The Network Species Model

TL;DR

This paper introduces a network-based theoretical model for species, emphasizing intrinsic organization over divergence or fate, unifying diverse biological classifications and aligning with models in other sciences.

Contribution

The proposed model treats species as networks of organisms based on reproductive mechanisms, challenging traditional hierarchical and divergence-based classifications.

Findings

Species, subspecies, and populations are unified under a single network model.

Units of diversity are recognized regardless of divergence.

Classification reflects causal events like vicariance, not post-event evolution.

Abstract

We propose a theoretical model for species that is focused on intrinsic organization and processes. Specifically, we regard species to be networks of organisms integrated by reproductive mechanisms (e.g., conjugation, meiosis, syngamy) regardless of degree or type of divergence, longevity, size, fate, or other criteria. Ramifications of viewing units of diversity in terms of inherent organization include the following: (1) Species, subspecies, population, deme, Evolutionary Significant Unit (ESU), and related terms cannot be distinguished on the basis of inherent organization and, consequently, do not reflect a hierarchy of organization. In other words, only one model is required to explain systems composed of organisms. (2) Temporarily isolated networks of organisms possess the same intrinsic organization and, therefore, the same ontological status as permanently isolated systems. (3) Units of diversity are recognized regardless of kind or degree of divergence. (4) Fate is not an intrinsic property of systems and is an inappropriate consideration in species models. (5) Networks are recognized at the moment they become isolated; therefore, resultant classifications reflect the causal events that generate diversity (e.g., vicariance) rather than post-vicariance events such as character evolution and, consequently, have greater historical relevance (e.g., biogeography). (6) Because the proposed model is based on organization, it is similar to models in other disciplines (e.g., astronomy, chemistry, and physics) and should lead to greater unification of thought within biology and among scientific disciplines. (7) Lineage concepts are problematic because they do not describe a unique level of biological organization and because ancestor-descendant relationships are not unique to living systems.