Neville H M, Isaak D J, Dunham J B, Thurow R F, Rieman B E
Department of Biology/314, University of Nevada, Reno, NV 89557, USA.
Mol Ecol. 2006 Dec;15(14):4589-602. doi: 10.1111/j.1365-294X.2006.03082.x.
Natal homing is a hallmark of the life history of salmonid fishes, but the spatial scale of homing within local, naturally reproducing salmon populations is still poorly understood. Accurate homing (paired with restricted movement) should lead to the existence of fine-scale genetic structuring due to the spatial clustering of related individuals on spawning grounds. Thus, we explored the spatial resolution of natal homing using genetic associations among individual Chinook salmon (Oncorhynchus tshawytscha) in an interconnected stream network. We also investigated the relationship between genetic patterns and two factors hypothesized to influence natal homing and localized movements at finer scales in this species, localized patterns in the distribution of spawning gravels and sex. Spatial autocorrelation analyses showed that spawning locations in both sub-basins of our study site were spatially clumped, but the upper sub-basin generally had a larger spatial extent and continuity of redd locations than the lower sub-basin, where the distribution of redds and associated habitat conditions were more patchy. Male genotypes were not autocorrelated at any spatial scale in either sub-basin. Female genotypes showed significant spatial autocorrelation and genetic patterns for females varied in the direction predicted between the two sub-basins, with much stronger autocorrelation in the sub-basin with less continuity in spawning gravels. The patterns observed here support predictions about differential constraints and breeding tactics between the two sexes and the potential for fine-scale habitat structure to influence the precision of natal homing and localized movements of individual Chinook salmon on their breeding grounds.
洄游到出生地是鲑科鱼类生活史的一个标志，但在当地自然繁殖的鲑鱼种群中，洄游的空间尺度仍知之甚少。精确的洄游（与有限的活动相结合）应会导致由于相关个体在产卵地的空间聚集而出现精细尺度的遗传结构。因此，我们利用相互连接的溪流网络中奇努克鲑（Oncorhynchus tshawytscha）个体之间的遗传关联，探索了洄游到出生地的空间分辨率。我们还研究了遗传模式与两个假设因素之间的关系，这两个因素被认为会影响该物种在更精细尺度上洄游到出生地和局部移动，即产卵砾石分布的局部模式和性别。空间自相关分析表明，我们研究地点的两个子流域中的产卵地点在空间上都是聚集的，但上子流域的产卵位置空间范围和连续性通常比下子流域更大，下子流域的产卵位置和相关栖息地条件分布更零散。在任何一个子流域中，雄性基因型在任何空间尺度上都不存在自相关。雌性基因型表现出显著的空间自相关，并且两个子流域之间雌性的遗传模式在预测方向上有所不同，在产卵砾石连续性较差的子流域中自相关更强。这里观察到的模式支持了关于两性之间不同限制和繁殖策略的预测，以及精细尺度栖息地结构影响奇努克鲑个体在其繁殖地洄游到出生地的精度和局部移动的可能性。
