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But how do these changes lead to the formation of new species?

AFTER THIS PPT YOU SHOULD BE ABEL TO… describe how you think the two subspecies of salamanders in southern California are becoming separate species . Factors such as natural selection and chance events can change the relative frequencies of alleles in a population.

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But how do these changes lead to the formation of new species?

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  1. AFTER THIS PPT YOU SHOULD BE ABEL TO… describe how you think the two subspecies of salamanders in southern California are becoming separate species.

  2. Factors such as natural selection and chance events can change the relative frequencies of alleles in a population. But how do these changes lead to the formation of new species?

  3. What is a species? • A species is a group of organisms that breed with each other and produce fertile offspring. • For example, these happy face spiders look different, but because they can all interbreed they are considered the same species: Theridiongrallator

  4. In this sense, a species is the biggest gene pool possible under natural conditions.

  5. Lion + Tiger = LIGER Horse + Donkey = MULE

  6. What is speciation? D S • Speciationis a lineage-splitting event that produces two or more species • It happens when members of two populations can no longer interbreed and produce fertile offspring

  7. Reproductive Isolation • Reproductive isolation occurs when members of two populations can no longer interbreed and produce fertile offspring • I.e. there is a barrier to the gene flowbetween the two populations.

  8. 3 Ways Reproductive Isolation Happens • Behavioral isolation • Geographic isolation • Temporal isolation

  9. Behavioral Isolation • Two populations, because of different sexual selection pressures, develop different mating rituals and behaviors. They do not recognize each other as mates.

  10. The eastern meadowlark and the western meadowlark have overlapping ranges. The do not interbreed because they have different mating songs.

  11. Geographic Isolation • Two populations cannot breed with each other because they are separated by geographic barriers like rivers, mountains, or canyons.

  12. Kaibab squirrel Abert squirrel

  13. Temporal Isolation • This is when two or more species reproduce at different times. Mates in the spring Mates in the fall

  14. How do behavioral isolation, geographic isolation, and temporal isolation lead to speciation? • Individuals must be able to mate with each other in order to be considered members of the same species! This is part of the definition of a species.

  15. Click HERE to watch a video showing Dr. Steebens research with salamanders in California…

  16. In 3 to 5 sentences, describe the process of speciation in the subspecies of salamanders in southern California. Show evidence of your new knowledge.

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