Diversity across organisational scale emerges through dispersal ability and speciation dynamics in tropical fish

AbstractBackgroundBiodiversity exists at different levels of organisation: e.g., individual, population, species, and community. These levels of organisation all exist within the same system, with diversity patterns emerging across organisational scale through several key processes. Despite this inherent interconnectivity, observational studies reveal that diversity patterns across levels are not consistent. However, the underlying mechanisms for variable continuity in diversity across levels remain elusive. To investigate these mechanisms, we apply a spatially explicit simulation model to reconstruct the global diversification of tropical reef fishes at both the population and species levels through emergent population-level processes.ResultsWe find significant relationships between the population and species levels of diversity which vary dependent on both the measure of diversity and the spatial partitioning considered. In turn, these population-species relationships are driven by modelled biological trait parameters, especially the divergence threshold at which populations speciate.ConclusionsTo explain variation in multi-level diversity patterns, we propose a simple, yet novel, population-to-species diversity partitioning mechanism through speciation which disrupts continuous diversity patterns across organisational levels. We expect that in real-world systems this mechanism is driven by the molecular dynamics that determine genetic incompatibility, and therefore reproductive isolation between individuals. We put forward a framework in which the mechanisms underlying patterns of diversity across organisational levels are universal, and through this show how variable patterns of diversity can emerge through organisational scale.【摘要】生物多样性存在于不同的生物组织层次，例如个体、种群、物种与群落。这些组织层级同处于一个系统之中，在多种关键过程的驱动下，多样性模式随组织尺度不断演变。尽管各层级间存在内在关联，但观测研究表明，不同层级的多样性模式并不一致。然而，不同层级间多样性连续性存在差异的潜在机制仍未明晰。为探究此类机制，本研究采用空间显式模拟模型，通过种群水平的涌现过程，重建热带礁鱼类在种群与物种两个层级的全球多样化进程。 【研究结果】本研究发现，种群与物种多样性层级间存在显著关联，且该关联随多样性度量方式与所考虑的空间分区方式的不同而发生变化。进一步而言，这些种群-物种多样性关联由模型中的生物学性状参数所驱动，尤其是种群发生物种形成时的分化阈值。 【研究结论】为解释多组织层级多样性模式的差异，本研究提出了一种简洁却新颖的、基于物种形成过程的种群-物种多样性分区机制，该机制可打破不同组织层级间的连续性多样性模式。我们推测，在真实生态系统中，该机制由决定遗传不相容性（进而决定个体间生殖隔离）的分子动力学所驱动。本研究提出了一个理论框架，即不同组织层级多样性模式背后的机制具有普适性，并通过该框架阐明了多样性的可变模式如何随组织尺度演变产生。