Essential idea: There is overwhelming evidence for the evolution of life on Earth. By Chris Paine https ://bioknowledgy.weebly.com/ http://images.nationalgeographic.com/wpf/media- live/photos/000/009/custom/993_1280x1024-wallpaper-cb1425504376.jpg This image of a fossilised primitive vascular plant called a horsetail. Fossils are just one example of evidence for evolution along with homologous structures, the universality of DNA, and antibiotic resistance. 5.1 Evidence for evolution
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Essential idea: There is overwhelming evidence for the evolution of life on Earth.
This image of a fossilised primitive vascular plant called a horsetail. Fossils are just one example of evidence for evolution along with homologous structures, the universality of DNA, and antibiotic resistance.
5.1.U2 The fossil record provides evidence for evolution.
The fossil record is the sum of all discovered and undiscovered fossils and their relative placement in rock.
The fossil record provides the dimension of time to the study of evolution – the layer of rock in which a fossil is found can be dated and therefore used to deduce the age of the fossil.
5.1.U2 The fossil record provides evidence for evolution.
The fossil record is the sum of all discovered and undiscovered fossils and their relative placement in rock.
The fossil record provides the dimension of time to the study of evolution – the layer of rock in which a fossil is found can be dated and therefore used to deduce the age of the fossil.
5.1.U2 The fossil record provides evidence for evolution.
Transitional fossils show the links between groups or species by exhibits traits common to both the ancestral group/species and its derived descendant group/species.
Archaeopteryx is a famous example transitional fossils – it gives evidence for the evolution of birds from dinosaurs.
5.1.U4 Evolution of homologous structures by adaptive radiation explains similarities in structure
when there are differences in function.
comparative anatomy of groups of animals or plants shows certain structural features are basically similar. Structures or anatomical features having similar basic structure as in other species said to be homologous.
homologous structures are those that are similar in shape in different types of organisms
The structural similarities imply a common ancestry
homologous structures used in different ways in different species
This illustrates adaptive radiation since the basic structure adapted to different niches
The more exclusive the shared homologies the closer two organisms are related.
NoS: Despite the obvious differences all the organisms share the same bones. For example the bones may vary in size and shape, but all vertebrates have five fingered ‘hands’ at the end of each limb.
If populations, e.g. fruit flies, become separated (e.g. a population is blown by a storm to a distant island). Then it is very likely the population will experience different ecological conditions.
Over many generations the shape of the flies, food preference, mating rituals etc. will likely diverge as the result of natural selection.
If the island fruit flies migrate back to the mainland they will not easily mate with the mainland flies as:• Mating rituals are
different• Because of genetic
differences the resulting offspring are infertile
Because genes cannot flow between the populations the island fruit flies are said to have evolved into separate
species (this process is called speciation).
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n.b. islands often have many endemic (unique to that island) species due to the fact that island environments can easily cause species to become separated.
Populations will gradually diverge over time and it is natural to see continuous variation across a geographical range.
It is a common problem in classification to determine when two populations of one species to have sufficiently diverged to become two separate species.
The Red Grouse and the Willow Ptarmigan where at one time classified as two separate species. The current scientific consensus is that they are both members of the same species (Lagopus lagopus)
The greater the geographical separation and the longer the populations have been separated the greater the divergence.
Variation: Peppered moths (Biston betularia) moths are found in two forms:
Normal environment: In unpolluted areas tree branches are covered in pale colouredlichens camouflage for the paler form (insularia).
The dark form (carbonaria) is normally very rare.
The moths fly at night to try to find a mate, but, during the day they rest on the branches of trees.
Selective pressure: Predation from birds (and other animals) whilst resting
Environmental change: sulphur dioxide pollution kills the lichens and soot (from coal burning) blackens the tree branches.
Result: the dark moths are well camouflaged from birds against dark tree branches are many survive to reproduce, but light coloured moths are easily found and predated by birds, few survive to reproduce.
Evolution: over a number of generations the dark (carbonaria) form of the peppered moth has increased with frequency - the heritable characteristics of the population have changed.
Variation: Peppered moths (Biston betularia) moths are found in two forms:
Normal environment: In unpolluted areas tree branches are covered in pale colouredlichens camouflage for the paler form (insularia).
The dark form (carbonaria) is normally very rare.
The moths fly at night to try to find a mate, but, during the day they rest on the branches of trees.
Selective pressure: Predation from birds (and other animals) whilst resting
Environmental change: sulphur dioxide pollution kills the lichens and soot (from coal burning) blackens the tree branches.
Result: the dark moths are well camouflaged from birds against dark tree branches are many survive to reproduce, but light coloured moths are easily found and predated by birds, few survive to reproduce.
Evolution: over a number of generations the dark (carbonaria) form of the peppered moth has increased with frequency - the heritable characteristics of the population have changed.
Variation: Peppered moths (Biston betularia) moths are found in two forms:
Normal environment: In unpolluted areas tree branches are covered in pale colouredlichens camouflage for the paler form (insularia).
The dark form (carbonaria) is normally very rare.
The moths fly at night to try to find a mate, but, during the day they rest on the branches of trees.
Selective pressure: Predation from birds (and other animals) whilst resting
Environmental change: sulphur dioxide pollution kills the lichens and soot (from coal burning) blackens the tree branches.
Result: the dark moths are well camouflaged from birds against dark tree branches are many survive to reproduce, but light coloured moths are easily found and predated by birds, few survive to reproduce.
Evolution: over a number of generations the dark (carbonaria) form of the peppered moth has increased with frequency - the heritable characteristics of the population have changed.