slide1
Download
Skip this Video
Download Presentation
horse

Loading in 2 Seconds...

play fullscreen
1 / 19

horse - PowerPoint PPT Presentation


  • 180 Views
  • Uploaded on

horse. donkey. Speciation. mule. Speciation. A. B. baby. Defined : evolution of new species from an existing species Species : group of organisms that can interbreed and produce fertile offspring Factors that lead to evolution Natural Selection Gene flow Mutations Sexual selection

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 ' horse' - abram


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
slide1

horse

donkey

Speciation

mule

speciation
Speciation

A

B

baby

  • Defined: evolution of new species from an existing species
  • Species: group of organisms that can interbreed and produce fertile offspring
  • Factors that lead to evolution
    • Natural Selection
    • Gene flow
    • Mutations
    • Sexual selection
    • Genetic drift

A

B

baby

A

B

Sterile baby

gene flow migration
Gene Flow(Migration)
  • Defined: Movement of alleles from 1 population to another
  • Increases variations in a population
  • Keeps differing populations similar
  • If gene flow prevented
    • No variations exchanged
    • Populations isolated
    • Organisms adapt to their own environment
reproductive isolation

Random DNA mutations

Random DNA mutations

Reproductive Isolation

Different predators

Different predators

Different resources

Different resources

  • When populations are isolated for a long time…gene flow stops
  • When populations can no longer reproduce, a new species develops
  • Geographic Isolation:
    • Organisms isolated by geographic barrier
slide7

Ancestral salamanders

B

A

One species

One species

famous fruit fly experiment

Fruit flies of the same species were placed into two separate cages

Famous fruit fly experiment

Once isolated, the 2 groups were fed different types of food

Although isolated, the flies continued to live and reproduce for many generations

When brought back together most separated during reproduction.

reproductive isolation1
Reproductive Isolation
  • When populations are isolated for a long time…gene flow stops
  • When populations can no longer reproduce, a new species develops
  • Geographic Isolation:
    • Organisms isolated by geographic barrier
  • Behavioral Isolation
    • Organisms isolated by differing mating rituals

If the mating calls do not attract each other, will they reproduce?

Is gene flow stopped?

reproductive isolation2
Reproductive Isolation
  • When populations are isolated for a long time…gene flow stops
  • When populations can no longer reproduce, a new species develops
  • Geographic Isolation:
    • Organisms isolated by geographic barrier
  • Behavioral Isolation
    • Organisms isolated by differing mating rituals
  • Temporal Isolation
    • Organisms isolated by differing times of reproduction

If one group mates during the spring…

Is gene flow stopped?

And the other mates during the fall…

genetic drift
Genetic Drift
  • Defined: Changes in gene pool due to chance (natural selection)
  • More likely in smaller populations
  • Results in a loss of genetic variation
  • Survival UNREALTED to adaptations
  • The bottle neck effect
  • Example: Natural disaster
    • Pre-forest fire: Green is best adapted (blend better)
    • Post-forest fire: Brown more likely to reproduce
review
Review
  • What is speciation?
  • What leads to speciation?
  • What is gene flow?
  • What happens if gene flow is prevented?
  • How are temporal, behavioral, and geographic isolation different?
  • How are temporal, behavioral, and geographic isolation similar?
  • What are the 5 factors that lead to evolution?
ad