Coexistence between the seastars Asterias vulgaris and A. forbesi in a heterogeneous environment: A non-equilibrium explanation
Coexistence between the seastars Asterias vulgaris and A. forbesi in a heterogeneous environment: A non-equilibrium explanation
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海星 Asterias vulgaris 和 A. forbesi 在异质环境中的共存：非平衡解释
DOI：
10.1007/bf00377430
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发表时间：
1979
期刊：
影响因子：
2.7
通讯作者：
B. Menge
中科院分区：
文献类型：
--
作者：
B. Menge
摘要 在新英格兰北部的八个研究地点对同域掠食性海星、海星和普通海星之间的相互作用进行了五年的研究。这些物种的深度范围从低潮间带到至少 50 m，并在从缅因州中部到哈特拉斯角的广阔地理范围内共生。两者在进食时间和强度、体型、饮食成分和猎物大小方面都有很大重叠。这些特征因地点而异，但始终呈正相关。资源维度上的这种相似性通常被认为表明物种对资源的竞争。在这项研究中，种间竞争似乎没有发生。尽管这些海星通常比它们的潜在尺寸要小，并且在某些亚栖息地食物似乎供应短缺，但在其他亚栖息地食物似乎是无限的。因此，剥削竞争可能是偶尔发生的，而不是长期发生的，并且可能是一种弱选择因素。实验室实验表明，这些海星之间既不发生种内攻击，也不发生种间攻击。因此，在这种情况下，干扰竞争似乎不存在。对疾病和风暴造成的大量死亡、海星密度的巨大变化以及食物供应的不均匀的观察表明，这些种群通常被一系列千变万化的选择剂控制在承载能力以下。在这种情况下，资源短缺不太可能产生强大的选择压力。因此，高度重叠很可能反映了普遍缺乏细分资源的压力，而不是激烈竞争的迹象。在竞争研究中，生态重叠应辅以其他证据，包括实验，然后才能将其用作竞争压力的指标。
SummaryThe interaction between the sympatric, predaceous seastars, Asterias forbesi and A. vulgaris was studied for five years at eight study sites in northern New England. These species range in depth from the low intertidal to at least 50 m and cooccur over a broad geographic range from central Maine to Cape Hatteras. Both overlap greatly in times and intensity of feeding, body size, diet composition and size of prey consumed. Variations occur in these characteristics from site to site but are always positively correlated.Such similarity along resource dimensions is generally taken to indicate that species compete for resources. In this study, interspecific competition does not seem to occur. Though these seastars are generally smaller than their potential size, and food seems in short supply in some subhabitats, food seems unlimited in other subhabitats. Hence, exploitation competition probably occurs sporadically, not chronically, and is probably a weak selective agent. Laboratory experiments suggest that neither intra- nor interspecific aggression occurs between these seastars. Hence, interference competition seems non-existent in this case.Observations of massive mortality from disease and storms, large variations in seastar density, and a patchy food supply suggests that these populations are generally held below carrying capacity by a kaleidoscopic suite of selective agents. Under such conditions resource shortage would be unlikely to exert strong selective pressure. The high overlaps are thus most likely a reflection of the general absence of pressure to subdivide resources rather than an indication of severe competition.In studies of competition, ecological overlaps should be supplemented by other evidence, including experiments before they can be used as indications of competitive pressure.