12.2 Applications and skills

12.2.4 Trends in behaviour and learning (HL)

  • Scientists perform laboratory experiments (e.g. Pavlov, Skinner) or field studies (e.g. Lorenz) in order to find trends and patterns in the data from which causal links can be established.
  • The best data is quantitative – this allows for objective analysis and the identification of discrepancies.

Application: Inheritance and learning in the development of birdsong

  • Male songbirds sing to attract mates and defend territories.
  • Isolation experiments involve removing male juveniles from the nest and then tutoring them with recordings of different birdsongs.
  • The data from these experiments demonstrate that there are innate and learned components to singing. The trends are summarised below.
    • Each species sings a different song, and juveniles learn their own species’ song more readily than other songs.
    • Juvenile birds inherit a template of their species’ song. The template song is innate – it is sung without any prior learning.
    • During a sensory period in the first few months of life, juvenile birds are most able to memorise the adult song when they hear it. After this phase, learning becomes more difficult.
    • When the young birds leave the nest, they produce a plastic song which they continue to practise. This is a sensory-motor period.
    • Individual practice leads to small differences in adult birds of the same species. This is the mature phase.

Activity 1: Analysing sonograms

The sonograms of juvenile male swamp sparrows Melospiza georgiana, and song sparrows Melospiza melodia, are compared to normal adult male songs in Figure 12.2.4a. The juveniles were isolated and reared without ever hearing another adult male song.

Figure 12.2.4a – Isolation dataFigure 12.2.4a – Isolation data
Comparison of two songbird species (image adapted from Marler, P. and Sherman, V. (1985) ‘Innate differences in singing behaviour of sparrows reared in isolation from adult conspecific song’. Animal Behaviour 33: 57-71.

  1. Compare the songs of the swamp sparrow and the song sparrow.
  2. Part (c) shows the songs produced by juvenile birds that were deafened at hatching. Suggest a reason for deafening birds in the experiment.
  3. Evaluate the conclusion that singing behaviour is both innate and learned.

Skill: Analysis of invertebrate behaviour

The behaviour of small invertebrates is easy to study in the laboratory because it is mostly innate. Some examples include:

  • Kinesis – introducing an environmental stimulus results in an increased rate of movement. The movement is random and non-directional. Movement stops at a specific threshold for the stimulus.
  • This behaviour aids in survival because the animal has a greater chance of randomly encountering favourable environmental conditions when it is moving quickly in different directions (e.g. cockroaches spin and scatter in light and are relatively inactive in dark conditions).
  • Taxis – a response in which the resulting movement is directional, either towards or away from the stimulus.
  • Tactic responses are classified according to the type of stimulus and direction of the response. For example, mosquitoes locate hosts by detecting the concentration of carbon dioxide. They move towards the source of carbon dioxide, so this is an example of positive chemotaxis.

Figure 12.2.4b – Kinesis and taxisFigure 12.2.4b – Kinesis and taxis
Invertebrate orientation behaviour: kinesis (left) and taxis (right).

Activity 2: How does orientation behaviour affect chances of survival?

Copy and complete the table below:

Invertebrate

Stimulus

Response

Behaviour

Effect on survival

Mosquito

Carbon dioxide

Moves towards source

Positive chemotaxis

Increases chance of obtaining food (blood)

Euglena

Light

 

Positive phototaxis

 

 

Earthworm

Vibration

 

Positive geotaxis

 

Earthworm

Moisture/
humidity

 

Negative hydrotaxis

 

 

Woodlouse

Moisture/
humidity

 

kinesis

 

12.2.4c – short-tailed babblerFigure 12.2.4c – Short-tailed babbler
A sonogram represents the frequency and amplitude of sounds. Follow along with the typical song of the short-tailed babbler Malacocincla malaccensis.

 

Concept help

  • Ethologists are often careful to distinguish between learned and innate behaviours, but in reality the two are at extreme opposite ends of a single continuum. Where would you place birdsongs and filial imprinting along the continuum?

Figure 12.2.4d – Learned innate behaviour

Figure 12.2.4d – Learned innate behaviour

Study hint

You should be able to describe how experiments and field investigations help scientists to look for patterns, trends and discrepancies when studying animal behaviour.

Course link

Individual differences in birdsong and courtship behaviour can lead to differential reproductive success through mate selection. See 12.1.6.

Language help

Writing about animal behaviour is difficult because of the tendency to anthropomorphise (attribute human characteristics or values to other species). Be careful about using objective language.

12.2.4e – woodlouseFigure 12.2.4e – Woodlouse

In the lab

Design an experiment investigating orientation behaviour as a response to a specific stimulus. Woodlice (shown above) and earthworms are good model organisms. Use caution when exposing an animal to artificial stimuli (Aim 8).

Further reading

Some birds have been found to imitate the calls of other species. What is the adaptive advantage of mimicry? Read more and listen to some mimicked calls here: theconversation.com.