Ch 1 reading "why ecology matters" Flashcards
geographic distribution of organisms
Key Points:
Species distributions are shaped by geographic barriers (mountains, oceans) and climatic factors (temperature, rainfall).
Human Activity: Humans have removed barriers by moving species into new regions, often leading to invasive species problems (e.g., cane toads in Australia, European starlings in North America).
Transplant Experiments: Demonstrate whether a species’ absence in an area is due to dispersal limitations or unsuitable conditions.
Examples:
Penguins: Found in the Southern Hemisphere due to tropical oceans acting as barriers.
Cane Toads in Australia: Introduced to control pests, but they failed and became an invasive species.
European Starlings: Introduced into Central Park in 1890 and rapidly expanded across North America.
Population dynamics
Key Points:
Populations cannot grow indefinitely due to resource limitations, predation, and competition.
Carrying Capacity (K): Maximum population size the environment can support.
Overexploitation leads to population collapse (e.g., overfishing, hunting).
Examples:
Atlantic Cod: Overfished to the point of collapse.
Snowshoe Hares: Cyclic population changes driven by predator-prey dynamics.
Habitat suitability
Key Points:
Every species has suitable and unsuitable habitats based on ecological requirements.
Indicator Species: Reflect the health of their ecosystems.
Fragmentation and destruction of habitats lead to biodiversity loss.
Examples:
Mangroves: Expand poleward with warming temperatures, replacing salt marshes.
Freshwater Fishes: Move upstream as water temperatures rise.
Community Recovery and Stability
Key Points:
Communities can recover from disturbances like fires or storms through succession.
Resilience: The ability of an ecosystem to return to its original state after a disturbance.
Multiple stable configurations are possible depending on the extent of the disturbance.
Examples:
Tropical Rainforests: Recover slower than temperate forests due to nutrient-poor soils.
Coral Reefs: Recovering depends on water temperature and pollution levels.
Keystone Species
Key Points:
Keystone species have a disproportionate impact on their ecosystems.
Their removal can cause trophic cascades, altering the entire ecosystem structure.
Examples:
Sea Otters: Control sea urchin populations, preserving kelp forests.
Wolves in Yellowstone: Reintroduction stabilized prey populations and vegetation.
evolution and natural systems
Key Points:
Evolution shapes ecosystems by promoting adaptations and species interactions.
Coevolution: Reciprocal evolutionary changes between interacting species.
Examples:
Pollination Systems: Coevolution of plants and pollinators (e.g., orchids and moths).
Predator-Prey Dynamics: Red Queen hypothesis (e.g., faster prey leads to faster predators).
Recycling and Energy in Ecosystems
Key Points:
Nutrient cycling and energy flow sustain ecosystems.
Solar Energy: Primary driver of photosynthesis and food webs.
Decomposers: Critical for nutrient recycling.
Examples:
Tropical Rainforests: Efficient nutrient cycling, despite nutrient-poor soils.
Ocean Currents: Distribute nutrients, supporting marine ecosystems.
Climate Change and Biodiversity
Key Points:
Climate change alters temperature, precipitation, and habitat suitability.
Species must acclimate, adapt, or migrate; otherwise, extinction occurs.
Biodiversity loss is irreversible and threatens ecosystem services.
Examples:
Range Shifts: Average species move poleward by 18 km/decade (Chen et al., 2011).
Mangrove Expansion: Replacing salt marshes due to reduced frost frequency.
Human Impacts and Conservation
Key Points:
Overexploitation, habitat destruction, and invasive species threaten biodiversity.
Conservation strategies include protected areas, sustainable resource use, and restoration projects.
Examples:
Cane Toads in Australia: A cautionary tale of poorly planned species introductions.
Marine Protected Areas: Preserve biodiversity and fisheries.
What factors limit the geographic distribution of species?
A: Geographic barriers (mountains, oceans), climatic factors (temperature, rainfall), and human activity.
What are transplant experiments, and what do they test?
A: Experiments that move species to new areas to determine if dispersal or unsuitable conditions limit their range.
Provide an example of a species affected by geographic barriers.
A: Penguins are confined to the Southern Hemisphere due to tropical ocean barriers.
How do humans affect species distributions?
A: By introducing species to new areas, often leading to invasive species problems (e.g., cane toads in Australia).
What is carrying capacity (K)?
A: The maximum population size an environment can support due to resource limitations.
What happens when populations exceed carrying capacity?
A: Overexploitation of resources leads to population collapse or environmental degradation.
