Evolution and Origin of Species Flashcards
convergent evolution
similar traits evolve independently in species that do not share a recent common ancestry.
EX: bats and birds both can fly but they’re not necessarily related
Describe how scientists developed the present-day theory of evolution
In the mid nineteen century Biologist Charles Darwin and Alfred Wallace travelled to the Galapagos islands off the coast of Ecuador, there they each arrived at the conclusion that evolution occurs due to natural selection this was evident by the variation in the beak sizes of Finches
Define adaptation
heritable trait or behavior in an organism that aids in its survival and reproduction in its present environment
divergent evolution
process by which groups of organisms evolve in diverse directions from a common point
EX: flowers share basic reproductive anatomy but look different due to living in different environments.
homologous structures
Structures in different species that are similar because of common ancestry. structures that share a similar form, but over time change in size and shape
vestigial structures
remnant of a structure that may have had an important function in a species’ ancestors, but has no clear function in the modern species.
EX: wings on flightless birds
Discuss misconceptions about the theory of evolution
Evolution is just a theory, evolution has been proven by test and natural observation, it is a mischaracterization to say that “evolution is just a thought or guess”
Individuals evolve, Evolution is the change in a population’s genetic composition over time, specifically over generations, resulting from differential reproduction of individuals with certain alleles
Evolution explains the origin of life. The theory of evolution explains how populations change over time and how life diversifies the origin of species not how life started.
Organisms evolved on purpose, evolution is not goal directed, a species adapts to an environment but their success depends on the circumstances.
Define species
a group of individual organisms that interbreed and produce fertile, viable offspring.
How do scientists identify species as different?
one species is distinguished from another when, in nature, it is not possible for mating between individuals from each species to produce fertile offspring.
Species are different based on genetic differences. Different species may have different genes that are active in development; therefore, it may not be possible to develop a viable offspring with two different sets of directions. Thus, even though hybridization may take place, the two species still remain separate
How does speciation occur?
For speciation to occur, two new populations must form from one original population and they must evolve in such a way that it becomes impossible for individuals from the two new populations to interbreed.
prezygotic barrier
a mechanism that blocks reproduction from taking place
EX: when breeding occurs certain times of the year
postzygotic barriers
occurs after zygote formation
EX: when they’re born sterile or don’t make it past the embryotic stage
allopatric speciation
the process of speciation that occurs with geographic isolation
EX: a river diverging, organisms that take a new path
What are two allopatric speciations?
Dispersal is when a few members of a species move to a new geographical area
vicariance is when a natural situation arises to physically divide organisms
adaptive radiation
speciation when one species radiates to form several other species
a population of one species disperses throughout an area, and each finds a distinct niche or isolated habitat.
EX: Darwin’s study on the differences in the Finch bird beaks
Hybrid Zone
We call an area where two closely related species continue to interact and reproduce, forming hybrids
Explain the two major theories on rates of speciation
gradual speciation model, species diverge gradually over time in small steps.
punctuated equilibrium model, a new species undergoes changes quickly from the parent species, and then remains largely unchanged for long periods of time afterward
reinforcement
Usually hybrids tend to be less fit; therefore, such reproduction diminishes over time, nudging the two species to diverge further
Fusion
If the hybrids are as fit or more fit than the parents, the two species may fuse back into one species
Stability
Scientists have also observed that sometimes two species will remain separate but also continue to interact to produce some individuals. no real net change is taking place.
Discuss misconceptions about the theory of evolution
Evolution is just a theory, evolution has been proven by test and natural observation, it is a mischaracterization to say that “evolution is just a thought or guess”
Individuals evolve, Evolution is the change in a population’s genetic composition over time, specifically over generations, resulting from differential reproduction of individuals with certain alleles
Evolution explains the origin of life. The theory of evolution explains how populations change over time and how life diversifies the origin of species not how life started.
Organisms evolved on purpose, evolution is not goal directed, a species adapts to an environment but their success depends on the circumstances.
vestigial structures
remnant of a structure that may have had an important function in a species’ ancestors, but has no clear function in the modern species.
EX: wings on flightless birds
homologous structures
Structures in different species that are similar because of common ancestry. structures that share a similar form, but over time change in size and shape
divergent evolution
process by which groups of organisms evolve in diverse directions from a common point
EX: flowers share basic reproductive anatomy but look different due to living in different environments
Define adaptation
heritable trait or behavior in an organism that aids in its survival and reproduction in its present environment
Describe how scientists developed the present-day theory of evolution
In the mid nineteen century Biologist Charles Darwin and Alfred Wallace travelled to the Galapagos islands off the coast of Ecuador, there they each arrived at the conclusion that evolution occurs due to natural selection this was evident by the variation in the beak sizes of Finches.
convergent evolution
similar traits evolve independently in species that do not share a recent common ancestry.
EX: bats and birds both can fly but they’re not necessarily related
