Your SlideShare is downloading. ×
0
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Evolution
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Evolution

339

Published on

Published in: Technology, Education
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
339
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
7
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Evolution IB Biology Topic 5.4
  • 2.  
  • 3.  
  • 4.  
  • 5.  
  • 6.  
  • 7.  
  • 8.  
  • 9.  
  • 10.  
  • 11. Analogous Structures are features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestral feature (compare to homologous structures) and which evolved in response to a similar environmental challenge. Example: Insects and birds both have wings to fly, although their wing structure is very different this is an example of an analogous structure. The fat-insulated, streamlines shapes of seals (mammals) and of penguins (birds) is another example.
  • 12.  
  • 13. 5.4.4 Population size and survival <ul><li>  It should be noted that the &apos;struggle for survival&apos; in this model is a consequence of over-population . </li></ul><ul><li>The struggle takes the form of individuals in the population being &apos;selected for &apos; or &apos;selected against &apos; . </li></ul><ul><li>Survivors form the new breeding population . </li></ul><ul><li>The frequency of advantageous alleles has increased. </li></ul><ul><li>The change in the heritable characteristics is by definition evolution .   </li></ul>
  • 14. 5.4.5 Variation in a species. <ul><li>Individuals in a species are not all identical, but show variations in their characteristics </li></ul>
  • 15. 5.4.6 Sexual reproduction and variation <ul><li>The sources of genetic variation in a populations : </li></ul><ul><ul><li>Meiosis and the independent assortment of chromosomes creates 2 n new combinations of chromosome in the next generation n = haploid number of chromosomes </li></ul></ul><ul><ul><li>Random fertilisation increases the variation in the population to 2 2n again where n = haploid number of chromosomes </li></ul></ul><ul><ul><li>The number of different genetic variations is increased further by cross-over in meiosis by an estimated 2 3 in addition to the two above. </li></ul></ul>
  • 16. &nbsp;
  • 17. &nbsp;

×