evolution Flashcards
What is evolution?
Change over time, specifically a change in the number of times specific genes that code for specific characteristics occur within an interbreeding population.
Do individuals or populations evolve?
Populations evolve, not individuals.
Is there an implied improvement in evolution?
No, there is no implied ‘improvement’ in evolution.
Do organisms change because they want or need to?
No, they change due to random change.
Who was Lamarke
A scientist who believed that features could be gained or lost through use or disuse, and these traits could be passed to offspring (1801).
What is the Inheritance of Acquired Characteristics?
The concept proposed by Lamarck that traits gained or lost could be passed to offspring.
Who is credited with studying and explaining evolution?
Charles Darwin.
What concept did Darwin develop in 1844?
The driving force for evolution, known as Natural Selection.
What is Natural Selection?
The process whereby organisms better adapted to their environment tend to survive and produce more offspring.
What are Darwin’s first two observations?
1) Organisms produce more offspring than can survive to adulthood. 2) There is variability among species, and this variability is passed from one generation to the next.
What is Darwin’s inference from his observations?
Individuals who inherit characteristics most fit for their environments are likely to produce more offspring than less fit individuals.
What is fitness in the context of evolution?
The ability to survive and produce offspring who can also survive and reproduce.
What is required for evolution by natural selection?
Genetic variation, one or more phenotypes are more suited to environment, these produce more offspring
How is genetic variation added to genotypes?
Genetic variation is added to genotypes by mutations.
What are mutations?
Mutations are any changes in DNA.
What do mutations lead to?
Mutations lead to changes in the phenotype.
What is a phenotype?
A phenotype is the observable characteristics of an organism.
What acts upon the phenotype?
Natural selection acts upon the phenotype.
What happens to individuals more suited to the environment?
Individuals more suited to the environment produce more offspring.
What do individuals contribute to the gene pool?
Individuals contribute more to the total gene pool of the population.
What changes over time in a population?
The population’s gene pool changes over time.
What is speciation?
Speciation is the creation of a new species.
When may speciation occur?
Speciation may occur if geographic and reproductive isolating mechanisms exist.
What is Directional Selection?
An extreme phenotype (very long or very short, etc.) is a favourable adaptation.
What is Stabilizing Selection?
-The average phenotype is a favourable adaptation, while extreme phenotypes are unfavourable.
-Operates most of the time in populations.
What is Disruptive Selection?
The most rare type of selection where two opposite extreme phenotypes are favourable over the average phenotype.
what are the other types of selection
sexual, artificial, and genetic drift
what is sexual selection
selection through preference by one sex for certain characteristics
what is artificial selection
selecting traits based on what humans find desirable in another species
what are the types of sexual selection
Intersexual selection- “female choice” female invest a lot of time in their offspring and want to ensure their offspring have the best genes
Intrasexual selection -“male-male” competition, members of the same sex fight for access to members of the opposite sex
what is genetic drift
genes in a population change due to random chance
what are the types of genetic drift
bottleneck effect- random event wipes out a large chunk of population
founder effect- individuals from a population break off and form their own population
gene flow- individuals from one population move into another population
what is antibiotic resistance
the ability of bacteria to survive exposure to antibiotic srugs
what is the process of antibiotic resistance
-bunch of bacteria including a resistant variety
-get bathed in antibiotics, most normal bacteria die
-the resistant bacteria multiply and become more common
-eventually the entire infection evolves to a resistant strain
how to prevent antibiotic resistance
-don’t overuse antibiotics or use them to treat viral infections
-practice good hygiene
-take all antibiotics
-don’t use antibiotics for preventive measures
what is speciation
evolutionary formation of new species
-if groups of organisms are reproductively isolated from other groups they could evolve independently and become different species
what are reproductive isolating mechanisms
any behavioural, structural, or biochemical trait that prevents individuals from reproducing successfully together
what are the two major types of reproductive isolation
prezygotic- prevention of mating or fertilization
postzyogtic-prevent maturation and reproduction in offspring from interspecies mating
what are the types of prezygotic isolation
ecological-different habitats or niches
temporal-different reproductive cycles (time of day, seasons)
behavioural- don’t respond to each others mating rituals
mechanical- structural differences prevent exchange of alleles
genetic - sperm and eggs are exchanged but chemical markers prevent fertilization
what are the types of post zygotic isolation
zygotic mortality- species can mate but no embryos develop to maturity
hybrid inviability- baby hybrids aren’t viable
hybrid infertility- baby hybrids viable but not fertile
what is convergent evolution
-evolution toward similar traits in unrelated species, same function in unrelated species
what is convergent evolution
-evolution toward similar traits in unrelated species, same function in unrelated species
divergent evolution
-evolution towards different traits in closely related species
-organisms share a common ancestor
-rapid divergent evolution is called adaptive radiation
coevolution
species evolve in response to changes in each other
-can occur in beneficial or competitive relationships
punctuated equilibrium
evolution is stable for a time and suddenly new forms appear
-occurs in areas where environmental conditions change rapidly
extinction
background extinction-occurs continuously at a low rate, affects a few species in a small area, due to local environmental changes
mass extinction- destroy many species at a global level, caused by catastrophic events
