Unit 7: Natural Selection Flashcards
natural selection
process by which organisms with traits better suited to the environment survive and reproduce more often
evolution
change in the gene pool
evolutionary fitness
measure of an organism’s ability to survive and reproduce
selective pressure
process by which organisms either live or die based on their traits
niche
organism’s role in an ecosystem
mutation
change in the nucleotide sequence of an organism
population
a group of same-species individuals located in the same area
speciation
formation of new species from one
genetic drift
change in allele frequences due to random chance event
bottleneck effect
change in allele frequencies due to clamactic event
founder effect
loss in genetic variation due small part of original population migrating
hardy-weinburg equilibrium
states that allele and genotype frequencies will remain constant in a population if there are no evolutionary forces acting on it
p^2 + 2pq + q^2 = 1
p + q = 1
nonrandom mating
sexual selection; female chooses mate
fossil
remains of a prehistoric organism captured in rock
vestigial structure
structures that we have that were once used by our ancestors but not used anynore
morphology
study of body structures and placements
phylogeny
evolutionary history of a kind of organism
phylogenetic tree
shows evolutionary relationships between organisms over time
cladogram
only shows the evolutionary relationships between organisms not with regard to time
outgroup
species that shares barely or not at all any similarities with the rest
lineage
descent from a common ancestor
reproductive isolation
barriers that prevent two species from reproducing
allopatric
different places
sympatric
same place
adaptive radiation
the exploitation of new niches by many organisms
extinction
total elimination of a species
convergent evolution
similar characteristics evolved in species without a recent common ancestor
divergent evolution
similar characteristics due to a recent common ancestor
species diversity
variety and abundance of species in a population
ecosystem
a region as well as all the organisms and abiotic factors present in it
RNA world hypothesis
idea that before cells, DNA, and the central dogma, RNA could form naturally and function like proteins
molecular clock
technique in which the rate at which mutations occur is used to figure out when speciation first occurred
What causes natural selection?
Overproduction
Variation
Selective pressure
How does natural selection affect populations?
Natural selection applies selective pressure on populations based on traits that better suit the environment and increase reproductive fitness
What is the importance of phenotypic variation in a population?
the more variation in a species, the less susceptible it as a whole is to disease, increasing reproductive fitness
How can humans affect diversity within a population?
Via artificial selection, humans can choose the traits they want in a population over generations
How do random occurrences affect the genetic makeup of a population?
genetic drift (random occurrences) leads to change in (may increase or decrease) allele frequencies of a population
What is the role of random processes in the evolution of specific populations?
random processes like genetic drift lead to changes in allele frequencies which over time is evolution
What is the change in the genetic makeup of a population over time called?
evolution
What are the conditions under which allele and genotype frequencies will change in populations?
- small population sizes
- gene flow
- mutations
- nonrandom mating
- natural selection
What will happen to the population if any of the conditions of Hardy- Weinberg are not met?
the population will evolve
What types of data provide evidence for evolution?
Biogeography (distribution of species in different environment)
Fossils
Homologies (similar morphological structure)
DNA and proteins
Mathematical models (Hardy-Weinburg)
How do morphological, biochemical, and geological data provide evidence that organisms have changed over time?
Morphological: organisms with homologous structures indicate a recent common ancestor implying that speciation has occurred.
Biochemical: mutations cause changes to the gene pool which is evolution
Geological: similar organisms changed due to being in different geographies (environments)
What are the fundamental molecular and cellular features shared across all domains of life, which provide evidence of common ancestry?
The last universal common ancestor of all life had:
DNA, RNA, Proteins, ATP, lipid membrane, cell division
What structural and functional evidence on cellular and molecular levels provides evidence for the common ancestry of all eukaryotes?
Membrane-bound organelles
Linear chromosomes
How is evolution an ongoing process in all living organisms?
organism populations generally have genetic variation that natural selection can act on, which drives evolution.
How can a phylogenetic tree and/or cladogram be used to infer evolutionary relatedness?
All organisms in the cladogram/phylogenetic tree are related via the recent common ancestor
Two species can be more closely related than others depending on how relatively recent speciation that created them occurred
What are the conditions under which new species may arise?
reproductive isolation
How does the rate of evolution and speciation differ under different ecological conditions?
Extinction can open up new ecological niches which can be rapidly exploited by organisms, leading to rapid evolution and speciation.
What are the processes and mechanisms that drive speciation and evolution?
Natural selection
Genetic drift
Gene flow
Non random mating
What factors can lead to the extinction of a population?
Abiotic factors (climate, asteroids, and comets, etc) Biotic factors (humans, hunting, low fitness, etc)
How can the risk for extinction increase due to changes in the environment?
Changes in the environment affect the ecological niches of organisms, which can lead to extinction if they can’t adjust to a new one.
How can species diversity in an ecosystem change from speciation and extinction?
Speciation increases species diversity while extinction decreases species diversity
How can extinction make new environments available for adaptive radiation?
Extinction clears up ecological niches that can be exploited by other organisms that survived the extinction event
How does the genetic diversity of a species or population affect its ability to withstand environmental pressures?
The more diverse a species is the greater its ability as a whole to withstand environmental pressures.
