Population ecology
Download
1 / 13

Population ecology - PowerPoint PPT Presentation


  • 326 Views
  • Updated On :

Population ecology Sea otters are smallest marine mammals Occur in coastal habitats in northern Pacific Ocean Where have all the sea otter gone? Feed on variety of fish and marine invertebrates Gregarious; live in ‘rafts’ of about 100 individuals Where have all the sea otters gone?

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Population ecology' - Olivia


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Population ecology l.jpg
Population ecology

  • Sea otters are smallest marine mammals

  • Occur in coastal habitats in northern Pacific Ocean

  • Where have all the sea otter gone?

  • Feed on variety of fish and marine invertebrates

  • Gregarious; live in ‘rafts’ of about 100 individuals

Where have all the sea otters gone?


Population ecology2 l.jpg
Population ecology

  • In late1700s, Americans, English and Russians hunting sea otters for pelts

  • Where have all the sea otter gone?

  • By 1911, when International Fur Seal Treaty enacted, sea otters nearly extinct

  • Currently, about 150,000 sea otters

Where have all the sea otters gone?


Population ecology3 l.jpg
Population ecology

  • Current range of sea otters a portion of former range

  • Where have all the sea otter gone?

Where have all the sea otters gone?


Population ecology4 l.jpg
Population ecology

  • Since 1990s, sea otter population has declined sharply in Aleutian Islands

  • Where have all the sea otter gone?

  • In next several lectures we will explore why

Where have all the sea otters gone?


Population ecology5 l.jpg
Population ecology

  • Population = groups of individuals of a given species that occur together

  • Members of a single species make up a population

  • But a species may be represented by many populations

  • Major properties of populations:

  • Distribution

  • Dispersion

  • Demography

Where have all the sea otters gone?


Population ecology6 l.jpg

  • range expansion of cattle egret

Population ecology

  • Biotic and abiotic conditions determine where a population can survive and reproduce

  • Distribution = geographic range of a population

  • Population distributions can change over time

  • Most population distributions are declining because of habitat destruction by humans

  • Others expand or contract naturally

Where have all the sea otters gone?


Population ecology7 l.jpg

Population ecology

  • Metapopulations = network of populations that interact occasionally by exchanging individuals

  • Distribution

  • Occur when habitat is patchily distributed and separated by unsuitable habitat

  • Characterized by suitable habitat patches going extinct and getting recolonized over time

Where have all the sea otters gone?


Population ecology8 l.jpg

Source-sink metapopulation

3 separate populations

sink

Source

3 populations of simple metapopulation

(arrows =migration of individuals)

Population ecology

  • Metapopulations

  • Simple metapopulation contains populations in equally suitable habitats

  • Distribution

  • Differences in habitat suitability produces a source-sink metapopulation

  • Sources = populations in high-quality habitat; continually produce ‘surplus’ individuals that colonize new habitats

  • Sinks = populations in low-quality habitat; can not persist without continuous input from neighboring populations

Where have all the sea otters gone?


Population ecology9 l.jpg
Population ecology

  • Dispersion = spacing between individuals in a population

  • Random

  • Individuals do not interact with each other or non-uniform habitat conditions

  • Uniform

  • Usually result of competitive interactions or territories

  • Clumped

  • Individuals cluster in response to uneven resources

Where have all the sea otters gone?


Population ecology10 l.jpg
Population ecology

  • Population size = number of individuals

  • Demography = statistical study of populations

  • Population growth = size of population over time

  • Population structure = proportion of individuals in different age classes

  • Population growth strongly influenced by age structure

  • Populations with large number of young individuals grow rapidly because an increasing proportion of individuals are reproductive

  • Populations with equal numbers of individuals in different age classes usually maintain same population size

Where have all the sea otters gone?


Population ecology11 l.jpg
Population ecology

  • Population pyramids show age structure

  • Demography

Where have all the sea otters gone?


Population ecology12 l.jpg
Population ecology

  • Life tables describe mortality and fecundity of different age classes

  • Demography

  • Mortality = number of individuals that die in a given period

  • Survivorship (lx) = proportion of individuals that survive from birth to age x

  • Mortality (Mx) = proportion of individuals that die between age x and age x+1

  • Fecundity = number of offspring produced in a given period

  • Age-specific fecundity (mx) = average number of offspring produced by females at age x

Where have all the sea otters gone?


Population ecology13 l.jpg
Population ecology

  • Example life table (Poa annua)

  • Demography

Where have all the sea otters gone?