Eventually the subpopulations become so genetically distinct that they cannot interbreed even if the physical barriers between them were removed.
最终，这些亚种群在基因上变得如此不同，以至于即使消除了它们之间的物理障碍，它们也无法杂交。
2
High rates of straying can be problematic because misdirected fish may interbreed with the existing stock to such a degree that any local adaptations that are present become diluted.