BIOL 1108 Lecture Notes - Lecture 45: Endocrine System, Natural Selection
Behavior
• Any action by an organism
• Generally, a response to a stimulus (a piece of
information gathered about the environment)
• Everything an organism does & how it does it – Muscular activities (e.g., movement, sound
production) – Secretion of scents – Learning
• Behavior is part of the phenotype
Core Concepts
• For any behavior, we can ask what causes it, how it develops,
what adaptive function it serves, and how it evolved.
• Animal behavior is shaped in part by genes acting through the
nervous and endocrine systems.
• Learning is a change of behavior as a result of experience.
• Orientation, navigation, and biological clocks all require
information processing.
• Communication involves an interaction between a sender and a
receiver.
• Social behavior is shaped by natural selection.
Important questions: Causality
• PROXIMATE (“how”) – What stimulus triggers a behavior? – What are the genetic, anatomical,
&
physiological mechanisms underlying the
behavior?
• ULTIMATE (“why”) – Why did natural selection favor the behavior? – How does the behavior
improve fitness?
Using Tinbergen’s Questions
Example: Why does a bird sing?
1. Causation? Need to communicate a message
2. Development? Varies across species
3. Adaptive Function? Territory, mate, offspring, etc.
4. Evolutionary History? Dinosaurs sang…
Behavior evolves by natural selection, just like
any other traits.
• Behavioral traits vary in populations – These traits have a (partial) genetic basis
• Individuals with advantageous behaviors
reproduce more
