Presentation on theme: "Honors Biology Unit 7 Powerpoint #"— Presentation transcript:
1 Honors Biology Unit 7 Powerpoint #2 2011-2012 Patterns of EvolutionHonors BiologyUnit 7Powerpoint #2
2 MacroevolutionLarge-scale evolutionary patterns and processes that occur over long periods of timeKey Concept: 6 important patterns of macroevolutions
3 1) Mass ExtinctionWhen many different species of organisms go extinct at the same time.End of Paleozoic: 95% of complex life (both plants and animals on the land and in the sea) went extinct.
4 Causes of Mass Extinction Climate Change: rapid changes in yearly weather patterns. Example: Ice AgeVolcanism: the sudden oozing of millions of cubic meters of lava from the earth that release gasses poisoning the atmosphereImpact Events: Meteors or asteroids impacting the earth
5 The Future of Mass Extinction E.O. Wilson of Harvard University predicts that man’s destruction of the biosphere will lead to the extinction of 50% of the species on earth in the next 100 years.70% of biologists agree
6 Example of Mass Extinction: 65 Million years ago (very recent) 50% of all species went extinct including dinosaursThought to be caused by the Chicxulub Meteor which hit the Yucatan Peninsula in Mexico.
8 Chicxulub Crater Made by a meteor 6 miles in Diameter Equivalent to exploding 190,000 gigatons of TNT
9 Tsar Bomba: By comparison: The most powerful nuclear bomb ever tested (Russia 1961) was only 0.05 gigatons
10 2) Adaptive RadiationA single species, or small group, evolves, through natural selection into diverse forms.Example:Darwin’s Galapagos Finches
11 3) Convergent Evolution When unrelated organisms come to resemble each other due to environmental demands.Example:Placental v. Marsupials
12 4) CoevolutionWhen two species evolve in response to changes to each other over timeExample:Insects and flowers
13 5) Punctuated Equilibrium Long stable periods interrupted by periods of rapid change.Example:Darwin’s Galapagos Finches
14 6) Developmental Genes & Body Plans Small changes in the activity of control genes can produce large changes in adult animalsExample:HOX genes
15 Fossil Evidence of Mass Extinction Fossilization does not happen very often.Mass Extinctions also do not occur very often.Scientist believe that there are more fossils to be found around the time of mass extinctions than any other time.
16 Strata Layers of dirt and stone from different time periods on earth. Form bands of rock layers.
18 Geologic TimeBased Upon major changes in the fossil record in the rock strataERAS are longer time divisions than PERIODSThere are four eras:Precambrian (4.6 billion – 544 million years ago)Paleozoic ( million years ago)Mesozoic (245 – 65 million years ago)Cenozoic (65 million – Present)
20 Dating of Fossils (p )Relative Dating: estimates a fossils age compared with other fossils but no info about age in yearsIndex Fossils: distinctive fossil used to compare the relative ages of fossilsRadioactive Dating: Calculate the age of a sample based on amount of remaining radioactive isotopes it containsHalf-life: length of time required for half of the radioactive atoms in a sample to decay