I should add regarding the taxonomy of hybrid parthenogenetic species of Aspidoscelis (whiptail lizards; formerly Cnemidophorus) – there have been several proposals over the years on how to deal with their taxonomy, including alternatives to standard Linnaean nomenclature. Won’t get into the details here but no alternatives have been widely accepted and we still use standard binomial scientific names to denote the hybrid species.
Generally, it has been accepted that even if multiple hybrid events have resulted in parallel lineages, if the same parental species were involved in creating each unisexual lineage, then all those lineages are included under the same species name. A recent change was the lumping of A. flagellicaudus (which was recognized on iNat) under A. sonorae although I believe there is evidence that these two forms arose from separate hybrid events.
1 Like
I believe that’s the case. The best way for me to think about it is using the Olympic Gull (Larus occidentalis × glaucescens). Right now, the taxonomic decision being considered is lumping the Western and Glaucous-winged Gull together despite the fact they are very different. We could elevate Olympic Gull to species status, especially when most Western/Glaucous-winged individuals in Washington or Oregon is 50-75% hybrids, these hybrids are still backcrossing with pure individuals.
But these lizard hybrids are not backcrossing with pure individuals or different species overall because they’re reproducing asexually so they’re creating a large sustainable population and hence the species’ status.
I’m also reminded of a research paper I read called The Avian Hybrids Project: gathering the scientific literature on avian hybridization (Ottenburghs 2015).The first paragraph in the paper is…
“Hybridization, the interbreeding of different species, plays an important role in several evolutionary processes, such as adaptive trait transfer (Arnold 2006, Arnold et al. 2008, Hedrick 2013), adaptive radiations (Seehausen 2004), and the origin of new species (Mavarez & Linares 2008, Abbott et al. 2013, Schumer et al. 2014). However, hybridization can have detrimental effects for the species involved: one of the species can be driven to extinction (Rhymer & Simberloff 1996) or two species can merge into one leading to a loss in biodiversity (Seehausen 2006, Seehausen et al. 2008), so hybridization has also become a relevant topic in conservation (Allendorf et al. 2001, Brumfield 2010).”