Unit 1 Global Climate Change Pt. 2 Flashcards
exponential growth
Exponential growth: occurs when the population size of each new generation is a multiple of the previous generation, for example, a population that doubles every generation.
- -Required unlimited resources and a nearly vacant environment.
- -This may happen after a disturbance wipes out most life in an area or when a new area is occupied.
- -No natural environment can possibly sustain exponential growth for very long.
limiting factors and carrying capacity
Limiting factors: environmental constraints that put a cap on the size of a population.
Carrying capacity: is the maximum population size than can survive in an environment, given the limiting factors that exist.
–Once the carrying capacity is met, the population size does not change because the birth rate and death rate equal each other.
logistic growth
Logistic growth: is where the size of a population grows rapidly until it nears its carrying capacity for that environment. At that point, the rate of population growth slows.
density-dependent limiting factors
Density-dependent limiting factors: factors that increase or decrease their effect depending on the density of the population. The most common is competition between individuals of the same species for limited resources.
–As the population grows, competition intensifies and birth rates lower.
interspecific interactions
Interspecific interactions: a community ecologist usually studies this. The relationships between species. Such interactions can be classified according to how they affect each population involved. The effect on each species may be beneficial, neutral or harmful.
density-independent limiting factors
Density-Independent limiting factors: factors for which the effect does not relate to population density. Abiotic factors such as weather or disturbances may affect population size by causing a rapid decline. The die-off is expected to be drastic whether the population size is large or small.
competitive exclusion principle
Competitive exclusion principle: the concept that populations of two species cannot coexist in a community if their niches (what they need to survive) are nearly identical. Using resources more efficiently and having a reproductive advantage, one of the populations will eventually outcompete and eliminate the other.
So, if the resources required by the two species are too similar, they cannot coexist.
mutualism
Mutualism: is a form of interspecific interaction in which both populations benefit. Mutualism often occurs among species that are symbiotic, living in close physical association with one another (don’t confuse symbiosis with mutualism; two organisms may live in contact but both may not benefit, as in a parasitic relationship.)
predators/predation
Predators/predation: is an interaction in which a predator species kills and eats a prey species.
herbivory
Herbivory: is the eating of plant parts by an animal.
Plants evolve adaptations that provide defense against herbivores such as the spines of a cactus.
pathogens vs parasites
Pathogens: are disease-causing microorganisms– most often bacteria, viruses, fungi or protists. Humans have many pathogens that cause disease (such as the cold virus) and so do most other large organisms.
Parasites: lives on or in (does not kill) a host, from which it obtains nutrients. Both plants and animals may have parasites. Animal parasites may live internally (tapeworms) or externally (ticks, lice, etc.).
trophic structure and trophic level
Trophic structure: describes the feeding relationships within a community. Each rank in the feeding hierarchy is called a trophic level.
- Understanding the trophic structure allows an ecologist to describe the flow of energy and nutrients through an ecosystem.
food chain and food web
is a simplified description of one part of the trophic structure, following the passage of food energy from one individual to another. (top image)
The food chain oversimplifies real-world biological communities. Several different species occupy most trophic levels and compete with each other for the same prey so actual feeding relationships within ecosystems must be expressed as a multibranched food web that interconnects multiple food chains. (bottom image)
biological magnification
Biological magnification: occurs because toxins (usually by industrial pollution) enter the food chain can cannot be digested and are passed from one trophic level to another. Definition: the tendency of toxins to become concentrated as they pass through a food chain. Thus, top-level predatory fish are often significantly more contaminated than bait fish because they consume more of the lower level organisms and inject way more toxins this way.
species richness vs diversity
Species diversity: the variety of species that live within a community.
—EX: modern agricultural fields have little diversity. Coral reefs and rainforests have extremely high species diversity.
The species diversity of a community has two components:
Species richness: is the number of different species in a community. A community with few different species has low species richness, while a community with many different species has high species richness.
