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Ecology Murcia
Murcia Ecology Unit 2
| Question | Answer |
|---|---|
| directional selection | form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness that individuals in the middle or at the other end of the curve |
| stabilizing selection | form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end |
| disruptive selection | form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle |
| genetic drift | random change in allele frequencies that occurs in small populations |
| Hardy-Weinberg principle | principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change |
| genetic equilibrium | situation in which allele frequencies remain constant |
| speciation | formation of new species |
| reproductive isolation | separation of species or populations so that they cannot interbreed and produce fertile offspring |
| behavioral isolation | form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding |
| geographic isolation | form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water |
| temporal isolation | form of reproductive isolation in which two populations reproduce at different times |
| Population | All the individuals of a species that live together in one place at one time. |
| Dispersion | The way the individuals of a population are arranged. |
| Carrying capacity | The population size that an environment can sustain. |
| r-strategist | Populations that grow exponentially when environmental conditions allow them to reproduce. |
| k-strategist | Populations that grow slowly and have small population sizes. |
| Hardy-Weinberg principle | The frequencies of alleles in a population do not change unless evolutionary forces act on the population. |
| Genetic drift | A change in allele frequency that appears to occur randomly. |
| Directional selection | When the frequency of a particular trait moves toward one extreme. |
| Stabilizing selection | When the frequency of a particular trait favors an average form. |
| Polygenic trait | A trait influenced by several genes. |
| population | all the members of one species in a particular area |
| community | all the different populations that live together in an area |
| ecology | the study of how living things interact with each other and their environment |
| population density | the number of individuals in a specific area |
| limiting factor | environmental factor that prevents a populations from increasing |
| carrying capacity | largest population that an environment can support |
| natural selection | the process by which changes that make an organism better suited for its environment develop |
| adaptation | the behaviors and physical characteristics of a species that allow it live successfully in its environment |
| competition | the struggle between organisms to survive in a habitat with limited resources |
| predation | the interaction where one organism kills and eats another |
| symbiosis | a close relationship between two species that benefits at least one of the species |
| mutualism | a relationship in which both species benefit |
| commensalism | a relationship in which one species benefits |
| parasitism | a relationship in which one organism lives on or inside another organism and harms it |
| parasite | the organism that benefits during parasitism |
| host | the organism that the parasite is living on or in |
| Genet | A genetic individual that arises from a single fertilized egg |
| Ramet | An individual member of a plant clone |
| Distribution | Arrangement of organisms within an area |
| Geographic Range | Area that encompasses all of the individuals of a species |
| Local Subpopulation | A subpopulation associated with a restricted patch of habitat |
| Metapopulation | A population broken into sets of subpopulations held together by dispersal or movements of individuals among them |
| Abundance | The number of individuals of a species in a given area |
| Population Density | The number of individuals in a population per unit area |
| Crude Density | The number of individuals per unit area; compare to ecological density |
| Ecological Density | Density measured in terms of the number of individuals per area of available living space; compare to crude density |
| Dispersal | Leaving an area of birth or activity for another area |
| Emigration | Movement of part of a population permanently out of an area |
| Immigration | Arrival of new individuals into a habitat or population |
| Migration | Intentional, directional, usually seasonal movement of animals between two regions or habitats; involves departure and return of same individual |
| Exponential Population Growth | Instantaneous rate of population growth, expressed as proportional increase per unit of time |
| Life Table | Tabulation of mortality and survivorship of population |
| Cohort | A group of individuals of the same age |
| Dynamic Life Table | Fate of a group of individuals born at the same time and followed from birth to death |
| Dynamic Composite Life Table | Pooled cohort of individuals born over several time periods instead of just one |
| Time-Specific Life Table | A population sample in some manner to obtain the distribution of age classes during a single time period |
| Crude Birthrate | The number of young produced per unit of population |
| Gross Reproductive Rate | Sum of the mean number of females born to each female age group |
| Net Reproductive Rate | Average number of female offspring produced by an average female during her lifetime |
| Population Projection Table | Chart of growth of a population developed by calculating the births and mortality of each age group over time |
| Age Distribution | The proportion of individuals in various age classes for any one year; also called age structure |
| Stable Age Distribution | Constant proportion of individuals of various age classes in a population through population changes |
| Finite Multiplication Rate | The geometric rate of increase by discrete time intervals |
| Geometric Population Growth | Factor by which the size of a population increases over time |
| Demographic Stochasticity | Random variations in birth and death rates that occur in a population from year to year |
| Environmental Stochasticity | Random variations in the environment that directly affect birth and death rates |
| Allele Effect | Reduction in reproduction or survival under low population densities |
| Density Dependence | Regulation of population growth by mechanisms controlled by the size of the population; effect increases as population size increases |
| Density-Dependent Mortality | Increase in mortality rates as population density increases |
| Density-Dependent Fecundity | Decrease in fecundity rates as population density increases |
| Density Independent | Being unaffected by population density; regulation of growth is not tied to population density |
| Competition | Any interaction that is mutually detrimental to both participants, occurring between species that share limited resources |
| Intraspecific Competition | Competition between individuals of the same species |
| Scramble Competition | Intraspecific competition in which limited resources are shared to the point that no individual survives |
| Contest Competition | Competition in which a limited resource is shared only by dominant individuals; a relatively constant number of individuals survive, regardless of initial density |
| Density-Dependent Growth | Inverse relationship between population density and individual growth |
| Self-Thinning | Progressive decline in density of plants associated with the increasing size of individuals |
| Zero-Growth Isocline | An isocline along which the net population growth rate is zero |
| Competitive Exclusion Principle | Hypothesis that when two or more species coexist using the same resource, one must displace or exclude the other |
| Fundamental Niche | Total range of environmental conditions under which a species can survive |
| Realized Niche | Portion of a fundamental nice space occupied by a population facing competition from other species |
| Niche Overlap | Sharing of niche space by two or more species |
| Competitive Release | Niche expansion in response to reduced interspecific competition |
| Character Displacement | The principle that two species are more different where they occur together than where they are separated geographically |
| Abundance | Also termed density. The number of individuals of a given species per unit area. |
| Acceleration phase | Stage of population growth indicated by the start of the upward-turning section of a curve denoting population growth. |
| Carrying capacity | Stabilized size reached by a given population in a given habitat. |
| Closed population | Population not subject to migration. |
| Community | A group of populations living and interacting with one another in a particular environment. |
| Deceleration phase | Stage of population growth indicated by the flattening out of an S-shaped curve as the carrying capacity is reached. |
| Density | Also termed abundance. The number of individuals of a given species per unit area. |
| Density dependent | Factors whose impact on members of a population is dependent on the size of the population. |
| Density independent | Factors whose impact on members of a population is not affected by population size. |
| Distribution | Pattern of spread of members of a population. May be uniform, clumped or random. |
| Environmental resistance | The limiting effect of environmental conditions on the growth of a population. |
| Exponential growth | Population growth whereby the rate of population growth increases as the size of the population increases. |
| J shaped curve | Plot of population size over time under conditions of exponential growth. |
| K-selected | Species characterized by less frequent breeding and fewer offspring. Typically found in stable environments where carrying capacity has or is about to be reached. |
| Lag phase | Stage of population growth indicated by the initial flat section of a curve. In this period population size is small and growth rates are low. |
| Logistic growth | Model of population growth whereby growth eventually slows as the population reaches carrying capacity. |
| Migration rate | Rate of immigration into and emigration out of a given population. |
| Open population | Population subject to migration. |
| Population | A group of individuals of the same species occupying a particular geographic area. |
| Population dynamics | The scientific study of changes in population size over time. |
| Quadrat | Any of a group of small, usually rectangular plots of land arranged for close study of the distribution of plants or animals in an area. |
| r-selected | Species which breed often and produce large numbers of offspring. Typically found where conditions are untable. |
| S shaped curve | Plot of population size over time under conditions where resource availability limits population size to the carrying capacity of the habitat. |
| Sampling | Technique used to estimate population size, based on examination of part of a given population. |
| Species richness | The number of populations within a given community. |
| Total count | Also called a true census. A count of all members of a species in a given area. |
| Transect | A sampling technique whereby various species present at regular intervals along a line crossing the area of study are recorded. |
| True census | A total count of all members of a species in a given population. Also called a total count. |
| Zero population growth | A stable population with no net growth. Birth and immigration rates are matched by deaths and emigration. |
| population growth | how the number of individuals increase or decrease with time |
| open population | populations in which immigration & emigration occur |
| closed population | populations in which movement into & out do not occur |
| exponential growth | instantaneous per capita growth; as population gets larger, the growth rate increases |
| linear growth | population increases at a constant, steady rate |
| life table | age-specific account of mortality (death) |
| dynamic life table | fate of a group of individuals born at the same time followed by birth to death |
| time-specific life table | distribution of age classes during a single time period |
| birth rate | number of individuals born at a given time |
| death rate | number of individuals that die in a given time |
| age distribution | the proportion of individuals in the various age classes for any one year |
Created by:
rydercrew
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