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96 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Tropisms |
Growth response Direction is the growth response related to the director of stimulus |
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Positive tropism growth |
Towards related stimulus |
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Negative tropism growth |
Away from stimulus |
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Hydrotropism |
Response to water concentration |
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Chemotropism |
Response to chemicals |
Nutrients, pH, salt, toxins |
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Thigmotropism |
Response to touch |
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Gravitropism |
Response to gravity |
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Phototropism |
Response to light Shoots- positive response Roots- zero or negative response Covered- no response Pigment (cryptochrome)- responds to blue light |
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Phototropism occurs in |
Lower stem Involving the hormone Auxin and IAA Hormones active in small concentrations, produced in one organ then transported away. Have effect in another organ- target or effector |
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Phototropism shows greater elongation.. |
Cells show on darker side than those on bright side IAA transported in 2 directions concurrently- away from tip (location produced) to zone of elongation Laterally in dark side |
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Geotropism- response to gravity |
Downwards response- positive response because towards origin of gravitational pull Production of IAA- root tips and shoot tips. Meristems with actively dividing cells. IAA transported away from meristems. Lateral transport- across root/shoot |
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In Geotropism the IAA example includes |
IAA accumulates on lower side of root possibly result of starch granules setting in cells- carrying IAA |
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Auxins |
IAA naturally occurs in Auxins Synthetic auxins used as rooting hormones for cutting and as herbicides and defoliants |
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Nastic response is a |
Non-directional response. Plants responds to light intensity of stimulus |
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Taxis |
Innate response- when organism moves away or towards an environmental stimulus. Innate- genetically determined Directional response Positive- towards Negative- away |
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Tropotaxis is |
When animal compares intensity of stimulus using 2 or more organs on either side of body to determine direction of stimulus. |
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Klinotaxis |
Non- directional response Rate of activity is dependent on intensity of stimulus. |
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Orthokinesis |
Organism response involves rate of movement |
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Klinokinesis |
Organism responses by changing rate of turning as it moves |
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Homing is the |
Ability of an animal to return over unfamiliar territory to its home usually on a regular basis |
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Migration |
Is the movement of animals from on geographic location to another. Animals display annual cycle of migration moving between breeding grounds and feeding grounds. Return migration common in birds may involve flight pathways of kms |
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Navigation is the |
Process in which animal finds its way from one location to another by environmental cues. For an animal to remain on course, it needs internal clock to compensate for the shift in position of environment cue with time. Innate- genetically programmed |
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Biorhythms |
Regular cycle of events in organism controlled endogenously. Modified in response to environmental cues. |
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In the absence of environmental factors the clock Still runs and the organism still displays activity |
Free-running period |
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Circadian |
Free running rhythm displays a period of 24 hours/one day |
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Cirannual |
Free running period displays a period of one year/365 days |
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Circatidal |
Free running period displays a period of 12 hours/one tide |
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Circalunar |
Free running period displays a period of about 30 days/ one month |
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Circasemilunar |
Free running period displays a period of 15 days |
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Activity rhythms under the control of an internal clock is known as |
Endogenous |
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A few activity patterns are determined by external factors only |
Exogenous |
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The clock is set by environmental cue known As |
Zeitgebar |
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Biological internal clock |
Is under generic control with several genes identified in range of organisms |
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Migration is the regular movement of a population of animals between habitat Purpose- breeding in favourable environment, food source, avoidance of climate of extremes Involves energy and significant amount of population Genetically controlled but initated by environmental factors day length temp changes lack of food and population size |
Homing is the ability of an animal to find it's way back home over unfamiliar territory Occurs as a result of unusual events or movements in search of food and mates etc |
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Predation Predator exploits prey. Predator kills and eats prey Predator + Prey - harmed |
Co evolution- Predator evolve better capture strategies Prey better escaped avoidance methods Long term influence of each species on other Natural selection pressure- best adapted prey individuals survive and produce greater number of surviving offspring Best adapted predator individuals catch most prey- produce greater number of surviving offspring |
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Prey strategies to avoid predation
Camoflague- disruptive patters spots strips
Behavioural response- groups- safety in numbers, vigilance escape hiding and freezing behaviours. Parents attracting predators away from young |
Chemical defenses- bitter toxic repellent
Structural defenses- prickles armour horns eyespots that confuse
Mimicry- organism resembles a poisonous species |
Intraspecific competition Some species have identical niches |
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Prey strategies to avoid predation
Camoflague- disruptive patters spots strips
Behavioural response- groups- safety in numbers, vigilance escape hiding and freezing behaviours. Parents attracting predators away from young |
Chemical defenses- bitter toxic repellent
Structural defenses- prickles armour horns eyespots that confuse
Mimicry- organism resembles a poisonous species |
Intraspecific competition Some species have identical niches |
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Hierarchies Dominance, social hierarchies or pecking order Linear hierarchies- simple order Alpha beta then omega Some species have seperate hierarchies in males females Highest ranked individuals achieve better food protection and mates- contribute more to gene pool of next generation |
Resources not shared equally Lower ranked while not reproducing can help rear young related younger members of group known as Kin selection |
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Prey strategies to avoid predation
Camoflague- disruptive patters spots strips
Behavioural response- groups- safety in numbers, vigilance escape hiding and freezing behaviours. Parents attracting predators away from young |
Chemical defenses- bitter toxic repellent
Structural defenses- prickles armour horns eyespots that confuse
Mimicry- organism resembles a poisonous species |
Intraspecific competition Some species have identical niches |
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Hierarchies Dominance, social hierarchies or pecking order Linear hierarchies- simple order Alpha beta then omega Some species have seperate hierarchies in males females Highest ranked individuals achieve better food protection and mates- contribute more to gene pool of next generation |
Resources not shared equally Lower ranked while not reproducing can help rear young related younger members of group known as Kin selection |
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Advantages of group Safety in numbers and group defense
Groups needed learning and passage of a culture
Specialization of functions within group possible
Cooperative food gathering |
Disadvantage Increase numbers- more competition many groups need to keep on move
Isolation suits relatively immobile species where food source is less concentrated but widely dispersed
Increase opportunity for conflict need behaviour to ritualise and minimize aggressive behaviour
More contact between individuals- greater likelihood to spread papasites and diseases |
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Prey strategies to avoid predation
Camoflague- disruptive patters spots strips
Behavioural response- groups- safety in numbers, vigilance escape hiding and freezing behaviours. Parents attracting predators away from young |
Chemical defenses- bitter toxic repellent
Structural defenses- prickles armour horns eyespots that confuse
Mimicry- organism resembles a poisonous species |
Intraspecific competition Some species have identical niches |
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Hierarchies Dominance, social hierarchies or pecking order Linear hierarchies- simple order Alpha beta then omega Some species have seperate hierarchies in males females Highest ranked individuals achieve better food protection and mates- contribute more to gene pool of next generation |
Resources not shared equally Lower ranked while not reproducing can help rear young related younger members of group known as Kin selection |
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Advantages of group Safety in numbers and group defense
Groups needed learning and passage of a culture
Specialization of functions within group possible
Cooperative food gathering |
Disadvantage Increase numbers- more competition many groups need to keep on move
Isolation suits relatively immobile species where food source is less concentrated but widely dispersed
Increase opportunity for conflict need behaviour to ritualise and minimize aggressive behaviour
More contact between individuals- greater likelihood to spread papasites and diseases |
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Kin selection Altruism towards relatives Altruistic act serves to promote survival of genes as relative have genes in common Rearing of young relatives offspring |
Intraspecific comp occurs Competing for same resources Damaging- promotes physiological stress effects health greater risk of disease. Increase mortality and decrease fitness Provoke aggression Males fight for mates during breeding season Badly injured die- genes lost in gene pool- group loses 1-2 males needed for protection management and breeding Aggressive encounters stress group |
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Agonistic behaviour Results in reduction of aggressive within members of species Postures vocalisations gestures- threatened another animal- show submissive behaviour |
Trials of strength Weaker- displays submissive behaviour Stronger healthier male wins- controls group and access to mates Fitter male will contribute a higher proportion of his ales to gene pool Highest ranking male alpha Next beta Then gamma |
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Agonistic behaviour Results in reduction of aggressive within members of species Postures vocalisations gestures- threatened another animal- show submissive behaviour |
Trials of strength Weaker- displays submissive behaviour Stronger healthier male wins- controls group and access to mates Fitter male will contribute a higher proportion of his ales to gene pool Highest ranking male alpha Next beta Then gamma |
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Territories Set up by individual breeding pair and group Defined boundaries marked by scent Defended by owners from other species Den or nest site- provides important resources food and water Safe place to court mate and rear young free from interference and aggressive attacks |
Successfully defend- their strength status in population Higher ranked bigger better located compared to lower Makes unable to secure defend territory- unable to attract mate and breed Act as population control and enhance gene pool of population as only stronger individuals able to establish territories and contribute genes to gene pool |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
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Temporal- breed at different times
Habitat- breed in different habitats
Behavioural courtship display is different
Gamatic barrier- eggs and Sperm fail to fuse- doesn't recognize chemical attachment from another species
Structural- shape of male and female reproductive organs are mating pheromones are species specific |
Reproductive isolating mechanisms is a barrier that prevents two organisms from differing species from mating and productive fertile offspring prevents successful interbreeding and gene flow
Preserve uniqueness of gene pools Prevent hybridization- reinforcing separateness of species Adding new genes from another species suited to another environmental =reduction of fitness |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
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Temporal- breed at different times
Habitat- breed in different habitats
Behavioural courtship display is different
Gamatic barrier- eggs and Sperm fail to fuse- doesn't recognize chemical attachment from another species
Structural- shape of male and female reproductive organs are mating pheromones are species specific |
Reproductive isolating mechanisms is a barrier that prevents two organisms from differing species from mating and productive fertile offspring prevents successful interbreeding and gene flow
Preserve uniqueness of gene pools Prevent hybridization- reinforcing separateness of species Adding new genes from another species suited to another environmental =reduction of fitness |
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Gradualism vs punctuated equilibrium Graduation evolutionary change that occurs at a relatively slow steady rate. Includes transitional forms that have accumulated adaptive characteristics
Punctuated equilibrium Short periods of rapid change interspersed with longer periods of relatively slow change Reasons of rapid change include Invasion of new habitat with niches available Sudden environmental change allows one group to diverge rapidly Evolution of a new characteristic with distinct advantage that allows one group to out compete thus replace another |
Convergent evo Species with similar niches tend to evolve similar adaptations despite having different ancestors
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
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Temporal- breed at different times
Habitat- breed in different habitats
Behavioural courtship display is different
Gamatic barrier- eggs and Sperm fail to fuse- doesn't recognize chemical attachment from another species
Structural- shape of male and female reproductive organs are mating pheromones are species specific |
Reproductive isolating mechanisms is a barrier that prevents two organisms from differing species from mating and productive fertile offspring prevents successful interbreeding and gene flow
Preserve uniqueness of gene pools Prevent hybridization- reinforcing separateness of species Adding new genes from another species suited to another environmental =reduction of fitness |
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Gradualism vs punctuated equilibrium Graduation evolutionary change that occurs at a relatively slow steady rate. Includes transitional forms that have accumulated adaptive characteristics
Punctuated equilibrium Short periods of rapid change interspersed with longer periods of relatively slow change Reasons of rapid change include Invasion of new habitat with niches available Sudden environmental change allows one group to diverge rapidly Evolution of a new characteristic with distinct advantage that allows one group to out compete thus replace another |
Convergent evo Species with similar niches tend to evolve similar adaptations despite having different ancestors
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Divergent evolution Occurs when two of more related groups evolve different adapatations because they occupy different niches |
Stabilizing selection Selection for those individuals with average phenotypes and against those with extreme phenotypes-provides selection pressurs which favour the average population- beneficial suited to environmental conditions
Disruptive is when natural selection provides selection pressures which favour two phenotypic extremes whilist not favouring the average phenotypes |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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|
Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
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Temporal- breed at different times
Habitat- breed in different habitats
Behavioural courtship display is different
Gamatic barrier- eggs and Sperm fail to fuse- doesn't recognize chemical attachment from another species
Structural- shape of male and female reproductive organs are mating pheromones are species specific |
Reproductive isolating mechanisms is a barrier that prevents two organisms from differing species from mating and productive fertile offspring prevents successful interbreeding and gene flow
Preserve uniqueness of gene pools Prevent hybridization- reinforcing separateness of species Adding new genes from another species suited to another environmental =reduction of fitness |
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Gradualism vs punctuated equilibrium Graduation evolutionary change that occurs at a relatively slow steady rate. Includes transitional forms that have accumulated adaptive characteristics
Punctuated equilibrium Short periods of rapid change interspersed with longer periods of relatively slow change Reasons of rapid change include Invasion of new habitat with niches available Sudden environmental change allows one group to diverge rapidly Evolution of a new characteristic with distinct advantage that allows one group to out compete thus replace another |
Convergent evo Species with similar niches tend to evolve similar adaptations despite having different ancestors
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Divergent evolution Occurs when two of more related groups evolve different adapatations because they occupy different niches |
Stabilizing selection Selection for those individuals with average phenotypes and against those with extreme phenotypes-provides selection pressurs which favour the average population- beneficial suited to environmental conditions
Disruptive is when natural selection provides selection pressures which favour two phenotypic extremes whilist not favouring the average phenotypes |
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Directional Natural selection for one end of the phenotypic range at expense of the other |
Coevolution Describes the reciprocal evolutionary effect that two interacting species can have on each other. Species act as a natural selective influence on the other |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
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Temporal- breed at different times
Habitat- breed in different habitats
Behavioural courtship display is different
Gamatic barrier- eggs and Sperm fail to fuse- doesn't recognize chemical attachment from another species
Structural- shape of male and female reproductive organs are mating pheromones are species specific |
Reproductive isolating mechanisms is a barrier that prevents two organisms from differing species from mating and productive fertile offspring prevents successful interbreeding and gene flow
Preserve uniqueness of gene pools Prevent hybridization- reinforcing separateness of species Adding new genes from another species suited to another environmental =reduction of fitness |
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|
Gradualism vs punctuated equilibrium Graduation evolutionary change that occurs at a relatively slow steady rate. Includes transitional forms that have accumulated adaptive characteristics
Punctuated equilibrium Short periods of rapid change interspersed with longer periods of relatively slow change Reasons of rapid change include Invasion of new habitat with niches available Sudden environmental change allows one group to diverge rapidly Evolution of a new characteristic with distinct advantage that allows one group to out compete thus replace another |
Convergent evo Species with similar niches tend to evolve similar adaptations despite having different ancestors
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Divergent evolution Occurs when two of more related groups evolve different adapatations because they occupy different niches |
Stabilizing selection Selection for those individuals with average phenotypes and against those with extreme phenotypes-provides selection pressurs which favour the average population- beneficial suited to environmental conditions
Disruptive is when natural selection provides selection pressures which favour two phenotypic extremes whilist not favouring the average phenotypes |
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Directional Natural selection for one end of the phenotypic range at expense of the other |
Coevolution Describes the reciprocal evolutionary effect that two interacting species can have on each other. Species act as a natural selective influence on the other |
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Convergent evolution Unrelated ancestors become more similar as they become adapted to similar conditions of have similar adaptations |
Parallel evolution Unrelated ancestors evolve in the same way for the same reason |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
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|
Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
|
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|
Temporal- breed at different times
Habitat- breed in different habitats
Behavioural courtship display is different
Gamatic barrier- eggs and Sperm fail to fuse- doesn't recognize chemical attachment from another species
Structural- shape of male and female reproductive organs are mating pheromones are species specific |
Reproductive isolating mechanisms is a barrier that prevents two organisms from differing species from mating and productive fertile offspring prevents successful interbreeding and gene flow
Preserve uniqueness of gene pools Prevent hybridization- reinforcing separateness of species Adding new genes from another species suited to another environmental =reduction of fitness |
|
|
|
Gradualism vs punctuated equilibrium Graduation evolutionary change that occurs at a relatively slow steady rate. Includes transitional forms that have accumulated adaptive characteristics
Punctuated equilibrium Short periods of rapid change interspersed with longer periods of relatively slow change Reasons of rapid change include Invasion of new habitat with niches available Sudden environmental change allows one group to diverge rapidly Evolution of a new characteristic with distinct advantage that allows one group to out compete thus replace another |
Convergent evo Species with similar niches tend to evolve similar adaptations despite having different ancestors
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Divergent evolution Occurs when two of more related groups evolve different adapatations because they occupy different niches |
Stabilizing selection Selection for those individuals with average phenotypes and against those with extreme phenotypes-provides selection pressurs which favour the average population- beneficial suited to environmental conditions
Disruptive is when natural selection provides selection pressures which favour two phenotypic extremes whilist not favouring the average phenotypes |
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Directional Natural selection for one end of the phenotypic range at expense of the other |
Coevolution Describes the reciprocal evolutionary effect that two interacting species can have on each other. Species act as a natural selective influence on the other |
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Convergent evolution Unrelated ancestors become more similar as they become adapted to similar conditions of have similar adaptations |
Parallel evolution Unrelated ancestors evolve in the same way for the same reason |
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Divergent evolution Common ancestor and species become more dissimilar as they become adapted to different niches |
Sequential evolution Common ancestor Species separated by time, one evolves into the next |
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Co evolution Is when unrelated ancestors that have a close relationship Each species has an evolutionary effect on the other |
Genetic drift is the chance that changes in gene frequencies - some genes become more or less common because individuals that carry them produce more offspring as a result oh change rather than adaptive advantage |
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Natural selection- Is where the best suited individuals have a chance of reproductive success- survival of species is promoted
Individuals with more suited/better adapted phenotypes will compete with less suited and more likely to reproduce passing on favourable alleles Alleles will increase in frequency within population |
Speciation is the process of forming new biological species. Speciation involves the loss of ability to interbreed to produce fertile offspring |
|
|
|
Sympatric speciation is the process which new species are formed from one common ancestor while in the same geographic region
Does not require large geographical distance to reduce gene flow in population
Variation of phenotype is due to the non-random mating and selection presages of comp
Species don't interbreed due to difference in niches |
Allopatric- speciation occurs in different geographic areas- gene flow prevented by islands glaciers etc Isolated populations subject to differing natural selection pressures Accumulated difference in two gene pools result in reproductive isolation persisting even if two population become sympatric |
|
|
|
Temporal- breed at different times
Habitat- breed in different habitats
Behavioural courtship display is different
Gamatic barrier- eggs and Sperm fail to fuse- doesn't recognize chemical attachment from another species
Structural- shape of male and female reproductive organs are mating pheromones are species specific |
Reproductive isolating mechanisms is a barrier that prevents two organisms from differing species from mating and productive fertile offspring prevents successful interbreeding and gene flow
Preserve uniqueness of gene pools Prevent hybridization- reinforcing separateness of species Adding new genes from another species suited to another environmental =reduction of fitness |
|
|
|
Gradualism vs punctuated equilibrium Graduation evolutionary change that occurs at a relatively slow steady rate. Includes transitional forms that have accumulated adaptive characteristics
Punctuated equilibrium Short periods of rapid change interspersed with longer periods of relatively slow change Reasons of rapid change include Invasion of new habitat with niches available Sudden environmental change allows one group to diverge rapidly Evolution of a new characteristic with distinct advantage that allows one group to out compete thus replace another |
Convergent evo Species with similar niches tend to evolve similar adaptations despite having different ancestors
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Divergent evolution Occurs when two of more related groups evolve different adapatations because they occupy different niches |
Stabilizing selection Selection for those individuals with average phenotypes and against those with extreme phenotypes-provides selection pressurs which favour the average population- beneficial suited to environmental conditions
Disruptive is when natural selection provides selection pressures which favour two phenotypic extremes whilist not favouring the average phenotypes |
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Directional Natural selection for one end of the phenotypic range at expense of the other |
Coevolution Describes the reciprocal evolutionary effect that two interacting species can have on each other. Species act as a natural selective influence on the other |
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Convergent evolution Unrelated ancestors become more similar as they become adapted to similar conditions of have similar adaptations |
Parallel evolution Unrelated ancestors evolve in the same way for the same reason |
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Divergent evolution Common ancestor and species become more dissimilar as they become adapted to different niches |
Sequential evolution Common ancestor Species separated by time, one evolves into the next |
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Co evolution Is when unrelated ancestors that have a close relationship Each species has an evolutionary effect on the other |
Genetic drift is the chance that changes in gene frequencies - some genes become more or less common because individuals that carry them produce more offspring as a result oh change rather than adaptive advantage |
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Founder effect Occurs when small number of individuals establishes new population. Gene pool will reflect genotype of founder individuals Genetic variation is reduced but otherwise rare genes may be common simply because they were carried by founders |
Bottleneck effect When a population becomes small and then expands New gene pool will reflect genotype of individuals at the bottleneck Important consideration for endangered species |
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Polyploidy Polyploids possess 3 or more sets of homologous chromosomes Polyploids show increase vigour pest and disease resistance and can cope with extreme environment
Autopolyploidy All sets of chromosomes are from same ancestral species |
Allopolyploidy Sets of chromosomes originate from 2 or more ancestral species New species arose from an otherwise sterile hybrid
Amphiploidy Doubling of chromosome number that occurs at first mitosis after fetilization Sterile 2n hybrid between two species becomes fertile 4n allopolyploid |
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