Molecular Evolution

By

John Doroshenk

Overview:

• History of Evolutionary Thought

• Competing Theories

• Topics in Biotechnology that deal with Evolutionary Understanding

History of Evolutionary Thought

Genesis-Chapter 1, Verse 1:

“And God created great whales, and every living creature that moveth, which the

waters brought forth abundantly, after their kind, and every winged fowl after his kind:

God saw that it was good.”

History Of Evolutionary Thought

Creationism

• Life and all of its existences are creations of god.

• The scientific name of this was given by Carolus Linnaeus as the “fixity of species.”

• It was Linnaeus’ goal to fit every species into a neat and strongly ordered taxonomy.

History of Evolution

• Believed that as the environment changed, an animal’s activity patterns would also change

• This Results in increased or decreased use of certain body parts

• As a result of use or disuse, body parts became altered.

Jean Baptiste Lamarck

History of Evolutionary Thought

• More beneficial traits will cause a species to have a higher reproductive success

• This success will cause the trait to be express with higher frequency in the population

• Also known as “Decent with Modification”

Charles Darwin’s Natural Selection

Competing Theories of Evolution on the Molecular Level

• Neutral Theory

• Natural Selection Theory

• Hypermutation

Neutral Theory

• Neutral alleles can be thought of as junk DNA or recessive genes

• At the molecular level most evolutionary change and most of the variability within species are by random drift of mutant alleles that are selectively neutral or nearly neutral

• So molecular evolution is caused by random events

Neutral Theory

For Example:

On an island of a hundred people, five people have type O blood and everyone else has type A blood. Then five type O people died in a car crash. The population has only A blood type. This genetic make up is purely random.

Neutral Theory

• Sees a mutation arise in one individual by chance

• Unless it is extremely advantageous, the spread to an entire population is governed entirely by chance.

Natural Selection

• States that natural populations contain a sufficient amount of genetic variability to respond to almost any kind of selection

• Environmental stresses are the driving factor for reproductive advantages and the force behind evolution

Hypermutation

• A new source of evolution

• A variation of Lamarck’s use and disuse thoery

• States: Cells may have mechanisms for choosing which mutations will occur

• Mutate to survive in dangerous situations

Hypermutation

• Research for this was conducted on bacteria that could not feed on lactose.

• The bacteria were placed in an environment that only contained lactose

• Mutations arose giving the bacteria the ability to use lactose

Hypermutation

Explanations

• Occurs possibly because the cells are under physiological stress and the DNA is more likely to break under such conditions

• These mutations could be an evolutionary adaptation to increase mutations in certain genes that correspond to starvation

Topics in Biotechnology that need Evolutionary Understanding

• The Molecular Clock

• Bacterial Resistance

• Darwinian Medicine

Molecular Clock

• Is an abstraction of the common observation that the number of amino acid or nucleotide substitutions separating a pair of species is roughly proportional to the time back to the their common ancestor

• Used to date divergences of species in the past

Molecular Clock

• Useful for Anthropologist.

• After extracting DNA from useable remains, can be placed in relative time to other species

Antibiotic Resistance

• All three theories of evolution influence antibiotic resistance

• An already present pool of variance creates a high reproductive advantage to some bacteria

• The high reproduction rate allows for mutations to arise in neutral sections of DNA that can create advantages

Antibiotic Resistance

• The possibility of Hypermutation in bacteria has them create new abilities to survive stressful situations

Darwinian Medicine

• Humans evolved along with diseases

• Therefore, humans evolved to coexist with the diseases

• New diseases arise when the environment that humans evolved in is changed

• Treating these diseases could be as simple as changing the living environment to that of our earlier human ancestors

Darwinian Medicine

• SIDS: Sudden Infant Death Syndrome

Found in only modern industrialized societies. No link could be found between genes, diet, or disease to explain SIDS.

• After many sleep studies; it was found that in modern industrial societies, parents and children do not co-sleep, in other societies they do.

Darwinian Medicine

• Humans have evolved to learn their cognitive patterns of breathing by mimicking that of the mothers.

• SIDS has never been found in a co-sleeping household

Darwinian Medicine

• Other aspects of our culture that science is striving to fix with biotechnology may be a result of changes in our environment that we did not evolve from:

• Such as diseases resulting from the influx of available dietary fat from our industrialized food market

Summary

By understanding the basic principles of evolution and the theories behind molecular evolution, biotechnology can be more efficient when combating such things as new diseases, problematic bacteria, and questions of our origin.

A New Biblical Interpretation

Ephraim Racker--

“On the fifth day God polymerized ATP, GTP, UTP, and CTP and created ribonucleic acid and God saw that it was good. On the sixth day the Lord said it was not good for RNA to be alone and He caused a deep sleep to fall upon RNA and He took a (rib)onucleic acid and made DNA from it, and RNA and DNA were both naked but they were not ashamed.”