Study Notes
Ecology and conservation involve understanding how species interact with their environment and the factors that affect their survival. Limiting factors, ecological niches, and keystone species play crucial roles in shaping ecosystems.
- Limiting factors — conditions that restrict the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem. Example: Light, temperature, and salinity are abiotic limiting factors.
- Ecological niche — the role and position a species has in its environment, including all interactions with biotic and abiotic factors. Example: A bird's niche might include its nesting area, food sources, and predators.
- Keystone species — a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically. Example: Sea otters are keystone species because they control sea urchin populations, which in turn maintains kelp forest ecosystems.
- Trophic levels — the hierarchical levels in an ecosystem, comprising producers at the bottom and various levels of consumers above. Example: Plants are producers, while herbivores are primary consumers.
- Biomagnification — the process by which the concentration of toxic substances increases in each successive link in the food chain. Example: Mercury levels increase in fish higher up the food chain.
- Primary succession — the series of community changes which occur on an entirely new habitat which has never been colonized before. Example: Lichens and mosses colonizing bare rock.
- Invasive species — non-native species that spread beyond their original introduction site and cause environmental or economic damage. Example: Kudzu vine in the United States.
Exam Tips
Key Definitions to Remember
- Limiting factors
- Ecological niche
- Keystone species
- Trophic levels
- Biomagnification
- Primary succession
- Invasive species
Common Confusions
- Confusing biotic and abiotic limiting factors
- Misunderstanding the difference between a niche and a habitat
Typical Exam Questions
- What is a keystone species? A species that has a disproportionately large impact on its environment relative to its abundance.
- How does biomagnification affect top predators? Top predators accumulate higher concentrations of toxins due to biomagnification.
- What happens during primary succession? New land is colonized by pioneer species, leading to soil formation and eventually a stable ecosystem.
What Examiners Usually Test
- Understanding of ecological niches and their importance
- Ability to explain the impact of keystone species
- Knowledge of the effects of invasive species on ecosystems