Evidence for Evolution

Transcription

1 Evidence for Evolution

2 Evolution Biological evolution is descent with modification.

3 It is important to remember that: Humans did not evolve from chimpanzees. Humans and chimpanzees are evolutionary cousins and share a recent common ancestor that was neither chimpanzee nor human. Humans are not "higher" or "more evolved" than other related species. humans and chimpanzees have each evolved traits unique to their own lineages.

4 Common ancestor

5 Peppered Moth During the Industrial Revolution, industrial wastes darkened tree trunks and killed off lichens. Light moths became rare and the dark moths became abundant. In 1819, the first dark moth was seen; by 1886, it was far more common: rapid evolutionary change. Before Industrial revolution

6 Eventually light moths were common only far from industrial areas. The cause of this change was thought to be selective predation by birds, which favored camouflage coloration in the moth. After the Industrial Revolution

7 Selective Breeding Selective breeding (or artificial selection) occurs when humans choose two organisms with desirable characteristics and breed them together to get offspring that also have these characteristics.

8 Short-legged dogs (bassets and dachshunds) developed from a single mutation on 1 gene The short-legged dogs were allowed to reproduce, passing the gene on

9 Darwin used pigeons as an example of how variation could be inherited and that the form of organisms was not fixed.

10 These common vegetables were cultivated from forms of wild mustard.

11 Similarity among Embryos In the embryo stage, most vertebrates look the same and follow a comparable development. This similarity seems to indicate a common ancestor among vertebrates.

12 Homologous structures A dolphin flipper, a human hand, and a bat wing are all just variations in size and shape of the same number of bones. These structures appear to have a similar origin and indicate a shared ancestor.

13 Homologous structures are produced through divergent evolution Same basic structure has changed to perform different tasks

14 Analogous Structures Organisms facing the same environmental selective pressures may evolve towards a similar form. Tasmanian wolf North American wolf

15 Analogous structures: wing of an insect, bird bat and pterosaur. Same purpose, different internal structure

16 Analogous structures are produced through convergent evolution.

17 Analogous structures: flying lemur and fruit bat Bat s wing is homologous with human hand

18 Vestigial Structures The presence of structures that have no apparent use implies that the organism's ancestors had a more useful version of the body part. Wisdom teeth

19 Over time through adaptation the role for these structures has been lost.

20 Fish species that live in caves have vestigial, non-functional eyes. When their sighted ancestors ended up living in caves, there was no longer any natural selection that maintained the function of the fishes' eyes. fish with better sight no longer out-competed fish with worse sight. these fish still have eyes but they are not functional

21 Biochemistry chemical relatedness All higher organisms share the same basic biochemistry including: Amino acids, proteins, lipids, carbohydrates and many enzymes All higher organisms use DNA as a genetic code.

22 DNA is a double helix molecule DNA sequences can be compared between species. The more similar the sequence, the more related.

23 Humans and chimpanzees share 98.7% of the same DNA sequences

24 Biogeography Organisms that are more closely related are found geographically closer together.

25 Geology A study of the earth's geology shows that the planet is a place of both slow gradual change and sudden catastrophic change. If organisms were unchanging they would not be able to keep up with the changes.

26 Fossil Record If evolution is occurring, organisms found in the fossil record should be different than those found today. The fossil record shows the appearance, change, and extinction of many organisms throughout time.

27 Increasing Complexity

28 Principle of Superposition: Organisms found in the lowest rock layers must be the oldest

29 We see the least complex organisms in the oldest layers and most complex in the youngest.

30 Punctuated Equilibrium The evolutionary process involving long periods without change (stasis) punctuated by short periods of rapid speciation. Gradualism is selection and variation that happens more gradually.

31 Explains why some species seem to change very slowly (sharks, crocodiles) over millions of years Some species seem to change very rapidly (Hawaiian birds, etc.)