• How genetic – development mechanisms influence the assembly of an animal and its internal components
  • How neuronal-hormonal mechanisms, which develop within an animals during its lifetime, control what an animals can do behaviorally


  • The evolutionary history of a behavioral trait as affected by descent with modification from ancestral species
  • The adaptive value of a behavioral trait as affected by the process of evolution by natural selection

Prairie Voles Monogamy:

Selection and Adaptation- Mate guarding ensures that the males will sire of a females offspring (Ultimate)

Hormonal/Nervous System Mechanisms

-Bonding of vasopressin with receptors triggers chemical activity that affects neural pathways, provides the male vole with positive rewards

Genetic-Development Mechanisms

-The avpr1a gene codes for the V1a protein receptor

Proximate and Ultimate Causes are interconnected

What are two possible explanations for dialect differences?

1. Genetic differences (may affect neural mechanisms)

2. Environmental differences (experience ans learning in young males)


Lab Experiments raising crowned sparrows in the lab from both Marin and Berkeley populations

  • Some raised in isolation (only twittered)
  • Some listened to tapes of adult male songs at 10-50 days
  • Start singing at 150 days, full song by 200 days
  • Sang the dialect that they heard

—–Environmental differences

Other Experiment

-Lab-reared isolated white crowns that only hear the songs of another species

Proximate mechanisms include neurophysiology and genetic activity

  • Part of brain where song memories are stored
  • Part of brain that controls sound ‘production
  • Neural mechanisms involve in song matching

Key sensory (environmental) inputs–> gene activity–>changes in biochemistry–>alters neurophysiology mechanisms (song control system)–> learning

ZENK gene activity causes protein production in the brain of a zebra finch after it hears the song of its species

Why sing?

  • Acquire a dialect that can be transmitted more effectively in a particular habitat
  • Matching a song to your social environment
  • Repertoire matching allows neighbor recognition. There territorial success of a male depends on how many song types he shares

Males that learn songs may be more attractive to females

–> Females get info about his dev. history and suitability

Females choose males who can copy their tutors







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