Terms : Hide Images
| 7980316802 | population | all individuals that belong to the same species and live in a given area at a particular time | 0 | |
| 7980316803 | community | 3rd level of complexity. All populations of organisms in a given area | 1 | |
| 7980316804 | population ecology | study of factors that cause populations to increase or decrease | 2 | |
| 7980316805 | population size | total number of individuals within a defined area at a given time | 3 | |
| 7980316806 | population density | # of individuals per unit area @ a given time | 4 | |
| 7980316807 | population distribution | how many individuals are distributed w/ respect to one another | 5 | |
| 7980316808 | sex ratio | ratio of males to females | 6 | |
| 7980316809 | age structure | how many individuals fit into particular age categories | 7 | |
| 7980316810 | density dependent factors | limiting factor that depends on population size | 8 | |
| 7980316811 | limiting resource | resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size | 9 | |
| 7980316812 | carrying capacity | the number of individuals that can be sustained in an area | 10 | |
| 7980316813 | density independent factors | Limiting factor that affects all populations in similiar ways, regardless of population size. | 11 | |
| 7980316814 | growth rate | # of offspring an idividual can produce in a given time period, minus the deaths | 12 | |
| 7980316815 | intrinsic growth rate | the maximum potential for growth of a population under ideal conditions with unlimited resources | 13 | |
| 7980316816 | exponential growth model | model which estimates a population's future size | 14 | |
| 7980316817 | j-shaped | starts slowly but then accelerates as the population increases because the base size of the population is increasing. | 15 | |
| 7980316818 | logistic growth model | a description of idealized population growth that is slowed by limiting factors as the population size increases | 16 | |
| 7980316819 | s-shaped | a plot of the number of individuals against time, also known as a logistic growth: involves rapid exponential population growth followed by a steady decrease in population growth with time until the population size levels off. | 17 | |
| 7980316820 | overshoot | The extent to which a population exceeds the carrying capacity of its environment | 18 | |
| 7980316821 | die-off | A rapid decline in a population due to death. | 19 | |
| 7980316822 | k-selected species | Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age. | 20 | |
| 7980316823 | r-selected species | Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period. | 21 | |
| 7980316824 | survivorship curves | They show the likelihood of survival at different ages throughout the lifetime of the organism. | 22 | |
| 7980316825 | corridors | A strip of natural habitat that connects two adjacent nature preserves to allow migration of organisms from one place to another | 23 | |
| 7980316826 | metapopulation | A collection of populations that have regular or intermittent gene flow between geographically separate units | 24 | |
| 7980316827 | community ecology | the study of how interactions between species affect community structure and organization | 25 | |
| 7980316828 | competition | the struggle between organisms to survive in a habitat with limited resources | 26 | |
| 7980316829 | competitive exclusion principle | ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time | 27 | |
| 7980316830 | resource partitioning | in a biological community, various populations sharing environmental resources through specialization, thereby reducing direct competition | 28 | |
| 7980316831 | predatation | an interaction in which one organism kills and eats another | 29 | |
| 7980316832 | pathogens | Microbes that cause disease | 30 | |
| 7980316833 | mutualism | the relation between two different species of organisms that are interdependent | 31 | |
| 7980316834 | commensalism | the relation between two different kinds of organisms when one receives benefits from the other without damaging it | 32 | |
| 7980316835 | symbiotic | mutually beneficial; supporting one another's life | 33 | |
| 7980316836 | keystone species | a species whose impact on its community or ecosystem are much larger and more influential than would be expected from mere abundance | 34 | |
| 7980316837 | predator mediated competition | Competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist. | 35 | |
| 7980316838 | ecosystem engineers | species that dramatically alter their environment | 36 | |
| 7980316839 | ecological succession | series of changes in the species in a community, often following a disturbance | 37 | |
| 7980316840 | primary succession | the series of changes that occur in an area where no soil or organisms exist | 38 | |
| 7980316841 | secondary succession | succession on a site where an existing community has been disrupted | 39 | |
| 7980316842 | pioneer species | first species to populate an area during primary succession | 40 | |
| 7980316843 | theory of island biogeography | The number of species found on an island is determined by a balance between two factors: the immigration rate (of species new to the island) from other inhabited areas and the extinction rate (of species established on the island). The model predicts that at some point the rates of immigration and extinction will reach an equilibrium point that determines the island's average number of different species (species diversity). | 41 | |
| 7980316844 | Ecosystem Diversity | The variety of ecosystems | 42 | |
| 7980316845 | Species diversity | The variety of species | 43 | |
| 7980316846 | Genetic diversity | variety of genes | 44 | |
| 7980316847 | Species richness | The number of different species in a community | 45 | |
| 7980316848 | Species evenness | Abundance of individuals within each species contained in a community | 46 | |
| 7980316849 | Evolution | A change in the genetic composition of a species over time | 47 | |
| 7980316850 | Microevolution | Change in gene frequencies between populations of a species over time | 48 | |
| 7980316851 | Macroevolution | Evolutionary change above the species level, including the appearance of major evolutionary developments, such as flight | 49 | |
| 7980316852 | Genes | physical locations on chromosomes within each cell of an organism | 50 | |
| 7980316853 | Genotype | complete set of genes in an individual | 51 | |
| 7980316854 | Mutation | occasional mistake in the copying process produces these random changes | 52 | |
| 7980316855 | Recombination | A combining of genes or characters different from what they were in the parents | 53 | |
| 7980316856 | Phenotype | An organism's appearance or other detectable characteristics | 54 | |
| 7980316857 | Evolution by artificial selection | selective breeding of domesticated plants and animals to produce offspring with desired genetic traits | 55 | |
| 7980316858 | Evolution by natural selection | the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations | 56 | |
| 7980316859 | Fitness | ability to survive and reproduce | 57 | |
| 7980316860 | adaptations | traits that improve an individual's ability to survive and reproduce | 58 | |
| 7980316861 | genetic drift | The gradual changes in gene frequencies in a population due to random events | 59 | |
| 7980316862 | bottleneck effect | a reduction in the genetic diversity of a population caused by a reduction in its size | 60 | |
| 7980316863 | founder effect | random change in the gene pool that occurs in a small, isolated colony of a population | 61 | |
| 7980316864 | geographic isolation | Separation of populations as a result of geographic change or migration to geographically isolated places | 62 | |
| 7980316865 | reproductive isolation | Separation of species or populations so that they cannot interbreed and produce fertile offspring | 63 | |
| 7980316866 | allopatric speciation | The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier | 64 | |
| 7980316867 | sympatric speciation | The formation of new species in populations that live in the same geographic area | 65 | |
| 7980316868 | genetic engineering | Process of making changes in the DNA code of living organisms | 66 | |
| 7980316869 | genetically modified organisms | An organism whose genetic material has been altered through some genetic engineering technology or technique | 67 | |
| 7980316870 | range of tolerance | Range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally | 68 | |
| 7980316871 | fundamental niche | The full potential range of the physical, chemical, and biological factors a species can use if there is no competition from other species | 69 | |
| 7980316872 | realized niche | Part of a species fundamental niche that it actually uses, limited by competition | 70 | |
| 7980316873 | distribution | the areas in the world where a species actually lives | 71 | |
| 7980316874 | niche generalists | a species that can live under a wide range of abiotic or biotic conditions | 72 | |
| 7980316875 | niche specialists | a species that is specialized to live in a specific habitat or to feed on a small group of species | 73 | |
| 7980316876 | fossils | Preserved remains of once-living organisms | 74 | |
| 7980316877 | mass extinction | Event in which many types of living things become extinct at the same time | 75 | |
| 7980316878 | Why is it challenging to determine the number of species on Earth? | It is challenging because some species are active only at night or live in inaccessible locations. | 76 | |
| 7980316879 | Why are estimates of species diversity valuable to environmental scientists? | They are valuable because they can tell environmentalists how much diversity is in a given area and what animals dominate it. | 77 | |
| 7980316880 | What is the difference between species richness and species evenness? Why are they both important measures? | The number of species in a given area, such as a pond, the canopy of a tree, or a plot of grassland, is known as species richness. However, species evenness tells us whether a particular ecosystem is numerically dominated by one species or whether all of its species have similar abundances. They are both important measures because they reflect biodiversity. | 78 | |
| 7980316881 | What is evolution, and what are the three main ways in which it occurs? | Evolution is the change in the genetic composition of a population over time. It occurs by artificial selection, by natural selection, and by random processes. | 79 | |
| 7980316882 | How are artificial and natural selection similar? How are they different? | With artificial selection, organisms are produced that humans find pleasing. However, with natural selection, the environment determines which individuals survive and reproduce. They are similar because traits are assigned to organisms in both cases. | 80 | |
| 7980316883 | How does evolution lead to biodiversity? | Evolution produces more changes within a species, therefore increasing diversity. | 81 | |
| 7980316884 | How does geographic isolation lead to reproductive isolation? | If individuals cannot move between the populations, then over time, the two geographically isolated populations will continue to become more and more genetically distinct. Eventually, the two populations will be separated not only by geographic isolation, but also by reproductive isolation: they will become so different that even if the physical barrier were removed, they could no longer interbreed and produce viable offspring. | 82 | |
| 7980316885 | What factors influence a species' chances of adapting successfully to a change in its environment? | The factors are rate of environmental change, genetic variation, population size, and generation time. | 83 | |
| 7980316886 | Why is the pace of human-driven evolution faster than that of natural evolutionary processes? | Using genetic engineering techniques, scientists can now copy genes from a species with some desirable trait, such as rapid growth or disease resistance. However, natural evolution occurs very slowly. | 84 | |
| 7980316887 | How do fundamental niches and realized niches differ? | The suite of ideal conditions is termed the fundamental niche of the species. However, the addition of biotic factors more narrowly defines the parts of the fundamental niche that a species actually uses. The range of abiotic and biotic conditions under which a species actually lives is called its realized niche. | 85 | |
| 7980316888 | How does environmental change determine species distribution? When does it lead to extinction? | Species vary in their ability to move physically across the landscape as the environment changes, so species distribution is affected. It leads to extinction when the environmental change is so severe that the organism cannot survive there any longer. | 86 | |
| 7980316889 | How are human activities affecting extinction rates, and why is their impact a particular concern? | Human causes include habitat destruction, overharvesting, introductions of invasive species, climate change, and emerging diseases. Because much of the current environmental change caused by human activities is both dramatic and sudden, environmental scientists contend that many species may not be able to move or adapt in time to avoid extinction. | 87 |
