A.6 Ethology

Testing a hypothesis—experiments to test hypotheses on the migratory behaviour of blackcaps have been carried out.

BlackcapMale8
Male blackcap warbler (Bird fieldguide)

In the 1950s, blackcap warblers (Sylvia atricapilla), a small European songbird, began to be observed wintering in Great Britain, instead of North Africa. These observations led to the formation of hypotheses regarding blackcap migratory behaviour: were the changes due to inherited (innate) factors, was it a response to the environment or did the birds simply lose the ability to migrate normally?

To test these hypotheses, it was necessary to use experimental methods, as fieldwork would have been unfeasible.  The birds were kept in specially designed cages that could register if birds began to become restless during the migratory season and then what direction they tried to orient towards.

The results showed that the offspring of birds that migrated to Britain oriented consistently in a NW direction, despite being raised in isolation from their parents. Follow-up genetic analysis showed a strong heritability for this trait in both British wintering blackcaps and those from other parts of Europe.  The authors were led to suggest that:

“Under moderate selection intensities and environmental conditions similar to those presented in this study, the southern German blackcap population could evolve into a short-distance migrant in 10-20 generations.” (Berthold and Pulido; p311)

These results represent rapid evolutionary changes in behaviour- it is worth considering what selection pressures are working to promote these changes.  Can you relate this back to the Evolution/Natural Selection topics (5.1/5.2)?

Sources:

Berthold, P and Pulido, F. Heritability of Migratory Activity in a Natural Bird Population.
Proc. R. Soc. Lond. B. 257. 1994. 311-315. Web. Mar 15, 2016. Full text available: at https://www.researchgate.net/profile/Francisco_Pulido/publication/216768532_Heritability_of_migratory_activity_in_a_natural_bird_population/links/0fcfd50c5c5adc29c9000000.pdf

Berthold, P. et al. Rapid microevolution of migratory behaviour in a wild bird species. Nature. 360.  1992. Web. Mar 15, 2016.

“Identify A Blackcap, Sylvia Atricapilla”. Birdfieldguide.co.uk. N. p., 2016. Web. 15 Mar. 2016.

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A.4 Innate and learned behaviour

Looking for patterns, trends and discrepancies—laboratory experiments and field investigations helped in the understanding of different types of behaviour and learning.

Both laboratory experiments and field investigations have been essential in understanding animal behaviour and learning.  Both forms of investigation are necessary: lab experiments allow for the precise control and manipulation of variables, but provide an artificial setting; field investigations provide the natural setting required but can face challenges in controlling the boundaries of the experiment.

A classic 1950s lab study investigated mimicry in butterflies in the lab by providing caged birds with different species and recording their feeding behaviour (van Zandt Brower, 1958). This was based on the observed toxicity of monarch butterflies (Danaus plexippus) and its presumed mimic, the viceroy butterfly (Limenitis archippus). The butterflies were prevented from flying by folding the wings together and then presented to the birds. Control butterflies that did not mimic the coloration of the monarchs  were eaten in every trial by all birds. The monarch was not eaten in any of the trials and the butterfly that mimicked the coloration of the monarch (the Viceroy) was similarly avoided.  The study helped expand our understanding of mimicry and bird foraging behaviour in a very controlled setting.

In contrast, field studies have a range of challenges in ensuring that the behaviour observed is free of bias or manipulation by the presence of the observers. One recent interesting study investigates foraging behaviour of harbour seals in Alaska (Womble et al.). Dive duration and depth were inversely correlated with prey density, which depended on the habitat of the seals (glacial or terrestrial). As part of the investigation, seals had to be captured, sedated, weighed and fitted with data logging devices to record temperature, time and depth. They were then released and the data provided by the devices used to determine their foraging strategy. Obviously, there is some invasiveness in this method, but it does enable the researchers to then collect data on the natural feeding behaviour of the seals.  Field studies regularly involve such trade-offs. Similarly to lab experiments, they must also acknowledge the potential ethical concerns of these studies.

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Data from Womble et al. (2014; p1368)

Extension: Using the graph above, consider the following possible DBQ-style questions:

  1. State the average dive depth for both locations at hour 12. (1)
  2. Compare and contrast the data for terrestrial and glacial seals over the 24 hour period. (2)
  3. Using the data, evaluate the hypothesis that glacial seals spend more time foraging than terrestrial seals. (3).

Sources

Jane van Zandt Brower. “Experimental Studies of Mimicry in Some North American Butterflies: Part I. The Monarch, Danaus Plexippus, and Viceroy, Limenitis Archippus Archippus”. Evolution 12.1 (1958): 32–47. Web. Mar 15, 2016.

Womble, J.N. et al. “Linking marine predator diving behavior to local prey fields in contrasting habitats in a subarctic glacial fjord.” Marine Biology 161. (2014): 1361–1374. Web. Mar 15, 2016. Full-text available for download at: https://www.researchgate.net/publication/261870558_Linking_marine_predator_diving_behavior_to_local_prey_fields_in_contrasting_habitats_in_a_subarctic_glacial_fjord 

2.8 Respiration and Ethics

Assessing the ethics of scientific research: the use of invertebrates in respirometers has ethical implications.

The use of animal models in biological experiments has a long history. Indeed, many of our most important discoveries were made possible by using animal test subjects. However, using animals at any time during an experiment has ethical implications that need to be evaluated.

Any scientific research involving animals will have to satisfy an ethics board as to the justification for using and/or experimenting on animals. Two key issues that scientists have to consider might include: what suffering or pain will the animal experience and are there alternatives to using animals?  There is a process in the UK called the 3R’s – replacement, refinement and reduction of the use of animals in research (Festing, S. and Wilkinson, R.).  This process, while acknowledging that animals may be required in certain circumstances, aims to ultimately reduce these to only the most essential experiments.

There is often a difference in concern between invertebrates and vertebrates in terms of what ethical rules apply to them.  Most people probably care less about the fate of cockroaches or crickets in a respirometer experiment than about the use of mammals in medical research.  However, it is still important to evaluate the ethical use of invertebrates in the same way as vertebrates. In addition to the issues of pain/suffering and replacement, we should consider:

  • whether the animals can be released back into their natural habitat
  • whether it is ethical to remove them in the first pace
  • whether we can minimise any pain or suffering that may take place in the experiment.

The IBO has published a document on the use of animals in experiments and it is very clear that any animal (invertebrate or not) must be treated ethically and must not be subject to any suffering or environment outside its normal range. This link from the Nuffield Foundation outlines an experiment based on this; take note of their ethical issues paragraph after the methods.

Sources:

Allott, Andrew, and David Mindorff. Biology. Oxford: Oxford University Press, 2014. Print.

Festing, Simon, and Robin Wilkinson. The Ethics Of Animal Research. Talking Point On The Use Of Animals In Scientific Research. EMBO Reports 8.6. 2007: 526-530. Web. 27 Jan. 2016.