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Transcript
Chapter 22 Evidence of Evolution & Phylogenetics Dodo bird Evidence Supporting Evolution Artificial selection human-caused evolution Fossil record transition species Anatomical record homologous & vestigial structures embryology & development Molecular record protein & DNA sequence Artificial Selection Artificial breeding can use variations in populations to create vastly different “breeds” & “varieties” “descendants” of wild mustard “descendants” of the wolf ‘Natural’ Selection in Action Insecticide & drug resistance insecticide didn’t kill all individuals resistant survivors reproduce resistance is inherited insecticide becomes less & less effective Fossil Record Layers of sedimentary rock contain fossils new layers cover older ones, creating a record over time fossils within layers show that a succession of organisms have populated Earth throughout a long period of time Fossil Record Geologist give us time for evolution… Charles Lyell (1797-1875) studied the Temple of Scrapis (Sicily) built on land & used until 200 AD high tide now above temple floor erosion in columns well above high tide Meaning: In less than 2000 years, temple sunk well below sea level, and then was raised up again — natural processes and immense periods of time could produce great changes. “the present is the key to the past” Fossil Record A record showing us that today’s organisms descended from ancestral species Evolutionary Change In Horses 550 500 Body size (kg) 450 Equus 400 350 300 250 Merychippus 200 150 Mesohippus Hyracotherium 100 50 Nannippus 60 55 50 45 40 35 30 25 20 15 10 5 0 Millions of years ago Evolution of Birds Archaeopteryx lived about 150 mya links reptiles & birds Smithsonian Museum, Washington, DC Land Mammal ? ? ? ? Vestigial Organs Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures? Vestigial Organs Modern animals may have structures that serve little or no function remnants of structures that were functional in ancestral species evidence of change over time some snakes & whales show remains of the pelvis & leg bones of walking ancestors eyes on blind cave fish human tail bone This is not LaMarck’s loss from “disuse”! Anatomical Record Homologous structures similarities in characteristics resulting from common ancestry Homologous Structures Similar structure Similar development Different functions Evidence of close evolutionary relationship recent common ancestor Homologous Structures Forelimbs of human, cats, whales, & bats share same skeletal structures similar structure similar embryological development different functions evidence of common ancestor branched off from common 4-limbed ancestor 2006 Fossil Discovery of Early Tetrapod “missing link” from sea to land animals YOUR INNER FISH! Analogous Structures Separate evolution of structures similar functions similar external form different internal structure & development different origin no evolutionary relationship Don’t be fooled by their looks! Solving a similar problem with a similar solution Convergent Evolution Flight evolved in 3 separate animal groups evolved similar “solution” to similar “problems” analogous structures Does this mean they have a recent common ancestor? Those fins & tails Convergent Evolution & sleek bodies are analogous structures! Fish: aquatic vertebrates Dolphins: aquatic mammals similar adaptations to life in the sea not closely related Parallel Evolution Parallel, but separate, evolutionary paths filling similar ecological roles in similar environments, so similar adaptations were selected but are not closely related marsupial mammals placental mammals Parallel Evolution Niche Burrower Placental Mammals Australian Marsupials Mole Marsupial mole Anteater Numbat Anteater Nocturnal insectivore Mouse Climber Marsupial mouse Spotted cuscus Lemur Glider Stalking predator Chasing predator Sugar glider Flying squirrel Ocelot Tasmanian cat Wolf Tasmanian “wolf” Comparative Embryology Similar embryological development in closely related species all vertebrate embryos have similar structures at different stages of development gill pouch in fish, frog, snake, birds, human, etc. Molecular Record Comparing DNA & protein structure universal genetic code! DNA & RNA Why compare these genes? compare common genes cytochrome C (respiration) hemoglobin (gas exchange) Human/kangaroo DNA & proteins are a molecular record of evolutionary relationships Nucleotide substitutions Closely related species have sequences that are more similar than distantly related species 100 Dog/ cow 75 Human/ cow Rabbit/ rodent 50 Horse/ donkey Llama/ cow Horse/cow Sheep/ goat 25 Human/rodent Pig/ cow Goat/cow 0 0 25 50 75 100 Millions of years ago 125 cytochrome c from 33 species Comparative Hemoglobin Structure Human Macaque Dog Bird Frog Lamprey 32 45 67 125 Why does comparing amino acid sequence measure evolutionary relationships? 8 0 10 20 30 40 50 60 70 80 90 100 110 120 Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans Globin Gene Family Tree looking at the DNA sequences of the different globins can show approximate time of divergence Evidence of Evolution by Natural Selection Using Molecular Evidence to check Testable Hypotheses Genome Sequencing What can data from whole genome sequencing tell us about evolution of humans? Primate Common Ancestry? Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo) gorilla (Gorilla) chimpanzee (Pan) human (Homo) 48 48 48 46 Hypothesis: Change in chromosome number? If these organisms share a common ancestor, then is there evidence in the genome for this change in chromosome number? Chromosomal Fusion Testable prediction: If common ancestor had 48 chromosomes (24 pairs), then humans carry a fused chromosome (23 pairs). Ancestral Chromosomes Fusion Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo) gorilla (Gorilla) chimpanzee (Pan) human (Homo) Homo sapiens Inactivated centromere Telomere sequences 48 48 48 46 Centromere Telomere Testing the Human Genome Hillier et al (2005) “Generation and Annotation of the DNA sequences of human chromosomes 2 and 4,” Nature 434: 724 – 731. Ancestral Chromosomes Fusion Homo sapiens Inactivated centromere Telomere sequences Chr 2 “Chromosome 2 is unique to the human lineage of evolution, having emerged as a result of head-to-head fusion of two acrocentric chromosomes Well I’ll that remained separate inbe other primates. The precise a monkey’s fusion site has located in 2q13– …orbeen an ape’s… 2q14.1, where our analysis confirmed the uncle? Cousin? presence of multiple subtelomeric Wait – what 1, 5, 8, 9, 10, duplications to chromosomes 12, 19, 21 and 22. During the formation of does this mean? human chromosome 2, one of the two centromeres became inactivated (2q21, which corresponds to the centromere from chimp chromosome 13) and the centromeric structure quickly deterioriated.” Human Chromosome #2 shows the exact point at which this fusion took place… On the left is a copy of the human chromosome ‘set’. On the right is the respective chromosome for the chimpanzee— our nearest cousin outside our species In case you had any doubts… Building “Family” Trees Closely related species (branches) share same line of descent until their divergence from a common ancestor more like evolutionary “bushes” Eukaryote Classification Old 5 Kingdom system Monera Protists Plants Fungi Animals Prokaryote New 3 Domain system Bacteria Archaebacteria Eukaryotes Protists Plants Fungi Animals Archaebacteria & Bacteria Linnaen Nesting KPCOFGS not used so much more as phylogenetics developed Phylogenetic Trees Plant Diversity Bryophytes non-vascular land plants Pteridophytes seedless vascular plants Gymnosperm pollen & “naked” seeds conifers mosses Angiosperm flowers & fruit flowering plants ferns seed plants vascular plants synapomorphies colonization of land Animal Diversity Cnidaria Porifera sponges jellyfish Nematoda Platyhelminthes Annelida Mollusca Echinoderm Arthropoda segmented flatworms roundworms mollusks worms insects spiders starfish vertebrates backbone segmentation protostomes Chordata coelom deuterostomes body cavity bilateral symmetry; triploblastic tissues multicellularity; diploblastic Ancestral Protist synapomorphies synapomorphies Any Questions??