Populations
Environment: includes all factors, living and nonliving, that affect an organism during the course of its life.
2. Ecology: the study of the interaction between organisms and their environment.
3. Ecological hierarchy: a method of arranging the various approaches to ecology in a step-wise manner.
4. Organismal ecology: focuses on the response of organisms or species to environmental factors; lowest level of the hierarchy.
5. Population: an assemblage of individuals of the same species that live in the same place at the same time.
6. Community: an assemblage of interacting populations that form an identifiable group.
7. Ecosystem: the sum total of all the species on a site, along with the physical factors that may affect them.
8. Landscape: an assemblage of adjacent ecosystems covering, perhaps, dozens of square miles.
9. Biome: a large (usually 100’s of square miles) ecological unit composed of many adjacent and overlapping landscapes; there
are 12 major biomes on earth.
10. Biosphere: the sum total of all life on earth, plus the surrounding physical environment.
11. Basic ecology: a subdiscipline of ecology that focuses on studying the interactions of organisms under natural conditions that
are not impacted by humans.
12. Applied ecology: a subdiscipline of ecology that focuses on the impact of humans on the environment and attempts to solve
environmental problems through ecological, scientific means.
13. Environmental science: focuses on the application of scientific principles to the understanding and solving of human
disturbances of nature.
14. Environmentalism: the sociopolitical movement concerned with the effects of humans on nature and which is devoted to
stopping or, at least, minimizing any harmful impacts caused to nature by humans.
15. Ethology: the study of animal behavior.
16. Ethologist: a biologist who specializes in the study of ethology.
17. Instinct: any behavior that is controlled primarily by genetics, but which can be modified and “turned off.”
18. Learning: the process of developing a behavioral response based on experience; learned behaviors are often perfected
through practice.
19. Abiotic Resources: environmental factors that are directly incorporated into an animal's body.
20. Abiotic Regulators: environmental factors that are not consumed directly, but which influence the survival of the animal.
21. Law of limiting resources: the survival and growth of an individual (or pop.) is limited by the resource that is in shortest
supply.
22. Tolerance range: the range over which a species can grow and survive; applies to each environmental variable.
23. Generalists: species that do well under a broad range of environmental conditions.
24. Specialists: species that survive only within a very narrow range of environmental conditions.
25. Environmental variability: fluctuations or changes in environmental conditions; can occur in time and/or space.
26. Biological clocks: an innate mechanism by which living organisms are able to perceive the lapse or flow of time.
27. Biorhythms: behaviors that occur in response to an animal’s biological clocks; also called cycles.
28. Navigation: a directional sense that enables an animal to get from one place to another, and back to their territory.
29. Territoriality: all behaviors associated with protecting and defending an area (territory) against other individuals.
30. Migration: regular (usually seasonal) movement of a species (or members of a species) from one geographical location to
another.
31. Navigational cues: any environmental variable or stimulus that an animal uses to navigate during migration.
32. Communication: any action by one animal that influences the action of another animal.
33. Habitat: a term that refers simply to where an animal lives.
34. Niche (=ecological niche): the sum of an organism's utilization of and interaction with its environment; an organism's “place”
or “role” in the environment.
35. Fundamental niche: what a species' interaction with its environ. would be under ideal circumstances/conditions.
36. Realized niche: those interactions between an organism and its environment that actually do occur in reality.
37. Principle of competitive exclusion: two species requiring the same resources cannot coexist in the same place indefinitely;
one species will always out-compete the other.
38. Indicator species: those species that are used to identify the relative environmental conditions at a specific place.
39. Dispersion: the way in which individuals are distributed in a given area (=in their habitat)
40. Intrinsic rate of growth: the maximum rate at which any given population can increase its numbers over time.
41. Environmental resistance: any environmental condition that slows or inhibits population growth.
42. Carrying capacity: number of individuals of a given species that an environment can support indefinitely; it is based on the
available resources.
43. Demography: the study of a species life history.
44. Life history: includes the beginning of life, a juvenile phase, a reproductive (=adult) phase, and death.
45. Survivorship: how long an individual within a population lives.
46. Fecundity: how many offspring an individual produces per unit time (usually one breeding season); reproductive output.
47. Cohort: a group of individual all born at about the same time; similar to a generation.
48. Survivorship curve: graph of the number of survivors of a species at progressively older ages; # of survivors of each cohort.
49. Mortality rate: proportion of individuals that die during a particular time interval.
50. Natality rate: proportion of individuals that are born during a particular time interval.
51. Reproductive strategy: the means an individual (or species) uses to maximize its reproductive success.
52. Density-dependent factors: those factors that operate to lower population numbers through mechanisms that have a greater
effect as population density increases.
53. Density-independent factors: those factors that operate to lower population numbers through mechanisms that are not
affected by population density.