-selected species
- introduced in unstable environment
- population rapidly increases due to available resources
- species reaches maximum reproductive potential
- population quickly decreases as resources diminish
Multiple offspring, bad parental care, small life cycle,
Eg. toads
K-selected species
- in stable environment
- have a steady population growth until they are close to their carrying capacity
- sometimes will abandon one young when resources are low
Fewer offspring, good parental care, live longer
Eg. Elephant
Triangle pyramid
- large number of children
- fast growing population as children reach reproductive age
