Subtopics are highlighted, terms are bolded, and definitions are underlined :)
What is Ecology?
Ecology is the interactions between organisms and their environment.
Ecology consists of both living and nonliving factors called...
Biotic - living factors
Abiotic - nonliving physical and chemical conditions
Examples of biotic factors would be animals, birds, plants, fungi, etc.
Examples of abiotic factors would be sunlight, temperature, soil, wind, water, etc.
There are 6 levels of ecological organization:
Individual, population, community, ecosystem, biome, and biosphere.
(These are in order from smallest to largest, individual being the smallest and biosphere being the largest)
Individual - an individual of a certain species, ex. a rabbit
Population - a group of individual organisms of the same species living in a particular area, ex. a herd of buffalo
Community - all the organisms inhabiting a particular area, ex. cheetahs and gazelles living in the same area
Ecosystem - includes all the biotic and abiotic factors in an area, ex. Tamaques Park
Biome - a regional ecosystem classified according to the climate and the predominant vegetations in the area, ex. desert*
Biosphere - the sum of all the biotic and abiotic factors on Earth
*Some other common biomes are marine biomes, tropical rainforests, savanna, temperate grassland, taiga, and arctic tundra.
What is behavior?
Behavior is everything an animal does and how it does it or its response to stimuli in its environment.
There are two types of behaviors...
Innate - inherited; instinctive; automatic; consistent, ex. drinking mom's milk or reproduction
This is something that the individual is born knowing how to do, which is why it comes naturally to them. Despite different environments, all individuals exhibit the behavior.
Learned - changes with experience and environment; variable; flexible, ex. manners
This is something that the individual is not born with and develops over time.
note: The ability to learn is innate, but the behavior develops during an individual's lifetime.
Social Behaviors - interactions between individuals develop as evolutionary adaptations, ex. communication, language, cooperation
Specific example: Bird song (communication)
Bird songs are the species identification and mating ritual. This is both a learned and innate behavior. The ability to sing is innate but what song to sing is learned.
One social behavior is called a dominance hierarchy.
Dominance hierarchy is a social ranking within a group, like a pecking order.
Another social behavior is cooperation.
Cooperation is working together in coordination, ex. a pride of lions hunting wildebeest or fire ants swarming together.
What are the evolutionary advantages of social cooperation between members of a species? (Herding, schooling, swarming, hunting in packs, etc.)
Cooperation makes certain tasks easier and prevents the species from being eaten. If we use the example of lions hunting wildebeest, having many lions hunt, makes catching the wildebeest easier. One lion alone might not be able to catch its food, but a group of them will be able to. Hunting in a group also allows helps lions to survive as other predators most likely won't try to bother a whole pride of lions.
As stated before, a population is a group of individuals of the same species living in the same area at the same time.
What are the factors that affect population size?
Factors that increase the population - birth, and immigration
Factors that decrease the population - death, and emigration
Exponential Growth - when a population multiplies by a constant factor at constant time intervals
Carrying Capacity (k) - the greatest number of individuals that a space can support with its available resources
In other words, it is when the birth rate = the death rate
note: The carrying capacity is always changing.
Limiting Factors - chemical or physical factors that limit the existence, growth, abundance, or distribution of an organism, ex. food, space, water, nutrients disease, competition, etc.
There are two types of limiting factors...
Density Dependent Factors - factors whose effects on the size or growth of the population vary with the population density, ex. competition for space, food, water availability, mates, disease, predators, parasites, etc.
These are factors that affect the growth of the population depending on the population density. For example, if there is a large population density, there is less food for each individual, which would decrease the growth of the population as fewer individuals are getting food. But if there is a small population density, there is more food for each individual, which would increase the growth of the population as every individual is getting food.
Density Independent Factors - factors that affect the size of the population regardless of the population density, ex. pollution, pesticides, seasonal weather, hurricanes, etc.
These are factors that affect the growth of the population no matter what the population density is. For example, whether the population is large or small, a hurricane is going to decrease the population density, as it might kill many individuals.
What is the predator-prey relationship?
The predators eat the prey, so when there is more prey, the predators have more food, which then increases their population. When there is less prey there is less food for the predators to eat, which decreases their population.
As you can see, when the prey line goes up, so does the predator's line. Same thing for a decrease in population.
A niche is a species unique living arrangement within a community that includes habitat, food resources, time of day when the species is most active, and other factors specific to that organism's way of life.
Habitat - a physical location where an organism lives
Competition - when members of different of the same species compete for limited resources such as food and places to live
There are two types of competition...
Interspecific Competition - competition between members of a different species, ex. squirrels and chipmunks
Intraspecific Competition - competition amongst members of the same species
What is the competitive exclusion principle?
The competitive exclusion principle is if two species are so similar in their requirements that the same resource limits both species' growth, one species may succeed over the other.
As you can see, each species does fine on its own, but when put together, because they have the exact same needs, one exceeds the other.
Similar species can however occupy the same area if their niches are slightly different from one another, hence an ecosystem.
Symbiotic Relationships - close interactions between species in which one of the species lives in, on, or near the other
Here are some examples...
Predation - an interaction in which one organism eats another, ex. prey and predator
This is a + and - relationship, as the predators get food (+) and the prey, dies (-).
Parasitism - one organism obtains its food at the expense of another organism, ex. host and parasite
This is a + and - relationship as the parasite gets a place to live (+) and the host has a parasite (-).
Mutualism - both organisms benefit, ex. bees and flowering plants
This is a + and + relationship as the bees get pollen (+) and the flowers get pollinated (+).
Commensalism - one organism benefits, while the other organism is neither harmed nor helped, ex. cattle egrets and water buffalo
This is a + and 0 relationship as cattle egrets feed on insects flushed out of the grass by grazing bison, in other words, they get food (+) and the water buffalo get nothing (0 or neutral).
Succession - a series of changes in the species makeup in a community following a disturbance.
There are two types of succession...
Primary Succession - when a community arises in a virtually lifeless area with no soil, ex. volcano erosion
Soil formation has to happen, which is when lichens and mosses break down rock and minerals and add organic material when they die.
Secondary Succession - when a change following a disturbance damages an existing community but leaves the soil intact, ex. fires
note: Primary Succession takes longer than secondary succession because of soil formation.
Biodiversity - the number of different species in a given habitat.
What are examples of a reduction in biodiversity?
Clearing the land, pollution, overhunting, invasive species.
Invasive species - species that enter into new ecosystems and spread causing damage to native species and their habitats.
They can do this because they have no natural predators.
What is the main energy source for life on Earth?
Producers - organisms that make their own food for energy, ex. plants
Consumers - organisms that feed on producers or other consumers for energy, ex. lions
Decomposers - organisms that break down other dead organisms for energy, ex. worms
There are three types of consumers...
Herbivores - eat plants
Carnivores -eat animals
Omnivores - eat plants and animals
What are food chains and food webs?
Food chains are a sequence of organisms each of which is a source of food for the next.
Food webs are all the food chains of a community connected together.
Feeding levels are otherwise known as trophic levels. There are 5 trophic levels...
Primary producers, primary consumers, secondary consumers, tertiary consumers, quaternary consumers.
These can get confusing because the primary consumer is the first consumer level, but the second trophic level.
note: 10% of the energy from one feeding level is converted into biomass at the next feeding level. 90% of the energy is lost to heat.