Evolutionary Paradigm
PARADIGM- set of assumptions about the nature of the
phenomena to be studied and how it will be approached. An
accepted theoretical framework
Evolutionary Theories
• Natural Selection Theory
• Sexual Selection Theory
• Sociobiological Theory
Natural Selection Theory
Understand the basic principles of
Natural Selection
•Know some examples of NS in action
•Understand terms
Individuals within a species vary
Behavioral variation
50
45
40
35
Run
Vocalize
freeze
Move low
Mob
30
25
20
15
10
5
0
Predation response
Traits are heritable
Behaviors related too...
• More offspring will be produced than will
survive (drives competition)
• Individuals with favorable traits will have an
advantage over others without those traits.
• Survival is dependent on context
• Those that survive will produce more
offspring.
VI. Some examples
• Peppered Moth
Modern Day Finches
Directional Selection
Behavioral changes
Unit of selection
• Natural Selection works on the level of
the individual.
• Evolution works on the level of the
population
Sexual Selection
Sexual Selection
• The differential ability of individuals to acquire
mates- features evolve, not to enhance survival but
to make one more attractive to a mate and compete
for access to mates.
•Male male competition
•Female choice
Sociobiology
• “the systematic study of the biological
basis for behavior” E. O. Wilson
– Reproductive success- number of offspring
produced.
– Genetic fitness- the relative contribution of
one’s genes into the next generation
TERMINOLOGY
• Natural Selection- mechanism of evolutionary
change for survival. Evolution- changes
(genetic) within populations.
• Sexual Selection- mechanism of evolutionary
change for reproduction (mate choice,
competition).
• Sociobiology-theory that states that behavior
has a biological basis, behaviors can function
as adaptations to improve overall
reproductive success of an individual.
More Terminology
• Reproductive success- # offspring one
produces that reaches reproductive age.
• Fitness- an individual’ relative genetic
contribution to the next generation.
• Adaptation- functional response of an
organism to it’s environment.
• Selection Pressure-environmental forces that
influence the Reproductive Success of an
individual.