國際研究人員最近在南美洲發(fā)現(xiàn)一些內(nèi)部關(guān)系特殊的魚群,，它們的外表非常相似,，在一個(gè)群落里和諧共處、共御天敵,，但它們卻是不同的物種,，在選擇食物時(shí)各有偏好，與中國傳統(tǒng)的“和而不同”理念不謀而合,。
英國《自然》雜志1月6日刊登報(bào)告說，英國班戈大學(xué)等機(jī)構(gòu)的研究人員和巴西同行在南美洲發(fā)現(xiàn)具有上述特點(diǎn)的甲鯰屬魚類,。這種俗稱“鼠魚”的魚種類很多，僅正式報(bào)告過的就有一百多種,。過去人們知道,，這些魚喜歡集群生活,，雖然一群魚中有多個(gè)物種，但它們的外形卻十分相似,，有差不多的鱗片斑紋和尖利的鰭刺。
一個(gè)群落的魚外表趨同可以互利,，比如某個(gè)掠食者想吃其中一條魚而嘗過鰭刺的苦頭后，就會對所有看起來差不多的魚“敬而遠(yuǎn)之”,，這種現(xiàn)象在生物學(xué)上稱為“繆氏擬態(tài)”。以前曾在蝴蝶等生物中發(fā)現(xiàn)這種現(xiàn)象,，但是這些生物往往因?yàn)楸舜颂嗨贫瑫r(shí)存在針對食物的內(nèi)部競爭,。
但本次研究發(fā)現(xiàn)了一種新型“繆氏擬態(tài)”關(guān)系,，南美洲的這些魚群為了維持集體內(nèi)部的穩(wěn)定關(guān)系而在食物選擇上有所不同,。研究人員捕獲了共同生活的許多種“鼠魚”，觀察它們的嘴形,，并通過分析其機(jī)體組織判斷它們的攝食情況。結(jié)果顯示,，一個(gè)群落中的不同種“鼠魚”的攝食對象存在差別，群落內(nèi)部的食物競爭不大,。
領(lǐng)導(dǎo)研究的馬丁·泰勒博士說,，這些“鼠魚”看起來差不多,，也在同一個(gè)地方生活，因此很容易認(rèn)為它們存在食物競爭,，但實(shí)際上它們卻進(jìn)化出各自選擇不同食物的習(xí)性,。正是這種“和而不同”的特點(diǎn),，增強(qiáng)了整個(gè)群體的生存能力,。（生物谷Bioon.com）
生物谷推薦原文出處：
Nature doi:10.1038/nature09660
Competition and phylogeny determine community structure in Müllerian co-mimics
Markos A. Alexandrou,Claudio Oliveira,Marjorie Maillard,Rona A. R. McGill,Jason Newton,Simon Creer& Martin I. Taylor
Until recently, the study of negative and antagonistic interactions (for example, competition and predation) has dominated our understanding of community structure, maintenance and assembly1. Nevertheless, a recent theoretical model suggests that positive interactions (for example, mutualisms) may counterbalance competition, facilitating long-term coexistence even among ecologically undifferentiated species2. Müllerian mimics are mutualists that share the costs of predator education3 and are therefore ideally suited for the investigation of positive and negative interactions in community dynamics. The sole empirical test of this model in a Müllerian mimetic community supports the prediction that positive interactions outweigh the negative effects of spatial overlap4 (without quantifying resource acquisition). Understanding the role of trophic niche partitioning in facilitating the evolution and stability of Müllerian mimetic communities is now of critical importance, but has yet to be formally investigated. Here we show that resource partitioning and phylogeny determine community structure and outweigh the positive effects of Müllerian mimicry in a species-rich group of neotropical catfishes. From multiple, independent reproductively isolated allopatric communities displaying convergently evolved colour patterns, 92% consist of species that do not compete for resources. Significant differences in phylogenetically conserved traits (snout morphology and body size) were consistently linked to trait-specific resource acquisition. Thus, we report the first evidence, to our knowledge, that competition for trophic resources and phylogeny are pivotal factors in the stable evolution of Müllerian mimicry rings. More generally, our work demonstrates that competition for resources is likely to have a dominant role in the structuring of communities that are simultaneously subject to the effects of both positive and negative interactions.
