Hatching time as an indicator of environmental incompatibility and outbreeding depression in intraspecific salmon hybrids
Abstract:We analysed hatching times of hybrids between two spatially separated pink salmon Oncorhynchus gorbuscha populations. We repeated the experiment in independent even‐ and odd‐year broodlines. In 1996 and in 1997, we made F1 hybrids from Auke Creek (Juneau, Alaska) females and Pillar Creek (Kodiak, 1000 km away) males and F1 controls from Auke Creek parents. Families were reared and released at Auke Creek. F2 hybrids, controls, and backcrosses were made from F1 returns in 1998 and 1999. In 2001, we made F1 hybrids at Pillar Creek with native females and Auke Creek males. Pillar Creek ancestry prolonged development: At Auke Creek, hybrid families (half Pillar Creek ancestry) developed more slowly (more Accumulated Temperature Units between fertilization and hatch; P < 0·0001) than did controls (only Auke Creek ancestry). At Pillar Creek, families with only Pillar Creek ancestry developed more slowly than did hybrids with half Auke Creek ancestry. Development times of backcrosses were intermediate between those of hybrids and controls. The variation in development times between Auke Creek and Pillar Creek pink salmon has a genetic component that probably results from local adaptation and illustrates a mechanism that can lead to outbreeding depression in intercrosses between salmon populations (e.g., occurring between wild and translocated stocks).
Document Type: Research Article
Affiliations: University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, 11120 Glacier Highway, Juneau, AK 99801, U.S.A.).
Publication date: December 1, 2004