When taxonomy lags behind evolution: Conservation implications of cryptic diversity in the Iberian rabbit

Abstract

Cryptic species are an overlooked component of global biodiversity with major implications for conservation. We examine the European rabbit (Oryctolagus cuniculus) as an example of how taxonomy can lag behind evolutionary divergence, generating conservation risks. Rabbits in the Iberian Peninsula are currently classified as two subspecies: O. c. algirus, restricted to Portugal and southern and western Spain, and O. c. cuniculus, in eastern Spain and introduced worldwide. Genomic evidence indicates that these lineages diverged approximately 2 million years ago and have remained largely reproductively isolated. Consistent differences in morphology, behaviour, reproduction, ecology, and demographic trends further support their recognition as distinct evolutionary entities. Nevertheless, both lineages continue to be managed as a single species in conservation policy, hunting regulations, and translocation programmes. This mismatch is particularly concerning because populations of O. c. algirus are undergoing marked declines, whereas O. c. cuniculus populations remain mostly stable or increasing. Continued translocations of O. c. cuniculus into areas occupied by declining O. c. algirus risk accelerating demographic and genetic replacement of the latter through competition, introgression, and maladaptive hybridisation. We therefore propose formal recognition of O. algirus as a distinct species, the Iberian rabbit, reflecting its independent evolutionary history, ecological distinctiveness, and conservation status relative to O. cuniculus.