Biogeography, competition, and microclimate:: The barnacle Chthamalus fragilis in New England
Biogeography, competition, and microclimate:: The barnacle Chthamalus fragilis in New England
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DOI：
10.1093/icb/42.4.872
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发表时间：
2002-08-01
影响因子：
2.6
通讯作者：
Wethey, DS
中科院分区：
文献类型：
--
作者：
Wethey, DS
物种的地理界限通常与气候或物理界限有关，但对分布界限的排除机制了解甚少。在声波潮间带种群中，与天敌相互作用的强度受小气候的调节，并决定地理限制。在新英格兰，藤壶Chthamalus fragilis的北部边界是马萨诸塞州科德角的南侧。在海角的南部，Chthamalus在高潮间带有一个避难所，那里太热了，它的优势竞争对手Semibalanus balanoides无法生存。在海角的北边。高潮间带温度较低，半巴拉努斯幸存下来，所以奇塔马洛斯没有避难所。因此，竞争强度的地理差异可能决定了Chthamalus的地理限制。不耐或寒冷，Chthamalus不能解释地理限制：Chthamalus 80杀死的移植超过其北部限制，在没有与Semibalanus竞争的情况下存活长达8年。在科德角运河的Chthamalus地理边界处，有两座相距5公里的桥梁。在南桥上，Chthamalus数量丰富，占据了Semibalanus上方的避难所。在2001年的北桥上，只有7只Chthamalus个体出现。尽管两座桥很近，但它们的小气候却大不相同。在Chthamalus丰富的南桥，温度比北桥高5摄氏度。较高的温度为Chthamalus在高潮间带提供了一个避难所。在较冷的北桥上，Chthamalus没有避难所。由于在运河中相遇的水团的温度不同，桥墩岩石中的热量储存导致桥梁之间的温度不同。因此，小气候的地理变化改变了竞争的强度，并决定了地理极限。“当我们从南到北旅行，或者从潮湿地区到干燥地区旅行时，我们总是看到声音物种逐渐变得越来越稀少，最终消失；气候的变化是显而易见的，我们很容易将其全部影响归因于气候变化的直接作用。但这是一个非常错误的观点：我们忘记了每一个物种，即使是在它最丰富的地方，在它生命的某个时期也经常遭受巨大的破坏，来自敌人或竞争对手对同一地点和食物的争夺，如果这些敌人或竞争对手在任何程度上受到任何轻微的气候变化的影响，它们的数量就会增加，因为每个地区已经充满了居民，其他物种就会减少。——查尔斯·达尔文，《物种起源》，1859年，第69页
Geographic limits of species are commonly associated with climatic or physical boundaries, but the mechanisms of exclusion at the limits of distribution are poorly understood. In sonic intertidal populations, the strengths of interactions with natural enemies are mediated by microclimate, and determine geographic limits. The northern limit of the barnacle Chthamalus fragilis in New England is the south side of Cape Cod, Massachusetts. South of the cape, Chthamalus has a refuge from competition in (lie high intertidal, which is too hot for survival of its superior competitor Semibalanus balanoides. North of the cape. the high intertidal is cooler, and Semibalanus survives, so Chthamalus has no refuge. Thus, geographic variation in the strength of competition may determine the geographic limit of Chthamalus. Intolerance or cold by, Chthamalus cannot account for the geographic limit: transplants of Chthamalus 80 kill beyond its northern limit survived up to 8 yr in the absence of competition with Semibalanus. At the geographic limit of Chthamalus in the Cape Cod Canal there are two bridges, 5 km apart. On the southern bridge, Chthamalus is abundant and occupies a refuge above Semibalanus. Oil the northern bridge in 2001, only, 7 individual Chthamalus were present. Despite the proximity of the bridges, their microclimates are very different. The southern bridge, where Chthamalus is abundant, is up to WC hotter than the northern bridge. This higher temperature creates a refuge in the high intertidal for Chthamalus. On the cooler northern bridge, there is no refuge for Chthamalus. Because of the difference in temperatures of the water masses that meet in the canal, heat storage in the rock of the bridge piers causes the temperatures to differ between the bridges. Thus, geographic change in microclimate alters the strength of competition, and determines the geographic limit."When we travel from south to north, or from a damp region to a dry, we invariably see sonic species gradually getting rarer and rarer, and finally disappearing; and the change in climate being conspicuous, we are tempted to attribute the whole effect to its direct action. But this is a very false view: we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food, and if these enemies or competitors be in the least degree favoured by any slight change of climate, they will increase in numbers, and as each area is already fully stocked with inhabitants, the other species will decrease."-Charles Darwin, On the Origin of Species, 1859, p. 69.