Variation in Reproductive Success Across Captive Populations: Methodological Differences, Potential Biases and Opportunities

Abstract

International audienceOur understanding of fundamental organismal biology has been disproportionately influenced by studies of a relatively small number of ‘model’ species extensively studied in captivity. Laboratory populations of model species are commonly subject to a number of forms of past and current selection that may affect experimental outcomes. Here, we examine these processes and their outcomes in one of the most widely used vertebrate species in the laboratory – the zebra finch (Taeniopygia guttata). This important model species is used for research across a broad range of fields, partly due to the ease with which it can be bred in captivity. However despite this perceived amenability, we demonstrate extensive variation in the success with which different laboratories and studies bred their subjects, and overall only 64% of all females that were given the opportunity, bred successfully in the laboratory. We identify and review several environmental, husbandry, life-history and behavioural factors that potentially contribute to this variation. The variation in reproductive success across individuals could lead to biases in experimental outcomes and drive some of the heterogeneity in research outcomes across studies. The zebra finch remains an excellent captive animal system and our aim is to sharpen the insight that future studies of this species can provide, both to our understanding of this species and also with respect to the reproduction of captive animals more widely. We hope to improve systematic reporting methods and that further investigation of the issues we raise will lead both to advances in our fundamental understanding of avian reproduction as well as to improvements in future welfare and experimental efficiency

Commentary: A Bird in the House: The Challenge of Being Ecologically Relevant in Captivity

“…At Fowlers Gap, this adds over 50 min of daylight to the estimates calculated by Beaulieu (2016), and therefore during the key months of breeding the day lengths are actually: August 11 h 47 min; September 12 h 42 min; October 13 h 41 min; November 14 h 39 min. The period of day length that is typically used in the laboratory (around 13.5 Griffith et al, 2017;13.8 h Beaulieu, 2016), matches well with the period of peak breeding (October) in the desert biome at Fowlers Gap, and across central Australia at a similar latitude.…”

“…We agree that these conditions are representative of typical conditions in captivity. In their recent review , also collated temperature, humidity, and day length across a number of representative laboratory studies and found to be similar to those presented by Beaulieu (2016): average temperature 20.7 • C ± 2.1 SD; humidity 48.9% ± 15.0 SD; day length 13 h 51 min (data from Table 1 in Griffith et al, 2017). As outlined below, we think that these laboratory conditions are representative of those experienced by wild zebra finches and that Beaulieu's (2016) representation of Australian climatic and photoperiodic conditions (and the interaction between them) is somewhat misleading.…”

“…The solid straight line is a line of best fit between the mean average temperature of September and November (on the x-axis the means are plotted in the middle of the month, 15 days before and after October). In panel b (i) plots the average temperature (± SD) in captive environments and (ii) plots the average humidity (± SD) in captive environments (data from Griffith et al, 2017).…”

“…Future studies should standardize conditions in captivity as far as possible, and report them (see also Griffith et al, 2017), so that variation in those abiotic factors raised by Beaulieu (2016), are less likely to confound research findings in captivity. There are also good opportunities for further experimental manipulations to examine the physiological effects of light, temperature and humidity in captivity.…”

Feeding on ripening and over-ripening fruit: interactions between sugar, ethanol and polyphenol contents in a tropical butterfly

“…temperature, humidity, light) and artificial (e.g. diet, lack of pathogens, competitors, predators) conditions in captivity have affected their physiology and behaviour (as observed in other species; Griffith et al, 2017). Therefore, the results of the present study may not be entirely comparable to those obtained in wild animals subject to natural conditions, and have to be considered with caution.…”