2 Flashcards
What is speciation and how does it occur?
Speciation occurs when populations become isolated long enough that their genetic makeup changes, preventing them from interbreeding. This is called phyletic evolution.
What role does geographic isolation play in speciation?
It can lead to reproductive isolation and divergence of gene pools, driving the formation of new species.
What is co-evolution?
A process where changes in one species cause reciprocal changes in another; can be antagonistic (arms race) or mutualistic (e.g., monarch butterfly and milkweed).
Define α, β, and γ diversity.
α diversity: species richness in a small, homogenous area
β diversity: rate of change in species composition across habitats
γ diversity: total species richness over a large region
What defines a biome?
A large terrestrial region characterized by specific climate, soil, plants, and animals.
What determines biome type?
Precipitation, temperature, and soil type.
Why are ecosystems so diverse globally?
Due to variations in solar energy, global air circulation, earth’s tilt/rotation, ocean currents, and topography.
How do mountains influence local climate?
They create rain shadows: moist windward sides and dry leeward sides due to rising and descending air.
What causes the Earth’s convection cells?
Uneven heating of the Earth’s surface creates vertical air currents that distribute heat and moisture globally.
Name one major human impact on desert ecosystems.
Soil destruction by off-road vehicles and depletion of groundwater.
How have humans degraded forests?
Through clearing for agriculture, pollution, and conversion to plantations.
What are threats to mountain ecosystems?
Agriculture, tourism, mining, and effects from ozone depletion and air pollution.
What are the biotic and abiotic components of an ecosystem?
Biotic components are the living organisms; abiotic components include non-living factors like temperature, sunlight, and soil.
What is the function of solar energy in ecosystems?
It warms the atmosphere, drives evaporation, recycles water, generates wind, and supports photosynthesis in plants.
What are desert biomes characterized by?
Low precipitation, high evaporation, sparse vegetation, and specialized flora and fauna adapted to dry conditions.
Why do tropical rainforests have such high biodiversity?
They have year-round warm temperatures, high humidity, and consistent rainfall, creating stable conditions for niche differentiation.
What is an example of how elevation mimics latitude in biomes?
As you move from lowlands to mountaintops, vegetation and climate zones change similarly to moving from equator to poles.
