ch5: devolution Flashcards
define evolution (2)
cumulative change in heritable characteristics of a population
adaptation of a population due to natural selection
new species arise from pre-existing species
outline the types of evidence that can be used to support the theory of evolution (4)
fossils: show species changed over time selective breeding of domesticated animals & crop plants artificial selection → rapid change homologous structures: common ancestry DNA sequences: common ancestry
ALL ADAPTIVE RADIATION QUESTIONS (5)
happens in a group of species that evolve from a common ancestor
ancestral species occupies new environment with a variety of niches
different members of the species are exposed to different selection pressures → allele frequencies diverge
evolution of a similar structure in diff ways for diff functions adapted to new env
new species with common structures
homologous structures are evidence of adaptive radiation
comparative anatomy provides evidence for evolution
reproductive isolation enhances adaptive radiation → speciation
e.g. vertebrate pentadactyl limb = limb-bone pattern found in vertebrates
human hand adapted for manipulation of tools
seal’s forelimbs adapted for swimming
distinguish between analogous and homologous structures, giving an example of each (2)
homologous structures evolved from a common ancestor while analogous structures did not
homologous: pentadactyl limb
analogous: wings of birds & insects
outline the evidence for evolution provided by selective breeding (3)
crop plants/domesticated animals are produced by selective breeding
e.g. dogs developed from wolves
artificial selection → eliminates undesirable varieties → significant change over time
shows that natural selection can cause evolution
explain the various possible consequences of overproduction of offspring (8)
overpopulation → competition for limited resources
e.g. water, space, food
struggle for survival → survival of the fittest
offspring whose traits adapt them to environment will survive and reproduce
less adapted die
natural selection
increase spread of disease in population
waste products of the population may reach toxic levels
may exceed carrying capacity → population crash
sigmoid population growth curve
y-axis: population
x-axis: time
lag phase → exponential phase → transitional phase → plateau phase
explain how DNA is used to pass on genetic information to offspring accurately but also produce variation in species (8)
pass on genetic info accurately: DNA is replicated semi-conservatively
produce variation
mutation → change of genes
independent assortment of homologous chromosomes during meiosis metaphase I: formation of haploid gametes with different alleles → ↑ genetic variety
crossing-over of non-sister chromatids in meiosis prophase I: shuffling of genetic material between paternal and maternal chromosomes + recombines linked alleles to produce new combinations
fertilisation: random combination of gametes of both parents in the zygote
different phenotypes among members of the same population
natural selection may lead to enhanced survival of recombinants
explain two examples of the evolution of specific populations of organisms in response to environmental change (8)
Gonorrhoea bacteria’s antibiotic resistance:
environmental change: exposure to penicillin
some bacteria have antibiotic-resistant gene due to mutation and others do not
antibiotic-sensitive bacteria die while antibiotic resistant bacteria survive
pass on antibiotic-resistance gene to other bacteria by plasmids/binary fission
over time resistance in the population ↑ due to natural selection
Galapagos finches’ beaks:
environmental change: wet years with abundant small seed to drought years with only large seeds
some with strong, big beaks and some with small beaks
small beaked finches cannot eat large seeds and die while large beaked finches can eat large seeds and survive
large beaked finches reproduce to pass gene to offspring
over time large beaks predominate due to natural selection
explain the evolution of antibiotic resistance in bacteria (6)
antibiotics are chemicals used to treat bacterial diseases
environmental change: exposure to antibiotics
some bacteria have antibiotic-resistant gene due to mutation and others do not
antibiotic-sensitive bacteria die while antibiotic resistant bacteria survive
natural selection favours those with resistance
increase allele frequency of resistant bacteria
pass on antibiotic-resistance gene to other bacteria by plasmids/binary fission
over time resistance in the population ↑ due to natural selection
more an antibiotic is used, more bacterial resistance
doctors use different antibiotics → resistance develops to those as well → multiple-antibiotic resistant bacteria → difficult to treat some infections
explain how the common ancestor might have given rise to two different species in different locations/speciation (4)
speciation = the splitting of a species into 2 separate populations
reproductive isolation due to geographic/behavioural isolation → gene pools separated
each group subjected to a different set of env conditions
differences in selective pressures → adaptive traits specific to the particular env conditions were selected by natural selection → gene pools diverge
evolve differently until genetic compositions are so different they cannot interbreed
speciation accumulating over long periods
punctuated equilibrium over a short time period
ALL EVOLUTION QUESTIONS
evolution = cumulative change in heritable characteristics of a population
populations produce more offspring that can survive
competition for limited resources
e.g. water, space, food
struggle for survival → survival of the fittest
there is genetic variation in the offspring:
mutation → change of genes
sexual reproduction promotes variation in species
independent assortment of alleles during meiosis: formation of gametes with different alleles
crossing-over of non-sister chromatids in prophase I: shuffling of genetic material between paternal and maternal chromosomes
fertilisation: random combination of gametes from both parents in the zygote
offspring whose traits adapt them to environment will survive
less adapted die
survivors reproduce and pass on favourable genes
genes of less adapted are eliminated + favourable variations will ↑ in the population
variation is heritable → change in gene pool
natural selection occurs
sustained selection of favourable traits → evolution → entire population exhibits new trait
NATURAL SELECTION AND SPECIATION: natural selection genetically isolates members of a species so eventually they can no longer produce fertile offspring
genetic divergence increases and leads to reproductive isolation
geographical factors may lead to reproductive isolation
prolonged reproductive isolation leads to speciation
taxonomy
domain Archaea (kingdom Archaebacteria) Eubacteria (kingdom Eubacteria) Eukaryote (kingdom Protista + Fungi + Plantae + Animalia)
kingdom kingdom Archaebacteria kingdom Eubacteria kingdom Protista kingdom Fungi kingdom Plantae kingdom Animalia
phylum kingdom Plantae Bryophyta Filicinophyta Coniferophyta Angiospermophyta kingdom Animalia Porifera Cnidaria Platyhelminthes Annelida Mollusca Arthropoda Chordata
class Fish Amphibians Reptiles Birds Mammals
order
family
genus
species
Plantae
google docs
Invertebrae
google docs
Chordata
google docs
