4/3/2018

Causation

Proximate- How genetic-developmental mechanisms influence the assembly of an animal and its internal components, including its nervous and endocrine systems. 

-How neuronal-hormonal mechanisms, which develop within an animal during its lifetime, control what an animal can do behaviorally. 

Ultimate- 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.

chart

Monogamy in Prairie Voles

Selection and Adaption:

  • Mate guarding ensures that males will sire all the female’s offspring. 
  • In the ventral pallidum, the bonding of vasopressin with receptors triggers chemical activity that affects neural pathways, provides the male vole with positive rewards. 

Genetic-Developmental Mechanisms

  • The avpr1a gene codes for the V1a protein receptor. 

What are the two possible explanations for dialect differences?:

  • Genetic differences (may effect neural mechanisms)
  • Environmental differences ( experience and learning in young males)

Laboratory experiments raising white crowned sparrows in the lab from both Marin and Berkely 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, regardless of which nest they came from. 

Supports the Hypothesis that the song the birds tweet is environmental 

Can we conclude that the genetic information present in the cells of white-crowned sparrows is irrelevent for the development of the bird’s singing behavior?

  • No, Genes construct the learning system.

Other experiments:

  • Lab-reared isolated white-crowns that only hear the songs of another species
    • Don’t sing that song (just twitter like hearing nothing)
  • Lab reared birds that hear both their own species and another species.
    • Sing the white-crowned dialect that it heard

Social experience influences song development

Proximate mechanisms include neurophysiology and genetic activity

  • Part if brain where song memories are stored
  • Part of brain that controls sound production
  • Neural mechanisms involved in songmatching

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

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