Genetic barcoding of museum eggshell improves data integrity of avian biological collections

Alicia Grealy,Clare E Holleley,Leo Joseph,Naomi E Langmore

doi:10.1038/s41598-020-79852-4

Abstract

Natural history collections are often plagued by missing or inaccurate metadata for collection items, particularly for specimens that are difficult to verify or rare. Avian eggshell in particular can be challenging to identify due to extensive morphological ambiguity among taxa. Species identifications can be improved using DNA extracted from museum eggshell; however, the suitability of current methods for use on small museum eggshell specimens has not been rigorously tested, hindering uptake. In this study, we compare three sampling methodologies to genetically identify 45 data-poor eggshell specimens, including a putatively extinct bird’s egg. Using an optimised drilling technique to retrieve eggshell powder, we demonstrate that sufficient DNA for molecular identification can be obtained from even the tiniest eggshells without significant alteration to the specimen’s appearance or integrity. This method proved superior to swabbing the external surface or sampling the interior; however, we also show that these methods can be viable alternatives. We then applied our drilling method to confirm that a purported clutch of Paradise Parrot eggs collected 40 years after the species’ accepted extinction date were falsely identified, laying to rest a 53-year-old ornithological controversy. Thus, even the smallest museum eggshells can offer new insights into old questions.

Highlights

Natural history collections are often plagued by missing or inaccurate metadata for collection items, for specimens that are difficult to verify or rare
The world’s natural history collections contain ca. 5 million specimens of avian eggshells[1], that can be used to address a myriad of otherwise intractable questions[3,4]
To fully realise the scientific potential of the vast repository of avian biodiversity data held in egg collections, we need to improve the confidence of species identification in eggs

Summary

Introduction

Natural history collections are often plagued by missing or inaccurate metadata for collection items, for specimens that are difficult to verify or rare. Et al.[8] demonstrated that DNA extracted from just 10 mg of museum eggshell can be used to identify species through the amplification and sequencing of molecular ‘barcodes’.

Results

Conclusion