Understanding Biodiversity

Biodiversity Overview

• Biodiversity refers to the variety of life, encompassing differences at various levels.
• Ecosystem diversity involves different environments and organisms.
• Species diversity refers to the variety of species within an ecosystem.
• Genetic diversity involves variety within a single species.

Estimating Species Numbers

• Estimating the number of species is challenging.
• Current estimates suggest there are between 2 and 10 million species of UK eukaryotes.
• This broad range acknowledges the existence of unidentified or unclassified species.
• Different species of prokaryotes (bacteria) are abundant and difficult to count.

Historical Biodiversity Trends

• Assessing the number of species that once existed is challenging, especially for extinct species.
• Fossil records indicate cycles of increasing biodiversity followed by mass extinctions throughout Earth's history.
• These cycles involve the formation of new species and subsequent extinctions.

Current Biodiversity Crisis

• The current period is experiencing increasing biodiversity, which is expected to end with increased extinction based on historical patterns.
• A key difference between the current potential mass extinction and previous ones is its anthropogenic cause, meaning it is caused by humans.
• Human activities such as over harvesting, poaching, habitat loss, invasive species, pollution, and global climate change contribute to the crisis.

Ecosystem and Biodiversity Loss

• Ecosystem loss is driven by human activities, impacting both biotic (living) and abiotic (non-living) factors in an area.
• Biotic features include plants, animals, fungi, and bacteria.
• Abiotic factors include water, sunlight availability, and rocks.
• The Aral Sea is an example of ecosystem loss due to the diversion of rivers for irrigation, which has led to significant environmental damage.

Biodiversity Crisis Characteristics

• The current decline in biodiversity is considered a crisis due to its unprecedented loss of ecosystems, species, and genetic diversity.
• The scope of biodiversity loss is more extensive than in historical mass extinctions.
• Evidence of the crisis is compiled by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).
• IPBES gathers evidence on habitat degradation, species diversity, population ranges, and genetic diversity.

Measuring Biodiversity Loss

• The Simpson's Diversity Index measures biodiversity loss.
• The index considers the total number of organisms, the number of individuals of a particular species, species richness and evenness.
• A high diversity index indicates a diverse ecosystem with many species and even distribution.
• A low diversity index indicates low diversity and potential dominance by one species.

Simpson's Diversity Index

• To calculate the diversity index take the total number of organisms of all species in an area and multiply that by that same number less one.

Worked Example of the diversity index

• Place A results show higher diversity because the species in the area are more evenly distributed.

Causes of Biodiversity Loss

• Unlike past extinctions caused by natural events such as volcanoes or asteroids, the current mass extinction is anthropogenic.
• Overpopulation is a major factor, leading to increased demand for resources and habitat destruction.
• Although humans have long engaged in activities like farming and irrigation, the scale of these activities has increased dramatically.

Conservation Strategies

• Conservation efforts should employ multiple strategies for greater effectiveness.
• Strategies can be categorized as in situ (in the natural environment) or ex situ (outside the natural environment).
• In situ conservation involves protecting natural environments and creating protected areas.
• This approach aims to minimize disruption to organisms' natural behavior and evolutionary processes.
• In situ conservation can be more cost-effective but may require active management of invasive species, predator populations, or feeding programs.
• Ex situ conservation involves removing individuals from their natural environment and placing them in zoos or other controlled environments.
• Ex situ conservation may involve captive breeding programs and preservation of sperm, eggs, or seeds.

Conservation Priorities

• Given the scale of biodiversity loss, conservation efforts must prioritize certain species.
• The Edge of Existence program focuses on species that are evolutionarily distinct and globally endangered.
• Evolutionarily distinct species are unique and lack closely related species.
• Globally endangered species have a high likelihood of extinction across all populations.
• Prioritizing conservation efforts on such species is a key goal of the Edge of Existence program.