EVOLUTION

1. EVOLUTION CHAPTERS 10, 11, 12

2. Theory of Natural Selection • Descent w/ modification and adaptation to the environment is the basis of Natural Selection. • Inherited better traits/adaptations, produce more offspring that reach reproductive age. • 4 main points: • Variation • Overproduction • Adaptation • Descent with modification

3. Variation • Artificial selection • Selective breeding of domesticated plants and animals for the sole purpose of human usefulness. • Can be completed in a short period of time, Natural selection does this over a longer period of time.

4. Variation • Embryonic development • Embryos of related species have similar developmental stages. • Study of a multicellular organism from a fertilized egg into adult hood.

5. Variation con’t • Molecular development • The sequencing of amino acids can be compared to show similarities in DNA. • The closer the DNA, more related an organism is. • The more different DNA, less related the organism is.

6. Overproduction • Most species are capable of producing more offspring than the environment can support. • When there are too many individuals in a population, there will be competition. • Competition will allow the more successful to grow faster and produce more offspring. • Offspring will carry some of the genes of the parents that made them better adapted = Fitness. • The struggle for survival between individuals of the same species = Natural Selection

7. Adaptation • Homologous structures • Particular structures that are similar among species, but may not have the same function. • Ex – forearm bones in mammals. • Shows evidence of adapting to the environment

8. Adaptation con’t • Vestigial structures • Structures in modern organisms that have no particular function, that once were functional. • Generally smaller in size. • Ex. Appendix in humans, hind limbs in whales, tail bone in humans

9. Descent with Modification • Traits passed on that favor the environment. • Evolutionary Biology – evolution due to response in environmental change • Modern medicine • Antibiotics - Kill or slow the growth of bacteria • Resistant bacteria • Evolves by natural selection • Resistance is transferred to next generation due to gene altering. • Viruses – vaccines • Pesticides – used to kill insects. Repeated uses is less effective over time due to resistance.

11. Microevolution • Change in allele frequency in a population over time. • Generation to generation change • Natural selection can change distribution of a trait through: directional, stabilizing or disruptive selection. • Cause of N.S. = change in alleles, mutations of existing traits.

12. Ch.11 Evolution of Populations • Population increases chance of individuals will survive. • Genetic variations several sources

13. Genetic Variation • Random process of events of Mutation and Sexual recombination, causing a change in frequency of alleles. • Mutation – change in DNA, can be passed on to offspring - changes allele frequency in gene pool. • Recombination – new allele combination - occurs during meiosis - • You are more similar to your family members, than the rest of the species.

14. Gene pool • All the alleles in all the individuals make up a population. Like a reservoir of genes. gg Gg GG GG gg GG G = Green g = Brown

15. Allele frequency – commonality of certain alleles in a population. gg Gg alleles for skin color trait Total alleles = Frequency of G = Frequency of g = GG GG GG gg G = Green g = Brown

16. Gene flow • Exchanging of genes with another population • Increase genetic variation in the receiving population

17. Genetic drift • Change in gene (alleles) pool of a population due to CHANCE. • Bottleneck effect– natural disasters reduce the population and gene pool size. • Founder effect– smaller the colony, less available gene pool. Limited variations among the population

18. Sexual selection – Females choose mates based on their traits, so if a male has favorable characteristics, the female will choose him and those traits.

19. Isolation of Speciation • Speciation • New species evolves from an existing species, causing Adaptive radiation. • Adaptive radiation – diversification of organisms into many new descendent species caused by different environments. Ex. - Cambrian Explosion • 2 forms • Gradual(ism) – over time, little changes among the species • Punctuated (equilibrium)– Long periods of no change, then short periods of drastic change in a species.

20. Isolation of Speciation Barriers between Gene Pools • Geographic isolation - result of separation of populations due geographic barrier. • Behavioral isolation - different courtship/ mating rituals • Temporal isolation - different breeding seasons • Mechanical isolation – Different reproductive parts

21. Patterns of Evolution • Convergent – process by which unrelated or distantly related organisms evolve similar body forms, coloration, organs, and adaptations. • Divergent – when two or more adaptations have a common evolutionary origin, but have diverged over evolutionary time. • Adaptive radiation • Coevolution – • 2 or more species evolve in response to changes in each other.

22. Extinctions • Elimination of a species from Earth, due to not being able to adapt to environment. • Sudden period of time of great loss of species = MASS EXTINCTIONS • Catastrophic event(s) • Surviving organisms had new opportunities to change and compete for food, mates and spaces = adaptive radiation • Fossil record shows: • Evidence of plant / animal extinctions • Biological diversity – speciation/ adaptive radiation

23. Ch. 12 Fossil record • Traces history of life and allows us to study history of particular organisms in rock layers • Over time, sediments bury organisms in rock layers. Giving time period when organism once lived and relative age. • Older layers are farther from the surface, while the younger layer is closer to the surface.

24. Formation of Fossils • Over time, soft bodied parts of an organism are dissolved away and replaced with minerals that calcify. • Types - • Permineralization – when minerals replace hard structures • Natural cast – bone or natural tissue is removed, leaving an impression.

25. Types con’t • Trace fossils - imprints left in soil, by objects. • Amber preserved – organisms is trapped in tree resin, then buried • Preserved remains – entire organism is encased; buried by sediment, dust, volcanic ash, tar pits, ice

26. Dating of Fossils • Scientists use 2 methods to determine the age of fossils. • Relative dating • Used to identify relative ages of organisms, based upon location in rock layers. • Absolute dating • Determines specific age of organic or inorganic objects using ISOTOPES • Every isotope has a half-life, number of years it takes 50% of the object to decay. • Radiometric dating – measures radioactive isotopes using half-life. • Uranium 238 used to date object, half life of 4.5 billion years • Not found in living things • Carbon dating – carbon 14 • Used to identify relative young fossils. • Half life of 5,730 years • Relatively accurate to 45 - 50,000 years

27. Formation of Pangea 250 mya End of palezoic period Continental Drift 180 mya to present Movement of landmasses due to the movement of the mantle. Similar plants and animals on different continents 2 major events of Earth’s History geology.rutgers.edu/.../Pangea_NB.html

28. Earth’s History Divided into a series of time; • Eras – 100 millions/billions of years • Periods – tens of million of years • Epochs – few million years Earth’s atmosphere formed about 3.6 bya • Cyanobacteria – photosynthesis • Stromatolites – colonies

29. Geologic Time Scale • Earth’s 4 main Eras 1. Precambrian: 4.6 bya -540 mya Origin of Earth crustal plates formed, 1st cells, one-celled organisms – bacteria, blue-green algae, soft bodied organisms 2. Paleozoic Era: 540 – 250 mya Cambrian explosion 90% of marine life extinct; 70% land life extinct Cambrian explosion- Multicellular organisms, hard body parts, Marine life, first amphibians, giant Ferns 1st seed plants

30. Geologic Time Scale con’t 3. Mesozoic Era: 250 – 65 mya Age of Reptiles dinosaurs were dominant, birds, cone bearing plants, flowering plants, Creataceous extinction - dinosaurs 1st direct mammal ancestor 3 main periods – Triassic, Jurassic, Creataceous 4. Cenozoic Era: 65 mya to present Recent life mammals evolved, grasses evolved, Hominids evolved - Homo sapiansancestors, modern homo sapiens 200,000 years ago, last recorded ice age

31. Primate Evolution • Hominid – humans and close relatives • Primates - mammals - upright walking - flexible hands and feet / opposable thumb - eyes forward looking - enlarged brain / body size - rotational arms - opposable thumbs

32. http://evolution.berkeley.edu/evosite/evo101/IIE2cHumanevop2.shtmlhttp://evolution.berkeley.edu/evosite/evo101/IIE2cHumanevop2.shtml

33. Mammal evolution • Prosimians – • oldest living primate group • Nocturnal • 55-50 mya • Native to Madagascar, Africa & Asia

34. Mammal evolution con’t • Anthropoids – human like primates • New world – native America’s, prehensile tail – live in trees • Old world – ground primates – ground dwelling • Hominids – walk upright - bipedal, opposable thumb; any human lineage, modern & extinct – Homo Sapiens 200,000 years • Lesser apes - gibbons • Great apes – orangutans, chimpanzees, gorillas

35. Formation of Fossils • Over time, soft bodied parts of an organism are dissolved away and replaced with minerals that calcify. • buried by sediment, dust, volcanic ash • skeletons, shells, seeds, insects trapped in amber • imprints or footprints of organisms • organisms frozen in ice (wooly mammoth),  or trapped in tar pits (saber-toothed tiger)