Evolution

Evolution- change in population over time

Evolution- Darwin

Darwin father of modern evolutionary theoryGalapagos IslandsHMS Beagle

Darwin HMS Beagle Trip around the world

Scientists who influenced Darwin

Lamarck- organisms change due to the pressures of their environment, traits are acquired

He proposed that by using or not using its body parts, an individual tends to developdevelop certain characteristicscharacteristics, which it passespasses on to its offspringoffspring.

Scientists who influenced Darwin- Lamarck

Example:Example:A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

Natural Selection Natural Selection-

organisms with traits best suited to the environment survive

have more offspring

Natural Selection Example: Peppered Moths during the

Industrial Revolution

Natural Selection

Extinction- permanent loss of a species

5 mass extinctions throughout history

Evidence for Evolution 1. Fossils 2. Comparative anatomy 3. Comparative embryology 4. Biochemistry 5. Genetic evidence 6. Direct evidence

Evidence for Evolution

1. Fossils mold or cast of organism leftin rock, fossilized

bone and teeth life becomes

more complex over time

record is incomplete

Evidence for Evolution

Most complete fossil record is for the horse

Evidence for Evolution

Relative dating- layers in rock

bed used to date organisms

Deeper is older, shallow is younger

tell when organisms lived in reference to other organisms

older organisms show simpler body structure, while more recent organisms are more complex

many fossils show strong similarities to existing organisms

Evidence for Evolution

Evidence for Evolution Radioisotope dating- uses half-life of

element to estimate age of organism

Carbon is used frequently

Evidence for Evolution phylogeny-

description of the lines of descent of plants and animals as they lived from one to the next

(how they are related)

Evidence for Evolution2.  Comparative Anatomy- the study of the structures of different organisms

homologous parts modified structures among different groups of descendants

Evidence for EvolutionComparative Anatomy

Evidence for EvolutionComparative Anatomy

analogous parts- structures in organisms that have no common origin but serve the same function

Example: bird’s wing, bat’s wing and insect’s wing

Evidence for EvolutionComparative Anatomy

vestigial organs- organs having no functions in the living organism

Vestigial pelvis and femur in whales Vestigial toes in the horse

Evidence for EvolutionComparative Anatomy

Vestigial spurs on a snake

Evidence for EvolutionComparative Anatomy

What vestigial organ do we have????

Evidence for Evolution

3. Comparative Embryologythe study of developing plants and animals

Evidence for EvolutionBelow is the pictures of embryos for a fish, human,

rabbit, tortoise, and chicken. Can you guess which one is each type of organism?

1 2 3 4 5

Evidence for Evolution Comparative EmbryologyHere the pictures of the second set of

development is added. Can you tell now? 1 2 3 4 5

Evidence for Evolution How about now? 1 2 3 4 5

Evidence for EvolutionComparative Embryology- The complete picture

Evidence for Evolution 4. Biochemistry comparison of DNA and proteins in

the body Example: comparison of

hemoglobin (blood protein) in human, chimp, and dog. Human and chimp hemoglobin more alike than dog

Evidence for Evolution

The closer related the fewer differences in DNA and proteins

Evidence for Evolution 5. Genetic

Evidence Mutations-

mistakes in the genetic code Causes changes in

populations over time

Evidence for Evolution 6. Direct Evidence Rapid Evolution

Strains of bacteria becoming resistant to antibiotics

Weeds and pesticides Insects and pesticide

Adaptations Adaptation- change in a species that

makes it better suited to its environment

Large feet for standing in the sand

A hump to store nutrition during long trips or when food or water is scarce

Calluses on the the knees to protect from abrasion

Long eyelashes to protect their eyes from the sand when the wind is blowing

Nostrils that close to keep sand out

Fur inside the ears to protect inner ear from sand

Types of Adaptations

Structural Changes in structure or anatomy Example: bird’s beak or claws Mimicry- a harmless species

resembles a harmful one, predators learn to avoid both species

Camouflage- species features blend in with the environment

Mimicry

Camouflage

                                                                                      

                                                          

Types of Adaptations

Physiological Changes in chemical

makeup Examples:

digestion enzymes, snake venom, octopus ink

Types of Adaptations Behavioral Responses to the environment Example: bird migration

Mechanisms for Evolution Species- group of organisms that

can interbreed AND produce viable offspring

Populations evolve NOT individuals

Origin of a Species

Common Misperception: Individuals Evolve

Species evolveNOT individuals

“And now there go the Wilsons!... SeemsLike everyone’s evolving except us!”

Mechanisms for Evolution Gene pool- all the alleles for

a trait in the population Over time gene pools shift to

traits that are best suited to the environment

Allelic frequency- the percent of any specific gene in a population

Genetic Equilibrium- when the percentage of alleles in a population remains stable over time

Natural Selection acts on variation in a population

1. stabilizing – favors average individual

2. directional – favors one extreme variation

3. disruptive – favors both extremes of variation

Natural Selection acts on variation in a population

Stabilizing selection

Directional Selection

Disruptive selection

Origin of Life on Earth

Spontaneous generation- non-living materials can produce life, life could be created out of nothing, from the air

Disproving Spontaneous Generation

Origin of Life

Biogenesis- living organisms only come from other living organisms

Origin of Cells Earth approximately 4.6 billion years

old Beginning- earth’s atmosphere Hot,

gases like CO2 and nitrogen, little O2

Gases helped to create the atmosphere

Origin of Cells 3.5 to 4 billion years ago Organic Molecules Protocells Prokaryotic cells (heterotrophs) First simple autotrophs/producer Eukaryotic cells Multicellular organisms

Origin of a Species

Speciation – formation of a new species, members of similar populations no longer interbreed

Origin of a SpeciesGeographic Isolation Physical barrier divides population River, canyon, mtn. splits group

Two species of squirrel split by the Grand Canyon

 Patterns in Evolution

Adaptive radiation – one ancestral species evolves into a number of species to exploit a number of habitats.

Patterns in Evolution Divergent evolution- one species

evolves into two species with different characteristics (get more and more different from each other)

Patterns in Evolution Convergent evolution – distant or

unrelated species evolve similar characteristics to take advantage of similar environments Example: fish and dolphin

Evolution