Two unresolved questions in marine population connectivity are: (1) the relative importance of contemporary and historical factors (e.g., ongoing gene flow versus past demographic events), and (2) to what extent species subject to the same evolutionary forces exhibit similar phylogeographic patterns. Here, we address these questions using two species from New Zealand’s rocky shore that have very similar distributions and life histories, but very different larval dispersal abilities: the cat’s eye snail Lunella smaragda has short-lived pelagic larvae (3–4 days) while the half-crab Petrolisthes elongatus has a longer pelagic larval duration (3–4 weeks). A large number of individuals of these species were collected (n = 727 and 440) at different locations (31 and 20) throughout their wide New Zealand distribution. These species were analysed for both mitochondrial DNA cytochrome oxidase I (COI) and nuclear ribosomal internal transcribed spacer (ITS-1) variation. Contrary to expectations, the species with much greater dispersal potential, P. elongatus, exhibited much greater population differentiation (> fivefold for mtDNA Φ_ST, > 50-fold for nDNA Φ_ST). This study highlights that species along the same coast can show remarkably different patterns of population structure, and that although there appear to be some common geographic discontinuities in New Zealand, there are few common overall patterns that apply to many species. The study reinforces the observation that predictions of population structure based on life history are often not upheld, and shows that differences in demographic history may be an important factor in driving contemporary patterns of genetic diversity.

海洋种群连通性中两个未解决的问题是：(1) 当代和历史因素的相对重要性（例如，正在进行的基因流动与过去的人口统计事件），以及 (2) 受相同进化力量影响的物种在多大程度上表现出相似的系统地理学模式. 在这里，我们使用来自新西兰岩石海岸的两个物种来解决这些问题，它们具有非常相似的分布和生活史，但幼虫传播能力却截然不同：猫眼蜗牛Lunella smaragda具有短命的远洋幼虫（3-4 天），而half-crab Petrolisthes elongatus具有较长的远洋幼虫持续时间（3-4 周）。收集了大量这些物种的个体（n = 727 和 440）在整个新西兰广泛分布的不同位置（31 和 20）。分析了这些物种的线粒体 DNA 细胞色素氧化酶 I (COI) 和核核糖体内部转录间隔区 (ITS-1) 变异。与预期相反，具有更大传播潜力的物种P. elongatus表现出更大的种群分化（对于 mtDNA Φ _ST来说 > 5 倍，对于 nDNA Φ _ST > 50 倍）。这项研究强调，同一海岸的物种可能表现出截然不同的种群结构模式，尽管新西兰似乎存在一些常见的地理不连续性，但适用于许多物种的通用整体模式却很少。该研究强化了基于生活史的种群结构预测往往不成立的观察结果，并表明人口历史的差异可能是推动当代遗传多样性模式的重要因素。