Abstract:

Aim: The species abundance distribution (SAD) intricately portrays the abundance dynamics of each diverse species within ecological systems, constituting a fundamental facet of diversity studies. Various theoretical models have emerged over time in an attempt to encapsulate SAD complexities, yet discerning the most fitting model remains a challenge. Prior investigations have revealed a recurrent pattern in SAD characterized by numerous rare species and a handful of dominant ones. A research has conducted an extensive analysis, employing a fractal model on approximately 20,000 samples, proposing a distribution pattern of N_r/N₁ as 1 : 1/2 : 1/3…… (where N_r and N₁ denote the abundance of the r-th and the first species, respectively). While this pattern has been acknowledged, a comprehensive understanding of the general SAD pattern and its connection to the fractal model persists as a research gap. The purpose of this study is to obtain more ideas from researchers that can improve the understanding of underlying mechanisms by testing the fractal model and the general pattern of SAD.  

Methods: This study employs datasets from Bivalvia of the Deep-sea Atlantic Database (242 samples) and Reading University Crop Pollinator Database (926 samples) to scrutinize the applicability of the fractal model and enhance insights into the general SAD pattern.

Results: The findings revealed that the fractal model aptly fitted both datasets, with R² ranging from 0.405 to 1.000. Notably, a substantial proportion (85.5% and 67.8%, respectively) of samples exhibit R² values exceeded 0.8. Furthermore, the predominant SAD pattern observed for both communities aligned with the distribution ration of 1 : 1/2 : 1/3……

Conclusion: Our investigation underscores the generality of the SAD pattern, supporting across diverse taxonomic groups, including Bivalvia and pollinator communities. The significance lies in introducing an academic inquiry into the inherent mechanisms governing the general SAD pattern. This exploration serves as a catalyst for innovative perspectives in species diversity research, offering a novel entry point for further investigation.

Key words: species diversity, species abundance distribution, fractal theory, fractal model, diversity indices