Iberian rabbit: species hidden by Spain and Portugal for 2 million years
A CSIC team and universities in Spain, Portugal and the UK say the European rabbit is in fact two species split 2 million years ago, one now in decline.
For more than a century, scientists took it for granted that only a single species of rabbit lived on the Iberian Peninsula, at most divided into two regional variants. A study published in 'Biological Conservation' now calls that into question.
According to its authors, from the Institute for Advanced Social Studies (IESA-CSIC) and research centres in Portugal and the United Kingdom, it is in fact a case of two species with separate evolutionary histories: two lineages, a single label.
The study 'When taxonomy lags behind evolution: Consevation implications of cryptic diversity in the Iberian rabbit' (PDF (source in Spanish)), coordinated by Rafael Villafuerte and Miguel Delibes-Mateos together with researchers from the TRAMAS group, distinguishes between the Iberian rabbit ("Oryctolagus algirus") and the European rabbit ("Oryctolagus cuniculus").
The former occurs naturally in Portugal and western Spain, while the latter dominates the eastern part of the peninsula and is the source of the populations introduced in Europe, Oceania and the Americas, where it often behaves as an invasive species.
https://www.sciencedirect.com/science/article/pii/S0006320726003137?via%3Dihub#f0010
The two animals diverged roughly two million years ago, when they became isolated in different refuges during glacial periods: one in the Ebro valley, the other in the Gulf of Cádiz. Since then, the researchers explain, they have barely interbred to any significant extent, despite looking very similar at first glance.
What sets them apart
The differences are not confined to the genome. The Iberian rabbit is smaller, with darker fur, smaller litters and earlier sexual maturity than the European species.
They also differ in their gut microbiome, the composition of their meat and the parasite communities they harbour. In Villafuerte's words, "the two species have always been there; what has changed is our knowledge of them".
https://www.sciencedirect.com/science/article/pii/S0006320726003137?via%3Dihub#f0010
The authors themselves point to precedents: something similar happened with giraffes, long grouped in a single species until genomics revealed that there were in fact four, or with African elephants, now divided into savannah and forest species.
Why does the discovery matter?
This is the aspect that most worries the researchers. While European rabbit populations remain stable or are even increasing across much of their range to the point of causing agricultural damage in some areas, the Iberian rabbit is in marked decline in Portugal and south-western Spain. Managing both as if they were the same species, they argue, has masked the severity of that fall.
The problem is not just statistical. Game restocking operations usually release European rabbits (source in Spanish), which are more abundant and prolific, into areas where only the Iberian rabbit previously lived. That can accelerate its replacement through competition and hybridisation, Delibes-Mateos warns: "We cannot go on managing as a single species two rabbits that have evolved separately for almost two million years".
The issue goes well beyond the animal itself. The rabbit is prey for up to 40 predator species, including the Iberian lynx and the Spanish imperial eagle, so its conservation status shapes that of much of Mediterranean wildlife.
Formally recognising the two species would, according to the authors, make it possible to design monitoring programmes, recovery plans and hunting regulations tailored to each lineage, instead of applying criteria devised for just one of them.
