Mod 3 Flashcards
species
largest group of organisms in which any two individual organisms of the opposite sex are able to interbreed and produce fertile offspring
genetic drift
random fluctuations in allele frequencies in a population
speciation
population considered to be two distinct species
genetic variation
produces phenotype variation (physical characteristics)
Provide an example of genetic variation:
peppered moths and white moths
gene flow
created by migration of species as genetic variants enter and leave population leading to decrease in genetic variation between populations because genetic material is exchanged
natural selection
a process which acts of populations to maintain favourable traits and eliminate unfavourable traits
gene pool
total genetic material in a population
What does a change within the gene pool suggest?
evolution
*allopatric speciation
speciation caused by geographical isolation (barrier)
- preventing gene flow between populations
- causing genetic drift and speciation
What are some examples of geographical barriers/isolators?
mountains, water dams, rocks
Explain what speciation is
Formation of a new species once one population becomes so diverse that they are unable to interbreed and produce a viable and fertile offspring due to factors such as geographical isolation and behavioural and physiological changes
abiotic characteristics are:
the non-living components of the environment
e.g. sunlight/heat and water availability, temperature, soil pH
biotic factors:
living components of an ecosystem
e.g. food availability, mating availability, predation
use an example to explain the Olympic Village Effect
- The cane toads that were more athletic gained more food which aided them in producing more fertile offspring
- These athletics toads breed with each other and this is called the Olympic Village effect as they produce offspring with the favourable trait of speed (longer legs, more active)
changes in a population of organisms due to selection pressures over time
- The cane toads in Australia are a “selective pressure”
- arrival of cane toads removed some genetic traits from the predator population
e.g. red-bellied blacksnakes. evolved into having smaller heads to prevent themselves from preying on big and more dangerous toads.
what are structural adaptations
an organism’s internal and external anatomy
e.g. certain features, relative size
- eucalyptus and banksia and thick waxy cuticle
- large ears -> release more heat
what are physiological adaptations
biochemical and internal processes carried out by an organism
- plants produce chemicals that are toxic to make them bitter or poisonous
- spinifex hopping mouse -> absorb water from their urine back into bloodstream
behavioural adaptation
organisms perform in response to a stimulus
e.g. venus flytrap -> react quickly to insect to absorb nitrogen nutrients from insect
- bird song to attract mating partners or warn predators
Describe Darwin’s observations of the Galapagos Finches and discuss how these observations may have contributed to his theory of evolution
- single group of finches from the mainland arrived, blown off course during migration
- finches spread to different islands, all of which had different environments
- exerted different selection pressures on the finches, meaning that different traits, such as beak length, were favoured on different islands
- speciation occurred i.e. the finches on the different islands became different enough from one another to be considered different species
- This process- a single species forming several as they evolve to fit empty ecological niches is called adaptive radiation
therefore the finches had evolved with different characteristics
What does natural selection state
- there is genetic variation within a population of species
- with environmental change, different traits are favoured
- favourable traits - survive
- favourable trait becomes more prevalent in the population
- survival of the fittest -> favourable trait population have more resources
therefore natural selection driven by mutation
What is the bottleneck effect
- when an initially large population is suddenly reduced in numbers such as by natural disaste
- reduced size of population increases inbreeding and reduces variation within gene pool
what is the founder effect
- when a small group of individuals move away from larger population
- increased interbreeding
- decreased allele frequencies
- small gene pool DOES NOT represent original gene pool
what does speciation often depend on?
reducing or stopping gene flow
What is the gradualism theory for evolution
proposes that speciation occurs relatively constant pace over time (linear line)
what is the punctuated equilibrium theory for evolution
- selection pressures remain constant, so that species are adapted to their environment -> species are undergoing little or no change, are at equilibrium
- sudden change in the environment (selection pressure) leads to rapid change in a population - new favourable traits
what are analogous structures
have the same function but no structural similarity
e.g. dolphin has skeleton and shark has cartilage
divergent evolution
closely related species become more and more dissimilar
e.g. Darwin’s finches
- diversify into species due to different selection pressures by enivronments
coevolution
two species evolve in response to changes in each other
e.g. flower and bee
microevolution
change in allele frequency within single species or population
- due to: natural selection, sexual selection, genetic drift and gene flow
Macroevolution
accumulation of microevolutionary changes that lead to speciation
biochemical evidence
the amino acid sequence of proteins
- cytochrome c and histones provide evidence for evolution due to being highly conserved
- inherited from common ancestor
pentadactyl limb
limb with five digits - homologous structures between many animals
analogous structures
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vestigial structurees
important function for an ancestor but not in the modern organism
e.g. tail bone, whales hip bone
comparative embryology
- comparing species in the utero, similarities can be observed
- indicates common ancestry and evidence of evolution
biogeography
how and why organisms live where they do. used to study isolation or migration
isolation
when a species is separated
migration
when members of a species move
what are fossils
remains of long-dead organism
e.g. trace fossil or impression fossils, petrification (conversation of organic materials to minerals)
relative dating
- law of superposition - cross section of sedimentary rock. older strata is below, young strata is above
- only indicates order of geological events
absolute dating
to know age of materials found
vertical gene transfer
new generations inherit the gene from parent cell through random mutation
horizontal gene transfer
resistance genes are transferred directly between bacteria
antibiotic resistance in terms of evolution by natural selection
- variation within population of species
- environmental changes
- favourable trait becomes prevalent
ecological niche
role of species in an ecosystem e.g. resources consumed, habitat occupied, interactions
competitive exclusion principle
only one species may occupy particular niche
carrying capacity
birth equal death - equilibrium
factors that affect abundance of predator prey distribution
- reproduction rate
- death rate
- prey’s food availability
- ecosystem size
