Species on earth
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What are the reasons why many species remain undiscovered
• small species • endemic species -haven’t investigated everywhere
What 4 factors is population controlled by
• births • deaths • immigration • emigration
Equation to determine population size
past pop + births + immigration - deaths - emigration = current pop
What factors affect birth rate
• age • number of females • number of offspring • predation • life cycle
What factors affect mortality rate
• food availability • presence of predators • presence of disease • water availability
Define carrying capacity
• a species’ average population size in a particular habitat, without it becoming damaging
Examples of density dependent factors
• disease • competition • food supply • parasitism
Examples of density independent factors
• fires • earthquakes • seasons • flooding • temperature change
What is the sigmoidal population growth definition
• growth pattern in which an organisms population density rises slowly originally ina fresh setting
What causes a population to increase
• increase prey = increase predators • decrease predators = increase prey
What causes a population to decrease
• decrease prey = decrease predators • decrease predators = increase prey
Examples of artificial population control
• culling of deer • removal of invasive species
What is meant by an r - selected species
• species that give birth to many young and have low parental involvement
What is meant by a k - selected species
• species that give birth to less and have high parental involvement
How do r and k populations differ in terms of their ability to recover after a drop in population
• r selected would recover quickly • k selected could take years to show any kind of recovery
Which population is easier to support, k or r
• r selected are quick and cheap as they don’t require a lot • k selected are expensive and extensive