Evidence of Evolution Key Concept Evidence For This Process Could Be Found In: The Fossil Record The Geographical Distribution of Living Species Homologous Structures of Living Organisms Similarities In Early Development

How do we study Evolution?

Comparative studies Researchers use comparative studies to establish evolutionary relationships between organisms

Homologous Body Structures Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone Structure May Differ In Form or Function Arms, Wings, Legs, Flippers

Homologous Body Structures

Homologous Body Structures Not All Serve Important Functions Vestigial Organs Appendix In Man Legs On Skinks

Comparative anatomy Comparing specific body structures Analogous structures have a similar function but the structure is different Ex the wing of an insect and the wing of a bird

Homologous structures are similar in structure but may have different functions Ex) human hand, cat paw, whale flipper, bat wing

Similarities In Early Development Embryonic Structures Of Different Species Show Significant Similarities Embryo – early stages of vertebrate development

Human Fetus – 5 weeks

Comparative embryology The comparison of embryonic development Early development is similar in many species The closer the relationship between species the more similar is development

Comparative cytology Observing similarities in cell structures All cells have some common organelles that perform identical functions Plasma membrane, cytoplasm, and ribosomes

Fossil Record Earth is Billions of Years Old Fossils In Different Layers of Rock (sedimentary Rock Strata) Showed Evidence Of Gradual Change Over Time

Fossils Imprints of bacteria, leaves or footprints Insects, pollen, or flower parts in amber Tools or pottery shards Bones of organisms in sedimentary rock Cave drawings

Macroevolution Long term changes that make a new species

General patterns for evolution Divergent evolution – different groups evolve from one ancestor

Convergent evolution – two or more different groups evolve so that they resemble one another strongly

Adaptive radiation – organisms spread into new environments and become adapted through natural selection