Abstract
Biologists employ a suggestive metaphor to describe the complexities of molecular interactions within cells and embryos: cytological components are said to be part of “ecosystems” that integrate them in a complex network of relations with many other entities. The aim of this essay is to scrutinize the molecular ecosystem, a metaphor that, despite its longstanding history, has seldom be articulated in detail. I begin by analyzing some relevant analogies between the cellular environment and the biosphere. Next, I discuss the applicability of the molecular ecosystem concept in actual scientific practice