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Transcript
Warm-up Questions: • What does the word speciation mean? When natural selection leads to the creation of a new species. • What is the difference between homology and analogy? Homology are structures that are similar in structure and share a common ancestor. Analogy is structures with similar functions that do not share a common ancestor. Evidence of Evolution Pt 2 Biogeography, cladograms • The study of what organisms live where and why. • Looks into the distribution of organisms on Earth, both past and present, and of related patterns in the numbers and kinds of living things. Bio Geography: • Phytogeography – The study of plants • Zoogeography – The study of animals • Microbial Biogeography – distribution of organisms over space and time. Specializations in Biogeography • Geographic regions have characteristic groups of organisms. • Closely related organisms tend to be closer together than more distantly related groups. • Similar environments are found in different places on Earth, BUT the same species may not be found in all. • Not closely-related species in similar environments may appear similar to each other due to convergent evolution, but are not related. Patterns Seen Across the Globe • Divergent evolution • Convergent evolution Types of Change: • When species that are similar and closely related become increasingly different from each other. THEY DIVERGE • This is also called Adaptive Radiation because it has to do with ADAPTING to different environments and RADIATING out into different species. Divergent Evolution: mammal Fish • When distantly-related organisms evolve to become more similar. • occurs when unrelated species occupy similar environments in different parts of the world. Convergent Evolution: • If organisms are well adapted to their environment, there is no need for change. • Fossil records show that some organisms have stayed exactly the same or hardly changed at all through many generations. Stasis: • Most organisms in the fossil record do not contain transitional forms. • Instead, there is a sudden appearance of a new form or organism that had not previously been seen in the fossils Cambrian Explosion Sudden Appearance: • The study of the evolutionary relationships of organisms. • In phylogeny, we use diagrams called phylogenetic trees and cladograms that show us how organisms are classified based on their evolution. Phylogeny: • The root is the common ancestor to all of the organisms shown in the tree. • The descendants are the extant (present-living) organisms from that ancestor. Reading a Cladogram: • The lineages are from the unique ancestor to the descendent. • This does not show all of the changes that occur along the way. Reading a Cladogram Contd: Reading a Cladogram Contd: • A clade is a grouping that includes an ancestor and ALL of the descendants of that ancestor (whether extant or extinct.) Reading a Cladogram Contd: A . B . D . C . E. Which one(s) are clades? • Cladograms show related organisms that share adaptations derived through evolution. • Derived shared characteristics: traits that appear through evolution that were not present in earlier ancestors. Reading a Cladogram Contd: Live birth • Which organisms in this cladogram have four limbs? • Which organisms in this cladogram have four limbs AND give live birth? Reading a Cladogram Check DIVERGENT EVOLUTION MORE RECENT COMMON ANCESTOR CONVERGENT EVOLUTION NOT A RECENT COMMON ANCESTOR