BIO 3060 - Species diversity (audio) - 10/20/25

Species Richness: Total number of species in a community (e.g., 683 species).
Species Evenness: Distribution of individuals among those species. High evenness indicates balanced populations, while low evenness reflects dominance by a few species.

Higher species evenness correlates with healthier communities.
The Shannon-Wiener Index measures species richness and evenness, considering both the proportion of species and their abundance.

A graphical representation comparing abundance of species.
Slope indicates the distribution of species and health of the community:
- Steep slope implies dominance of one species.
- Gentle slope indicates more even distribution.

Latitude Gradient: Species diversity decreases from the tropics to polar regions.
Productivity: Higher productivity supports increased species diversity.
Spatial Heterogeneity: Complex environments (more niches) enhance diversity.
Peninsula Effect: Species diversity decreases as one moves further from the mainland.
Ecotones: Diversity is often higher where ecosystems overlap (area of transition between biomes).
Intermediate Disturbance Hypothesis: Moderate disturbances maintain higher diversity by preventing dominance and allowing new species to establish.

Larger sample sizes lead to more accurate representations of community distributions.
Log-normal distributions represent relative abundance in healthy communities, while smaller samples can show skewed data.