Evidence of Evolution

I. Biological Evolution:• A change in a population from one generation

to the next

BUT ITS NOT THAT SIMPLE – all things can change but if they do not involve descent through genetic inheritance, it cannot be described as an example of biological evolution

Changes are due to GENE FREQUENCY in populations

Changes involve DESCENT of a different species from a COMMON ANCESTOR over generations

Leaves on trees change color and fall over several weeks.

NOT

EVOLUTION!

Mountain ranges erode over millions of years.

NOT

EVOLUTION!

A genealogy illustrates change with inheritance over a small number of years.

NOT

EVOLUTION!

Over a large number of years, evolution produces tremendous diversity in forms of life.

EVOLUTION!

Traits

change

over time

II. Evidence of Evolution

a. Fossil Records: RELICS or IMPRESSIONS of organism from the past preserved in ROCK showing the succession of organisms

• Each layer is a boundary of CATACLYSMIC CHANGES that destroyed many species at that time in an area

FloodsEruptionsMeteor Impacts

• The DIVERSITY of species increased the chance of some species surviving these events due to adaptation over time

b. Homology: different organisms share similar characteristics from a COMMON ANCESTOR

• Structures may look similar, BUT HAVE A DIFFERENT FUNCTION

• Altered version of ancestors

• Ex: All MAMMALS have same number of bones in forelimb, but the position, shape, and function are different

What are the functions of each of these limbs?

We call these homologous structures…similar structure, different function

c. Analogy: different organisms share similar characteristics despite DIFFERENT ANCESTORS

• Structures look similar, AND HAVE THE SAME FUNCTION

• Changes due to response to ENVIRONMENT, nature shaped ADAPTATIONS

• Ex. Winged animals: insects, birds, and bats

d. Embryonic Development:• Adult homology MAY NOT be apparent• During mitotic divisions, stages of offspring

DEVELOPMENT of different species may have similar appearances (morphologies)

• Similar structures may develop different functions

Ex. All vertebrates have PHARYNGEAL POUCHES – which develop into gills in fish, or tubes in ears that connect to throat in humans

e. Biochemistry: similar species share nearly the same genetic machinery• Similar DNA and

RNA sequences• Similar AMINO

ACID sequencing• Ex. Hemoglobin

and digestive enzymes

Learning CheckAnswer the following questions based on the information covered in your notes.

Example:1. Humans, chimpanzees, whales, and bats all have the same bones in their arms, fins, or wings.a. What type of evidence is this? homologous structures

b. Why is this evidence of evolution?This is evidence of evolution because if all these animals have the same bones, they probably all evolved from one creature that had those bones a very long time ago. Some of its children evolved (or changed) into humans, and other evolved into whales or bats or chimpanzees.

2. Scientists find fossilized bones of a huge animal that doesn’t exist today.

a. What type of evidence is this?

b. Why is this evidence of evolution?

3. The human gene for your muscle protein is different from monkey muscle protein in 4 places and different from a chicken’s gene in 25 places.

a. What type of evidence is this?

b. Why is this evidence of evolution?

4. Honey possums lick nectar from flowers using a long tongue made of soft muscle. Butterflies lick nectar from flowers using a long tongue made of hard protein.

a. What type of evidence is this?

b. Why is this evidence of evolution?

5. Humans, rabbits, and zebras all have an appendix, an extra piece in their digestive system, although in humans it’s much smaller.

a. What type of evidence is this?

b. Why is this evidence of evolution?

Let’s get this straight…• Misconceptions about humans…The phylogeny of

living species most closely related to us looks like this

It is important to remember that:• Humans did not evolve from chimpanzees.

Humans and chimpanzees are evolutionary cousins and share a recent common ancestor that was neither chimpanzee nor human.

• Humans are not "higher" or "more evolved" than other living lineages. Since our lineages split, humans and chimpanzees have each evolved traits unique to their own lineages.

From http://evolution.berkeley.edu