Biodiversity Measurement Methods to Know for Intro to Ecology

Biodiversity measurement methods help us understand the variety of life in ecosystems. By examining species richness, diversity indices, and sampling techniques, we can assess ecosystem health and resilience, which are key concepts in ecology.

1. Species richness

   • Refers to the total number of different species present in a given area.
   • It is a simple measure of biodiversity and does not account for the abundance of each species.
   • Higher species richness often indicates a healthier and more resilient ecosystem.

2. Shannon diversity index

   • A mathematical formula that accounts for both species richness and evenness in a community.
   • Values range from 0 (no diversity) to higher values indicating greater diversity.
   • Useful for comparing diversity across different habitats or time periods.

3. Simpson's diversity index

   • Measures the probability that two individuals randomly selected from a sample will belong to the same species.
   • Values range from 0 (infinite diversity) to 1 (no diversity), with lower values indicating higher diversity.
   • Particularly sensitive to changes in the most abundant species.

4. Evenness

   • Describes how evenly individuals are distributed among the different species in a community.
   • High evenness means species are represented in similar numbers, while low evenness indicates dominance by one or a few species.
   • Important for understanding community structure and stability.

5. Rarefaction

   • A statistical method used to estimate species richness from a subset of data.
   • Helps to compare biodiversity across different samples by standardizing sample size.
   • Useful for assessing the completeness of species inventories.

6. Mark-recapture method

   • A technique used to estimate population size by capturing, marking, and releasing individuals, then recapturing them later.
   • The ratio of marked to unmarked individuals in the second sample provides an estimate of the total population.
   • Important for studying animal populations and their dynamics.

7. Quadrat sampling

   • Involves dividing a study area into smaller, manageable sections (quadrats) to assess species presence and abundance.
   • Provides a systematic way to collect data on plant and animal communities.
   • Useful for studying stationary organisms and understanding spatial distribution.

8. Transect sampling

   • A method where a line (transect) is established across a habitat, and species are recorded at regular intervals along the line.
   • Helps to assess changes in biodiversity across environmental gradients.
   • Effective for studying larger areas and understanding habitat transitions.

9. Point-count method

   • Involves counting the number of individuals of different species observed from a fixed point over a set period.
   • Commonly used in bird surveys to assess species richness and abundance.
   • Provides a snapshot of community composition and can be repeated over time for monitoring.

10. Genetic diversity measures

    • Assess the variety of genetic characteristics within a species or population.
    • Important for understanding evolutionary potential and resilience to environmental changes.
    • Methods include analyzing allele frequencies, heterozygosity, and genetic distance among populations.