A4.1 Flashcards
What is evolution
Evolution is defined as the process of cumulative change in the heritable characteristics of a population
what is cumulative change
a gradual accumulation of small changes
what are heritable characteristic
features which can be inherited (caused by genes, passing from one generation to the next, so it takes a long time to happen) (think about life span of different organisms; life span of bacteria vs cats and dogs vs human beings)
level of organisation
species –> population –> community –> ecosystem –> biome –> biosphere
what is species (Not define)
Species is the basic unit of classification and a taxonomic rank
define species
A species is a group of organisms that can potentially interbreed to produce fertile, viable offspring
what are fertile offsprings
Those which can in turn interbreed and pass on their genes to another generation.
define population
A population is a group of organisms of the same species that are living in the same area at the same time
define community
A group of populations living together and interacting with each other within a given area
define habitat
The environment in which a species normally lives, or the location of a living organism
define ecosystem
A community and its abiotic environment (i.e. habitat)
what are abiotic factors
Non-living factors, such as pH, salinity, wind speed, type of soil, etc.
what are biotic factors
Living factors in an ecosystem, such as the plants and animals.
define biome
A collection of ecosystems sharing similar climatic conditions
define biosphere
That part of the Earth inhabited by organisms
can members from one species reproduce with another species?
Members of a single species are unable to produce fertile, viable offspring with members from a different species
What happens when two different species interbreed?
When two different species do produce offspring by cross-breeding, these hybrids are reproductively sterile (e.g. liger, mule)
What is ecology?
The study of the relationship between living organisms, or between living organisms and their environment
What are the 3 ways organisms can obtain chemical energy?
autotrophs
heterotrophs
mixotrophs
biochemical evidence for evolution
Evidence for evolution from base sequence in DNA or RNA and amino acid sequences in proteins
sequence data
Sequence data gives powerful evidence of common ancestry
selective breeding for evolution
Evidence for evolution from selective breeding of domestic animals and crop plants
how is selective breeding an evidence for evolution
Variation between different domesticated animal breeds and varieties of crop plant, and between them and the original wild species, shows how rapidly evolutionary changes can occur
what is artificial selection
Farmers and breeders choose desirable genetic characteristics to keep and eliminate less desired features from a population
The driving force of this kind of evolution is human choice
Ethical concerns on animal breeding
Animal cruelty and suffering derived from selective breeding animals e.g.: broiler chickens that grow quickly, but too quick that cannot support their own weight. These chickens will have numerous health problems
Breeding small cats and dogs for selective breeding, they may suffer from health problems
Breeders claim they provide clean, safe nutritious food (+ vaccination) for the animals to make sure they stay healthy. They also provide affordable food (diary meat) for the public
what are homologous structures
structures found in different organisms that were derived from the same ancestral feature/evolutionary origin and they do not necessary serve the same function
what are analogous structures
structures found in different organisms that serve similar functions but not derived from the same ancestral feature
what did Darwin find about homologous structures
Darwin found a lot of homologous structures (occupy similar positions in organisms) in seemingly dissimilar species - evidence of organisms evolved from a common ancestor
examples of homologous structures
Pentadactyl limbs
‘penta’ means five and ‘dactyl’ refers to fingers
Mammals, birds, amphibians and reptiles all share a similar arrangement of bones in their appendages based on a five-digit limb
what are the differences between pentadactyl limbs of humans, birds, bats, horses, whales and dolphins
Human hands are adapted for tool manipulation (power vs precision grip)
Bird and bat wings are adapted for flying
Horse hooves are adapted for galloping
Whale and dolphin fins are adapted for swimming
analogous structures examples
wings in birds and chicken, fins in fish and dolphin flippers, legs in insects and legs in horse
convergent evolution features
Evolved from different ancestor
Converge to produce analogous structures
Species appearance becomes more similar over time
Examples:
Wings of the birds, bats and insects
Fins of the fish and dolphin flippers
divergent evolution features
Evolved from common ancestor
Diverge to produce homologous structures
Species appearance becomes more different over time
Examples:
Pentadactyl limb structures in vertebrates
what is speciation
Speciation is an evolutionary process that results in the formation of a new species from a pre-existing species
It occurs when reproductive isolating mechanisms prevent two breeding organisms from producing fertile, viable offspring
speciation vs extinction
speciation increases the total number of species on Earth, and extinction decreases it
is gradual evolutionary change in a species speciation
no
Speciation example: iguanas
Speciation by divergence of isolated population
Some iguanas got isolated on the galapagos islands and they adapted to the environment and became the only marine iguanas that can dive into the ocean to find algae for food
what is reproductive isolation
Members of the same species can be prevented from reproducing because there is an insurmountable barrier between them.
Eventually, the populations will change so much that the individuals from the two separate populations will not be able to reproduce with each other successfully to produce fertile offsprings.
types of reproductive isolation
temporal, geographical, behavioural
what is geographical isolation
Geographic isolation occurs when two populations occupy different habitats or separate niches within a common region
example of geographical isolation
Plants of the same species got spread to different parts of the world and adapted to different soil pH. Those plants will not be able to grow close to each other to breed.
bonobos Pan paniscus and common chimpanzees Pan troglodytes by the Congo RIver
what is pan
what genus it is
what are paniscus/troglodytes
what species they are
what is temporal isolation
Temporal isolation occurs when two populations differ in their periods of activity or reproductive cycles
example of temporal isolation
Leopard frogs and wood frogs reach sexual maturity at different times in the spring and hence cannot interbreed
what is behavioural isolation
Behavioural isolation occurs when two populations exhibit different specific courtship patterns
example of behavioural isolation
Certain populations of crickets may be morphologically identical but only respond to specific mating songs
Allopatric speciation
Groups from an ancestral population evolve into separate species due to a period of geographical separation
The two populations begin to evolve separately as a result of cumulative mutation, genetic drift and natural selection
Eventually the two populations reach a degree of genetic divergence whereby they can no longer interbreed (speciation)
sympatric speciation
Groups from the same ancestral population evolve into separate species without any geographical separation
Sympatric speciation may result from the reproductive isolation of two populations as a result of genetic abnormalities
Typically, a chromosomal error may arise which prevents successful reproduction with any organism lacking the same error
what prevents hybridization in animals
Courtship behaviour often prevents hybridization in animal species. A mule is an example of a sterile hybrid
examples of hybrids
liger
mule
zorse
what are courtship behaviours
Courtship behaviours are behaviours aimed to facilitate attraction and mating with the opposite sex
allele
alternate forms of the same gene
Allopolyploid speciation
Allopolyploidy is a kind of polyploidy
Caused by fusion of gametes of different species
Increases the chance of survival in plants
Advantages of polyploidy in plants
Hybrid plants formed by cross breeding same genus but different species allow the offspring to be fertile
New species can be generated and they may be able to adapt to the environment very quickly and more easily with more chances of getting genetic variations (weed are well adapted to different environments)
This does not need to wait for a long time to generate a new species, it can be done right at the moment of fusing of gametes (abrupt speciation)
Adaptive radiation
Adaption radiation occurs when many similar but distinct species evolve relatively rapidly from a single species or form a small amount of species.
This happens because variation within a population allows certain members of that population to occupy different niches.
E.g. Lemus found in Madagascar, Hawaiian honeycreepers in Galapagos island
- Occupy different niche and habitat e.g. ground, trees, rainforests, desert
- Diurnal and nocturnal
- Minimize compe&&on
What does adaptive radiation allow
It allows closely related species to coexist without competing, thereby increasing biodiversity in ecosystems where there are vacant niches
Speciation by polyploidy in Allium
Polyploidy is when an error leads to an individual having more than 2 sets of
chromosomes_
- In some plant groups there is a trend for the species to have chromosome numbers that are all multiples of_one basic number_.
- Most Allium species have a diploid number that is a multiple of 16, ancestral. Allium probably had this number.
- Allium species with 32 chromosomes evolved from polyploidy, which an individual with 32 chromosomes is tetraploid (4n).
- If it crosses with a diploid individual, all the offspring are infer&le triploids(3n). - Because of this, a tetraploid is _reproduc&vely isolated_from diploids, is therefore
instant specia&on. - Many plant species have been produced by polyploidy.
