The driving forces behind the evolution of early metazoans are not well understood, but key insights into their ecology and evolution can be gained through ecological analyses of the in situ, sessile communities of the Avalon assemblage in the Ediacaran (~565 million years ago). Community structure in the Avalon is thought to be underpinned by epifaunal tiering and ecological succession, which we investigate in this study in 18 Avalon communities. Here we found that Avalon communities form four distinctive Community Types irrespective of succession processes, which are instead based on the dominance of morphologically distinct taxa, and that tiering is prevalent in three of these Community Types. Our results are consistent with emergent neutrality, whereby ecologically specialized morphologies evolve as a consequence of neutral (stochastic or reproductive) processes within niches, leading to generalization within the frond-dominated Community Type. Our results provide an ecological signature of the first origination and subsequent loss of disparate morphologies, probably as a consequence of community restructuring in response to ecological innovation. This restructuring led to the survival of non-tiered frondose generalists over tiered specialists, even into the youngest Ediacaran assemblages. Such frondose body plans also survive beyond the Ediacaran–Cambrian transition, perhaps due to the greater resilience afforded to them by their alternative ecological strategies.

早期后生动物进化背后的驱动力尚不清楚，但通过对埃迪卡拉纪（约 5.65 亿年前）阿瓦隆组合的原位固着群落进行生态分析，可以获得对其生态和进化的关键见解。阿瓦隆的群落结构被认为是以动物区系分层和生态演替为基础的，我们在本研究中对 18 个阿瓦隆群落进行了调查。在这里，我们发现阿瓦隆群落形成了四种独特的群落类型，无论演替过程如何，这些群落类型都是基于形态上不同的类群的优势，并且分层在其中三种群落类型中普遍存在。我们的结果与新兴中性相一致，即生态位中的中性（随机或生殖）过程导致生态特殊形态的进化，从而导致叶状群落类型中的泛化。我们的结果提供了不同形态的最初起源和随后丧失的生态特征，这可能是响应生态创新而进行群落重组的结果。这种重组导致了非分层叶状通才相对于分层专家的生存，甚至进入了最年轻的埃迪卡拉组合。这种叶状的身体结构也能在埃迪卡拉纪-寒武纪过渡期之后幸存下来，这或许是因为它们的替代生态策略赋予了它们更大的恢复力。