5 evolution and biodiversity Flashcards
when does natural selection occur
when populations have genetic variations.Some variations are an advantage over others to the population in its particular environment. These advantages may help the organism to catch prey, avoid predators, find mates, or survive environmental changes. Those individuals that possess the most advantageous characteristics live to a reproductive age and are able to pass those characteristics to their offspring through their genes.
when does selective breeding happen
practised by humans for thousands of years, is a form of selection and another bit of evidence for evolution. In contrast to natural selection, this form is artificial and is often referred to as artificial selection. Humans select the animal or plant with the best characteristics and try, through genetic crosses, to create a breed or plant line that retains these desired characteristics. The differences between the ‘wild’ ancestor and the present day organism (created through artificial selection) can be enormous.
natural selection definition
Natural selection occurs when species have variation and certain traits are selected because they help the species to reach a reproductive age and pass on their genes.
selective breeding definition
A form of artificial selection in which organisms with certain characteristics are chosen by humans because they are of some benefit. These organisms are bred to produce offspring that have the same genes and, therefore, the same characteristics.
can artifical selection cause evolution
yes
waht is a breed
a group of animals within a species tha that haev specific and similar characteristics
microevolution
occurs on a small scale withina species
homologous
similar in position, structure, and evolutionary origin but not necessarily in function.
similarities betwen doplphins and human arms
5 phalanges
same bones (humerus, ulna, radius, carpals, phalanges)
Pentadactyl limb –
A limb with five digits, found in amphibians, reptiles, birds and mammals.
divergent evolution
when two separate species have a similar structure, but use it in different ways because of their environment.
Adaptive radiation
a process in which organisms rapidly diverge from the form of the original species into several new forms specialised to make use of different environmental niches. This can lead to divergent evolution and the development of a new species.
analogous
performing a similar function but having a different evolutionary origin, such as the wings of insects and birds.
what is convergent evolution
unrelated organisms evolve similar structures or features
waht is divergent evolution
shared ancestor but different end points (species evolve different strucutres or features)
Speciation
the process by which new species form, is one of the success stories of evolution.
discontinuous variations
not affected by environment eg blood type
is a type of variation that is influenced by a gene or a few genes, can be put into categories, and is not influenced by the environment.
continuous variations
affected by environment eg height
is a type of variation that is controlled by many genes, has a wide range of variability, and is easily influenced by the environment.
how do species form
When two species become genetically different enough that they can no longer interbreed to produce fertile offspring, then speciation has occurred. A possibility is that one species (species A) evolves over time until it is genetically different enough from the original species that it is considered a new species (species B) and so on (species C).
industrial melanism
widespread burning of fossil fuels by power machinery
The allele for the dark allele is dominant over the the light allele and codes for the moth to make more melanin, which is the pigment causing the dark colour. The darker coloured variety, also called the melanistic morph, was better camouflaged in the highly industrial areas where pollution had changed the environment. The lighter coloured moth was better adapted to non-polluted areas, because the trees were still covered in lichen and had little or no soot – making it less visible to predators. In these non-polluted areas the recessive allele for the light colour was found at higher frequency than the dominant allele for the dark colour. The result of this environmental change was that in the industrial areas the numbers of the darker moth increased, and the numbers of the lighter moth declined. This can be explained by the fact that the lighter peppered moths were easily spotted and eaten while resting on dark and sooty tree barks, while darker peppered moths were well camouflaged in polluted areas and many survived to reproduce and pass on the dark variety of the gene. Therefore, the pollution brought about by the industrial revolution caused environmental change and acted as a natural selection pressure that favoured the darker moth over the lighter moth. This led to a change in the frequency of the alleles in the peppered-moth gene-pool.
transient polymorphism
where one allele variation replaces another
balanced polymorphism
equililibrium between the two variations of the gene
Industrial melanism definiton
is the change in the melanin-producing allele frequency from light to dark due to environmental changes brought on by industry pollution.
transcient polymorphism defintiion
is the gradual change in the allele frequency of a population due to the slow replacement of one gene of another.
balanced polymorphism definition
is a balance between both forms of the allele variations within a population.
causes of variation
mutation
meiosis
sexual reproduction
mutation
any change to the DNA sequence is classified as a mutation. It can range from a single base change to removal of one segment of a chromosome.
meiosis
produces gametes with unique combinations of alleles, thus increasing the genetic variation of individuals within the species.
sexual reproduction and random fertilisation
the combination of gametes is random and results in a zygote that has genes from both of its parents.
when are mutations harmful
those which cause a gene not to function properly or not to function at all. (non sense mutations)
what are missense mutations
may cause variation that benefits the organism by changing a codon, which in turn alters the protein.
what are silent mutations
when the codon still codes for the same amin oacid, so no natural change in the protein occurs. no effect
how does meiosis produce variation
crossing over on homologous chromosomes
chromosome lineup
evolution definition
the change in the frequency of an inherited trait in a population over time
allele
version of a gene
natural selection def
Differential survival and reproduction of individuals with favourable traits in the current environment.
survival of the fittest definition
Fitness refers to the ability to survive to reproductive age,find a mate,and produce offspring, not now big or strong an organism is.
Heritable characteristics are
the characteristics that an organism possesses due to its genetic make-up. These characteristics can be inherited by the organism’s offspring.
macroevolution
occurs on a large scale leading to the development of new species.
Natural selection :
Natural selection occurs when species have variation and certain traits are selected because they help the species to reach a reproductive age and pass on their genes.
Selective breeding :
A form of artificial selection in which organisms with certain characteristics are chosen by humans because they are of some benefit. These organisms are bred to produce offspring that have the same genes and, therefore, the same characteristics.
breed
a group of animals within a species that have specific and simialr characteristics
examples of selective breeding
Breeding egg-laying hens to lay lots of eggs
Breeding race horses for speed
Breeding dogs for herding, hunting or simply for specific physical features
Breeding cattle for increased meat or milk production
Breeding of crops to be disease- or cold-weather-resistant in order to increase production
Breeding of plants to produce larger and sweeter fruits.
microevolution
occurs on a small scale within a species
homologous
simialr in position, structure and evolutionary origin
Pentadactyl limb –
A limb with five digits, found in amphibians, reptiles, birds and mammals.
Divergent evolution
is when two separate species have a similar structure, but use it in different ways because of their environment.
adaptive radiation
Adaptive radiation is a process in which organisms rapidly diverge from the form of the original species into several new forms specialised to make use of different environmental niches. This can lead to divergent evolution and the development of a new species.
opposite of a homologus structure is
an anagolous structure
anagolous
performing a similar function but having a different evolutionary origin, such as the wings of insects and birds.
convergent evolution
when organisms that are not closely related evolve similar structures that are used for similar purposes.
divergent evolution
shared ancestor but the end points are two different lines with two structure that have differnt functions
speciation
the process by which new species form
discontinuous variation
a type of variation that is influenced by a gene or a few genes, can be put into categories, and is not influenced by the environment.
continuous variation
a type of variation that is controlled by many genes
what did darwin discover about finches
have evolved to adapt to particular food sources available on the islands. This change is clearly visible in their beaks. Some beaks can crack larger seeds and some smaller beaks cope better with smaller seeds. This adaptive radiation has allowed the various finch populations to survive side by side, even on smaller islands, because of food specialisation.
occurd on daphne major
for a scientific theory to be accepted it must be able to
explain and predict natual phenomena. beak length increase and decreae supports the theory of evolution by natural selection
why has antibiotic resistnace spread so widelt and rapidly
Bacterial generation times are short, ranging from 20 minutes to several hours. This means that evolution can progress rapidly.
There has been widespread use of antibiotics in the general population and in animal feed. People often do not finish a course of antibiotics, leaving residual populations of bacteria in their system that have been exposed and are likely to have developed partial or full resistance.
Antibiotic resistance is often coded for by a gene or genes located on plasmids. The plasmids are easily exchanged between bacteria, even if they are not of the same species or strain.
Hospitals are breeding grounds for antibiotic resistance, because that is where patients with severe infections are treated with high doses of antibiotics, creating enormous selective pressure on the bacteria.
how does antibiotic resistance come about in bacteria through natural selection
As with most species, variation is present in bacterial populations. This variation leads to natural selection. When exposed to antibiotics, bacterial mutations can occur leading to more variation within the population. Those bacteria with variations that are resistant to the antibiotic are the most fit for their environment and will survive to pass on their resistant genes to their offspring or through plasmids. Those bacteria that are susceptible to the antibiotics will die. The allele for the antibiotic-resistant characteristic will increase in frequency in the gene pool and eventually, more and more bacteria become resistant.
what is convergent evolution
the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. For example, the fusiform shape of the penguin and the dolphin. Both organisms are from different lineages but have evolved a similar shape suited for an aquatic environment. The cladistic term for the same phenomenon is homoplasy, from Greek for same form.
what is a clade
a group of organisms that have evolved from a common ancestor
what is a node on a cladogram
where clades branch off, which shwos where speciation has occured
anagolous traits evolve
seprately but have simialr function
homologus traits evolve
together but are the seperate traits formed after speciation
homologous
tructures that are similar because of shared ancestry, but that may have different functions due to divergent evolution, e.g. the pentadactyl limb of man and bats.
anagolous
Structures that have similar functions but have evolved separately, through convergent evolution, from different ancestral features, e.g. insect wings and bat wings.
what is divergent evolution
the process whereby groups from the same common ancestor evolve and accumulate differences, resulting in the formation of new species. Divergent evolution may occur as a response to changes in abiotic factors, such as a change in environmental conditions, or when a new niche becomes available. Alternatively, divergent evolution may take place in response to changes in biotic factors, such as increased or decreased pressure from competition or predation. A good example would be the finches of the Galapagos Islands studied by Charles Darwin.
waht are clades typically based off
anatomical characteristics such as the composition of skeletons but most clades nowadays are based on the moleclar similarity of dna base sequences of amino acids sequences. this is more rleiable.
clade:
A group of organisms, both extant and extinct that share an ancestor.
cladistics
A system of classifying organisms according to shared characteristics, based on ancestry.
Cladogram:
A diagram that shows the evolutionary relationship of a group of organisms.
genus
a group of species that share common characteristics but may not be able to interbreed.
species
a group of organisms in the same genus that are able to interbreed to produce fertile offspring.
what comes frist genus or species
genus
everything in a name should be
italics or underlined when handwritten
highest level of classification is a
domain
waht are the three domains
bacteria, archea, eukaroyota . should be referred to as abcteria, archaeans and eukaryotes
features of bacteria
cell membrane - Glycerol-esters of lipids, D-form of glycerol
cell wall - peptidoglycan
no histones
features of archeans
cell membrane - Glycerol-ether lipids, L-form of glycerol
cell wall - not peptidoglycan
sometimes has histones
features of eukaryota
cell membrane - Glycerol ester lipids, D-form of glycerol
cell wall - not peptidoglycan sometimes absent
has histones
eubacteria
the remaining prokaryotic organisms lacking a nucleus and are often considered pathogenic or disease causing.
arcehea are usuaslly
unicellular organisms that lack a nucleus and often live in extreme habitats, such as hot water springs, deep earth sediments, cow intestines and lakes or pools with extremely high salt concentrations. However, they may also live in less extreme habitats such as the ocean’s surface, soil and marshlands.
of the three domains, only the eukaryotes have been further classified into kingdoms into:
protoctista, fungi, plantae, animalia
a dichotomous key is
A dichotomous key is a series of paired opposing statements which guide the user to the identity (or allows the classification) of an item or organism.
bryophytes
no roots, leaves or stems
reproduce via spores
no vascularisation
rhizoids as anchors
eg moss
filicinophyta
roots, leaves and stems
reproduces via spores
vascularisation
pinnate leaves
eg fern
coniferophyta
roots, leaves and stems
reproduces via seeds in cones
vascularisation
woody stem
eg conifer
angiospermophyta
roots, leaves and stems
reproduces via seeds from fruits
vascularisation
produces floweres and fruits
eg flowering plants
porifera
no symmetry
no gut openings
no segmentation
use spicules for support
eg sea sponge
cnidaria
radical symmetry
1 gut opening
no segmentation
cnidocytes
eg coral, jellyfish hydra
platyhelmintha
bilateral symmetry
1 gut opening
no segmentation
flattened body
eg tapeworm
annelida
bilateral symmetry
2 gut openings
segmentation
use peristalsis for moving
eg leech earthworm
mollusca
bilateral symmetry
2 gut openings
non visible segmentation
some have a shell made by mantle
octopus, snail, slug, oyster
arthropoda
bilateral symmetry
2 gut openings
segmentation
have exoskeleton made of chitin
eg spider, crab, scorpion
chordata
bilateral symmetry
2 gut openings
segmentation
Have a notochord to support the body and sophisticated digestive system
eg Fish, dog, whale, zebra, human
chordata
a large phylum of animals that includes the vertebrates together with tunicates (sea squirts) and lancelets. They are distinguished by the possession of a notochord at some stage during their development
key characteristics of mammalia
skin covered in hair or fur
skin also has sweat glands
habitat on land and in water
warm-blooded
breathing through lungs
key characteristics of aves
skin covered in feathers, which are waterproof and insulate the body
habitat on land
most species can fly and some can also swim
warm-blooded and lay eggs
breathing through lungs
key characteristics of reptilia
skin is dry and has scales
habitat on land
cold-blooded and most species lay eggs
breathing through lungs
homodont are sharp and cone-shaped
key characteristics of amphibia
skin is exposed and moist
habitat on land and in water
cold-blooded and lay eggs
no external ears
key characteristics of fish
covered in slimy scales
habitat in fresh or sea water, with fins and tails adapted to swimming and balancing
cold-blooded and lay eggs
breathing through gills
State the name of the scientist who used rRNA analysis to change the traditional classification system, in 1977.
carl woese
In which domain do organisms have no histones but they do have a peptidoglycan cell wall?
bacteria/eubacteria
Name one product of the light-dependent reactions which is not needed for the light-independent reactions.
oxygen
The amino acid binding site on the tRNA is not part of the loop structures found within the tRNA molecule. trye or false
true
Name the process that generates electrons for use in the light-dependent reactions.
electron transport chain
Leopard frogs and wood frogs reach sexual maturity at different times in the spring and hence cannot interbreed. This is an example of:
temporal isolation
