2E2 Interdependence and Dynamics of Ecosystems Flashcards
Study fundamental ecological concepts, including ecosystems, population dynamics, and symbiotic relationships.
Define an ecosystem.
The interaction between all biotic (living) and abiotic (non-living) factors within a geographic area.
What is a habitat?
The natural home or place within an ecosystem that provides the kind of food, water, shelter, and living space an organism needs to survive.
What is a niche?
The special role an organism plays within its ecosystem, involving specific conditions it takes advantage of for survival.
What kind of factors make up an ecosystem?
- Biotic factors (living organisms)
- Abiotic factors (non-living factors)
Biotic factors - plants, animals
Abiotic factors - soil, water, weather
Why don’t different species occupy the same niche?
To minimize competition for the same resources.
Describe the Serengeti-Mara ecosystem.
It is a large grassland savanna in east-central Africa with seasonal tropical climate, volcanic ash-based soil, and diverse grasslands.
What are some of the abiotic factors in the Serengeti-Mara ecosystem?
- Volcanic ash-based soil
- Seasonal rains
- Fire
- Seasonal temperature ranges from 15°C to 27°C
How do animals in an ecosystem try to avoid competition?
Animals occupy different niches, with each having specific needs and capabilities for food, water, space, and shelter.
What is population density?
The number of organisms of the same species living within a specific area.
What are density-dependent factors?
Include disease, competition for resources, predation, and environmental degradation that affect population density based on population size.
What are density-independent factors?
Include extreme weather, natural disasters, fire, pollution, and other abiotic factors that affect population density regardless of population size.
How does competition affect niches?
Competition for the same resources often results in one species adapting, migrating, or declining to avoid direct competition.
What roles do herbivores play in their niches?
They have specific feeding habits and preferences for certain plants, which help them avoid competition with other species.
What determines an animal’s niche in an ecosystem?
By its living habits, including how, what, when, and where it eats, shelters, raises young, and finds water.
Define a population.
All of the organisms in a particular geographic area that belong to the same species.
How can population density be determined?
- By direct counting.
- Estimation through indirect indicators.
- Sampling.
- The mark-recapture method.
What is the sampling method for determining population density?
- Biologists mark off representative plots.
- They count individuals in each plot.
- They calculate density based on these samples.
What are some indirect indicators used to estimate population density?
- Nests
- Burrows
- Tracks
- Droppings
- Markings
Describe the mark-recapture method.
- Biologists capture, mark, and release animals.
- Later, they capture animals again and use the proportion of marked individuals to estimate the total population size.
What is the significance of survivorship curves in studying populations?
They help illustrate the survival rates of individuals at different ages, providing insight into the life history and reproductive strategies of a species.
What characterizes a Type I survivorship curve?
Species with low death rates in early and middle life but high death rates in older age.
e.g. humans, elephants
What characterizes a Type II survivorship curve?
Species with a relatively constant death rate throughout their lifespan.
e.g. songbirds
What characterizes a Type III survivorship curve?
Species with high death rates early in life and lower death rates for survivors reaching adulthood.
e.g. frogs
What makes coral reefs complex biological communities?
They host a diverse range of species, including coral polyps, fish, sea urchins, sponges, algae, and various microbes that interact and depend on each other for survival.
Define predation in a biological community.
An interaction where one species (predator) hunts and eats another species (prey), benefiting the predator’s survival and influencing the prey’s natural selection.
What is camouflage, and how does it relate to abiotic factors?
An adaptation where animals blend into their abiotic surroundings, like rocks or dirt, to avoid predators or ambush prey.
Describe how parasitism occurs.
- Occurs when one organism is used by the other as a host, which provides shelter and a food source.
- The host is harmed by the relationship and the parasite benefits and is typically able to complete its life cycle via the host.
In parasitoid relationships, the host is eventually killed by the dynamic shared by the organisms.
Distinguish between food chains and food webs.
- Food chains: show direct energy transfer between organisms and the trophic levels
- Food webs: a complex network of interconnected food chains within an ecosystem, showing how various organisms are related through multiple feeding relationships.
Food chains and food webs are important in any given ecosystem, as if a population is too large or too small, it may have devastating effects on the entire ecosystem.
