Subtle genetic clustering among south australian colonies of little penguins (Eudyptula minor): A reply to Colombelli-Negrel et al. (2020)

The identification of genetically distinct populations is a common goal of conservation genetic studies because they can represent demographically independent units—the logical entities for management (Frankham et al. 2010). Furthermore, such studies can also highlight genetic novelties that may be significant for local adaptation, either presently or in the future (Frankham et al. 2010). With these goals in mind, Colombelli-Négrel et al. (2020) recently published data and population genetic analyses of the Australian little penguin, Eudyptula minor (hereafter Eudyptula novaehollandiae; see Grosser et al. 2015). They analyzed individuals from 8 breeding colonies from central-southern Australia (the state of South Australia), represented by a final dataset of 75 individuals and 754 single nucleotide polymorphism (SNP) markers. Colombelli-Négrel et al. (2020) tested for population genetic structuring among these colonies and made a comparison to previous investigations of this question based on mitochondrial DNA (mtDNA) and microsatellite datasets (Burridge et al. 2015). Colombelli-Négrel et al. (2020) advocate the existence of 3 or up to 4 genetic clusters within their study region and suggest that Burridge et al. (2015) falsely inferred only 2 genetic clusters. Here I seek to highlight several aspects of Colombelli-Négrel et al. (2020) that appear erroneous, along with instances of misinterpretation of related work published by different authors. Eudyptula novaehollandiae represents a challenge for typical conservation genetics approaches that rely on an equilibrium between genetic differentiation and contemporary gene flow (Whitlock and McCauley 1999).