The article addresses the problem of nature of species which could be reduced to the question: Are species classes (universals) or individuals (particular things)? Reflecting on the discussion between traditionalist (e.g. Kitts and Kitts, Ruse) and proponents of a radical solution (Ghiselin, Hull) - by way of the S-A-I thesis (Species As Individuals) - we concentrate on the third possibility under which species are viewed as a hybrid category such as a ''complex particular,'' ''individualized class'' or ''event-entities'' (Supe, Ruse). My argument centers on an interchangeability of parts, and it concludes that we must distinguish three types of relation between parts and wholes: constructivist, emergent and reproductive. Thanks to this differentiation, I tend to view species as individuals, but not in the usual constructivist or emergent sense. In order to do justice to the individual character of species, a special logico-ontological structure or type-which I propose to call ''reproductive type''-needs to be devised. and Vladimír Havlík
Vegetation and biocrust play crucial roles in dune stability and mobility, and their interaction can lead to bistability, temporal oscillations, and hysteresis. We studied a two-dimensional (2D) mathematical model of vegetation and biogenic crust cover dynamics on sand dunes. Under a certain parameter range, the space-independent version of the model exhibited the bi-stability of an oscillatory state and a steady state, and we studied the 2D dynamics of the model under these parameters. The patterns developed by the 2D model showed a high degree of spatial heterogeneity and complexity depending on the initial conditions and on the state type across the front. The results suggest that spatial heterogeneity and complexity can evolve from the intrinsic dynamics between vegetation and biocrust, even without natural geodiversity and spatiotemporal climate fluctuations. In the real world, these two types of intrinsic and extrinsic heterogeneity processes interact such that it is difficult to distinguish between them.