Introduction:
Species diversity refers to the variety of species present in a given ecosystem. It is influenced by various factors that can either increase or decrease the number of species within an ecosystem. In this question, we are asked to identify the factor that does not contribute to an increase in species diversity.

Explanation:
The correct answer is option 'A' - Competitive exclusion. Competitive exclusion is a process in which two species with similar ecological requirements compete for limited resources, leading to the elimination of one species by the other. This process reduces species diversity as it results in the dominance of one species over the other, leading to the exclusion of the less competitive species.

Factors that increase species diversity:
While competitive exclusion reduces species diversity, there are several factors that act to increase it. These factors include:

1. Patchy environments:
Patchy environments refer to habitats that consist of patches or small areas with different environmental conditions. These patches can support different species with specific adaptations to those conditions. As a result, species diversity is increased as different species can occupy different patches within the same ecosystem.

2. Migration of populations:
Migration of populations refers to the movement of individuals from one area to another. When populations migrate, they bring new genetic material and introduce new species to different areas. This increases species diversity as new species are added to the existing ones.

3. Moderate disturbances:
Moderate disturbances, such as fires or storms, can create openings in an ecosystem. These openings provide opportunities for new species to colonize and establish themselves. The presence of disturbances prevents the dominance of a single species and allows for the coexistence of multiple species, thereby increasing species diversity.

Summary:
In summary, species diversity can be influenced by various factors. While competitive exclusion reduces species diversity, patchy environments, migration of populations, and moderate disturbances act to increase species diversity by providing opportunities for different species to coexist and thrive.