Populations

What is a population Population - is a set of individuals within a species living in the same place at the same time. Populations are described in terms of: Size, density and dispersion Density – the number of individuals per unit of area or volume Dispersion – describes the arrangement of its individuals in space Clumped, even or random

How does a population grow The change in the size or a population over a given period of time is called a ___________ growth rate Growth rates can be positive, negative or even zero Change in the population size Births Deaths

How fast can a population grow Population growth is directly related to how fast and how many offspring an organism can have. This is called reproductive potential. Some species have much higher reproductive potentials than others Bacteria can produce 19 million descendants in a few days A pair of whales would take hundreds of years to have that many descendants

Which organism has a higher reproductive potential?? Humans or Rabbits

Shape of the graph of number of dogs over time Exponential Growth Some populations undergo exponential growth – which means they grow faster and faster. Example A pair of dogs gives birth to 6 puppies, this is generation one what happens for generation 2? Each puppy has 6 puppies it goes to 36 dogs in generation 2 and so on… Shape of the graph of number of dogs over time

Q’n: under what conditions does exponential growth take place? Answer: Exponential growth takes place when the populations have plenty of food and space and have little or no completion or predators

What limits population growth? With your partner generate a list of what would limit population growth These things include : Resources – food water shelter Environmental changes Deaths Migration Natural selection

Carrying Capacity Carrying capacity – is the population size where birth rates and death rates are equal. Or the maximum population that its ecosystem can support. A population can increase beyond its carrying capacity but it cannot stay there for long because of limiting resources Example - rabbits in Australia (video)

http://animal. discovery http://animal.discovery.com/tv-shows/weird-true-and-freaky/videos/outback-rabbit-invasion.htm

What carrying capacity looks like

Your task – on the back of the half sheet Create a carrying capacity comic strip Must have at least five different scenes (boxes). Must include the vocabulary terms: Carrying capacity Resources (food, water shelter etc) Population Be creative and use color.