Biology II exam 1 Flashcards
population density
the number of individuals of a species per unit of area or volume at a given time
dispersion
Individuals in a population may exhibit characteristic patterns of spacing (dispersion) relative to one another
Random dispersion
occurs when individuals in a population are spaced throughout an area in a manner that is unrelated to the presence of others
Clumped dispersion
which occurs when individuals are concentrated in specific parts of the habitat.
Uniform dispersion
occurs when individuals are more evenly spaced than would be expected from a random occupation of a given habitat.
Population growth
the increase in the number of individuals within a specific species in a given area over a period of time
2 types of Dispersal
active dispersal and passive dispersal
Exponential Population growth
the accelerating population growth rate that occurs when optimal conditions allow that growth ( J shape plot)
Logistic Population Growth
a population increasing from a small number of individuals to a larger number that limited later by the environment (S shape plot).
Immigration
occurs when individuals enter a population and increase its size
Emigration
occurs when individuals leave a population and decrease its size
Carrying capacity
the maximum number of organisms that a specific environment can support over time
Explain how population size changes
Changes in population size are caused by natality, mortality, immigration, and emigration
Identify the levels of biological organization
How dispersal affects the population size?
Type I, II, and III survivorship curves
graphs that show how likely individuals in a population are to survive to different ages
Type 1
Individuals have a high probability of surviving to adulthood, but the death rate increases dramatically as they age
Type 2
Individuals have a constant chance of dying, regardless of age
Type 3
Individuals have a high death rate in early life, but a relatively low death rate for those who survive to middle and old age
distinguish among species exhibiting an r strategy from those with a K strategy
Ecological niche
ecological role within the structure and function of a community
habitat
the local environment in which a species lives
competition
when organisms or species compete for resources that are in limited supply
Intraspecific competition
When members of the same species compete for resources. For example, male birds of the same species competing for mates.
Interspecific competition
When members of different species compete for resources. For example, predators of different species competing for the same prey.
Three types of interactions among species in a community:
*Competition
*Predation
*Symbiosis
mutualism
a symbiotic relationship in which both partners benefit
commensalism
symbiosis in which one species benefits and the other is neither harmed nor helped
parasitisim
symbiotic relationship in which one member, (the parasite) benefits, and the other (the host) is harmed
evolution
the accumulation of genetic changes within populations over time
natural selection
the process through which populations of living organisms adapt and change For survival
adaptation
an evolutionary modification that improves the chances of survival and reproductive success in a given environment
artificial selection
a biological process where humans deliberately select for specific traits in plants and animals
the four premises of evolution by natural selection
variation
overproduction
limits on population growth, or a struggle for existence
differential reproductive success.
variation
difference between individuals or groups of organisms in the same species
overproduction
The reproductive ability of each species has the potential to cause its population to geometrically increase over time
limits on population growth, or a struggle for existence
There is only so much food, water, light, growing space, and other resources available to a population, so organisms compete with one another for these limited resources.
differential reproductive success.
Those individuals that have the most favorable combination of characteristics (those that make individuals better adapted to their environment) are more likely to survive and reproduce.
Summarize the evidence for evolution obtained from the fossil record
demonstrating a progression of life forms over time, where older rock layers contain fossils of simpler organisms, while newer layers show more complex organisms, indicating that species have changed and evolved throughout Earth’s history
biogeography
The study of the past and present geographic distribution of organisms
the names of the supercontinents
What evidence for evolution is derived from comparative anatomy?
Homologous Features
And Homoplasy
vestigial structures
Nonfunctional or degenerate remnants
Structures occasionally become vestigial
Homoplasy
Features that are analogous, not homologous
Homologous Features
Basic structural similarities
Derived from same structure
Indicate organism’s evolutionary affinities
population gene pool
All individuals living in a particular place at the same time
population genetics
Study of the distribution of alleles in populations and causes of allele frequency changes
genotype
the complete genetic makeup of an organism
phenotype
the observable physical properties of an organism
Alleles
one of multiple alternative forms of a gene
Calculate the frequency of genotypes, phenotypes and alleles
p² + 2pq + q² = 1
p + q = 1
p²
AA homozygous dominant
2pq
Aa heterozygous
q²
Homozygous ressesive
Describe the purpose of the Hardy-Weinberg principle
predicts how gene frequencies will be inherited from generation to generation given a specific set of assumptions.
the four mechanisms of microevolution
mutation
genetic drift
natural selection
migration
mutation
mutation can cause a gene to change, which can alter the traits of an organism
genetic drift
a chance change in allele frequencies that occurs from generation to generation.
natural selection
when organisms with certain traits are more likely to survive and reproduce, passing their traits on to their offspring
migration
when individuals move from one population to another, which can change the allele frequencies in both populations
stabilizing selection
a type of natural selection that favors average traits and selects against extreme traits
directional selection
Selection against either dominant or recessive homozygote
Additive effects
disruptive selection
type of natural selection that favors extreme traits over intermediate traits
the biological species concept
a species consists of individuals that can successfully interbreed with one another but not with individuals from other species
the evolutionary species concept
defines a species as a single lineage of ancestor-descendant populations that maintains its identity from other lineages
allopatric speciation
process that occurs when a population of a species becomes isolated from the rest of the species, leading to the development of a new species
sympatric speciation
the evolution of a new species from a single ancestral species while both populations continue to inhabit the same geographic region
prezygotic
before fertilization, or before the gametes join to form a zygote. prevent the formation of hybrids between different species.
Premating
a reproductive barrier that prevents different species from mating
postmating
events that occur after mating, such as the prevention of fertilization or the production of viable offspring
Gamete Incompatibility
Postzygotic Barriers
One of several reproductive isolating mechanisms that prevent gene flow between species after fertilization has taken place
punctuated equilibrium
long periods of stasis are
interrupted by short periods of rapid speciation
gradualism
a slow, steady change in species occurs over
time.
extinction
Death of a species
Background extinction
continuous, low-level extinction of species
Mass extinction
extinction of numerous species, higher taxonomic groups
