Details

Autor(en) / Beteiligte

• Singh, D.
• Reed, S.M.
• Kimmitt, A.A.
• Alford, K.A.
• Stricker, C.A.
• Polly, P.D.
• Ketterson, E.D.

Titel

Breeding at higher latitude is associated with higher photoperiodic threshold and delayed reproductive development in a songbird

Ist Teil von

• Hormones and behavior, 2021-02, Vol.128, p.104907-104907, Article 104907

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Many seasonally breeding animals exhibit a threshold day length (critical photoperiod; CPP) for gonadal growth, and populations breeding at higher latitudes typically have a higher CPP. Much less is known about latitudinal variation in CPP in migratory population that winter away from their breeding range and must time their reproduction to match favorable conditions at their destination. To address the relationship between migration, breeding latitude, and CPP, we held two closely related songbird populations in a common environment. One population is resident (Junco hyemalis carolinensis), the other winters in sympatry with the residents but migrates north to breed (Junco hyemalis hyemalis). We gradually increased photoperiod and measured indices of readiness to migrate (fat score, body mass) and breed (cloacal protuberance volume, baseline testosterone, and gonadotropin releasing hormone challenged testosterone). To estimate breeding latitude, we measured hydrogen isotopes in feathers grown the preceding year. As we predicted, we found a higher CPP in migrants than residents, and a higher CPP among migrants deriving from higher as opposed to lower latitudes. Migrants also terminated breeding earlier than residents, indicating a shorter breeding season. To our knowledge, this is a first demonstration of latitudinal variation in CPP-dependent reproductive timing in bird populations that co-exist in the non-breeding season but breed at different latitudes. We conclude that bird populations appear to exhibit local adaptation in reproductive timing by relying on differential CPP response that is predictive of future conditions on the breeding ground. •Dark-eyed junco populations winter in sympatry and show allochrony in breeding.•Populations differ in critical photoperiod (CPP) to elicit a reproductive response.•Hydrogen isotope measured in post-nuptial feathers can estimate breeding latitude.•Low latitude residents exhibit lower CPP, start breeding earlier and terminate later.•High latitude migrants exhibit higher CPP, delay breeding and terminate sooner.