Natural Selection

A simple, powerful idea that explains how populations of reproducing individuals respond to environmental challenges.

Speaker Notes:

A Professor selects a book, you select a course. Those processes have a fundamental difference from natural selection. The fundamental difference is that reproduction of individuals is an essential part of natural selection, but not of the other selections.

Assignment

Read Chapter 2 Water & Carbon
Think About
- What is the result of a cycle of replication?
- How many individuals will there be if 5 individuals each go thru 3 cycles of replication?

Speaker Notes:

Natural Selection

Is a process associated with a population of individuals and their offspring, NOT change within the life of an individual.
The reproduction of individuals is essential to natural selection.

Speaker Notes:

Actually you are a population of cells – a clone. Sometimes a clone within your body grows when it should not.

Natural Selection

‘Success’ of biological individual is defined by longer persistence and/or increase in abundance within the population.
- Resistance to antibiotics is a classical case of selection leading to ways to survive.
The process that generates ‘winners’ and ‘losers’ within the population is named natural selection.

Speaker Notes:

The term ‘fitness’ is used to measure success.

Populations with individuals that reproduce are subject to Natural Selection

Natural selection takes place in all systems with reproduction (formation of new individuals similar to their parent(s)).
Study of BIOLOGY encompasses all things with reproduction of this type.
Viruses reproduce in this way, even though virus are not considered living organisms, they are subject to natural selection.

Speaker Notes:

Biology studies everything that can reproduce (in some environment).

Attributes of LIFE

Boundary (inside and outside)
Capacity to acquire energy and materials from the environment
Processing of materials and energy so that duplication can take place.
Storage of information necessary to build parts needed for acquisition and processing, ie. Reproduction.

Speaker Notes:

Actual history is unknowable but probable history is the subject of science.

“Reproduction’ implies a boundary, energy and material acquisition and duplication.

Early Organisms

The simplest living systems today are a logical place to look for ideas about origin of organisms.
What elements and molecules are part of even the simplest organism that exists today?

Speaker Notes:

Getting down to basics.

Components of all LIFE

WATER as the ‘matrix’ in which chemical reactions take place.
Life requires large molecules with many atoms.
CARBON as the only element which bonds in a way that macromolecules can be built.
SIX elements essential to all organisms are: Hydrogen, Carbon, Nitrogen, Oxygen, Phosphorus and Sulfur.

Speaker Notes:

Basic chemistry seems to be the starting place.

Macromolecules

Nucleic acids = DNA & RNA
Proteins, all enzymes are proteins
Carbohydrates, CH2O
Lipids or fats
- Form boundary between inside & outside

Speaker Notes:

Early Life: Current Ideas

All studied individuals store information in nucleic acids, but perform function thru proteins.

RNA can store information and perform some function, so it seems likely that the earliest organisms were based on RNA.

Speaker Notes:

RNA is sequence (info storage) but it also folds into 3D shapes (function at cellular level).

Organisms evolve, even the simplest

Once individuals can reproduce, there will be evolution (= differential reproduction).
Individuals of a type that survives longer and/or reproduces faster will increase their proportion of the population.
The ability to vertically transmit or ‘pass on’ attributes to offspring results in a increase in the abundance of the better function.

Speaker Notes:

Autonomous reproduction implies evolution.

SCIENCE versus LAW

In science, observations are the source of truth.
Human institutions, i.e., law, give authority to the words written by the government (or religion).
Science explores the (real =observable) world and authority emerges from interpretation of observations and the ability to create (engineer) things.
Science tries to get close to ‘truth’, but never expects not to learn more in future.

Speaker Notes:

Governmental law and religious law are based on the authority of institutions rather than being subject to constant revision (though in fact they too are revised.)

EVOLUTION of organisms

Biological evolution is both a logical consequence of a population of reproducing individuals, i.e. an inescapable DEDUCTION.

AND based on observation of patterns of structure and sequence among species that exist today and those that are now extinct, i.e. INDUCTION.

Speaker Notes:

Creationists often agree with the inescapable logic, but use ‘microevolution’ to describe the process they acknowledge must be true. The say that ‘microevolution’ does not explain ‘species’.

EVOLUTION requires reproduction and populations.

All change is not similar to biological evolution. Changes, such as the ‘evolution of universe’ or your mental or physical growth via education and exercise, are not based on competition among reproducing individuals.
Most change through time (development) is fundamentally distinct from biological evolution.

Speaker Notes:

Populations are a necessary element of natural selection.

Evolution and Continuity

There is a continuity of life – like begets like, but offspring are not typically identical to either parent.
At the molecular level the continuity of life is maintain by the duplication process of the nucleic acid DNA.

Speaker Notes:

Having a mother and a father is NOT necessary for evolution. Populations of cells that reproduce uniparentally will evolve.

HOMOLOGY

Sequence similarity (of bases in DNA or amino acids in protein) is a direct, unambiguous and quantifiable way to measure similarity (& differences) between pairs of species and among collections of species.

Speaker Notes:

The problems of counting differences with sequences are not insignificant, but they are much less unclear than comparisons of structure at ‘higher’ levels such as morpho;ogy.

Alternatives to EVOLUTION

Almost all peoples of the world have generated ‘ORIGIN’ stories.
In the USA, historical circumstances generated a subgroup of Christians that believe the English words of the Bible tell the true CREATION of the world.
Known as fundamentalists, they insist on having their origin story taught in schools.

Speaker Notes:

The origin story of Christians and Jews dominates culture because of abundance within the USA not because it is intrinsically more logical than that of Shoshone or another culture.

‘Intelligent’ Design: Origin

Religion and government have been separated by USA government, so that the religious beliefs of the majority are not promulgated thru the government (as they were long ago in Europe and currently are elsewhere in world).
Biblical creation stories have been morphed into ‘Intelligent Design’ in an attempt to get religious ideas into schools.

Speaker Notes:

‘Intelligent’ Design: The Idea

ID asserts that complexity can only arise by the design process. As life is complex, it must have been designed.
ID is impossible to evaluate by observation, because it asserts everything that ever existed was designed.
As you study biology, you may conclude that the ‘design’ is flawed.

Speaker Notes:

I added the quotes to the word ‘Intelligent’ because as you study biology to are likely to conclude the design was very flawed.

Take Home Problem

The fact that people choose to wear clothes suggests that, if they were designed, they could have been designed better.
Pretend you are a designer. What features would you add to the human body to design it better than what we have now?

Speaker Notes:

There are so many better ways one can think of. Biologists would hypothesize some things will improve but others are constrained by trade-offs.

Vocabulary

Abundance, N
Attribute
Authority =law?
Population growth
Homology

Intelligent design
Natural selection
Offspring
Reproduction
Populations

Speaker Notes:

What words would you pick from this lecture?