Evolutionary Biology Primer

9/3 Lecture (Bio 302)

Anaximander (520 BC)

first to suggest species
change over time

Xenophanes (500 BC)

world’s first
paleontologist (?)

Aristotle (384-322 BC)

scala naturae “Ladder of
being”/ “Great chain of
being”

Scala Naturae (“Ladder of
being”)

the concept of a hierarchical arrangement of nature, placing all beings in a linear order of increasing value and complexity, from inorganic matter at the bottom to God at the top

Bishop James Ussher
(1581-1656)

• Studied the Old Testament to
determine chronology
• Creation dated to October 23rd,
4004 BC

Chronology

the arrangement of events or dates in the order of their occurrence

Georges Louis Buffon
(1707-1788)

• Environment influenced
changes in animal form
• Extended Earth’s age to
70,000 years

William Paley (1743-1805)

• Equates evolution with
chance/randomness

Jean-Baptiste de Lamarck
(1744-1829)

• Strong proponent of evolution
• Inheritance of acquired
characteristics
• A physiological mechanism
for evolution based on
use/disuse (Ex. Giraffes)

James Hutton (1726-
1797)

• Geological change
occurred gradually
• Earth much older than
prevailing view

Sir Charles Lyell (1797-
1875)

• Uniformitarianism
• Popularized ideas of
Hutton
• Friend of Charles Darwin

Uniformitarianism

the geological principle that the Earth's physical, chemical, and biological processes operating today are the same ones that operated in the past and are sufficient to explain all geological phenomena

Erasmus Darwin
(1731-1802)

• Grandfather of Charles
Darwin
• Zoonomia (1794)
• Discussed common
descent but not natural
selection

Voyage of the Beagle (1831-1836)

five-year scientific expedition aboard the HMS Beagle on which Charles Darwin served as a gentleman naturalist, surveying South America's coasts and collecting specimens; provided foundation for groundbreaking theories of evolution

Alfred Russel Wallace

Also know for going on a scientific expedition, collecting similar data to Darwin; Wallace and Darwin worked together on their theories of evolution by natural selection (joint paper presented at the Linnean
Society)

On the Origin
of Species

a work of scientific literature by Charles Darwin that is considered to be the foundation of evolutionary biology (written after his expedition aboard the HMS Beagle)

Theory of Evolution (Broad Definition)

evolution is the theory that the
universe is not constant but instead changing over
the course of time

Theory of Evolution (Biological Definition)

a change in the frequencies of
genes found in natural populations over
generations

Darwins 5 Evolution Theories

1. Organisms are transformed over time
2. Every group of organisms descended from a common
ancestor
3. Species have multiplied over time
4. Evolutionary change takes place through gradual
changes in populations rather than the sudden
production of new types
5. Heritable variation leads to differential survival of
individuals who will then give rise to subsequent
generations (Natural selection)

4 Tenets of Natural Selection

1. Individuals within populations are variable
2. Some of the variation among individuals is
heritable
3. An excess of offspring are produced
4. Survival and reproduction of these offspring is
nonrandom

Four Forces of Darwinian
Evolution

1. Natural Selection

2. Mutation

3. Gene Flow

4. Genetic Drift

Natural Selection

the process whereby organisms better adapted to their environment tend to survive and produce more offspring

Mutation

a lasting change in the DNA sequence of an organism, which can occur spontaneously or be induced by external factors like mutagens

Gene Flow

the process of genetic material being exchanged between different populations or species, typically through the movement of individuals or their gametes

Genetic Drift

variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce

Geneticists

an expert in or student of heredity and the variation of inherited characteristics

Naturalist

an expert in or student of natural history; understood species concepts and speciation but ignorant of advance genetics

Proximate Cause

immediate, mechanistic factors that explain how a behavior or trait functions; focusing on the “how” (Ex. hormones and genes)

Ultimate Cause

an evolutionary explanation of a behavior addressing the “why” by considering long-term adaptive significance for survival and reproduction within a population.