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Speciation

Speciation. Speciation in Darwin’s Finches. Speciation in the Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population’s gene pool, reproductive isolation, and ecological competition. Founder’s Arrive.

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Speciation

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  1. Speciation

  2. Speciation in Darwin’s Finches • Speciation in the Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population’s gene pool, reproductive isolation, and ecological competition.

  3. Founder’s Arrive • Finches from the mainland of South America arrive on the Galapagos islands. • As finches do not usually fly over open water, it is assumed they were blown off course by a storm.

  4. Separation of Populations • As finches do not fly over open water, they remained on whatever island they landed on.

  5. Changes in the Gene Pool • Each island of the Galapagos has its own unique flora and fauna (plants and animals)—the finches slowly adapted to their islands through natural selection.

  6. Species • A species is a group of organisms that breed with one another and produce fertile offspring. • This population will share a common gene pool.

  7. Reproductive Isolation • When members of two populations cannot interbreed and produce fertile offspring,

  8. Behavioral Isolation • Occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies.

  9. Geographic Isolation • Two populations are separated by a geographic barriers such as rivers, mountains, or bodies of water.

  10. Temporal Isolation • Two or more species reproduce at different times.

  11. Ecological Competition • All organisms compete for limited resources. • The finches evolved specialized beaks for particular foods to limit the competition.

  12. Continued Evolution • The process of isolation, genetic change, reproductive isolation, most likely repeated itself over and over again. • As a result, there are 13 different species of Galapagos finches.

  13. Human Evolution

  14. Primates • The evolutionary history of primates began about 85 million years ago. • Fossils have been found primarily in North America, however they were widespread throughout Eurasia and Africa • Notharctus • Discovered in Germany • ~ 16.5 million years old

  15. Primates to Humans • Nakalipithecus (Kenya) & Ouranopithecus Ouranopithecus (Greece) • Last common ancestors between gorillas, chimpanzees, and humans. • Between 8-4 mya, chimpanzees and gorillas split from the line leading to humans.

  16. Becoming Human • Savannah Theory • Proposed by Raymond Dart • Stated that hominids began to stand on two legs to peer over savannah grasses to hunt and hide from predators. • Aquatic Ape Hypothesis • States that early hominids lived around water and often dove, waded, and swam. • Accounts for our lack of hair, subcutaneous fat, and abundance of sebaceous glands.

  17. Hominids • Homo habilis • 2.4 to 1.4 million years ago (mya) • Found in Africa • Possessed small molars and large brains • Was surrounded by stone and bone tools • Nicknamed “Handy Man”

  18. Hominids • Homo rudolfensis and Homo georgicus • 1.9-1.6 million years ago • H. rudolfensis • Incomplete skull found in Kenya. Scientists debate whether this is another species, or another H. habilis • H. georgicus • Found in Georgia (near Russia) • Thought to be an intermediate form between H. habilis and H. erectus

  19. Hominids • Homo ergaster and Homo erectus • H. ergaster • Discovered in Indonesia • 1.8-1.25 mya, seen as a subspecies of H. erectus • H. erectus • 1.5-1 mya, found in Africa, Asia, and Europe • Used elaborate stone tools • First human ancestor to truly walk upright • May have used fire • Peking Man

  20. Hominids • Homo cepranensis and Homo antecessor • Both thought to be intermediate forms between H. erectus and H. heidelbergensis • H. cepranensis • 1.2 mya-500,000 ya • Based on fossils found in Spain and England • H. antecessor • 800,000 ya • Based on a single skull cap found in Italy

  21. Hominids • Homo heidelbergensis • lived from 800,000 ya to 300,000 ya • Heidelberg Man

  22. Hominids • Homo rhodesiensis • 300,000-125,000 ya—disputed separation from H. Heidelbergensis • Rhodesian Man • Gawus Cranium • Discovered in 2006 in Gawis, Ethiopia • 500,000-250,000 ya • Might possibly be an intermediate species between H. erectus and H. sapiens

  23. Hominids • Homo neanderthalensis • 300,000 ya to 30,000 ya • Mitochondrial DNA studies suggest that H. neanderthalensis is a separate species from H. sapiens • Neanderthals are NOT our ancestors

  24. Hominids • Homo sapiens • 250,000 ya to the present • Direct evidence suggests we migrated out of Africa • However, this does not preclude multiregional speciation • H. sapiens idaltu • Oldest known anatomically modern human • 160,000 years old, found in Ethiopia

  25. Hominids • Homo floresiensis • 100,000-12,000 years old • Skeleton of a 30 year old woman found (~18,000 yo) • One meter (3 feet) tall • Nicknamed “Hobbit”

  26. Hominids • Homo floresiensis • Separate Species or Homo Sapien? • At first scientists thought that H. florensiensis was a separate species • Now, they believe that H. floresiensis is a H. sapien that has insular dwarfism • Modern day people on the island of Flores are pygmies

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