Box 1 The ecological Tower of Babel: environmental heterogeneity

The need for a common language among ecologists and closely related disciplines (e.g. biogeography, evolution and conservation biology) has been repeatedly stressed (e.g., [84–89]). This need is becoming ever more urgent. Ecology has matured into a nomothetic science [90] with an ever-expanding literature replete with neologisms and encompassing a growing range of subdisciplines.

The construction of a common ecological language needs to adhere to two guiding principles: utility and standardization [91]. Unfortunately, many ecological terms lack standardization, directly compromising their utility. Terms have frequently been assigned to different definitions, definitions are used interchangeably (often within the same manuscript), and there is a general lack of precision in the use of terminology. This has led to widespread confusion and conceptual stagnation: an ecological Towel of Babel (the construction of many languages from one).

The existence of this ecological Tower of Babel has led various authors to plead for a common language (see [88, 92–96]), and a few authors have taken on the challenge (see [94, 95, 97]) and proposed standardized definitions for the most fundamental ecological concepts (environment, community, habitat, biotope, niche). However, even if Looijen’s definitions help resolve the problematic use of concepts like habitat and biotope at a theoretical level, in practice the description and determination of these concepts in real situations is still problematic.

The practical problem of defining and measuring heterogeneity in nature is especially prominent in fields such as biogeography and macroecology, where much ink has been spent inter alia on the role of ‘habitat diversity’ in regulating species richness patterns. In these sub-disciplines a clear, standardized and, most importantly, applicable definition of habitat (and related terms, like biotope, habitat diversity, habitat heterogeneity, ecotope etc.) is of critical importance to advance our understanding of biodiversity regulation. The Aegean islands, with their broad spectrum of natural and human-made habitats provide an excellent system for establishing a coherent terminology in regards to environmental heterogeneity.