Local communities thrive when immigration rates are stable and diverse.
The study looked at how different species of plants and animals are distributed in local communities compared to larger areas. They found that as the size of the local community increases, its species diversity becomes more similar to the larger surrounding area. By allowing for the possibility of new species forming within local communities and considering varying rates of species migration, they showed that high variability in migration rates can reduce species diversity in local areas. Additionally, they discovered a simple relationship between a key diversity parameter and a commonly used diversity index, which can help us understand how immigration affects estimates of species diversity in local communities.