Summary
Combines the number of species (richness) and their relative abundances (evenness) in a community.
In depth
The Simpson index D = 1 - ฮฃ(n/N)ยฒ. A community of equal abundance of 4 species has higher diversity than one dominated by one species. Diversity is also assessed at alpha (local), beta (between sites) and gamma (regional) scales.
Diversity indices combine richness and evenness. Diversity affects stability and productivity. Sampling effort influences richness estimates.
Key idea: more diverse communities generally respond better to disturbance.
Diversity has richness (number of species) and evenness (distribution of abundance), and the Shannon index combines both. Alpha diversity is local, beta is the turnover between sites and gamma is regional. Latitudinal gradient shows more species in the tropics, explained by more energy, stability, area and history. Measuring uses rarefaction to compare samples of unequal effort.
Biodiversity underpins ecosystem function: experiments such as Cedar Creek in Minnesota show that more diverse grassland plots have higher productivity and stability. Hotspots such as Madagascar, the Philippines and the Tropical Andes hold many endemic species and are under threat.
Key idea: a community with more evenly distributed species is typically more diverse than one dominated by a single species, even with equal richness.
Frequently asked questions
What is Species Diversity?
Combines the number of species (richness) and their relative abundances (evenness) in a community.
Which area of biology covers Species Diversity, and how advanced is it?
Species Diversity is one of the 54 topics in Ecology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Ecology, Keystone Species, Macroecology.
Can you give an example of Species Diversity?
A plantation has low diversity compared with natural forest.
What should I learn before Species Diversity?
Work through the Beginner topics in Ecology first, such as Ecology, Ecosystem, Biotic and Abiotic Factors, then return to Species Diversity. Intermediate topics assume the Beginner vocabulary.
What topics are related to Species Diversity?
The closest topics to Species Diversity are Ecology, Keystone Species, Macroecology, Biomes. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Species Diversity?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Species Diversity. To practise the whole of Ecology, use the Ecology quiz.
How is Species Diversity different from Ecology?
Species Diversity: Combines the number of species (richness) and their relative abundances (evenness) in a community. Ecology: The study of how organisms interact with each other and with their physical environment. Read both side by side and note what each one explains.
How should I study Species Diversity step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Ecology and explain the difference aloud. Finally, take the Ecology quiz and come back to this page for any question you miss.