Topic 5 Flashcards
1
Q
Evolution
A
- the process of cumulative change in heritable characteristics and/or allele frequency in the gene pool of a population over time
- can cause populations of a species to gradually diverge into separate species
2
Q
List the evidence for evolution.
A
- fossil record
- selective breeding
- homologous structures
- related DNA sequences
- vestigial structures
3
Q
Fossil record
A
- the fossil record provides evidence for evolution
- the sequence in which the fossils appear matches the sequence in which the organisms would be expected to evolve
- the sequence fits with the ecology of the groups (plant before animals)
- many sequences of fossils are known, which link together existing organisms with their likely ancestors
4
Q
Selective breeding
A
- proves that artificial selection can cause evolution
- domesticated breeds were made by repeatedly selecting for and breeding the individuals most suited to human uses
5
Q
Vestigial structures
A
reduced structures that serve little or no function; can be explained by evolution as structures that no longer have function are gradually being lost
6
Q
Niche
A
- the role/job a species plays in its community
7
Q
Adaptive radiation
A
- the diversification of a group of organisms into forms filling different ecological niches
8
Q
Convergent evolution
A
- the process whereby organisms (not closely related) independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
9
Q
Homologous structures
A
- evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function
- structures that look superficially different and perform a different function, but actually share structural similarity when looking closer at the bone positions
- structure has the same origin/ancestor but they have become different because they perform different functions (adaptive radiation)
10
Q
Analogous structures
A
- structure is different, but function is similar
- the structures have different origins, but have become similar over time because they perform the same/similar function (convergent evolution)
11
Q
Speciation
A
- the formation of new and distinct species in the course of evolution
- requires barriers between gene pools to separate gene pools enough for the populations to be considered two separate species
12
Q
Outline the barriers between gene pools
A
- genetic isolation: gametes incompatible
- temporal isolation: different breeding seasons
- ecological isolation: usually in plants that are growing in different habitats; their gametes rarely cross paths
- behavioural isolation: for example, bird dances only attract members of the same species
- hybrid inviability: for example, mules (the product of a male donkey and a female horse) are infertile
13
Q
Allopatric speciation
A
when one population is separated into two distinct populations by some geographical barrier (ie. river, elevation of mountain range, desert)
14
Q
Sympatric speciation
A
individuals within a population acquire different traits while in the same geographic area (some other form of isolation occuring)
15
Q
Explain the development of melanic insects in polluted areas with reference to evolution.
A
- adult Biston betularia moths fly at night to try to find a mate and reproduce
- during the day, they roost on the branches of trees - predators (ie. birds) predate moths during the day if they can find them
- in unpolluted areas, tree branches are covered in pale-coloured lichens and peppered moths are well-camouflaged against them
- however, in polluted areas, sulphur dioxide in the air kills lichens and the soot from coal burning blackens the tree branches
- thus, melanic moths are well-camouflaged against the dark tree branches in polluted areas
- therefore, in unpolluted areas, peppered moths are favoured and in polluted areas, melanic moths are favoured
- natural selection does its job and the favoured species survives/reproduces
16
Q
Continuous variation & gradual divergence
A
- continuous variation is variation in which is quantitative and can have a range of values (ie. height)
- matches the concept of gradual divergence, the idea that populations gradually diverge over time to become separate species
- if gradual divergence is true, we would expect to be able to find examples of all stages of divergence
- examples can be seen with Galapagos finches
17
Q
Compare the pentadactyl limbs of different animals
A
- the four vertebrate classes that have limbs, amphibians, reptiles, birds and mammals, all have pentadactyl limbs
- crocodiles (reptiles) walk/crawl on land using their webbed hind limbs for swimming
- penguins (birds) use their hind limbs for walking and their forelimbs as flippers for swimming
- echidnas (mammals) use all four limbs for walking and also use their forelimbs for digging
- frogs (amphibians) use all four limbs for walking and their hind limbs for jumping
- although they have have pentadactyl limbs, they have different functions
- differences can be seen in the relative lengths and thicknesses of the bones
18
Q
Define natural selection
A
a process that leads to the increased reproduction of individuals with favourable heritable variations, as better adapted individuals tend to survive and reproduce more than the less well adapted individuals
19
Q
Outline the process of natural selection
A
- can only occur if there is variation amongst members of the same species
- there is a struggle for survival
- causes organisms that have favourable genetics (are better adapted) to survive while organisms that have unfavourable genetics (less well adapted) die/produce fewer offspring
- individuals that reproduce pass on characteristics to their offspring
- therefore, increases the frequency of characteristics that make an individual better adapted while decreasing the frequency of other characteristics (which do not make the individual better adapted); leads to changes within the species
20
Q
What causes genetic variation?
A
- mutations
- meiosis
- sexual reproduction
21
Q
Define adaptation
A
- characteristics that make an individual suited to its environment and way of life
22
Q
Changes in beaks of finches on Daphne Major
A
- there are 14 species of finches on Galapagos Islands, each having varying sizes and shapes of beaks
- beak characteristics and diet are closely related; when one changes, the other does too
- two finches of interest on the island Daphne Major: Geospiza fortis and Geospiza fuliginosa
- G. fortis is a medium ground finch that can feed on small AND larger seeds, whilst G. fuliginosa can only feed on small seeds
- resultantly, G. fuliginosa is nearly extinct
- in 1977, a drought on Daphne Major caused a shortage of small seeds; G. fortis fed on the larger, harder seeds
- most of the population died, with the highest mortality among the shorter beaks b/c larger beak makes it easier to crack open the larger seeds
- in 1982-83, a severe El Nino event caused an increased supply of small, soft seeds and fewer large, hard seeds for 8 months
- during the 8 months, G. fortis bred rapidly in response to the increase in food
- after the 8 months, dry weather conditions ensued and breeding stopped until 1987
- in 1987, G. fortis had longer and narrower beaks than the 1983 average, correlating with the reduction in supply of small seeds in 1977
- variation in the shape and size of the beaks is mostly due to genes (heritability)
- one of the objections to the theory of evolution by natural selection is that significant changes caused by natural selection have not been observed actually occuring; the case of G. fortis serves as an example of significant changes occurring as a result of natural selection
23
Q
Explain the evolution of antibiotic resistance in bacteria
A
- antibiotic resistance is due to genes in bacteria, so it can be inherited
- begin with a population of bacteria without antibiotic resistance
- bacteria receives antibiotic resistance gene either through mutation or from another bacterium from another population
- when an antibiotic is used, the bacteria with resistance survive while the bacteria without the resistance die off (strong natural selection for resistance)
- therefore, the bacteria with resistance reproduce and the population contains more antibiotic resistant bacteria
- note: without the presence of antibiotic resistance, there is a weak natural selection against the gene for resistance; therefore, if you do not use antibiotics, the population will contain fewer bacteria with antibiotic resistance
24
Q
Explain why the evolution of antibiotic resistance in bacteria is so rapid
A
- Widespread use of antibiotics (ie. treating diseases, animal feeds)
- Bacteria can reproduce rapidly (generation time of less than an hour)
- Populations of bacteria are often huge (increased chance of mutation)
- Bacteria can pass genes to other bacteria in several ways (ie. plasmids allow one species of bacteria to gain antibiotic resistance from another species)
25
Q
What is an acquired characteristic?
A
- characteristics that develop during the lifetime of an individual
- STUDENTS SHOULD BE CLEAR THAT ACQUIRED CHARACTERISTICS ARE NOT HERITABLE
- I repeat, the IB says that characteristics ACQUIRED DURING THE LIFETIME OF AN INDIVIDUAL are NOT HERITABLE
- This is explicitly stated in the guidance, so regardless if it is 100% true or not, commit it to memory, okay?
26
Q
State and explain the system used to name species, making reference to writing conventions
A
- binomial system/binomial nomenclature
- it is universal among biologists and has been agreed and developed at a series of congresses
- the international name of a species consists of two words; the first is the genus and the second is the species
- genus name begins with upper-case letter and the species name begins with lower-case letter
- binomial is italicized (if typed) or underlined (if handwritten)
- after a binomial has been used once in a piece of text, it can be abbreviated to the initial letter of the genus name with the full species name
- the earliest published name for a species, from 1753 onwards for plants and 1758 onwards for animals, is the correct one
27
Q
Explain what is meant by “hierarchy of taxa”
A
- taxonomists classify species using a hierarchy of taxa
- taxon is greek for “group of something” (taxa is the plural)
- species are grouped into a genus; genera are grouped into families; families are grouped into orders and so on
- the taxa form a hierarchy, as each taxon includes taxa from the level below
- going up the hierarchy, the taxa include larger and larger numbers of species, which share fewer and fewer features
28
Q
List the three domains
A
All organisms are classified into one the three following domains:
- eubacteria
- archaea
- eukaryota
Guidance: Viruses are not classified into any of the domains because they are NOT LIVING ORGANISMS
39
Q
Dichotomous keys
A
- used in identifying specimens
- a dichotomous key consists of a numbered series of pairs of descriptions; one description should clearly match the species and the other should be clearly wrong
- each of the pair of descriptions either leads to another of the numbered pairs of descriptions in the key, or to an identification
- a second type of dichotomous key is a branching flow chart
- you should know how to construct a dichotomous key
67
Q
Construct a cladogram including humans and other primates
A
