• Effects on fitness traits of intercrossing three geographically separate populations of southeast Alaska coho salmon (Oncorhynchus kisutch)

      Granath, Karla Louise (2002-08)
      Adaptive differences among three geographically separate populations of coho salmon (Oncorhynchus kisutch) were investigated by forming first generation intercrosses (hybrid lines) and comparing them to parental types (control lines). Survival, development time, size at ponding, and first year growth were measured as indicators of locally adapted fitness traits. Significant differences (p <0.05) were found between mid-hatching times for control and hybrid groups. Effects of intercrossing on development time are consistent with additive genetic variation, indicating that important genetic divergence exists between the populations. Growth studies were broken down into four different experiments; a 'common garden' experiment, containing all possible controls and reciprocal crosses between pairs of populations, and three 'hybrid' experiments which contained one of the three control lines and all reciprocal crosses associated with the control. Effects of intercrossing on growth were more apparent in the hybrid experiments where there were fewer interactions between different lines.