Unformatted text preview: Summary from the last lecture Summary from the last lecture We have a reliable method for determining the age of rocks and fossils. As a result we know: – The Earth and the solar system are 4.6 billion years old. – The oldest fossil organisms on Earth (bacteria) are 3.5 billion years old. – There is plenty of time for evolution Thousands of Transitional Fossils Now Thousands of Transitional Fossils Now Exist Evolution of the horse over 55 million years Whale evolution over 55 million years EIVIDENCE FROM ANATOMY EIVIDENCE FROM ANATOMY AND EMBRYOLOGY EIVIDENCE FROM ANATOMY EIVIDENCE FROM ANATOMY Deduction: If the hypothesis of evolution is correct then we should see evidence of this in the anatomy. Test: Study comparative anatomy – Look for trends Aristotle DATA DATA Forelimb of vertebrates Homology=Similar structure from a Homology=Similar structure from a common ancestor e.g. The basic structure of the limb evolved before the two groups separated. It evolved in fish! L imbs fr om fins Homology in Leaf Structure Homology in Leaf Structure ANALOGY=Similar function of two ANALOGY structures independently evolved i.e. not from a common ancestor Bird Bat Fly Analogous Structures How can you tell if 2 structures are How can you tell if 2 structures are homologous ? Answer these questions: Are the two structures fundamentally similar in their basic structure? Do the structures have the same embryology? Does the common ancestor have a similar structure? – If so, the structures are probably homologous even if they are performing different functions Clicker Question Clicker Question Which structures are homologous? A) Eye of a dog and eye of a fly B) Leg of an elephant and the leg of a crab C) Dorsal fin of a whale and dorsal fin of a shark D) Tentacle of a jelly fish and the tentacle of an octopus E) None of the above REMEMBER REMEMBER In order for the structures to be homologous the organisms’ common ancestor had to have the structure ! question have classically been considered analogous.
– They perform similar functions but evolved independently All of the examples in the previous clicker BUT it is more complex than that! BUT it is more complex than that! The eyes of dogs and flies are very different and so were thought to be analogous But genes have been found that code for all eyes. So some of the genes are homologous but most are not, SO should we consider the eyes homologous too ? Which structures are analogous? Clicker Question Clicker Question A) Hair of a tarantula and the hair of a dog. B) Heart of a cow and the hoof of a horse C) Eye of a bat and the eye of a snake D) Claw of a lobster and the claw of a crayfish E) Hand bones of a human and the wing bones of a bat DATA: Trends in organ structure Evolution of the vertebrate heart
Number of Chambers Respiration DATA: Trends in organ DATA: Trends in organ structure – FishGills – AmphibianGills & Simple Lungs – ReptileComplex Lungs – Birds & MammalsVery Complex Lungs Vestigial Structures= Structures with Vestigial Structures= no apparent function e.g. Human – Goose bumps when you are cold – Tail bonecoccyx – Muscles to move the ears & scalp Snakes’ lung Cave animals’ blind eyes Wings of flightless birds EIVIDENCE FROM EIVIDENCE FROM EMBRYOLOGY Deduction: If the hypothesis of evolution is correct then we should see evidence of this in the embryology. Test: Examine the development of embryos – Look for trends Aristotle Evidence from Embryology Evidence from Embryology Von Baer (1866) The development of all vertebrate embryos is similar – Law of Development General traits will evolve first Specific traits will evolve later Vertebrate Embryos Vertebrate Embryos Haeckel’s Principle of Haeckel’s Principle of Recapitulation “Ontogeny Recapitulates Phylogeny”
– – – “Biogenetic Law” Ontogeny= Individual development of embryo Recapitulates= Repeats Phylogeny= Evolutionary History The individual development of the individual repeats the sequence of events that occurred during evolution Whale Examples Whale Examples Whale nostrils Whale teeth Whale hair Human examples Human examples
Gill Pouches Tail Aortic Aortic Arches Vertebrate Embryo & Fishes Adult Frog Adult Mammal Evaluation Evaluation The data from anatomy & embryology support the hypothesis of evolution NEXT TIME NEXT TIME Assignment Before Next Class Assignment Before Next Class 1. Read the chapter on the cell 2. Print out the table on the next slide and bring it to class filled in with information that you have gleaned from your text. Differences between organisms: (Complete before class):
CHARACTERISTIC What are the types and shapes of the genetic material? Virus Prokaryote Eukaryote What is the structure of the outer protective barriers? What types of internal structures are found in each? How does each reproduce? What size are they? How would they appear under a light microscope? ...
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