brown bear (ursus arctos) is one of the most important carnivores in iran. however, information on its habitat associations is scared. based on ecological niche factor analysis (enfa) method, a summer habitat suitability model was developed for this species in the southern part of alborz protected area. our results showed that, brown bears prefer higher altitudes and northern aspects in their p...

We have studied the dynamics of expansion of diploid, sexually reproducing populations onto new territories demanding different genetic adaptations. Populations succeeded in the new habitats if the mutations of alleles responsible for adaptation to the new conditions were recessive. If behind the hostile territory another friendly habitat exists, several different scenarios are possible, includ...

We study a model that describes the spatial spread of a species along a habitat gradient on which the species' growth increases. Mathematical analysis is provided to determine the spreading dynamics of the model. We demonstrate that the species may succeed or fail in local invasion depending on the species' growth function and dispersal kernel. We delineate the conditions under which a spreadin...

Many notorious invasive plants are clonal, spreading mainly by vegetative propagules. Propagule pressure (the number of propagules) may affect the establishment, growth, and thus invasion success of these clonal plants, and such effects may also depend on habitat conditions. To understand how propagule pressure, habitat conditions and clonal integration affect the establishment and growth of th...

Floodplains are composed of aquatic and terrestrial habitats that are frequently reshaped by hydrologic processes operating at various spatial and temporal scales. I hypothesized that floodplain habitat complexity is maximized at intermediate discharges because small changes in flow result in substantial aquatic habitat changes and extreme discharges are associated with a decreased habitat hete...