Ecosystems, Biodiversity, and Human Impacts

Ecosystems Review

• Populations change in size via births, deaths, immigration, and emigration.

• Species interact through predation, herbivory, mutualism, and competition.

• Energy and matter transfer in ecosystems via trophic interactions, influenced by abiotic factors.

Human Impacts on Ecological Systems

• Human activities have adverse impacts on species and habitats, causing a global phenomenon.

• Extinction rate is 100 to 1,000 times faster than in pre-human times.

Biodiversity Loss

• Biodiversity loss is a concern due to human dependence on species for ecosystem goods and services, psychological benefits, and ethical issues.

Levels of Biodiversity

• Genetic diversity: variation within and between populations.

• Species diversity: number of species in an ecosystem or biosphere.

• Ecosystem diversity: variety of ecosystems in the biosphere.

Endangered and Threatened Species

• Endangered species: in danger of extinction throughout its range.

• Threatened species: likely to become endangered in the foreseeable future.

Causes of Threatened Status

• Habitat loss is the biggest threat.

• Other major threats: exotic species, pollution, and over-exploitation.

Extinction Vortex

• Reduced population size leads to further declines, creating an extinction vortex.

Minimum Viable Population Size

• Minimum viable population (MVP) is the minimum population size at which a species can sustain its numbers.

Threats to Biodiversity

• Habitat loss is due to agriculture, forestry, urban development, mining and pollution.

• Introduced species can prey upon or outcompete native organisms.

• Overharvesting occurs when harvesting exceeds the population's ability to rebound.

• Global change includes nutrient enrichment, toxin accumulation, climate change and ozone depletion.

Nutrient Enrichment

• Human activity removes nutrients from one area and adds them to another.

Toxins in the Environment

• Humans release toxic chemicals that persist and accumulate in animal tissues.

Plastic Waste

• Plastics are a major source of marine waste.

• Microplastics contaminate oceans and food chains.

Greenhouse Gases and Climate Change

• Climate change is driven by human activities releasing gaseous waste into the atmosphere.

Climate Change Effects

• Increasing temperature affects enzymatic reactions and cellular defense responses.

• Global warming increases the risk of overheating in some species.

• Climate change affects population size, timing of growth, reproduction, and migration.

• Species migration can cause changes in ecological communities.

Modeling Climate Change

• Models predict an additional 3°C (5°F) rise in temperature by the end of the 21st century.

Biodiversity and Human Welfare

• Humans benefit from biodiversity through biophilia, morality, obligation, and various services.

Benefits of Species and Genetic Diversity

• Species related to crops have important genetic qualities.

• Many prescriptions contain chemicals from plants.

Ecosystem Services

• Ecosystem services sustain human life through processes like purification, detoxification, pollination, and moderation of weather extremes.

Addressing Climate Change

• Reducing energy use and converting to renewable sources can slow global warming.

• Conservation biology integrates multiple fields to conserve biological diversity.