LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 25 The History of Life on Earth Lectures by Erin Barley Kathleen Fitzpatrick 2011 Pearson Education, Inc.
Early Earth
Polymers Self Replication Protocells 1. Abiotic synthesis of small organic molecules 2. Joining of these small molecules into macromolecules 3. Packaging of molecules into protocells 4. Origin of self-replicating molecules 2011 Pearson Education, Inc.
Amino acids have also been found in meteorites 2011 Pearson Education, Inc.
Miller-Urey type experiments demonstrate that organic molecules could have formed with various possible atmospheres
Abiotic Synthesis of Macromolecules RNA monomers have been produced spontaneously from simple molecules Amino acids have also been joined together to form small proteins Small organic molecules polymerize when they are concentrated on hot sand, clay, or rock 2011 Pearson Education, Inc.
2011 Pearson Education, Inc. Protocells
The fossil record documents the history of life The fossil record reveals changes in the history of life on Earth 2011 Pearson Education, Inc.
The fossil record is biased in favor of species that Existed for a long time Were abundant and widespread Had parts that could readily fossilize 2011 Pearson Education, Inc.
Key events in life s history include: - the origins of single-celled - multi-celled organisms 2011 Pearson Education, Inc. - the colonization of land
Figure 25.7-1 Origin of solar system and Earth Archaean 4 3 Prokaryotes Atmospheric oxygen
Photosynthesis and the Oxygen Revolution Most atmospheric oxygen (O 2 ) is of biological origin Autotrophs were first, consumers later 2011 Pearson Education, Inc.
Endosymbiotic origin of mitochondria and plastids 2011 Pearson Education, Inc.
Endosymbiotic origin of mitochondria and plastids Inner membranes are similar to plasma membranes of prokaryotes Division is similar in these organelles and some prokaryotes These organelles transcribe and translate their own DNA Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes 2011 Pearson Education, Inc.
Figure 25.7-2 Animals Origin of solar system and Earth Multicellular eukaryotes 1 Proterozoic Archaean 4 Single-celled eukaryotes 2 3 Prokaryotes Atmospheric oxygen
The Cambrian Explosion The Cambrian explosion refers to the sudden appearance of a multitude of modern body designs (530 million years ago) first evidence of predator-prey interactions 2011 Pearson Education, Inc.
Figure 25.7-3 Cenozoic Humans Colonization of land Animals Origin of solar system and Earth Multicellular eukaryotes 1 Proterozoic Archaean 4 Single-celled eukaryotes 2 3 Prokaryotes Atmospheric oxygen
How many mass extinctions have there been (50% of species extinct)? 25 1,100 1,000 900 Total extinction rate (families per million years): 20 15 10 800 700 600 500 400 300 Number of families: 5 200 100 Era Period 0 Paleozoic E O S D C P Tr Mesozoic J C Cenozoic P N 0 Q 542 488 444 416 359 299 251 200 145 65.5 0
Massive Death Means Massive Opportunity Mass extinction can pave the way for adaptive radiations 2011 Pearson Education, Inc.
Phylogeny is the evolutionary history of a species or group of related species The discipline of systematics classifies organisms and determines their evolutionary relationships Systematists use fossil, molecular, and genetic data to infer evolutionary relationships 2011 Pearson Education, Inc.
Figure 26.2a Create a cladogram of
Figure 26.2
Create a cladogram of the following 1. AAG CAT ATA CGT 2. GAG CAT ATA CAT 3. ACG GAT ATA CGT 4. ACG GGT ATA CGC
Concept 26.1: Phylogenies show evolutionary relationships Taxonomy is the ordered division and naming of organisms 2011 Pearson Education, Inc.
Figure 26.3 Domain: Bacteria Kingdom: Animalia Domain: Eukarya Species: Panthera pardus Genus: Panthera Family: Felidae Order: Carnivora Class: Mammalia Domain: Archaea Phylum: Chordata
Linking Classification and Phylogeny Systematists depict evolutionary relationships in branching phylogenetic trees 2011 Pearson Education, Inc.
Figure 26.4 Order Family Genus Species Carnivora Felidae Mustelidae Panthera Taxidea Lutra Panthera pardus (leopard) Taxidea taxus (American badger) Lutra lutra (European otter) Canidae Canis Canis latrans (coyote) Canis lupus (gray wolf)
Figure 26.5 Branch point: where lineages diverge Taxon A Taxon B Taxon C Sister taxa Taxon D ANCESTRAL LINEAGE This branch point represents the common ancestor of taxa A G. Taxon E Taxon F Taxon G This branch point forms a polytomy: an unresolved pattern of divergence. Basal taxon
A phylogenetic tree represents a hypothesis about evolutionary relationships Each branch point represents the divergence of two species Sister taxa are groups that share an immediate common ancestor 2011 Pearson Education, Inc.
Concept 26.2: Phylogenies are inferred from morphological and molecular data To infer phylogenies, systematists gather information about morphologies, genes, and biochemistry of living organisms 2011 Pearson Education, Inc.
Sorting Homology from Analogy When constructing a phylogeny, systematists need to distinguish whether a similarity is the result of homology or analogy Homology is similarity due to shared ancestry The more complex two similar structures are, the more likely it is that they are homologous Analogy is similarity due to convergent evolution 2011 Pearson Education, Inc.
Figure 26.7 Convergent evolution of analogous burrowing characteristics.
Evaluating Molecular Homologies Systematists use computer programs and mathematical tools when analyzing comparable DNA segments from different organisms 2011 Pearson Education, Inc.
1 Evaluating molecular 2 homologies 1 2 1 2 Insertion Deletion 3 1 2 4 1 2
Cladistics Cladistics groups organisms by common descent A clade is a group of species that includes an ancestral species and all its descendants Clades can be nested in larger clades, but not all groupings of organisms qualify as clades 2011 Pearson Education, Inc.
Groupings within trees are called clades (a) Monophyletic group (clade) (b) Paraphyletic group (c) Polyphyletic group A A A B C Group Ι B C B C Group ΙΙΙ D D D E E Group ΙΙ E F F F G G G A valid clade is monophyletic, signifying that it consists of the ancestor species and all its descendants
A shared ancestral character is a character that originated in an ancestor of the taxon A shared derived character is an evolutionary novelty unique to a particular clade What are some examples? 2011 Pearson Education, Inc.
Figure 26.11 CHARACTERS Vertebral column (backbone) Hinged jaws Four walking legs Amnion Lancelet (outgroup) 0 0 0 0 Lamprey 1 0 0 0 TAXA Bass Frog 1 1 1 1 0 1 0 0 Turtle 1 1 1 1 Leopard 1 1 1 1 Vertebral column Hinged jaws Four walking legs Lancelet (outgroup) Lamprey Bass Frog Turtle Hair 0 0 0 0 0 1 Amnion Hair Leopard (a) Character table (b) Phylogenetic tree
Figure 26.12 Drosophila Lancelet Frog Zebrafish Chicken Human Mouse In some trees, the length of a branch can reflect the number of genetic changes that have taken place in a particular DNA sequence in that lineage
In other trees, branch length can represent chronological time, and branching points can be determined from the fossil record Drosophila Lancelet Zebrafish Frog Chicken Human PALEOZOIC MESOZOIC 542 251 65.5 Millions of years ago CENOZOIC Present Mouse
Systematists can never be sure of finding the best tree in a large data set Maximum parsimony assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely The principle of maximum likelihood states that, given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events 2011 Pearson Education, Inc.
Figure 26.14 Human Mushroom Tulip Human 0 30% 40% Mushroom 0 40% Tulip 0 (a) Percentage differences between sequences 15% 5% 5% 15% 15% 10% 20% 25% Tree 1: More likely (b) Comparison of possible trees Tree 2: Less likely
Phylogenetic bracketing allows us to predict features of an ancestor from features of its descendants (e.g. dinosaurs) Lizards and snakes Crocodilians Common ancestor of crocodilians, dinosaurs, and birds Ornithischian dinosaurs Saurischian dinosaurs Birds
Relationships reinforced: Birds and crocodiles share several features: four-chambered hearts, song, nest building, and brooding These characteristics likely evolved in a common ancestor and were shared by all of its descendants, including dinosaurs The fossil record supports nest building and brooding in dinosaurs 2011 Pearson Education, Inc.
Figure 26.17 Front limb Hind limb Eggs (a) Fossil remains of Oviraptor and eggs (b) Artist s reconstruction of the dinosaur s posture based on the fossil findings
Concept 26.4: An organism s evolutionary history is documented in its genome Comparing nucleic acids works really well DNA that codes for rrna changes relatively slowly and is useful for investigating branching points hundreds of millions of years ago mtdna evolves rapidly and can be used to explore recent evolutionary events 2011 Pearson Education, Inc.
Two types of homologous genes: Formation of orthologous genes: a product of speciation Ancestral gene Formation of paralogous genes: within a species Ancestral gene Ancestral species Species C Speciation with divergence of gene Gene duplication and divergence Orthologous genes Paralogous genes Species A Species B Species C after many generations
Concept 26.5: Molecular clocks help track evolutionary time A molecular clock uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change In orthologous genes, nucleotide substitutions are proportional to the time since they last shared a common ancestor In paralogous genes, nucleotide substitutions are proportional to the time since the genes became duplicated 2011 Pearson Education, Inc.
Mammal molecular clock Number of mutations 90 60 30 0 30 60 90 120 Divergence time (millions of years)
New-ish: 3 domains of life Eukarya Land plants Dinoflagellates Green algae Forams Ciliates Diatoms Red algae Cellular slime molds Amoebas Animals Fungi Euglena Trypanosomes Leishmania Thermophiles Sulfolobus Green nonsulfur bacteria (Mitochondrion) Spirochetes Halophiles Methanobacterium Archaea COMMON ANCESTOR OF ALL LIFE Green sulfur bacteria Chlamydia Cyanobacteria (Plastids, including chloroplasts) Bacteria
Horizontal gene transfer complicates efforts to build a tree of life Horizontal gene transfer is the movement of genes from one genome to another It occurs by exchange of transposable elements and plasmids, viral infection, and fusion of organisms 2011 Pearson Education, Inc.