EVOLUTION

EVOLUTIONEVOLUTIONEvidence of Change

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Evolution:Evolution:

The process by which modern organisms have descended from ancient organisms



Charles DarwinCharles DarwinFirst published his book “Origin of

the Species by Means of Natural Selection” in 1859. .



In this book, he explained that if you look back far enough in time, you would see that all species have a common ancestor. He called this the principle of Common Descent.



He also explained that because of the

VARIATION that naturally occurs within species, some individuals will have more FITNESS to survive than others. Those individuals will have a better chance of REPRODUCING, and passing on the advantageous GENES.

He called this process ADAPTATION.



How does a longer neck help a giraffe adapt to its environment?

http://www.hww.ca/hww2.asp?id=94

The mountain sheep is very agile, it has high ability to climb steep terrain

http://www.youtube.com/watch?v=YadP3w7vkJA&feature=related

http://www.gla.ac.uk/~gbza22/jpegs/birds/starling.jpg

Birds keep track of 7 others -gives them ability to stay close together

AdaptationsAdaptations

Inuit people, who live in the extreme cold of the Arctic, have short, stout bodies that conserve heat.

Plant adaptationsPlant adaptations

Venus Fly TrapCaptures animalsAcquires minerals

for photo- synthesis

An example: Bird vocalizationAn example: Bird vocalizationBirds call/sing to

◦Attract mates ◦Defend their territory

SongbirdCawing crow

Owl hoots

Reid et al. (2005) used 20 years of data from song sparrows on Mandarte Island, B.C., Canada

Result: males with larger song repertoires contributed more offspring and grand-offspring to the population◦This was not because females mated to

males with larger repertoires laid or hatched more eggs

◦Rather, these males (1) lived longer; and (2) reared a greater proportion of hatched chicks to independence

http://209.85.173.104/search?q=cache:FQlkM9-WVrIJ:www.sjsu.edu/faculty/fry/123/birdsong2.pdf+bird+songs,+fitness&hl=en&ct=clnk&cd=3&gl=ca

Where is the evidence?Where is the evidence?

1. Fossil evidence (palaeontology)2. Radioactive dating in sedimentary

rock (stratigraphy)3. Comparative embryology4. Comparative biochemistry

EVIDENCE OF EVOLUTION IN EVIDENCE OF EVOLUTION IN STONESTONEHutton and Lyell proposed that Earth

was very old and had changed slowly and gradually over time.

James HuttonCharles Lyell

FOSSILS:FOSSILS: Geologists have discoveredfossils of organisms that no longer EXIST, but have very similar CHARACTERISTICS to present-day species. QuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.

Many of these fossils could be compared and placed in a plausible SEQUENCE of change from ANCIENT organisms to the present day. This isn’t proof, but it is a piece of EVIDENCE.



Fossils are formed along with SEDIMENTARY rock. Sometimes, parts of organism’s bodies are PRESERVED.



Other times, rock forms around the HARDER parts of the dead organisms, (the BONES, WOOD, SHELLS) and it creates a bit of a MOLD. The ORGANIC material from the bodies will eventually be REPLACED by harder, longer lasting INORGANIC compounds inside those “molds”. They call this process PETRIFICATION.



Fossilization is a tricky process, requiring VERY SPECIFIC CONDITIONS, and so the fossil record has to be put together like a PUZZLE that has many broken and lost pieces!



Fossil successionof the Trilobite genera

Cambrian

Wherever these fossils are found they always occur in the same succession.

Ordovician

Silurian

Devonian

http://cache.eb.com/eb/image?id=46897&rendTypeId=4 http://www.geocities.com/mrbbug1/meso4.jpg

Discovery of fossilsSome of the fossils resembled living organisms; others did not

The Fossil RecordThe Fossil Record

What are sedimentary rocks?◦ Rock that forms when grains of eroded rock and

other materials are carried to the bottom of a body of water and build up under pressure into layers

http://www.ucmp.berkeley.edu/education/explorations/tours/stories/middle/C7.html

Most fossils are foundin sedimentary rock

B. Sedimentary Rocks and Geology Using the LAW OF

SUPERPOSITION geologists can find the RELATIVE date of fossils.





The law states that the LOWER layers of SEDIMENTARY rock are OLDER than the upper layers. Fossils found in the layers of rock are the same RELATIVE AGE as the rock itself.

Through RADIOACTIVE DATING geologists are able to tell the ABSOLUTE age of some preserved bones that have been uncovered, or determine the absolute age of some of the ELEMENTS that are found in the IGNEOUS rocks surrounding the fossils.

Using RADIOACTIVE DATING, geologists have calculated that the Earth is about 4.5 BILLION years old.



The fossil record shows us that change happened first on the EARTH, and then change in the organisms FOLLOWED.



2. EVIDENCE IN 2. EVIDENCE IN COMPARATIVE EMBRYOLOGYCOMPARATIVE EMBRYOLOGY

When you compare EMBYROS of several species in an EARLY STAGE of their development, they are very SIMILAR in APPEARANCE. Later, the EMBRYOS look vastly DIFFERENT. Why?



The theory of EVOLUTION explains these different animals had a COMMON ANCESTOR that passed down the sequence of developmental GENES. As the animals evolved, they added steps to the developmental sequence.



3. Evidence in Comparative Anatomy

Many species have HOMOLOGOUS structures – body parts that have very similar INTERNAL structure but they have different FUNCTIONS.



Homologous structures: parts of different organisms, often quite dissimilar, that developed from the same ancestral body parts.

Bird Wing

Porpoise Flipper

Homologous structures: body parts that have very similar internal structure but they have different functions

Bird Wing

Porpoise Flipper

Examples include: human arm and BAT WINGS

human arm and WHALE FLIPPERS

One of the classic examples of a homologous structure is the pentadactyl (= five digit) limb.

VESTIGIAL STRUCTURESThere are also

many VESTIGIAL structures – body parts present that are similar to those of other organisms, but are NO LONGER USED.



Examples include: HUMAN APPENDIX

SNAKE LEGS



Cassowary

Wisdom teeth

Human tail boneMale breast tissue and nipples

The wings on flightless birds (e.g. The cassowary)◦ Wings of a bird are adapted for flight◦ Not completely useless, use for balance during running

Human tail bone (coccyx)◦ Fused vertebrae, only vestige left of tail that other animals

use for balance, communication, (for some primates as a prehensile limb)

Wisdom teeth◦ Human jaw got smaller over time◦ How may have it been beneficial to our ancestors?

Male breast tissue and nipples◦ Was man descended from a woman? No! During early

stages of fetal development a fetus is sexless. Later in development testosterone causes sex differentiation.

◦ A small number of men have been able to lactate. Cancer can grow on male and female breast tissue

Whiptail lizards

Hind leg bones in whales

Fake sex in virgin whiptail lizards (vestigial behaviour)◦ Only females exist in several species of lizards◦ Reproduce by parthenogenesis (unfertilized egg

develops into a new individual, forming clones of themselves)

◦ They still try copulating, though futile

Hind leg bones in whales◦ Biologists believe that for 100 MYA the only

vertebrates on Earth were water-dwelling creatures with no arms or legs

◦ The “fish” began to develop hips and legs, eventually able to walk out of water

◦ Land dwelling creatures evolved, some mammals moved back into water (50 MYA) ancestors of modern whales

◦ Traces of hind legs—can be seen even now.

The Blind Fish Astyanax Mexicanus

The Sexual Organs of Dandelions

Sexual organs of dandelions◦ Like many flowers that have proper organs (stamen and

pistil) for sexual reproduction, but do not use them◦ Instead, they make clones of themselves◦ Asexual reproduction can be a good strategy in an

environment that is constant, if species are well suited

Blind fish◦ Species of fish dwell in caves deep underground off the

coast of Mexico; they cannot see◦ Has eyes, but as they develop in egg, their eyes

degenerate◦ Born with collapsed remnant of eye covered by a flap of

skin◦ Fish of the same species that live directly above the blind

fish, near the surface where there is plenty of light, have functioning eyes

◦ Scientists have removed lenses from surface water fish, implant them into blind eye fish, can develop functional eye with pupil, cornea, and iris.

Snakes “legs”

Human appendix

Biologists believe it is a vestigial organ left behind from a plant-eating ancestor

**do not confuse HOMOLOGOUS structures with ANALOGOUS structures – ANALOGOUS structures have a similar FUNCTIONS but have very different INTERNAL structure.



Fly wing

Bird Wing

EXAMPLES: Bird Wings and FLY WINGS

Analogous: Whale fin and Fish Fin

Comparative anatomy structuresComparative anatomy structures

Analogous:1. Different

ancestors2. “analogy”=like3. Different

underlying structures

4. Same Function5. Similar

Environments

Homologous:1. Same ancestor2. “homo”=same3. Same underlying

structures4. Different

Functions5. Different

Environments

Comparative BiochemistryComparative BiochemistryAlmost all living

organisms use the same basic biochemical molecules, including DNA, ATP and many enzymes.

In fact, molecules such as hemoglobin have been used to determine how distantly related some species are.

Haemoglobin is the iron-containing protein attached to red blood cells that transports oxygen from the lungs to the rest of the body

http://www.sciencecollege.co.uk/SC/biochemicals/haemoglobin.jpg

The greater the number of differences in the molecule, the more distantly related the organism are.

http://newsimg.bbc.co.uk/media/images/42343000/gif/_42343831_evolution_tree_2_416.gif

Comparative BiochemistryComparative Biochemistrysimilar DNA

sequences= similar gene segments of the DNA

Code for similar traits in closely related species

NATURAL VARIATION



EVOLUTION

Documents

Transcript of EVOLUTION