Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
History of Life Biogeography | Homologies History of Life Learning Objectives • Describe how biogeography and homology provide evidence for evolution • Distinguish between anatomical, molecular, and developmental homologies Fossil Record • Fossil – the preserved traces or remains of living organisms from the past – See progressive change in organisms Fossil Record • Fossil record from Equus genus – Almost complete – Supports theory of common ancestry *Simplified fossil record Fossil Record • Stasis – the periods of time in the fossil record that show limited change Fossil Record • Limitations of fossil record – Fossilization requires specific conditions – Organisms can appear suddenly in fossil record – Incomplete fossilization results in gaps in fossil record Fossil Record • Fossil record supports theory of sequential evolutionary change – Older fossils located in older strata – Younger fossils located in younger strata Fossil Record • Ex) Sequential evolution of the coiled oyster – Coiled oyster shells became • Larger • Thinner • Flatter Biogeography • Biogeography – the study of the distribution of species, organisms, and ecosystems through geologic space and time – Earth’s land masses have moved over time Biogeography • Fossils provide evidence of species that were present across Earth’s original land mass • Allopatric speciation occurred as land mass split – South American and African monkeys share common ancestor Homologies • Homology – the similar features between different organisms resulting from common ancestry – Anatomical – Molecular – Developmental Homologies • Anatomical homology – a group of similar structures between different organisms resulting from common ancestry Homologous Structures ARM LEG Flipper Wing 13 Homologies • Vestigial structure – nonfunctional structure left over from a common ancestor – Ex) Pelvis in whale which lacks hind limbs Homologies • Anatomical homology – Result of common ancestor with that trait • Convergent evolution – Creates similar structures/functions – Are not anatomical homologies Homologies • Molecular homology – the similar stretches of genetic material between different organisms resulting from common ancestry – Shared genetic code indicates common ancestor – Organisms likely to be related have retained same stretches of DNA #5 Molecular and Genetic Evidence AKA Biochemical Evidence Two closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences. This also gives evidence of a common ancestor. 17 18 Homologies • Developmental homology – the similar features in the embryos of different organisms resulting from common ancestry – Hox genes – the sections of the genome that allow embryos to develop structures in the correct place – Similarities in development in different species indicate common ancestry #3 Embryology Embryo (early developmental stage) gives evidence of evolution Identical larvae, different adult body forms Similar embryos, related but diverse organisms Shows common Larva ancestry Adult crab Adult barnacle 20 #3 Embryology Vertebrates all share gill slits and a tail in their early embryo stage; Share a common ancestor 21 History of Life Learning Objectives • Describe how biogeography and homology provide evidence for evolution • Distinguish between anatomical, molecular, and developmental homologies