Studied by 11 people
Evolution
The change in a population's genetic makeup (gene pool) through successive generations. Populations, not individuals, evolve by becoming genetically different
microevolution
Change in allele frequencies in a population over generations
macroevolution
Large-scale evolutionary changes that take place over long periods of time. New species are formed from ancestral species and other species are lost through extinction
gene pool
consists of all genes, including all the different alleles, that are present in a population
mutation
A random change in a DNA sequence that affects genetic information.
differential reproduction
Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits.
adaptation or adaptive trait
any heritable trait that improves the ability of an individual organism to survive and to reproduce at a higher rate than other individuals in a population under prevailing environmental conditions.
natural selection
the process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species
directional natural selection
Favours the phenotype of one extreme over the average or other phenotype
stabilizing natural selection
a population of organisms shift towards the average phenotype. This is the most common form of natural selection.
diversifying natural selection
occurs when environmental conditions favor individuals at both extremes of the genetic spectrum and eliminate or sharply reduce number of individuals with normal phenotypes
coevolution
The mutual evolutionary influence between two different species interacting with each other and reciprocally influencing each other's adaptations.
speciation
the evolution of two species from one due to natural selection
geographic isolation
Physical separation of populations as a result of geographic change or migration.
reproductive isolation
Mutation and change by natural selection operate independently in the gene pools of geographically isolated populations and change the allele frequencies in different ways. As a result, these populations become so genetically different that they can no longer interbreed.
divergent evolution
the process by which two or more related but reproductively isolated populations become more and more dissimilar
background extinction
normal extinction of various species as a result of changes in local environmental conditions
mass extinction
A significant rise in extinction rates above the background level. It is catastrophic, widespread (usually global) about 25-70% of species.
Population dynamics
The change in size, density, dispersion, and age distribution in a population in response to environmental stress or changes in the environment.
population density
the number of individuals of a population in a certain place at a given time
population dispersion
the spatial pattern in which the members of a population are found in their habitat; affected by the movement of individuals out of (emigration) or into (immigration) a population's normal geographical range
clumping
members of a population exist in clumps throughout their habitat; occurs because resources are found in patches, not uniformly; some animal populations clump together for protection against predators, before or during migration, during mating season, or because they live in social groups
uniformly dispersed
rare; occurs when individuals of the same species compete for resources that are scarce and spread fairly evenly, or when individuals are antagonist to one another and defend their access to resources by physical or chemical means; there is an ongoing direct competition occurring among the individuals for limited resources
randomly dispersed
occurs if resources and other environmental conditions are fairly uniform throughout a habitat and if the members of the population do not attract or repel one another most of the time; rare; far less direct competition is occurring because resources are NOT as limited
population change equation
(births+immigration) - (deaths+emigration)
biotic potential
a population's capacity for growth
intrinsic rate of increase
rate at which a population could grow if it had unlimited resources
critical size
if a population dips below this, certain individuals may not be able to locate mates
environmental resistance
all factors acting jointly to limit the growth of a population
carrying capacity
the number of individuals of a given species that can be sustained indefinitely in a given space
exponential growth
a trait of populations that do not have resource limitations that starts out with slow growth and proceeds to be faster and faster as population increases
logistic growth
involves exponential population growth when the population is small and a steady decrease in population growth with time as the population approaches the carrying capacity
overshoots
to exceed the carrying capacity of an area
reproductive time lag
the period required for the birth rate to fall and the death rate to rise in response to resource over consumption; in other words, the corrective negative feedback does not take effect immediately.
dieback or crash
when a population exceeding in its carrying capacity may begin an ecological roller-coaster ride with its population alternately exceeding and falling below its carrying capacity size because of reproductive time lag.
density-independent population controls
population limiting factor that is affected population's size regardless of its population density
density-dependent population controls
population limiting factor that is correlated to population density. Examples include competition for resources, predation, parasitism, and disease
population fluctuations
stable, irruptive, and cyclic ways of population to grow, irrupt is when it occasionally explodes, cyclic explodes then falls then explodes then falls, stable stays relatively the same always
r-strategists or r-selected
algae, bacteria, rodents, annual plants, bony fish, insects, they are opportunists meaning they reproduce and disperse rapidly when conditions are favorable or when a new habitat or niche becomes available for invasion, as in the early stages of ecological succession
k-strategists or k-selected
species that tend to reproduce late and have few offspring with long generation times, they typically develop inside their mothers, are large, and mature slowly.
survivorship curve
shows the number of survivors of each age group for a particular species
late loss curve
typical for K-Strategists that produce few young and care for them until they reach reproductive age
early loss curve
typical for r-strategists species with many offspring, high juvenile mortality, and high survivorship once the surviving young reach a certain age and size
constant loss curve
typically have intermediate reproductive strategies with a fairly constant rate of mortality in all age classes and thus a steadily declining survivorship curve
minimum viable population
The smallest population size at which a species is able to sustain its numbers and survive.
risk assessment
involves using data hypotheses and models to estimate the probability of harm to human health, to society, or to the environment that may result from exposure to a specific hazard
cultural hazards
unsafe work conditions, smoking, poor diet, drugs, drinking, driving, criminal assault, unsafe sex, and poverty
chemical hazards
harmful chemicals in the air, water, or food
physical hazards
noise, fire, tornadoes, hurricanes, earthquakes, volcanic eruptions, floods, ionizing radiation
biological hazards
pathogens (bacteria, viruses, parasites), pollen, other allergens, animals (bees, poisonous snakes)
toxicology
the study of the adverse effects of chemicals on health
toxicity
measure of how harmful a substance is
water soluble toxins
(often inorganic compounds) can move throughout the environment and get into water supplies and the aqueous solutions that surrounds the cells in our body
fat soluble toxins
compounds need a carrier to move through the environment, but once inside the body they penetrate tissues easily and cross cell membranes. They are stored in body fat and persist for many years.
persistence
a characteristic of certain chemicals that are extremely stable and may take many years to be broken down into simpler forms by natural processes
dose
the amount of a potentially harmful substance that a person has ingested, inhaled, or absorbed through the skin
response
the amount of the resulting type and amount of damage to health
acute exposure
involves a single dose
chronic exposure
occurs over most or all of an entire lifetime
sub-chronic exposure
involves repeated exposure for some fraction of time. Usually for life period such as infancy.
acute effects
immediate or rapid harmful reaction to an exposure ranging from dizziness or rash, to death
chronic effect
a permanent or long lasting consequence (kidney or liver damage for example) of exposure to a harmful substance
bioaccumulation
is an increase in the concentration of a chemical in specific organs or tissues at a level higher than would normally be expected.
biological half-life
the time required for the quantity of the chemical in the body to be reduced by half.
biomagnification
levels of some toxins in the environment can also be magnified as they pass through food chains and webs.
synergistic interactions
increase harmful effects of one or more chemicals in a reaction.
antagonistic interactions
reduce harmful effects of the chemicals in a reaction.
poison
a chemical that has LD(50) of 50 mg. or less per kilogram of body weight.
LD(50)/median lethal dose
the amount of chemical received in one dose that kills exactly 50% of the animals(usually rats and mice) in a test population(60-200 animals).
metabolites
potentially harmful chemicals to which the original chemical maybe converted within the body.
risk assessment
involves using data hypotheses and models to estimate the probability of harm to human health, to society, or to the environment that may result from exposure to a specific hazard
cultural hazards
unsafe work conditions, smoking, poor diet, drugs, drinking, driving, criminal assault, unsafe sex, and poverty
chemical hazards
harmful chemicals in the air, water, or food
physical hazards
noise, fire, tornadoes, hurricanes, earthquakes, volcanic eruptions, floods, ionizing radiation
biological hazards
pathogens (bacteria, viruses, parasites), pollen, other allergens, animals (bees, poisonous snakes)
toxicology
the study of the adverse effects of chemicals on health
toxicity
measure of how harmful a substance is
water soluble toxins
(often inorganic compounds) can move throughout the environment and get into water supplies and the aqueous solutions that surrounds the cells in our body
fat soluble toxins
compounds need a carrier to move through the environment, but once inside the body they penetrate tissues easily and cross cell membranes. They are stored in body fat and persist for many years.
persistence
a characteristic of certain chemicals that are extremely stable and may take many years to be broken down into simpler forms by natural processes
dose
the amount of a potentially harmful substance that a person has ingested, inhaled, or absorbed through the skin
response
the amount of the resulting type and amount of damage to health
acute exposure
involves a single dose
chronic exposure
occurs over most or all of an entire lifetime
sub-chronic exposure
involves repeated exposure for some fraction of time. Usually for life period such as infancy.
acute effects
immediate or rapid harmful reaction to an exposure ranging from dizziness or rash, to death
chronic effect
a permanent or long lasting consequence (kidney or liver damage for example) of exposure to a harmful substance
bioaccumulation
is an increase in the concentration of a chemical in specific organs or tissues at a level higher than would normally be expected.
biological half-life
the time required for the quantity of the chemical in the body to be reduced by half.
biomagnification
levels of some toxins in the environment can also be magnified as they pass through food chains and webs.
synergistic interactions
increase harmful effects of one or more chemicals in a reaction.
antagonistic interactions
reduce harmful effects of the chemicals in a reaction.
poison
a chemical that has LD(50) of 50 mg. or less per kilogram of body weight.
LD(50)/median lethal dose
the amount of chemical received in one dose that kills exactly 50% of the animals(usually rats and mice) in a test population(60-200 animals).
metabolites
potentially harmful chemicals to which the original chemical maybe converted within the body.
epidemiology
studies of populations of humans exposed to certain chemicals or diseases. the study of the patterns of disease of toxicity to find out why people get sick and others do not.
dose-response curve
shows the effects of various doses of a toxic agent on a group of test organisms.
toxic chemicals
substances that are fatal to over 50% of test animals at given concentrations.
hazardous chemicals
cause harm by being flammable or explosive, irritating or damaging the skin or lungs(strong acidic or alkaline substances such as oven cleaners), interfering with or preventing oxygen uptake and distribution, or inducing allergic reactions of the immune system.
mutagens
agents such as chemicals that cause random mutations in the DNA molecules found in cells.
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