Question

Explain how resource partitioning may lead to the following two processes :

• modification of a population's realized niche
• speciation.

Answer 1

Answer:

modification of a population's realized niche :-

Explanation:

Humans compete with other humans all the time – for jobs, athletic prizes, dates, you name it. But do we compete with other species? If you've ever gone camping and had your food stolen by an enterprising raccoon, bear, or other critter, you've had a little taste of interspecific competition – competition between members of different species that use overlapping, limited resources.

Resources are often limited in a habitat, and many species may compete to get ahold of them. For instance, plants in a garden may compete with each other for soil nutrients, water, and light. The overall effect of interspecific competition is negative for both species that participate. That is, each species would do better if the other species weren't there.

The niche concept :

A species' niche is its ecological role or "way of life," which is defined by the full set of conditions, resources, and interactions it needs (or can make use of). Each species fits into an ecological community in its own special way and has its own tolerable ranges for many environmental factors. For example, a fish species' niche might be defined partly by ranges of salinity (saltiness), pH (acidity), and temperature it can tolerate, as well as the types of food it can eat.

As we'll see, two organisms with exactly the same niche can't survive in the same habitat (because they compete for exactly the same resources, so one will drive the other to extinction). However, species whose niches only partly overlap may be able to coexist. Also, over long periods of time, they may evolve to make use of more different, or less overlapping, sets of resources.

Resource partitioning :-

Competitive exclusion may be avoided if one or both of the competing species evolves to use a different resource, occupy a different area of the habitat, or feed during a different time of day. The result of this kind of evolution is that two similar species use largely non-overlapping resources and thus have different niches. This is called resource partitioning, and it helps the species coexist because there is less direct competition between them.

The anole lizards found on the island of Puerto Rico are a good example of resource partitioning. In this group, natural selection has led to the evolution of different species that make use of different resources. The figure below shows resource partitioning among species of anole lizards. Each species lives in its own preferred habitat, which is defined by type and height of vegetation (trees, shrubs, cactus, etc.), sunlight, and moisture, among other factors.

speciation:-

Speciation is a process within evolution that leads to the formation of new, distinct species that are reproductively isolated from one another.

Types of Speciation:

1. Allopatric Speciation:-

Allopatric speciation occurs when members of a population become geographically isolated from one another, to the extent that genetic exchange, through mating, is prevented or interfered with.

2. Sympatric Speciation:-

Sympatric speciation is the evolutionary process whereby species are formed from a single ancestral species while inhabiting the same geographic area. In contrast to allopatric speciation, the distribution ranges of species which evolve through sympatry may be identical or they may only overlap.

3. Parapatric Speciation:-

Parapatric speciation is an extremely rare case of speciation that occurs when a population is continuously distributed within a geographic area without any specific barriers to gene flow.

4. Peripatric Speciation:-

Peripatric speciation is a form of allopatric speciation that occurs when populations that have become isolated have very few individuals. Through this process, the population goes through a genetic bottleneck.

5. Artificial Speciation:-

Artificial speciation is the form of speciation that can be achieved by the input of human influence. By separating populations, and thereby preventing breeding, or by intentionally breeding individuals with desired morphological or genotypic traits, humans can create new, distinct species. This is also known as ‘artificial selection’; most modern domesticated animals and plants have undergone artificial selection.