Notes on Biodiversity, Ecosystem Services, and Biogeography

2.1 Intro to Biodiversity

Learning Objective

ERT-2.A: Explain levels of biodiversity and their importance to ecosystems.

Suggested Skills

1.A: Concept Explanation - Describe environmental concepts and processes.

Essential Knowledge

ERT-2.A.1: Biodiversity in an ecosystem includes:

  • Genetic Diversity: Refers to the variety of genes within a population, which is vital for a population's ability to adapt and evolve.

  • Species Diversity: This encompasses the variety of species within a given ecosystem. It includes both the number of species (species richness) and their relative abundance (species evenness).

  • Habitat Diversity: Refers to the variety of habitats in a particular region, which supports a wider range of species and ecological processes.

ERT-2.A.2: Importance of Genetic Diversity

  • Enhanced ability of a population to respond to environmental stressors: Populations rich in genetic diversity have a better chance of surviving drastic changes like climate shifts, diseases, or habitat changes.

  • Population bottleneck can lead to loss of genetic diversity: This occurs when a population's size is significantly reduced due to events like natural disasters, drastically lowering genetic variability and increasing vulnerability.

ERT-2.A.3: Ecosystem Diversity and Recovery

  • More species within an ecosystem enhance recovery from disruptions: Diverse ecosystems can better absorb shocks from environmental changes or disasters; for example, diverse plant species can provide varied protection against soil erosion after a flood.

ERT-2.A.4: Habitat Loss

  • Loss of habitat leads to:

    • Loss of specialist species: These species rely on specific environmental conditions, and their inability to adapt results in their extinction.

    • Loss of generalist species: These are less affected in diversity but may still suffer from reduced availability of resources.

    • Reduced numbers of species with large territorial requirements: The decline in habitats jeopardizes species needing large, continuous areas for survival, affecting their reproductive success and overall populations.

ERT-2.A.5: Species Richness

  • Species richness refers to the total number of different species found in an ecosystem. It is a fundamental measure of biodiversity, which correlates with ecosystem health and resilience.

Biodiversity Basics

  • Levels of Measurement:

    • Genetic Diversity: Variation of genes within a population, critical for adaptability.

    • Species Diversity: Number of different species and their population balance in an ecosystem, contributing to ecological stability and resilience.

    • Ecosystem Diversity: Variety of habitats within a given area, influencing the overall health and functioning of ecosystems.

  • Higher biodiversity indicates higher ecosystem and population health, leading to more robust ecological interactions and stability.

Species Richness & Evenness

  • Species Richness (r): Total number of different species, which positively correlates with ecosystem health.

  • Evenness: Refers to the distribution balance of individuals among species; high evenness means that species are approximately equal in numbers. High species richness and evenness imply healthy ecosystems with sufficient resources available for wildlife.

Genetic Diversity in Populations

Exists due to:

  • Random DNA mutations: These mutations can introduce new traits into a population.

  • Recombination during sexual reproduction: This process shuffles genes from both parents, further increasing genetic diversity.

Benefits of Genetic Diversity:

  • Helps populations survive environmental stressors (e.g., drought, disease) and ensures adaptability over generations.

Bottleneck Events

  • Bottleneck events occur due to:

    • Environmental disturbances (like natural disasters) that drastically reduce population size, limiting genetic variability and making populations more vulnerable to future disturbances.

Inbreeding Depression

  • Inbreeding: Mating between closely related individuals. This can lead to numerous problems such as:

    • Increases chances of harmful genetic mutations.

    • Example: The Florida panther shows defined conditions like kinked tails and heart defects caused by the population decline, illustrating the dangers of reduced genetic diversity.

Ecosystem Resilience

  • Resilience: The ability of ecosystems to return to their original conditions after disturbances. A diverse ecosystem is more resilient to changes, as higher species diversity correlates with higher resilience, providing essential resources for recovery (e.g., plants that can prevent soil erosion and provide food for animals).

Ecosystem Services

Learning Objectives:

ERT-2.B: Describe ecosystem services.
ERT-2.C: Results of human disruptions to ecosystem services.

Essential Knowledge:

ERT-2.B.1: Four categories of ecosystem services:

  • Provisioning: Goods obtained from ecosystems, such as food, timber, and fresh water.

  • Regulating: Ecosystem processes that regulate climate, air quality, and water flow, contributing to public health and safety.

  • Supporting: Ecosystem functions like pollination, nutrient cycling, and soil formation that enable other ecosystem services to occur.

  • Cultural: Recreational, spiritual, and aesthetic benefits derived from natural environments that enhance quality of life.

Human Disruptions to Ecosystem Services

Human activities, such as urbanization, deforestation, and pollution, harm ecosystem functions and negatively impact economic value and ecological balance, leading to biodiversity loss and impaired ecosystem services.

Island Biogeography

Learning Objectives:

ERT-2.D: Describe island biogeography.

Essential Knowledge:

ERT-2.D.1: Study of ecological relationships and organism distribution on islands, which provides insights into species diversity, evolution, and conservation strategies.

Concepts in Island Biogeography

  • Larger Islands: Support higher ecosystem diversity and species richness due to a greater variety of habitats and resources.

  • Proximity to Mainland: Closer islands tend to have greater species richness due to easier colonization by species, enhancing biodiversity and ecosystem stability.

Context of Adaptation and Evolution

Organisms adapt to environmental changes over time through genetic variations driven by natural selection, and those that cannot adapt rapidly may face extinction, illustrating the dynamic nature of biodiversity.

Ecological Succession

  • Primary Succession: Occurs on bare rock, lacking soil, such as post-volcanic eruptions, and involves the gradual colonization of pioneer species.

  • Secondary Succession: Follows disturbances in areas where soil is already present (e.g., after a forest fire), allowing for faster recovery because soil and nutrients remain.

  • Pioneer species play a critical role in establishing ecosystems by modifying the environment to allow other species to thrive.

Additional Notes

Be familiar with each level of biodiversity, its importance, as well as how human and natural disturbances impact these ecosystems. Understanding these concepts is crucial for conservation efforts and sustainable practices that support biodiversity.