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Patterns of Evolution: Endosymbiosis, Sexual Reproduction, and Diversity of Life

This overview explores key patterns in evolution, including the endosymbiotic theory which posits that complex eukaryotic cells arose from prokaryotic invaders. It highlights the evolution of sexual reproduction and its role in increasing genetic diversity, alongside the emergence of multicellularity. Additionally, the text discusses extinction events, adaptive radiation in Anole lizards, convergent evolution in aquatic species, and coevolution between plants and pollinators. It touches on gradualism, punctuated equilibrium, and the impact of developmental genes and mutations on evolution.

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Patterns of Evolution: Endosymbiosis, Sexual Reproduction, and Diversity of Life

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Presentation Transcript

  1. Patterns in evolution: 17-2, 17-4

  2. Endosymbiotic theory • Proposes that complex cells arose from smaller prokaryotes invading the larger eukaryotes. • The cells that used oxygen to make ATP became mitochondria. • Those that could photosynthesize became chloroplasts. • Evidence: both contain DNA different from nuclear DNA

  3. Sexual reproduction • Eukaryotic cells begin to reproduce sexually. • The reshuffling of genes greatly increases gene combinations and variation. • This increaseddiversity and the speed of evolutionary change Tetrahymenathermophila

  4. Multicellularism • Began a few million years after sexual reproduction. • Life became multicellular, experiencing great diversity over time. • All developed in the sea. • Because of their soft bodies, few fossils remain. microfossils hydra

  5. Big ideas of evolution: Extinction • 99% of all species once living are now extinct • Most succumb to natural selection • Mass extinctions have several causes • Survivors experience a burst of evolution, producing many new species Diatrymas: 55-65 MYA stood 2 m tall

  6. Adaptiveradiation Anole lizards of the Caribbean islands • A single species or a small group of species evolve into many diverse forms, living in different niches.

  7. Convergent evolution • Unrelated organisms can develop to look similar to others if they adapt to the same environment • Ex: all species that swim in the water are streamlined, with paddles for locomotion Shark, dolphin, and penguin represent aquatic fish, mammal, and bird species

  8. Coevolution • Organisms that are closely connected often evolve together • Occurs often in flowers and their pollinators • Plants evolve poisons to ward off insects that eat them, who become immune over time.

  9. Gradualism • The idea that evolution happens at a slow, steady pace. • Exception: horseshoe crabs have changed little from their fossils.

  10. Punctuated equilibrium • Evolution can proceed at different rates • There can be long periods of stability, then brief periods of more rapid change

  11. Developmental genes and body plans • Master control genes guide the development of major body parts in animals • Small changes in the expression of developmental genes can cause large changes in the adult Antennapedia and wingless fruit flies

  12. Plant and animal mutations

  13. The human evolutionary tree

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