The Diederik cuckoo, Chrysococcyx caprius, is a small Afrotropical bird in the family Cuculidae. It is taxonomically related to 13 other species within the genus Chrysococcyx and is migratory in sub-Saharan Africa. It has a unique breeding behaviour of being a brood parasite: Breeding pairs lay their eggs in the nests of a host species and hatchlings expel the eggs of the host species. The aim of the present study was to investigate diversity in two circadian clock genes, Clock and Adcyap1, to probe for a relationship between genetic polymorphisms and their role in circannual timing and habitat selection (phenology) in intra-African migrants. DNA extracted from blood was used for the PCR amplification and sequencing of clock genes in 30 Diederik cuckoos. Three alleles were detected for Clock with similar genotypes between individuals from the Northern and Southern breeding ranges while 10 alleles were detected for Adcyap1, having shorter alleles in the North and longer alleles in the South. Population genetic analyses, including allele frequency and zygosity analysis, showed distinctly higher frequencies for the most abundant Clock allele, containing 10 polyglutamine repeats, as well as a high degree of homozygosity. In contrast, all individuals were heterozygous for Adcyap1 and alleles from both regions showed distinct differences in abundance. Comparisons between both clock genes and phenology found several phenotypic correlations. This included evidence of a relationship between the shorter alleles and habitat selection as well as a relationship between longer alleles and timing. In both instances, evidence is provided that these effects may be sex-specific. Given that these genes drive some of the synchronicity between environments and the life cycles of birds, they provide valuable insight into the fitness of species facing global challenges including climate change, urbanisation and expanding agricultural practices.
Die Diederik koekoek, Chrysococcyx caprius, is ’n klein Afrotropiese voël in die Cuculidae familie. Dit is taksonomies verwant aan dertien ander spesies in die genus Chrysococcyx en is ’n migrant in sub‐Sahara Africa met die unieke teling fenologie van broeisparasietisme (broeipare lê nul eiers in die neste van gasheerspesies en kuikens verwyder die eiers van hul gashere). Die doelwit van die huidige studie is om diversiteit in twee gene van die sirkadiese klok, Clock en Adcyap1, te ondersoek om moontlike verwantskappe tussen polimorfisme en fenologie soos tydsberekening en habitat keuse te ontleed. DNS vanaf bloed monsters was gebruik vir PKR amplifikasie en reeksbepaling in dertig Diederik koekoek. Drie allele was bespeur vir die Clock geen, met soortgelyke genotipes onder individue van beide die Noordelike en Suidelike teling streke, terwyl tien allele bespeur is vir die Adcyap1 geen, met korter allele in die Noord en langer allele in die Suid. Genetiese analise van die populasies, insluitend alleel frekwensie en sigositeit, het kenmerkend hoër frekwensies getoon vir die mees algemene Clock geen, met tien poli‐glutamien herhalings, sowel as ‘n hoë mate van homosigositeit. In teenstelling was alle individue heterosigoties vir die Adcyap1 geen met afsonderlike verskille in mate. Vergelykings tussen beide gene en fenologie het verskeie korrelasies ontbloot. Onder andere is tekens vir ‘n verwantskap tussen korter allele en habitat seleksie sowel as langer allele en tydsberekening gevind. In beide gevalle is verdere bewyse gelewer dat die effek seks‐spesifiek mag wees. Aangesien hierdie gene die ritmiek van jaarlikse lewensiklusse reguleer verskaf hul belangrike insig tot die fiksheid van spesies wat globale uitdagings die hoof bied.
Keywords: Adcyap1; Chrysococcyx caprius; Clock; avian; brood parasitism; circannual; cuckoo; intra‐African; migration.
© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.