Chapter 24/25 Evidence of Evolution Geological, Anatomical, Chemical, Molecular 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 the wolf “descendants” of wild mustard

‘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

 Charles Lyell ( )  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” Geologist give us time for evolution…

Fossil Record  A record showing us that today’s organisms descended from ancestral species

Evolutionary Change In Horses Millions of years ago Equus Hyracotherium Mesohippus Merychippus Nannippus Body size (kg)

Evolution of Birds Smithsonian Museum, Washington, DC  Archaeopteryx  lived about 150 mya  links reptiles & birds

? ? ? ? Where are the Intermediates? 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 Solving a similar problem with a similar solution Don’t be fooled by their looks!

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?

Convergent Evolution  Fish: aquatic vertebrates  Dolphins: aquatic mammals  similar adaptations to life in the sea  not closely related Those fins & tails & sleek bodies are analogous structures!

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 marsupial mammals placental mammals placental mammals

Parallel Evolution NichePlacental MammalsAustralian Marsupials Burrower Mole Anteater Mouse Lemur Flying squirrel Ocelot Wolf Tasmanian “wolf” Tasmanian cat Sugar glider Spotted cuscus Numbat Marsupial mole Marsupial mouse Anteater Nocturnal insectivore Climber Glider Stalking predator Chasing predator

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 Millions of years ago Horse/ donkey Sheep/ goat Goat/cow Llama/ cow Pig/ cow Rabbit/ rodent Horse/cow Human/rodent Dog/ cow Human/ cow Human/kangaroo Nucleotide substitutions  Comparing DNA & protein structure  universal genetic code!  DNA & RNA  compare common genes  cytochrome C (respiration)  hemoglobin (gas exchange) Closely related species have sequences that are more similar than distantly related species  DNA & proteins are a molecular record of evolutionary relationships Closely related species have sequences that are more similar than distantly related species  DNA & proteins are a molecular record of evolutionary relationships Why compare these genes?

cytochrome c from 33 species

Comparative Hemoglobin Structure LampreyFrogBird Dog MacaqueHuman Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans Why does comparing amino acid sequence measure evolutionary relationships?

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)48 gorilla (Gorilla)48 chimpanzee (Pan)48 46 human (Homo)46 Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo)48 gorilla (Gorilla)48 chimpanzee (Pan)48 46 human (Homo)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? 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: Testable prediction: If common ancestor had 48 chromosomes (24 pairs), then humans carry a fused chromosome (23 pairs). Centromere Telomere Ancestral Chromosomes FusionHomo sapiens Inactivated centromere Telomere sequences Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo)48 gorilla (Gorilla)48 chimpanzee (Pan)48 46 human (Homo)46 Chromosome Number in the Great Apes (Hominidae) orangutan (Pogo)48 gorilla (Gorilla)48 chimpanzee (Pan)48 46 human (Homo)46

Testing the Human Genome “Chromosome 2 is unique to the human lineage of evolution, having emerged as a result of head-to-head fusion of two acrocentric chromosomes that remained separate in other primates. The precise fusion site has been located in 2q13– 2q14.1, where our analysis confirmed the presence of multiple subtelomeric duplications to chromosomes 1, 5, 8, 9, 10, 12, 19, 21 and 22. During the formation of 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.” Hillier et al (2005) “Generation and Annotation of the DNA sequences of human chromosomes 2 and 4,” Nature 434: 724 – 731. Human Chromosome #2 shows the exact point at which this fusion took place… Chr 2 Ancestral Chromosomes FusionHomo sapiens Inactivated centromere Telomere sequences Well I’ll be a monkey’s …or an ape’s… uncle? Cousin? Wait – what does this mean?

In case you had any doubts… 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

Building “Family” Trees  Closely related species (branches) share same line of descent until their divergence from a common ancestor  more like evolutionary “bushes”

Archaebacteria & Bacteria Classification  Old 5 Kingdom system  Monera  Protists  Plants  Fungi  Animals  New 3 Domain system  Bacteria  Archaebacteria  Eukaryotes  Protists  Plants  Fungi  Animals Prokaryote Eukaryote

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 Angiosperm flowers & fruit seed plants vascular plants mosses ferns conifers flowering plants colonization of land synapomorphies

Cnidaria Platyhelminthes sponges jellyfish flatworms roundworms Nematoda MolluscaArthropodaChordata AnnelidaEchinoderm mollusks multicellularity; diploblastic Ancestral Protist tissues bilateral symmetry; triploblastic body cavity segmentation Porifera Animal Diversity coelom starfish vertebrates segmented worms insects spiders backbone protostomes deuterostomes synapomorphies

Any Questions??

put peppered moth in lab 17

Peppered Moths  Dark vs. light variants Year % dark % light

Peppered Moths  What was the selection factor?  early 1800s = pre-industrial England  low pollution  lichen growing on trees = light colored bark  late 1800s = industrial England  factories = soot coated trees  killed lichen = dark colored bark  mid 1900s = pollution controls  clean air laws  return of lichen = light colored bark  industrial melanism