Letters to Nature

Nature 407, 183-186 (14 September 2000) | doi:10.1038/35025058; Received 6 January 2000; Accepted 20 June 2000

Genetic evidence for female host-specific races of the common cuckoo

H. Lisle Gibbs1, Michael D. Sorenson2, Karen Marchetti1,3, M. de L. Brooke4, N. B. Davies4 & Hiroshi Nakamura5

  1. Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada
  2. Department of Biology, Boston University , Boston, Massachusetts 02215, USA
  3. Department of Zoology, Downing Street, University of Cambridge, Cambridge CB2 3EJ, UK
  4. Faculty of Education, Shinshu University , Nagano 380, Japan
  5. Present address: Department of Biology 0116, University of California at San Diego, La Jolla, California 92093, USA.

Correspondence to: H. Lisle Gibbs1 Correspondence and requests for materials should be addressed to H.L.G. (e-mail: Email: gibbs@mcmaster.ca).

The common cuckoo Cuculus canorus is divided into host-specific races (gentes)1. Females of each race lay a distinctive egg type that tends to match the host's eggs, for instance, brown and spotted for meadow pipit hosts or plain blue for redstart hosts2, 3, 4. The puzzle is how these gentes remain distinct. Here, we provide genetic evidence that gentes are restricted to female lineages, with cross mating by males maintaining the common cuckoo genetically as one species. We show that there is differentiation between gentes in maternally inherited mitochondrial DNA, but not in microsatellite loci of nuclear DNA. This supports recent behavioural evidence that female, but not male, common cuckoos specialize on a particular host5, and is consistent with the possibility that genes affecting cuckoo egg type are located on the female-specific W sex chromosome6. Our results also support the ideas that common cuckoos often switched hosts during evolution7, 8, and that some gentes may have multiple, independent origins, due to colonization by separate ancestral lineages.