What is functional diversity?

Functional diversity depends on the role of the organism and its different functions within the community or the ecosystem. This is a part of biodiversity that depends on the functional traits or characters of the organisms that are part of ecology. It is the distinct range of traits that directly influence the functioning of the ecosystem. These characters of different species in the ecosystem maintain stability and resources within the community.

Example of a functional diversity

Among the different ecosystems, the functions of the organisms differ. These functions have a direct effect on the ecosystem and the biodiversity of a particular niche. Some examples of functional diversity include the patterns of species co-occurrence, community assembly, and understanding species competitive abilities. The major role of this factor is to maintain important functions and services of ecosystems. We require an explanation based on a specific ecosystem and related ecology to provide the best example of functional diversity.

Microbial functional diversity

There is a huge diversity of microbes in every ecosystem. These microbes play an important role in the ecosystem because of their specific functions like mineral recycling, cleaning environment, and oxygen supply. Microorganisms residing in an environment are responsible for the maintenance of the ecological balance and biodiversity pattern. They are responsible for different biochemical functions, especially maintaining the biogeochemical cycle of various components. Therefore, the function and interactions of all microorganisms (culturable and non-culturable) are responsible for microbial functional diversity.

It is possible to culture a few microbes from the environment. But the number of unculturable microbes is still way more in number. It is important to consider all the functions of every type of microbe in the environment while determining the microbial functional diversity. They together help with nutrient richness, ecological stability, and ecosystem dynamics. Different microorganisms have different functional traits that together lead to functional richness.

Ecological factors related to functional diversity

The functional diversity of any ecosystem depends on various environmental factors and species. Some of the crucial factors include functional richness and evenness and also the level of productivity that the ecosystem shows as an effect. These characters are possible for the various functional traits of different organisms belonging to taxonomic categories.

Functional richness

Functional richness depends on the total space in the niche where different species in the community can reside. The entire idea is dependent on the species abundance and their functions. The space is essential because it defines the level of productivity in that specific niche. It is important for relative abundance and species richness in the population.

Functional evenness

The term is used to measure the evenness of the distribution of a particular species in a given space. Different types of resources are available in a specific niche. The species present in the community depend on these resources, and hence the species distribution in the specific niche differs. Limited natural resources enable the diversification between species. Functional evenness is possible with the proper utilization of resources by the species so that all the functional traits can be explained. It measures the regularity of the distribution of species and their differences in functional space.

Productivity of the ecosystem

The level of productivity in the ecosystem depends on species from different trophic levels. It depends on species composition in the ecosystem and the level of species richness. Growing productivity keeps the ecosystem balanced with all the ecosystem functions. Activity or functions of the species at any ecological level is the key to all biochemical functions in the ecosystem. If there are any specific changes in the functional diversity or the functional traits that will be considered detrimental to productivity.

Ecosystem functioning depends on all these characters. If the trait diversity is present, then the functional diversity metrics will indicate taxonomic diversity and species richness in the specific ecosystem.

Measuring indices

Functional diversity can be evaluated using various diversity indices introduced by scientists. Along with the species diversity in a specific niche, trait diversity is taken into account. This defines a community-level understanding of the diversity indices. The organisms functionally affect the ecosystem either positively or negatively depending on the growth in the community and new functional traits.

Simpson's index

Among the biodiversity measuring indices Simpson's index is widely used. Simpson's index is measured using the number of species that exist and the relative abundance of each of these species. It is mainly related to species richness, which affects the diversity of the specific region. By suitably considering the ecosystem functions and the resource availability, the functional diversity metrics often tend to change.

This value is calculated for every single species. Taking individuals of one particular species to the total number of persons or individuals in the population (or populace) from all species in the region. The specific value for this diversity index ranges from zero to one. The values start from zero for a region where there is no diversity and it reaches the value one for infinite diversity.

Shannon's index

Shannon's diversity index is another measure of biodiversity depending on species richness or evenness. This index determines a specific string of interest and for a particular species, the specific number of individuals is calculated. Among the data set of all the species that are part of the string of interest, determining the Shannon index requires quantifying that species.                          

Value for Shannon's diversity index generally ranges between 0-1. It is different from Simpson's diversity index as the lower value of this index determines higher biodiversity, while the higher values indicate a lower diversity. This is one of the unique types of functional diversity metrics that can be used to define functions in biodiversity.

Significance of measuring indices in functional diversity

• Using all the indices, one can measure the number of individuals of specific species in a given population. This includes the functional traits of the particular species and how these traits can put an impact on the ecosystem's functioning.
• Functional diversity from all the species together maintains balance in the ecosystem. It leads to eventual species richness inside the population by functionally separating the types of species. Knowing the species biodiversity of a specific population helps determine the functional diversity.
• Functional ecology is completely based on a species-area relationship. Functional traits can also be characterized according to the phylogenetic diversity of species involved. This forms a major part of ecology as the whole ecosystem functioning is dependent on the understanding of taxonomic characters and their relation to functional traits.
• Communities and functional groups of the community establish related species from similar taxonomic categories. The biodiversity is formed with multiple communities like this with organisms having many functional groups. These organisms have similar functions with specific roles in the ecological pyramid. This character is observed in both animal and plant communities.

Context and Application

This subject is directly associated with the concept of taxonomy and ecosystem functions. Students pursuing higher education in few specific fields are going to need ideas about functional diversity.

• Plant and Animal Taxonomic Characters
• Ecology
• Evolution and Phylogenetics
• Population Genetics

Practice Problems

1. How does phylogenetic diversity influence the functional diversity of a particular ecosystem?
   1. Negatively
   2. Positively
   3. Does not affect
   4. Depends on the diversity

Correct Answer: b. Positively. Phylogenetic diversity can estimate the functional trait that affects the function of the ecosystem.

2. Which of the following is not a functional diversity?
   1. Microbial Diversity
   2. Chemical Diversity
   3. Protein Diversity
   4. Species Diversity

Correct Answer: b. Chemical Diversity. It means the variety of metabolic chemical compounds in a particular ecosystem.

3. What is species evenness?
   1. Species at the same trophic level
   2. Species showing similar phenotypic character
   3. Relative abundance of a specific species in a region
   4. Effective control of species growth

Correct Answer: c. Relative abundance of a specific species in a region. It defines the closeness in numbers of each species in an environment.

4. What is the meaning of Simpson's index value as one?
   1. No Diversity
   2. Stable diversity
   3. Infinite Diversity
   4. Can't have a value less than 1.5

Correct Answer: c. Infinite Diversity. In this diversity index, one represents infinite diversity, and zero means no diversity.

5. Shannon’s Diversity Index depends on which factor?
   1. The measurement of species mortality
   2. The measurement of species growth
   3. The measurement of species richness or evenness
   4. The measurement of isolated species

Correct Answer: c. The measurement of species richness or evenness. According to this index, a large number of species can elevate the level of diversity.

Common mistakes

Functional diversity is not associated with the combined functional traits of all species. There can be similar functional traits that are different from species-based traits. A single type of functional trait is not considered more than once in the ecological structure. Species composition differs at specific trophic levels and these species have functionally different characters.