what is sexual selection and how does it lead to evolution l.
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what is sexual selection and how does it lead to evolution

What is sexual selection and how does it lead to evolution?

Warmup:

Review

Why do diseases evolve so quickly?

Explain how the tuberculosis bacteria evolved drug resistance in the Russian prisons?

yesterday s summary
Yesterday’s Summary
  • How is antibiotics resistance similar to selective breeding?
  • Why would you want to make sure you finish antibiotics even after you feel better?
  • Why do bacteria and viruses evolve so quickly?
  • Antibiotic resistance is an example of natural selection: What do you think natural selection might mean?
evolution
Evolution
  • Review Definition
    • Evolution is a process of species changing over time.
    • Variation comes from mutations.
    • Certain traits reproduce more than others.
    • Traits that get to reproduce get enhanced.
    • Selective Breeding is one way humans have caused evolution
    • Nature has its ways.
can selective breeding happen in nature
Can Selective Breeding Happen in nature?
  • How could a species maybe do “selective breeding” on their own.
    • What if female cardinals were more attracted to bright red feathers?
    • Which cardinals get to reproduce?
    • If females always chose reddest feathers what happens to cardinals over time?
cardinal selection
Cardinal Selection

Which cardinal will the female most likely pair up with?

Which genes get passed on?

Where does the variety come from?

How is this like selective Breeding?

sexual selection
Sexual Selection
  • The example of the cardinal evolving red feathers is from sexual selection.
  • When organisms choose mates based on a certain trait that leads to evolution of that trait.
  • Examples Guppy Fins. Peacock feathers. Bird of paradise
peacocks feathers
Peacocks Feathers

How has sexual selection lead to peacocks extravagant feathers?

drawbacks
Drawbacks
  • Is sexual selection always good for a species?
    • Why do peacocks feathers make it harder to survive?
    • How can being a bright red cardinal be a disadvantage?

Most organisms don’t have Crazy traits.

    • So what stops sexual selection from continuing to extremes?
      • Survival. The traits have to allow for the mates to survive.
      • If you cant survive you cant get chosen!
guppies
Guppies
  • Why do guppies have fancy fins?
    • Females prefer fancy males
    • In murky water its harder to see dull mates.

Why would females Have fins that are more plain?

the predator effect
The Predator Effect
  • Why would bright fins be a bad thing?
  • Which lake would have more fancy guppies: One with lots of predators or ones with a few? Why?
  • How can predators cause sexual selections effects to be limited?
summary
Summary
  • How does sexual selection lead to evolution of a certain trait?
  • How is sexual selection similar to selective breeding?
  • How do predators limit the effect and evolution from sexual selection?
  • Predators help determine Natural Selection which is what we learn tomorrow