Paper 8 Discussion Question

In this paper the authors used a relatively common North American bird from a study site located in a very large urban park in a large city where there are likely 100s – 1000s of the birds living. Given that the authors state “Variation among individuals in late learning may reflect variation in their developmental histories upon entering the lab.” do you think that the study would have benefited from using more birds?

Related, what are the benefits vs. the costs of using more or using fewer animals in research studies like this one that involve manipulating hormone levels?

3 thoughts on “Paper 8 Discussion Question

  1. This number of birds was enough to show the effect of T on crystallization of songs.However, the difference in late song learning was not significant between the groups, so they would have a better chance to find the significant difference (if there is) if they used more birds.

    The benefit of using more birds is the more robust result.
    The biggest cost of using more birds is affecting the population in ways we cannot really predict. We cannot be sure what is the number of birds and the degree on manipulation that will have a very visible or even irreversible effect on the population.

  2. In an ideal world, where you can capture and keep as many birds as you need for your experiment design, without hurting the population, and where you have the resources to conduct your experiments (lab space, money etc.), you have to use more individuals. There should be groups of young from different physiological and song maturation levels, treated with different hormone levels, etc..
    There are finite individuals in the populations, and by removing and treating an individual (even the isolated lab-life is a very stroing treatment), you might hurt the population in some way. Eight individuals might be enough to see whether very strong mechanisim are there or not – and here they found this mechanism.

  3. A larger sample size would benefit the study by showing whether differences between individuals can be explained by natural variation or is caused by the treatment. Benefits of using more individuals include more reliable results and reducing the effects of outliers. However, it is often difficult to capture so many. The care of more individuals can also be more costly. Finally, taking into regard one of the three R’s of animal welfare, reduction, it is better to use fewer individuals when doing invasive experiments.

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