User:PonderosaPine0/Environmental gradient

An environmental gradient is a gradual change in abiotic factors through space (or time). Environmental gradients can be related to factors such as altitude, temperature, depth, ocean proximity and soil humidity. Often times a multitude of biotic characteristics are closely related to these gradients. As a result of a change in an environmental gradient, many species and life history traits such as: species abundance, population density, morphology, primary productivity, predation, and local adaptation may experience a change of greater or lesser magnitude.

Abiotic Influence
The species distribution along environmental gradients has been studied intensively due to large databases of species presence data (e.g. GBIF). The abiotic factors that environmental gradients consist of can have a direct ramifications on organismal survival. Generally, organismal distribution is tied to those abiotic factors, but even an environmental gradient of one abiotic factor yields insight into how a species distribution might look. For example, aspects of the landscape such as soil composition, temperature, and precipitation all factor in to an accurate idea of habitable territory a plant species might occupy; information on one of those factors can help form an environmental gradient by which a proximate species distribution may be generated. At an ecotone, species abundances change relatively quickly compared to the environmental gradient.

Biotic Interactions
Although environmental gradients are comprised gradually changing and predictable patterns of an abiotic factor, there is strong interplay between both biotic-biotic factors as well as biotic-abiotic factors. For example, species abundances usually change along environmental gradients in a more or less predictive way. However, the species abundance along an environmental gradient is not only determined by the abiotic factor associated with the gradient but, also by the change in the biotic interactions, like competition and predation, along the environmental gradient.

Local Adaptation Along Environmental Gradients
Depending on the size of the landscape and the gene flow between populations, local adaptation could arise between populations inhabiting two extremes of the landscape. The opposing extremes in abiotic conditions that are faced between populations and the lack of homogenizing gene flow could present conditions where two populations are able to differentiate. Often times when comparing fitness or phenotypic values across an environmental gradient, the data are fixated into a reaction norm framework. In this way, an individual can directly assess the changes across a landscape of a particular species' phenotype or compare fitness and phenotypes of populations within a species across environmental gradients (particularly when performing reciprocal transplant studies).