Chapter 4 Evolution Flashcards
define population
group of individuals of the same species that live in the same area and can produce fertile offspring
true or false populations may be isolated geographically
true
define gene pool
all copies every type of allele at every locus in all members of the population
what do we called the allele if only one exists for a particular locus in a population
fixed in the gene pool
if there is 500 flowers and each of them are diploid, how many copies of flower colour gene in total?
1000
how do you calculate the frequency of a certain allele
eg. calculate frequency of colour red allele (CR)
500 wild flowers
- 320 red
- 160 pink
- 20 white
red flowers CRCR
pink flowers CRCW
white flowers CWCW
(320x2)+(160x1)=800
800/1000-0.8
what are the 5 conditions for populations to be in Hardy-Weinberg equilibrium
- no genetic mutations ie introduction of a new allele
- mating has to be random ie no kind of preference
- no natural selection
- extremely large population size
- no gene flow ie no introduction of new allele
what do we call the departure of any of the 5 conditions of H-W’s equilibrium
evolution
what’s the H-W equilibrium equation and what’s it purpose
p^2+2pq+q^2=1
- to test evolution in a population
- estimating % of population carrying allele for an inherited disease
define genetic drift
describes chance events that cause allele frequencies to fluctuate especially in small pops
what are the two main ways genetic drift can have a big impact on pops
- founder effect
- small portion of a bigger population is isolated and only them survives
- small group start their own population (gene pool of new pop may differ from source pop) - bottleneck effect
- size of pop drastically reduced from natural disasters or human actions
- surviving portion is no longer genetically representative of og pop
- alleles may be overrepresented or underrepresented
differentiate micro and macro evolution
microevolution
- evolutionary change below the species (in a pop)
macroevolution
- evolutionary change that result in new species (species level and above)
what is the smallest unit of organism that can evolve
populations
- individuals do not evolve
define adaptations
inherited characteristics that enhance survival survival and reproduction rate
inference 2: what does the unequal ability of individuals to survive and reproduce lead to
an accumulation of favourable traits in the population over generations
where can we find evidence of evolution in natural evolution
- fossils
- comparative embryology
- evolution of drug-resistant bacteria
- molecular evidence
- homology (similarity in shared ancestry)
- artificial selection
define homology
it’s the similarity in characteristics resulting from a shared ancestry
what is an example of artificial selection
selective breeding
what is divergent evolution
when population becomes separated from rest of the species
when there is a difference in selection pressure/evolutionary pattern
define convergent evolution
- process by which organisms that are not closely related evolve similar features
- evolve similarities, but no shared ancestry
- occurs when they occupy similar environments
what is cryptic and aposematic colouration
cryptic: camouflage
aposematic: warning colours/bright colours=danger
what do you call when palatable or harmless species mimic unpalatable or harmful species
batesian mimicry
what is mullerian mimicry
- when two or more unrelated species bear a biological resemblance that exhibit similar warning systems
- 2 or more unpalatable species resemble each other
define relative fitness
an individual’s contribution to the gene pool of the next generation relative to the contribution of other individuals
what are the three types of natural selection that can alter the frequency distribution of heritable traits
- directional selection
- when conditions favour one extreme of a phenotypic range - disruptive selection
- when conditions favour both extremes of phenotypic range - stabilizing selection
- when conditions favour intermediate variants and acts against extreme phenotypes
- reduces variation
natural selection refers to selection by
- environment
- non random mating (sexual selection)
- differential fertility (eg. early maturation)
how do you call the process by which one species splits into two species
speciation
define reproductive isolation
refers to the inability of organisms from different species to interbreed due to to geographical, behavioral, physiological, or genetic barriers or differences
differentiate pre zygotic and post zygotic barrier
pre zygotic are mechanisms that prevent/block fertilization from occurring
post zygotic barriers are mechanisms that prevent the development/survival of hybrid offspring, they ensure the hybrid offspring are not selected
what are the 5 types of pre zygotic barriers
- habitat isolation
geographical isolation, one encounter another one rarely - temporal isolation
species breed at varying times (time of the day, seasons, years) - behavioural isolation
unique courtship rituals specific to species - mechanical isolation
morphological differences preventing mating from completing - gametic isolation
sperm of one species may not be able to fertilize egg of another
what are the three types of post zygotic barriers
- reduced hybrid viability
hybrids might be frail, not fully developed for survival - reduced hybrid fertility
hybrids may sterile - hybrid breakdown
some first gen hybrids are fertile but their next gen are feeble and sterile
differentiate allopatric speciation and sympatric speciation
allopatric
- populations are geographically isolated, forming a new different specie
sympatric
- a subset of a population forms a new species with geogr separation
what are the three ways sympatric speciation may occur
by
1. polyploidy
- accident/error during cell division
- habitat differentiation
- subpopulation exploit habitat/resource not used by parent population - sexual selection
- female preferences in male characteristics, eg. two groups of female prefer different colours, two different species of males evolve into respective colour
