unit 2 evolution Flashcards
charles darwin
wrote the book on the origin of species by means of natural selection which had two points organisms present today are descendants of ancestral species that were different and the mechanism for evolution is natural selection. sailed HMS beagle and went to the galapagos islands 3 tortoises on different islands and had adapted to the vegetation on their own island. and finch- beaks- different seeds
darwins theory
- individuals differ
- organisms produce more offspring than can survive (over -production)
- struggle to survive ( competition since not all can live)
- best adapted = survival (fitness)
- organisms past best adapted traits to offspring
- this is process of natural selection=change
- species today are descendants with modification
james hutton and charles lyell
age of earth- must be millions of years old. geological processes shaping earths surface are very slow
jean baptiste lamarck
living things change. species descend from others. organisms adapt in their life time with selective use and disuse organisms gained or lost traits in life time if they used them a lot and they would pass that trait on to their offspring.
thomas malthus
population to big gunna keep growing and darwin thought this applied to plants and animals even more.
evidence of evolution
fossil record- species come and gone evolving into new ones fossils have changed
geographic distribution- similar species in different locations. different animals on different continents had similar behaviour because they have the same ancestor
homologous structures- same types of bone or muscle used for different things. evolve to use structure in different ways
embryology- embryos develop similar at early stages for some species resulting in homologous structures similar genes = similar development
vestigial structures- remnants of evolutionary heritage FROM THE PAST. unused bones and such.
dating fossils
relative dating- looks at fossil record- fossils in order shows change in organism.
absolute dating- carbon dating- age in years uses the amount of radio active isotopes present or not present
miller and urey
produced amino acids through passed sparks ( lightning) through a mixture of gases like NH3 H20 H2 CH4 that resembled earths early atmosphere and created amino acids the building blocks of life
proteinoid microspheres
tiny non living bubbles that have similar properties to living this- semipermeable membranes and they stored and released energy.
endosymbiotic hypothesis
2 billion years ago prokaryotic cells began to evolve internal membranes and other prokaryotic cells enter them and began living in them with a symbiotic relationship
traits
features inherited at conception
homozygous vs heterozygous
homozygous same gene BB bb
heterozygous different genes Bb
phenotype
outward appearance of gene
monohybrid crosses
one gene pair that is studied and the rest of the traits are ignored
gregor mendel
father of modern genetics and realized that characteristics and repeated and the passing of traits is heredity
genes
units of nucleotide base pairs that instruct cells to produce specific traits
alleles
two or more alternate forms a gene
dominant alleles
determine the expression of genetic trait
recessive alleles
masked by dominant alleles.for them to show there must be two of the same recessive genes
genotype
refers to genes of a trait for an organisms BB Bb bb
incomplete dominance
two alleles interact and are equally dominant creating a new phenotype and are BLENDED
codminance
both genes expressed at the same time not blended
somatic
zygote
gamete
somatic- all body cells
zygote- fertilized egg - first somatic cell
gamete- sex cells half genetic info
law of segregation
homologous pairs of chromosomes must be separated and end up in different sex cells only one copy of the allele
multiple alleles
genes may have more than two alleles that exist in a population such as eye colour brown green and blue
polygenic traits
traits that are produced by interaction of several genes. they are controlled by two or more genes.
differentation
cells become specialized through a process of differentiation. hot genes control differentiation of cells and tissue and they are interchangeable between two different organisms (weird)
dihybrid crosses
two traits that are on different homologous chromosomes and how they will interact. To find out all the different combinations that could occur for the gametes use FOIL
gene pool
all alleles present in a population
relative frequency
number of times an a allele occurs in a gene pool compared to the number of times the other alleles occurs
evolution
any change in the relative frequency of alleles in any population
heritable variation
two sources- mutations and genetic shuffling which occurs during the production of gametes and can result from the crossing over of chromosomes.
evolution in population
genetic drift and natural selection
natural selection
affects phenotype in 3 different ways- directional selection, stabilizing selection, and disruptive selection
directional selection
individuals at one end of the “curve have a higher fitness that individuals in the middle and other end of the curve the range of phenotypes will shift in the direction of higher fitness.
stabilizing selection
selection AGAINST both extremes of the “curve” this favours individuals that are average and near the centre of the curve. the individuals in the centre have the higher
disruptive selection
individuals at BOTH ends of the curve have higher fitness than average individuals in the middle of the curve. the population splits and two new species could be created
genetic drift
evolution by CHANCE when a small part of the population gets separated from the individual population. this can change the allele frequency and this is also known as the founder effect.
hardy weinberg principle
conditions where evolution does NOT occur- and the allele frequencies remain constant. if the allele frequencies remain constant the population reaches a genetic equilibrium. conditions- 1. random mating-all members of population must have an equal opportunity to produce offspring to pass on their alleles. 2. large population- genetic drift has a lower effect on large populations. 3.no movement into or out of population- individuals may bring in new alleles or take them with them changing the gene pool. 4. no mutations- if genes mutate new alleles could be introduces. 5. no natural selection- all genotypes must have equal probabilities of survival and reproduction-no phenotype can have an advantage.
hybrid
also means heterozygous
pure line
organism whose genes for a trait are the same- pure bred
vectors
organisms that carry diseases to other organisms usually through a bite.
endemic species
found exclusively in one area
isolating mechanisms
time geography behaviour and ecological
speciation
reproductive isolation results from the isolating mechanisms such as behavioural isolation which refers to things such as mating rituals, geographic isolation which refers to physical separation, and temporal isolation which refers to the different mating times. these independently evolving populations result in speciation
adaptive radiation
divergent evolution
macro evolution
large scale evolutionary patterns and processes that occur over a long period of time such as extinction, adaptive radiation,convergent evolution,coevolution, punctuated equilibrium and changes in development of genes.
unrelated species
- can form inter relationships with each other resulting in coevolution which is the change in the genetics of one species due to the change in another species. cheetah and gazelle.
- in similar environments species can undergo convergent evolution where organisms that are not related independently evolve similar traits to other species due to similar environments. which results in analogous structures that are different but used the same way.
related species
- in small populations a punctuated equilibrium can occur which is a long stable period disrupted by periods of rapid change.
- species in different environments can undergo divergent evolution which are differences in a species that can result in new species. homologous structures are evidence of this- same structures evolving to do different things.
gradualism
darwin- biological change is slow and steady
sexual reproduction
advantages- variety in offspring
disadvantages- wasteful with sperm and egg
-takes energy to find mate
-takes two
asexual reproduction
advantages-only needs one
-not wasteful
disadvantages-all offspring are the same
