LO 15: Conservation Biology and Global Change Study Guide

Conservation Biology

Integrates ecology, genetics, physiology, molecular and evolutionary biology to protect Earth's biodiversity.

Levels of Biodiversity

Genetic Diversity: Variation within and between populations; its loss reduces adaptive potential.

Species Diversity

Number and relative abundance of species; currently ~14% of birds and 26% of mammals are threatened.

Ecosystem Diversity

Variety of ecosystems; >50% of U.S. wetlands have been drained.

Minimum Viable Population (MVP)

Smallest population size at which a species can persist; depends on factors like catastrophe risk.

Effective Population Size

Number of breeding individuals; often much lower than census size.

Extinction Vortex

Small populations suffer inbreeding, genetic drift, reduced fitness, further declines.

Background vs. Current Rates

Fossil‐record (background) extinction rates vs. today's 100-1,000× higher rates.

Causes of Mass Extinctions

Driven by habitat loss, overharvesting, invasive species, climate change.

Consequences of Mass Extinctions

Results: ecosystem collapse, loss of ecosystem services.

Habitat Destruction & Fragmentation

Conversion by agriculture, urbanization, forestry; smaller, isolated patches increase local extinctions.

Introduced Species

Lack natural predators ⇒ invasive spread (e.g., kudzu, zebra mussels).

Overharvesting

Ivory poaching, overfishing (e.g., bluefin tuna down to 20% in 10 yrs).

Nutrient Enrichment (Eutrophication)

Excess N & P runoff ⇒ algal blooms and "dead zones" (Mississippi Basin).

Biological Magnification

Toxins (PCBs, DDT) concentrate up the food chain, harming top predators.

Global Change / Climate Change

↑ CO₂ & other GHGs ⇒ greenhouse effect ⇒ ~1.1 °C warming since 1900; shifts in range, phenology, ecosystem function.

Movement Corridors

Strips linking fragments; promote gene flow but may spread disease.

Biodiversity Hotspots

Small areas (< 2% land) with high endemism; protecting them preserves ~30% of bird species.

Climate vs. Weather

Weather: Short‐term atmospheric conditions. Climate: Long‐term patterns (> 30 yrs); climate change alters temperature, precipitation, extreme events, with cascading ecological impacts.

Biological Magnification Process

Low‐biomass top predators accumulate higher toxin concentrations because each trophic transfer concentrates fat-soluble chemicals.

Conservation biology

An interdisciplinary science aiming to document biodiversity, understand human impacts, and develop strategies to protect species, habitats, and ecosystems.

Three levels of biodiversity

Genetic diversity, species diversity, and ecosystem diversity.

Minimum Viable Population (MVP)

The smallest population size at which a species can persist without falling into an extinction vortex.

Extinction vortex

Inbreeding, genetic drift, reduced fitness, demographic stochasticity in small populations.

Background extinction rates vs current rates

Today's extinction rates are 100-1,000× higher than typical fossil‐record rates.

Habitat fragmentation example

Los Angeles foothills: road‐cut patches reduce interior forest species and boost edge species.

Eutrophication

Excess nutrients (N, P) in water cause algal blooms and hypoxic 'dead zones.'

Biological magnification

Toxins become more concentrated in fat tissues at each higher trophic level, harming predators.

Biodiversity hotspot

A small region with exceptionally high endemism and threatened species; 2% of land holds ~30% of birds.

Movement corridors pros and cons

Pros: promote dispersal, reduce inbreeding; Cons: may facilitate disease spread, invasive species movement.

Climate vs weather

Climate is long‐term average conditions; weather is short‐term atmospheric state.

Earth's warming since 1900

Approximately 1.1 °C (2 °F).

Threatened ecosystem service

Pollination, water purification, carbon storage, nutrient cycling, etc.

Small populations extinction-prone

Greater vulnerability to demographic fluctuations, inbreeding depression, genetic drift.

Greenhouse effect

Gases like CO₂ absorb IR radiation and re-radiate heat back to Earth, warming the planet.

Species conservation success

Northern elephant seals rebounded from ~20 to ~150,000 individuals despite low genetic diversity.

Anthropogenic activity doubling fixed nitrogen supply

Industrial fertilizer production.

Introduced species cause extinctions

Predation, competition, disease; lacking natural enemies they outcompete natives.

Acid rain example of global change

SO₂ and NOₓ emissions form sulfuric/nitric acids, harming aquatic and terrestrial life.

Why protect ecosystem services?

They sustain human life—food, water, climate regulation, cultural benefits, and more.