Extreme rarity of competitive exclusion in modern and fossil marine benthic ecosystems
Extreme rarity of competitive exclusion in modern and fossil marine benthic ecosystems
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现代和化石海洋底栖生态系统中竞争排斥极为罕见
作者：
A. Klompmaker;S. Finnegan
随着时间的推移，竞争性相互作用被认为是生态和进化趋势的主要驱动力，但这种相互作用的强度和频率是众所周知的难以评估。在这里，我们使用物种共生模式的推论，以确定在现代和化石底栖海洋无脊椎动物组合的竞争-竞争性排斥的极端端员的频率。在环境和时间约束良好的物种池内，我们研究了所有物种对的百分比，共同出现的机会比预期的少（隔离对）作为竞争性排斥的最大措施。分离对是非常罕见的，与大多数组合不包含任何，分离对的频率显示整个中生代没有趋势。与竞争相关性假说相反，我们发现很少有证据表明，隔离对更常见的密切相关的物种之间，除了潜在的同源对在较深的水环境中的物理干扰相对较低。虽然埋藏，死后运输，和时间平均可能会掩盖原来的共生模式，分析表明，这些因素不太可能完全解释分离对的频率低。我们的研究结果支持这一假设，捕食和干扰保持海洋底栖生物群落低于承载能力，从而减少竞争性相互作用的潜力，决定在浅水沃茨的社区组成。导言海洋生态系统在整个中生代在分类学和生态学上变得更加多样化（Bambach等人，2007; Alroy等人，2008年），几条证据表明，这种多样化可能是由日益复杂的生态相互作用促进或驱动的（瓦格纳等人，2006;亨特利和Kowalewski，2007; Nürnberg和Aberhan，2015）。各种无脊椎动物的钻孔、疤痕和其他痕迹的丰富化石记录提供了一些证据，证明捕食和寄生随着时间的推移变得越来越普遍（亨特利和科瓦莱夫斯基，2007年; Klompmaker和Boxshall，2015年），但量化竞争的证据更加困难。除了结壳类群中的过度生长关系（Taylor，2016），种间竞争的直接证据非常罕见。因此，人们对竞争在海洋生态系统中的长期作用仍然知之甚少。虽然竞争是进化理论的基石（达尔文，1859年），并已被援引来解释一些主要的分支更换（斯坦利和纽曼，1980年;塞普科斯基等人，2000; Liow等人，2015年），其他人认为竞争不是海洋生态系统的主要进化力量（Benton，1996; Stanley，2008; Myers和Lieberman，2011）。很难量化现代海洋物种之间竞争性相互作用的强度，对大多数化石物种也不可能这样做，但也许可以认识到竞争排斥，即竞争的极端成员，其中两个具有相同生态位的物种不能在当地共存（哈丁，1960年）。在这里，我们采用了最近开发的分析方法（里昂等人，2016年，以及其中的参考文献），以评估化石和现代底栖海洋无脊椎动物组合中竞争性排斥的频率。我们检查了当地物种库内的共现模式，以确定物种对是否比预期的偶然共现频率更低（分离或负对）（Sfenthourakis等人，2006年）。我们评估（1）竞争排斥的共性，通过组合内所有对的分离物种对的百分比来衡量，在现代和化石海洋组合中，随着时间的推移;（2）分离对是否更经常发生在密切相关的分类群中，正如竞争相关假说所预测的那样（Cahill等人，2008）最初由Charles达尔文（达尔文，1859）提出;（3）分离对的频率和分类分布是否受水深的影响，水深是干扰频率和强度的粗略代理。
Competitive interactions have been invoked as major drivers of ecological and evolutionary trends through time, but the strength and frequency of such interactions is notoriously difficult to evaluate. Here we use inferences from species co-occurrence patterns to determine the frequency of the extreme endmember of competition—competitive exclusion—in modern and fossil benthic marine invertebrate assemblages. Within environmentally and temporally well-constrained species pools, we examine the percentage of all species pairs that co-occur less often than expected by chance (segregated pairs) as a maximum measure of competitive exclusion. Segregated pairs are very rare, with most assemblages containing none, and the frequency of segregated pairs shows no trend throughout the Phanerozoic. Contrary to the competition-relatedness hypothesis, we find little evidence that segregated pairs are more common among closely related species except potentially for congeneric pairs in deeper water settings where physical disturbance is relatively low. Although taphonomy, post-mortem transport, and time-averaging could obscure original co-occurrence patterns, analyses suggest that these factors are unlikely to fully explain the low frequency of segregated pairs. Our findings support the hypothesis that predation and disturbance keep marine benthic communities below carrying capacity and thus reduce the potential for competitive interactions to dictate community composition in shallow waters. INTRODUCTION Marine ecosystems have become more taxonomically and ecologically diverse throughout the Phanerozoic (Bambach et al., 2007; Alroy et al., 2008), and several lines of evidence suggest that this diversification may have been facilitated or driven by increasingly complex ecological interactions (Wagner et al., 2006; Huntley and Kowalewski, 2007; Nürnberg and Aberhan, 2015). The rich fossil record of drill holes, scars, and other traces in a variety of invertebrates provides some evidence that predation and parasitism have become more common through time (Huntley and Kowalewski, 2007; Klompmaker and Boxshall, 2015), but quantifying evidence of competition has been more difficult. With the exception of overgrowth relationships in encrusting taxa (Taylor, 2016), direct evidence of interspecific competition is extremely rare. Hence, the role of competition in marine ecosystems through time remains poorly understood. Although competition is a cornerstone of evolutionary theory (Darwin, 1859) and has been invoked to explain some major clade replacements (Stanley and Newman, 1980; Sepkoski et al., 2000; Liow et al., 2015), others have argued that competition is not a major evolutionary force in marine ecosystems (Benton, 1996; Stanley, 2008; Myers and Lieberman, 2011). It is difficult to quantify the strength of competitive interactions among modern marine species and impossible to do so for most fossil species, but it may be possible to recognize competitive exclusion, the extreme endmember of competition in which two species with identical niches cannot locally coexist (Hardin, 1960). Here we employ a recently developed analytical approach (Lyons et al., 2016, and references therein) to evaluate the frequency of competitive exclusion in fossil and modern benthic marine invertebrate assemblages. We examine cooccurrence patterns within local species pools to determine whether species pairs co-occur less often than expected by chance (segregated or negative pairs) (Sfenthourakis et al., 2006). We assess (1) the commonness of competitive exclusion, as measured by the percentage of segregated species pairs of all pairs within assemblages, in modern and fossil marine assemblages through time; (2) whether segregated pairs occur more often among closely related taxa, as predicted by the competition-relatedness hypothesis (Cahill et al., 2008) originally proposed by Charles Darwin (Darwin, 1859); and (3) whether the frequency and taxonomic distribution of segregated pairs is affected by water depth, a rough proxy for disturbance frequency and strength.
显生宙海洋无脊椎动物的专业化和生物多样性的相互依赖性
影响因子：
16.6
作者：
Nürnberg;Aberhan
通讯作者：
Aberhan