topic 7 - genetics, populations, genetics and ecosystems Flashcards
genotype defneiton
the genetic constituition of an organism ( the allels it has for a gene )
phenotype deff
the expression of the genes and its interactoin with the environemtn
homozygous deff
a pair of homologoups chormozones carryinf the same allels for a single gene
heterozygous
a pair of hologous chromozones carrying two different alles for a single gene
rescessive allels
an allele only expressed if no dominant allele is present
dominant allels
an allele that will always be expressed in the phenotype
codominant deff
both allels are equally dominant and expressed in the phenotype
multiple allels
more than two allels for a single gene
sex linkage
a gene whos locus is on the x chromozones
autosomal linkage
genes that are locasted on the same chromozone ( not the sex chromozone )
epistasis deff
when one gene modifies or masks the expression of a different gene at a different locus
monogybrid
genetic inheretence cross of a charachteristic determined by one gene
dihybrid
genetic inheretence cross for a chaterchterisctis determined by two genes
what does crossing over reuslt in?
new combos of allels in the gametes, this means the gametws in your punnet square may differ
autosomonal linkage impact predicted gametes
allels for each gene linked on the same chromozome will be inhereted together so?
three types of selectoin
stabalising
selectional
disruptive
what is disruptive selection
indivuduals containing alleles coding for either extreme trait are more likely to survive and pass om htier allels, the allele frwuencey changed and more individuals possess the allsle for the extreme trait
contunided disruptive selectoin can ultimately lead to speciation
speciation is…
the process that results in the creation of a new species
speciation occurs when one og population of the same species become _ iscolted
repodcutively iscolasted
this iscolation means there are now teo popilations of the same species but can not breed together
speciation can result in accumulation of…
differences in their gene pools to the extent that two populatoins would be unable to interbreed to make fertile ofspring
therefore clasified as two different species
what is allopatric speciation
populations become seperated geographically leading to reporductive iscolation
e.g mountain ranges
what is sympatric speciation
populations can be repoductively iscolated due to differenced in their behaviout
this could imact reproductivr behvaiour e.g it may cause indivuals to perfom different courtship rituals for indidivuals to be fertile at different times of the year
what is genetic drift
the change in allele frequence within a population between generations
there will alwayds be genetci drift from one generatoin to the next but continual substantial genetic drift results in evolution
the smaller popuation is the bigger the impact allel feuwncy changed have proportionally
this is why evolution often occurs more rapidly in smaller populations
popualtion defenition
group of orgnims of the same soecies living in the same habitat
habitat deff
part of an ecosystem in wich paeticilar orgnaisms live
community deff
all populations of diiferent species in the same area at the same time
ecosystem deff
a comunity and the non living componants of an environment ( biotic and abiotic factors ) can range in size
niche
an organisms role within an ecosystem including their position in the food web and habitat. each species occupied thier own niche goverend by adaptation to both abiotic and biotic factors
carrying capscity deff
the maximum population size an ecosystem can support
difference between abiotic and biotic factors
abiotic - non lving components of an ecosystem
what are biotic factors
biotic fasctors and the living components of an ecosystem interacting together such as interspecific and intradpecific competion and predation can also affect pop size
interspecific competiton
members of different soecies are in coetion for the same rescporce that is in limited suply
intraspecific competiton
when members of the same speciies are in compettion for resepoces and a mate
why do we sample?
more time effiecient
if impletmented correctly it can be mroe accurate
sampels must accurately represent the pop. this is ensured by:
random sampling in uniform areas to eliminrate bias
live transects to examine a change over distance
large number of samples ( 30+ )
steps to a random sampling method
- lie two tape measures at a right angle to creat a gridded area
- use a random number generator to generate two co ordinates
- place the quadrat and collect the data
- repeat at least 30x and calculate a mean
line transpects are used to estimate?
populatoin size when they are unevenley distrubuted e.g populations wich chasnge over distance
common example of where we use line transects
sandy / rockey shores
across a path or river
two types of transect
belt transect - the quadrat is palced at every position along the tape measure
interrupted transect - the quadrat is placed at unifrom intervals along the tape measure e.g every 5 mitres
line transects method
- place the tpae measure at a right angle to the shore line
- place the quadrat every 5 mitres / every position
- collect the data ( density / % cover / local freuqnecy
- repet by plcing another 30 transects along the beach at right angled to the shore line
