1 / 13

Speciation

horse. donkey. Speciation. mule. lion. Speciation. Defined : evolution of a new species Species : group of organisms that can interbreed and produce fertile offspring Different species rarely breed Interspecies breeding often results in sterile offspring Ex: Horse x Donkey = Mule

cloris
Download Presentation

Speciation

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. horse donkey Speciation mule

  2. lion Speciation • Defined: evolution of a new species • Species: group of organisms that can interbreed and produce fertile offspring • Different species rarely breed • Interspecies breeding often results in sterile offspring • Ex: Horse x Donkey = Mule • Ex: Lion x Tiger = Liger • Are horses & donkeys a different species even though they can produce offspring? tiger liger

  3. Causes of Speciation • 1) Geographic Isolation: mountains, rivers, canyons, oceans may separate apopulation • Natural selection allows favorable organisms to survive in different environments • Divergent Evolution: 1 species evolves into 2 or more with different characteristics

  4. Kaibab Squirrel (Grand Canyon)

  5. Divergent Evolution: 14 Species of Galapagos Finches Species A blown onto the islands from the mainland Because of the new environment, the birds adapt and change Species B spreads out across the new islands Species C spreads out across the islands Species C develops as the they begin to adapt to the new island Species D adapts to its new environment B A C D B C

  6. 2) Reproductive Isolation • Although not geographically separated, reproduction is prevented • 1) Different mating rituals • 2) Different sexual organs (lock & key) • 3) Sperm unable to fertilize egg • 4) Offspring created sterile (ex: liger and mule)

  7. 3) Genetic Drift • Defined: Changes in gene pool due to chance (not natural selection) • Gene pool: collection of genes within a population • Ex: Forest fire destroys 90% of a forest • Survival unrelated to advantageous traits • Survivors can only reproduce with other survivors • Therefore, the next generations might inherit different traits

  8. 4) Polyploidy • Defined: Having more than two copies of a chromosome • Diploid sperm (2n) + diploid egg (2n) = tetraploid (4n) offspring • Tetraploids behave as new species because they are unable to reproduce with original species • More common in plants because they can reproduce asexually by self-pollinating

  9. Other Patterns of Evolution • Convergent Evolution: different species evolve similar traits due to similar habitats • Ex: Fish and dolphins • Unrelated species with a similar environment

  10. Dragonfly Convergent Evolution

  11. Mimicry • Many structural and behavioral adaptations to copy/mimic the environment • Variations aid in their survival • Viceroy butterflies mimic the poisonous monarch • King snakes mimic the poisonous coral snake • Fish mimic the ocean floor • Insects mimic vegetation

  12. Coevolution • Defined: evolution of two or more interdependent species • Ex: Plants and Insects • Plants: provide insects with nectar • Insect: transfers pollen from one plant to another

  13. Quick Review • New species are created (speciation) when populations become isolated • A changing or new environment greatly affects natural selection • Evolution shapes life on earth

More Related