evolution Flashcards
fuck
wots evolution
descent with modification
whats micro evolution
change in allele frequencies in a population over successive generations; no new species form
link between micro and macro evolution
microevolution will eventually lead to macro evolution given enough time
whats macroevolution
change in allele frequencies in a population over successive generations; new species form
what is variation
refers to the phenotypic difference between indivs in the same species, arises due to mutations, meiosis and sexual reproduction; is the raw material for NS to act on
whats the 5 agents of evolutionary change
- natural selection
- disruption of gene flow
- mutations
- non-random mating
- genetic drift
what is OCSVSLF
- overproduction of offspring
- constancy of numbers
- struggle for existence
- variation within a population
- survival of the fittest by natural selection
- like produces like
- formation of a new species
how does variation occur ( full ans scheme)
when environmental changes occur, the phenotypic variation amongst indivs results in the best adapted individuals surviving better and reproducing more successfully than others as they will have a selective advantage and will be selected for through NS. hence the population can continue to survive.
how do environmental factors act as forces of NS and wots the examples
Variation exists in a population –> confers selective advantage and is hence selected for due to selection pressures; those who had a selective advantage reproduce more frequently and thus that particular trait frequency increases
bacteria and antibiotic resistance
explain why the population is the smallest unit that can evolve
since a change in allele frequencies can only be measured in a population over successive generations over time, and not in an individual, the pop is the smallest unit that can evolve.
what is a population
a population is a group of interbreeding individuals of the same species
what is the biological species definition
a species is a group of organisms capable of interbreeding and producing fertile viable offspring
why is the biological species definition important?
members of the same species are reproductively isolated from other species, share a common gene pool and have the same chromosome number, and usually have similar morphological, physiological and behavioural features
ADV: can be interbred to see if they produce fertile viable offspring
limitations: cannot be applied to asexually reproducing organisms and extinct species
genetic species concept definition
a species is a group of genetically compatible interbreeding organisms genetically isolated from other groups
why is the genetic species definition important?
different genetic species are genetically distinct and evolve indep of each other, and have undergone genetic changes that lead to behavioural changes or changes in the type of pheromones produced that are associated with species recognition; thus diff genetic species do not interbreed in nature. however, genetic isolation is not equal to reproductive isolation
adv: genetic data from mitochondrial and nuclear DNA to identify species can be unambiguous in deducing evolutionary relationships.
LIm: tech required is relatively expensive
ecological species concept definition
a species is a group of organisms sharing the same ecological niche
why is the ecological species definition important?
a niche is the interactions of an organism with the environment and the place where it lives
advantage: every organism has a niche
limitation: sometimes unrelated species occupy the same niche
phylogenetic species concept definition
a species is the smallest group of organisms that share a most common ancestor and can be distinguished from other such groups.
