Evidence Evidence forfor

EvolutionEvolution

What does evolution mean?What does evolution mean?

Individual organisms do NOT evolve; Individual organisms do NOT evolve; populations/species do.populations/species do.

Two meaningsTwo meanings

1. History of life = change of 1. History of life = change of populations over time (really long populations over time (really long time)time)

2. A Process = Natural Selection2. A Process = Natural Selection

1. FOSSILS1. FOSSILS What is a fossil?What is a fossil?

Anything left behind by a once Anything left behind by a once alive organism. Examples include alive organism. Examples include bones, shells, teeth, impressions, bones, shells, teeth, impressions, and feces. and feces.

Rarely Rarely do soft tissues leave a fossil do soft tissues leave a fossil behind.behind.

2. Cladistics (later)2. Cladistics (later) Depicts the evolutionary Depicts the evolutionary

history of a group of related history of a group of related organisms over timeorganisms over time

Ex=Ex=phylogenetic (family) phylogenetic (family) trees trees of of birds, birds, horses & whales horses & whales

Whale Ear Bone is UniqueWhale Ear Bone is Unique

Note changes in Note changes in body proportions body proportions and elongation of and elongation of feet for foot-feet for foot-powered swimming powered swimming in in RodhocetusRodhocetus, then , then later reduction of later reduction of the hind limbs and the hind limbs and feet as the tail-feet as the tail-powered swimming powered swimming of modern whales of modern whales evolved inevolved in Dorudon Dorudon. .

Maicetus inuus

3. Transitional(intermediate) 3. Transitional(intermediate) fossils fossils (aka, “missing links”)(aka, “missing links”)

Organisms that fit between Organisms that fit between major splits in a phylogenetic major splits in a phylogenetic tree. tree.

ExamplesExamples

1. Archeopteryx (p.432) 1. Archeopteryx (p.432)

part bird/part reptilepart bird/part reptile

2. Tiktaalik 2. Tiktaalik (fish(fishamphibian)amphibian)

Inuit word for “fish”)Inuit word for “fish”)

3. Platypus=part mammal/part 3. Platypus=part mammal/part reptile reptile

4. Comparative Anatomy4. Comparative Anatomy

HomologousHomologous structures= structures=

same design, different functions same design, different functions suggests common ancestry with suggests common ancestry with “descent w/ modification”“descent w/ modification”

VestigialVestigial structures= structures=

present but reduced in size w/ no present but reduced in size w/ no apparent function; Ex=appendix, apparent function; Ex=appendix, tailbone, hips in snakes, rear legs in tailbone, hips in snakes, rear legs in whaleswhales

Vestigial StructuresVestigial Structures

5. Comparative 5. Comparative DevelopmentDevelopment Studies the way organisms develop Studies the way organisms develop

during their life cycle—what controls during their life cycle—what controls how they progress from an earlier to how they progress from an earlier to a later stage? Genetics must control a later stage? Genetics must control this process—the more similar two this process—the more similar two organisms develop, the more closely organisms develop, the more closely they should be related. they should be related.

HOX genes found in all animals that HOX genes found in all animals that control body parts / organized from top control body parts / organized from top

downdown

Evolutionary Development Evolutionary Development = =

“Evo Devo”“Evo Devo” The genetic ingredients that assemble you are The genetic ingredients that assemble you are

strikingly similar to those that assemble a fly. So strikingly similar to those that assemble a fly. So why do you and a fly look so different as adults? why do you and a fly look so different as adults? The answer lies in where, how, and for how long The answer lies in where, how, and for how long those ingredients "turn on" during your embryonic those ingredients "turn on" during your embryonic development. The intricacies of this early stage of development. The intricacies of this early stage of life are now being revealed thanks to the new field life are now being revealed thanks to the new field of "evo devo," and that all animals share the same of "evo devo," and that all animals share the same basic toolkit of body-building genes.basic toolkit of body-building genes.

http://www.pbs.org/wgbh/nova/beta/http://www.pbs.org/wgbh/nova/beta/evolution/what-evo-devo.htmlevolution/what-evo-devo.html

SticklebacksSticklebacks shows that the shows that the

control of genes for control of genes for the development of the development of unique body parts unique body parts can accelerate can accelerate speciation speciation depending when depending when during development during development and where on the and where on the body part the genes body part the genes are turned on/offare turned on/off

6. Comparative 6. Comparative BiochemistryBiochemistry

Probably the greatest advance in Probably the greatest advance in supportive evidence in last 25 yearssupportive evidence in last 25 years

The more closely related proteins The more closely related proteins (amino acid sequences) or DNA base (amino acid sequences) or DNA base sequences between organisms, the sequences between organisms, the more closely related on the tree of more closely related on the tree of life that they are.life that they are.

What accounts for the differences? What accounts for the differences?

Examples of Comp. Examples of Comp. Biochem.Biochem.

Human, chimp, gorilla, vs. orangutan

Ape vs. Human KaryotypeApe vs. Human Karyotype

Used to be #12 and #13Human #21 is actually the smallest at50 mbp—originally looked the smallest.

The fused Chromosome #2The fused Chromosome #2

Evidence for fusion:Evidence for fusion: 1. The correspondence of chromosome 2 1. The correspondence of chromosome 2

to two ape chromosomes. The closest to two ape chromosomes. The closest human relative, the bonobo, has near-human relative, the bonobo, has near-identical DNA sequences to human identical DNA sequences to human chromosome 2, but they are chromosome 2, but they are found in two found in two separate separate chromo-somes. (True of the chromo-somes. (True of the more distant gorilla & orangutan.) more distant gorilla & orangutan.)

2. The presence of a 2. The presence of a vestigial vestigial centromerecentromere. Normally a chromosome has . Normally a chromosome has just one centromere, but in chromosome 2 just one centromere, but in chromosome 2 we see remnants of a second. we see remnants of a second.

3. The presence of vestigial telomeres. These are 3. The presence of vestigial telomeres. These are normally found only at the ends of a normally found only at the ends of a chromosome, but in chromosome 2 we see chromosome, but in chromosome 2 we see additional telomere sequences additional telomere sequences in the middle. in the middle.

Chromosome 2 is thus strong evidence in favor of Chromosome 2 is thus strong evidence in favor of the common descent of humans and other apes. the common descent of humans and other apes. According to researcher J. W. Ijdo (HHMI), "We According to researcher J. W. Ijdo (HHMI), "We conclude that the locus cloned in cosmids c8.1 conclude that the locus cloned in cosmids c8.1 and c29B is the relic of an ancient telomere-and c29B is the relic of an ancient telomere-telomere fusion and marks the point at which two telomere fusion and marks the point at which two ancestral ape chromosomes fused to give rise to ancestral ape chromosomes fused to give rise to human chromosome 2.“ (human chromosome 2.“ (Proceedings of the Proceedings of the National Academy of SciencesNational Academy of Sciences , 1991) , 1991)

7. Biogeography7. Biogeography The study of past and present The study of past and present distributiondistribution of of

individual species in the context of individual species in the context of evolutionary theory (over space & time).evolutionary theory (over space & time).

Finding related fossils/living species in Finding related fossils/living species in different locations suggests different locations suggests geographical geographical isolationisolation of different populations of similar of different populations of similar species.species.

Example: camels and llamas are related genetically Example: camels and llamas are related genetically and have similar physical characteristics but and have similar physical characteristics but evolved on different continents (both have Eocene evolved on different continents (both have Eocene cannelid ancestor found in N. America)cannelid ancestor found in N. America)

Geographical Movement & Geographical Movement & Isolation of Organisms Over Isolation of Organisms Over

TimeTime

Plate Plate TectonicsTectonics

225 mya

65 mya

Ex: Ring speciesEx: Ring species a geographic distribution that a geographic distribution that

forms a ring & overlaps at the forms a ring & overlaps at the ends. The many subspecies of ends. The many subspecies of EnsatinaEnsatina salamanders in CA salamanders in CA exhibit subtle morphological exhibit subtle morphological & genetic differences all along & genetic differences all along their range. They all their range. They all interbreed with their interbreed with their immediate neighbors with one immediate neighbors with one exception: where the extreme exception: where the extreme ends of the range overlap in ends of the range overlap in Southern California, Southern California, E. E. klauberiklauberi and and E. eschscholtziiE. eschscholtzii do not interbreed. Why not?do not interbreed. Why not?

Biogeography=the study of how species are Biogeography=the study of how species are scattered across the planet & how they got scattered across the planet & how they got that way—a historical tribute.that way—a historical tribute. Alfred Wallace travelled (1840-1860s) the Alfred Wallace travelled (1840-1860s) the

Amazon & Indonesia, collecting and notating Amazon & Indonesia, collecting and notating thousands of different species including thousands of different species including exactly where he found them. He came to exactly where he found them. He came to the same conclusion as Darwin: the same conclusion as Darwin: biogeography was simply a record of biogeography was simply a record of inheritance; as species colonized new inheritance; as species colonized new habitats and their old ranges were divided by habitats and their old ranges were divided by mountain ranges or other barriers, they took mountain ranges or other barriers, they took on the different adaptations that led to on the different adaptations that led to population distributions they have today.population distributions they have today.

The archipelago known as The archipelago known as the Galapagos Islandsthe Galapagos Islands

MicroMicroevolutionevolution

Changes in allele frequencies of Changes in allele frequencies of a population as a result of a population as a result of natural selectionnatural selection

Ex=finches beak size from small Ex=finches beak size from small to big based on seeds availableto big based on seeds available

Ex=Heterozygote advantage in Ex=Heterozygote advantage in sickle cell/ malaria lab simulationsickle cell/ malaria lab simulation

MacroMacroevolutionevolution Involves origin of speciesInvolves origin of species Novel designs appear almost “out of Novel designs appear almost “out of

thin air” (Cambrian Explosion of Life)thin air” (Cambrian Explosion of Life) Evolutionary Trends begin in one Evolutionary Trends begin in one

branch of the tree of life (ex: opposable branch of the tree of life (ex: opposable thumbs in primates, jaw bone in bony thumbs in primates, jaw bone in bony fish, the amniotic egg in reptiles)fish, the amniotic egg in reptiles)

Adaptive radiation (Darwin’s Finches, Adaptive radiation (Darwin’s Finches, Hawaiian honeycreepers)Hawaiian honeycreepers)

Extinction is a vital part of this.Extinction is a vital part of this.

Batesian MimicryBatesian Mimicry

Industrial MelanismIndustrial Melanism

Variations of the Peppered Moth

How did they evolve into How did they evolve into separate species?separate species?

1. Ecological opportunity1. Ecological opportunity 2. Isolation (geographic or 2. Isolation (geographic or

reproductive)reproductive) 3. “Mistakes” = Changes in the gene 3. “Mistakes” = Changes in the gene

pool pool byby

--natural selection --Evo. Devo. (HOX)--natural selection --Evo. Devo. (HOX)

--symbiogenesis--symbiogenesis --horizontal gene --horizontal gene

(L. Margulis)(L. Margulis) transfertransfer

How fast does evolution How fast does evolution happen?happen?

Metabolic changes can happen in Metabolic changes can happen in fewer than 200 generations for fewer than 200 generations for bacteria.bacteria.

Punctuated equilibrium vs. Punctuated equilibrium vs. gradualismgradualism

(the work of Niles Eldridge and (the work of Niles Eldridge and Stephen Jay Gould)Stephen Jay Gould)

The origin of species—walking The origin of species—walking stick insect in Santa Ynez stick insect in Santa Ynez

mountains of CAmountains of CA

Hawthorne fliesHawthorne flies

Historically mated and laid their eggs Historically mated and laid their eggs on the fruit of the Hawthorne tree.on the fruit of the Hawthorne tree.

Sometime in the mid-1800s, some Sometime in the mid-1800s, some began to prefer apple trees.began to prefer apple trees.

Now both have become genetically Now both have become genetically distinct species.distinct species.

The species of wasps that prey on The species of wasps that prey on them have become genetically them have become genetically separate as well!separate as well!

Never—great science in action but Never—great science in action but remember there will always be remember there will always be “holes.” The beauty of science is “holes.” The beauty of science is its ability to analyze and adjust as its ability to analyze and adjust as evidence is added. evidence is added. ObsevationsObsevationsinferences is where inferences is where scientists often disagree.scientists often disagree.

Evolution—an Evolution—an absolute dogma, absolute dogma,

right?right?

Temporal Paradox=time controversy Temporal Paradox=time controversy for the ancestry of birds (Archeopteryx for the ancestry of birds (Archeopteryx @ 150 mya and @ 150 mya and Microraptor/Deinonychus @ 120 mya) Microraptor/Deinonychus @ 120 mya)

The consensus view is that birds evolved from The consensus view is that birds evolved from dinosaurs, but the most bird-like dinosaurs, and dinosaurs, but the most bird-like dinosaurs, and those most closely related to birds (the those most closely related to birds (the maniraptorans) are known mostly from the maniraptorans) are known mostly from the Cretaceous, by which time birds had already Cretaceous, by which time birds had already evolved and diversified. If bird-like dinosaurs are evolved and diversified. If bird-like dinosaurs are the ancestors of birds they should be older than the ancestors of birds they should be older than birds, but birds, but ArchaeopteryxArchaeopteryx is 155 million years old, is 155 million years old, while the very bird-like while the very bird-like DeinonychusDeinonychus is 120 my old. is 120 my old. This idea is sometimes summarized as "you can't This idea is sometimes summarized as "you can't be your own grandmother.” be your own grandmother.”

Deinonychous (“terrible Deinonychous (“terrible claw”)claw”)

Note: have NOT found feathers ass. w/

Microraptor fossilsMicroraptor fossils

Haekel’s DrawingsHaekel’s Drawings

Very few embryos actually look like his drawings!

Microevolution ≠ origin of Microevolution ≠ origin of speciesspecies

Bird studies in the Galapagos Bird studies in the Galapagos demonstrates directional selection of demonstrates directional selection of phenotype differences back and forth phenotype differences back and forth but never to the creation of new but never to the creation of new species.species.

Industrial Melanism—moths Industrial Melanism—moths often not even found on birch often not even found on birch

treestrees

1. Large cactus finch (Geospiza conirostris)1. Large cactus finch (Geospiza conirostris)2. Large ground finch (2. Large ground finch (Geospiza magnirostris))3. Medium ground finch (3. Medium ground finch (Geospiza fortis))4. Cactus finch (Geospiza scandens)4. Cactus finch (Geospiza scandens)5. Sharp-beaked ground finch (Geospiza 5. Sharp-beaked ground finch (Geospiza difficilis)difficilis)6. Small ground finch (Geospiza fuliginosa)6. Small ground finch (Geospiza fuliginosa)7. Woodpecker finch (Cactospiza pallida)7. Woodpecker finch (Cactospiza pallida)8. Vegetarian tree finch (Platyspiza 8. Vegetarian tree finch (Platyspiza crassirostris)crassirostris)9. Medium tree finch (9. Medium tree finch (Camarhynchus pauper))10. Large tree finch (10. Large tree finch (Camarhynchus psittacula))11. Small tree finch (Camarhynchus 11. Small tree finch (Camarhynchus parvulus)parvulus)12. Warbler finch (Certhidia olivacea)12. Warbler finch (Certhidia olivacea)13. Mangrove finch (Cactospiza heliobates)13. Mangrove finch (Cactospiza heliobates)

(From BSCS, Biological Science: Molecules to (From BSCS, Biological Science: Molecules to Man, Houghton Mifflin Co., 1963)Man, Houghton Mifflin Co., 1963)

Fig. 4.Fig. 4. Representative phenotypes of the parental complete armor ( Representative phenotypes of the parental complete armor (AA), parental low ), parental low armor (armor (BB), F1 mapping hybrid (), F1 mapping hybrid (CC), and F2 mapping hybrid (), and F2 mapping hybrid (DD––GG) generations. The major ) generations. The major

axes of variation in the F2 intercross generation indicate the segregation of armor loss as axes of variation in the F2 intercross generation indicate the segregation of armor loss as a 9:3:3:1 dihybrid Mendelian ratio (red; observed ratio in black) of the parental armor a 9:3:3:1 dihybrid Mendelian ratio (red; observed ratio in black) of the parental armor classes. (classes. (DD) The complete-armor phenotype of the F2 generation. () The complete-armor phenotype of the F2 generation. (GG) The low-armor ) The low-armor

phenotype. (phenotype. (EE and and FF) The complete-plate/low-pelvic structure and complete-pelvic/low-) The complete-plate/low-pelvic structure and complete-pelvic/low-plate recombinant phenotypes, respectively. plate recombinant phenotypes, respectively.

Evolution of CoelomatesEvolution of Coelomates

Study finds “junk” DNA contributes to animal social interactions: Study finds “junk” DNA contributes to animal social interactions: The length of a DNA region (in red) near the vasopressin receptor The length of a DNA region (in red) near the vasopressin receptor gene (green) was discovered to have an effect on social behavior gene (green) was discovered to have an effect on social behavior in voles. Genome data for this same region reveals strong in voles. Genome data for this same region reveals strong similarities in DNA sequences between humans and bonobos similarities in DNA sequences between humans and bonobos (known for its strong social bonds), while DNA of the more-(known for its strong social bonds), while DNA of the more-aggressive chimpanzees differs from both humans and bonobos in aggressive chimpanzees differs from both humans and bonobos in this region. <Credit: Nicole Fuller, Nat. Science Foundation>this region. <Credit: Nicole Fuller, Nat. Science Foundation>

Over 200 different species in Lk. Over 200 different species in Lk. TanganyakiTanganyaki