Evolutionary ParadigmEvolutionary 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 TheoriesEvolutionary Theories

• Natural Selection TheoryNatural Selection Theory

• Sexual Selection TheorySexual Selection Theory

• Sociobiological TheorySociobiological Theory

Natural Selection TheoryNatural Selection Theory

Understand the basic principles of Natural Selection•Know some examples of NS in action•Understand terms

Individuals within a species varyIndividuals within a species vary

Behavioral variation Behavioral variation

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Predation response

RunVocalizefreezeMove lowMob

Traits are heritableTraits are heritable

Behaviors related too...Behaviors related too...

• More offspring will be produced than will survive (drives competition)More offspring will be produced than will survive (drives competition)

• Individuals with favorable traits will have an advantage over others Individuals with favorable traits will have an advantage over others without those traits. without those traits.

• Those that survive will produce more offspring.Those that survive will produce more offspring.

• Survival is dependent on contextSurvival is dependent on context

VI. Some examplesVI. Some examples

• Peppered MothPeppered Moth

Modern Day FinchesModern Day Finches

Directional SelectionDirectional Selection

Behavioral changesBehavioral changes

Unit of selectionUnit of selection

• Natural Selection works on the level of Natural Selection works on the level of the individual. the individual.

• Evolution works on the level of the Evolution works on the level of the populationpopulation

Sexual SelectionSexual Selection

Sexual SelectionSexual 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

SociobiologySociobiology

• “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

TERMINOLOGYTERMINOLOGY• Natural SelectionNatural Selection- mechanism of evolutionary - mechanism of evolutionary

change for survival. change for survival. Evolution- Evolution- changes (genetic) changes (genetic) within populations.within populations.

• Sexual SelectionSexual Selection- mechanism of evolutionary - mechanism of evolutionary change for reproduction (mate choice, change for reproduction (mate choice, competition).competition).

• SociobiologySociobiology-theory that states that behavior has a -theory that states that behavior has a biological basis, behaviors can function as adaptations to biological basis, behaviors can function as adaptations to improve overall reproductive success of an individual. improve overall reproductive success of an individual.

More TerminologyMore Terminology

• FitnessFitness- - an individual’ relative genetic an individual’ relative genetic

contribution to the next generation.contribution to the next generation.

• Reproductive success- Reproductive success- # offspring one # offspring one produces that reaches reproductive age.produces that reaches reproductive age.

• Adaptation-Adaptation- functional response of an functional response of an organism to it’s environment. organism to it’s environment.

• Selection Pressure-Selection Pressure-environmental forces that environmental forces that influence the Reproductive Success of an influence the Reproductive Success of an individual. individual.