Metapopulations and the Sinai Baton Blue ( Pseudophilotes sinaicus Nakamura): an introduction

Abstract

Most species on most spatial scales have a patchy distribution (Hanski & Gilpin 1997; Hanski 1999). Because species have evolved specific habitat requirements, only some habitats some of the time will provide the resources necessary for population persistence. The landscape is therefore complex, a mosaic of different habitat types changing in their quality over time. On a large-scale, the patchy distribution of a species might occur because of the physical features of its landscape e.g. amphibians in small ponds (Sjogren Gulve 1994), or be a result of its history. Local breeding populations might be distributed in discrete habitat patches containing adequate resources; for example, the bog fritillary butterfly (Proclossiana eunomia) occurs only in the natural wet meadows in Belgium which contain its sole larval food plant, Polygonum bistorta (Baguette & Neve 1994). On a smaller-scale individuals may aggregate in response to the patchiness of resources within an area of suitable habitat; this is particularly the case for small species, or those with limited mobility. Patches may also be formed because of the spatial and temporal variation in the quality of the landscape elements (Wiens 1997). In addition to naturally defined patches, human activities have directly altered the landscape, generally causing destruction of natural habitats, their increased fragmentation, and deterioration of habitat quality (Henle et al. 2004). Indirect human-induced factors, most notably global warming (Houghton et al. 2001), are also changing the quantity and quality of habitats available to many species (Parmesan et al. 1999; Thomas et al. 2001; Beever et al. 2003; Crozier 2003). Thus for many species the world is becoming ever more patchy, and consequently an increasing number of species are gradually becoming more and more confined to networks of small habitat patches. This will have an effect on the size and connectivity of suitable habitat, and may also cause large changes in the physical environment (Saunders et al. 1991). The effects of habitat destruction and its impact on species survival in fragmented landscapes are likely to prove to be the greatest challenges to animal and plant conservation in the twentyfirst century (Root et al. 2003; Travis 2003; Henle et al. 2004; Thomas et al. 2004).