Vocal Learning part I

Question 1

Auditory learning

Answer 1

• auditory learning is associating a sound and action, but cannot reproduce sounds themselves
• vocal learning is not possible without auditory learning

Question 2

Vocal learning

Answer 2

• ability to imitate and reproduce sounds
• imitation of a heard sound
• auditory feedback needed - to hear a sound you create and establish if it is the same as the intended sound

Question 3

Poole et al (2005)

Answer 3

elephants are also vocal learners

- imitate a sound of a lorry

Question 4

Vocal immitation

Answer 4

• ability to incorporate into one’s vocal repertoire novel sounds/ calls that are perceived in the environment
• based on ability to display auditory learning and vocal learning
• e.g. bottlenosed dolphins
• e.g. lyre birds can imitate the call of at least 20 species and other forest sounds

Question 5

All vocal learners have close relatives who do not show vocal learning. Why? Jarvis (2006)

Answer 5

1. vocal learning evolved independently from a common ancestor
2. common ancestor of VL birds and VL mammals, but VL learning was lost multiple independent times in closely related bird and mammalian groups
3. all birds mammals and reptiles have vocal learning to various degrees, but vocal learning birds and mammals independently amplified this trait to develop full vocal learning

Question 6

Vocal learning evolved independently from a common ancestor

Answer 6

• would be very coincidental

Question 7

Common ancestor of VL birds and VL mammals, but VL learning was lost multiple independent times in closely related bird and mammalian groups

Answer 7

• if this were the case, then similarities are not so remarkable, and there must eva strong natural selection to extinguish vocal learning

Question 8

All birds mammals and reptiles have vocal learning to various degrees, but vocal learning birds and mammals independently amplified this trait to develop full vocal learning

Answer 8

• structure doesn’t always follow behaviour

- if this is the case, then non-learning species should have primordial brain structures for vocal learning

Question 9

Pre-existing connectivity

Answer 9

• connections of anterior and posterior vocal pathways in both birds and mammals

Question 10

Jarvis (2006)

Answer 10

What selects for vocal learning?

1. individual identification
2. semantic communication
3. territory defence and mate attraction
4. rapid adaption to sound propagation in different environments

Question 11

Individual identification

Answer 11

• each VL learner learns own individual song
• BUT not a unique characteristic of vocal learners due to anatomical and physical differences
• due to VL, can be identified by name, so likely that identification is not a driving force

Question 12

Semantic communication

Answer 12

• attach a label to an object
• BUT vervet monkeys can use innate calls to communicate semantically
• VL birds also use innate calls - not learned imitations
• most semantics are al innate

Question 13

Territory defence and mate attraction

Answer 13

• VL birds use learned vocalisations to defeat/attract mates
• e.g. singing in humans can use variability
• varied frequency modulation
• mate attraction is a major driving force

Question 14

Rapid adaption to sound propagation

Answer 14

• non VL produce their vocalisations only in specific habitats
  VL change frequency of calls to allow for better communication - move around more

Question 15

Predation strong selection factor for vocal learning

Answer 15

• nice and varied singing may also be more attractive to predators as calls stand out more than non-vocal learners (which can be habituated to)
• animals with more varied calls attract more mates, but die more because they are prey
• handicap principal

Question 16

Predation strong selection factor against vocal learning

Answer 16

• vocal learners are top predators normally e.g. humans and whales
  Bengalese finches bred in captivity for last 250 years show more variability in songs, because there are no predators - Kazuo and Okanoya (2002)

Question 17

Jarvis conclusion of vocal learning

Answer 17

• predator pressure overcome first to see if vocalisation diversify
• after predation pressure is overcome
• what selects for vocal learning?: mating preferences, need for a rapid adaption to communicate in varied environments
• what selects against?: predation

Question 18

Jarvis (2006) paper

Answer 18

• brain pathways in birds and humans are similar
• therefore, must be common selection pressures
• in birds and humans, there are brain regions in the cerebrums that control the acoustic structure of their vocal behaviour, but in non-vocal learners, their vocalisation centres are only in the midbrain and medulla regions

Question 19

Stoeger et al (2012)

Answer 19

• vocal imitation has evolved in many species
• Korean formants and fundamental frequencies, put trunk inside mouth to make a vocal tract like a humans
• Koshik the elephant was able to make Korean vowel sounds
• humans were able to identify the vowel sounds
• apes cannot make human speech 0 stems from poor cortical-motor control of the larynx and the vocal tract
• Koshiks F1 and F2 matched the humans
• BUT cannot do x-ray images to see positioning of tongue