Positive and Negative Ecology, a Conceptual Overview

Animal populations, even among common species, often exhibit demographic heterogeneity. This is particularly evident in species with metapopulation structures, where geographically distinct subpopulations experience varying degrees of inbreeding due to limited interbreeding. A phenomenon termed ‘negative ecology’ highlights cases where species, despite suitable habitat availability, display fragmented distributions within small geographic areas (<20 km2). These subpopulations, however, do not conform to classic metapopulation dynamics, as even vagile species such as birds can theoretically move freely between them. Similar patterns emerge at larger scales (>100 km2) in birds and butterflies, suggesting ecological constraints—either abiotic or biotic—underpin these structured distributions. Understanding these constraints is essential, particularly in conservation efforts. The principles of positive (extant) and negative (locally absent/extinct) ecology have profound implications for species re-introductions, as historical occupancy does not guarantee successful re-establishment. Abiotic and biotic factors may hinder the recolonization of previously inhabited or entirely new habitats. This article primarily explores the ecological forces shaping such fragmented distributions in birds and butterflies, two especially well-studied taxa in the UK and mainland Europe, in the hope that such a new perspective may thereby contribute to broader conservation and ecological restoration strategies.