What do the following represent in a given graph? Describe one evidence that decisively prove that birds have evolved from reptiles?a. If operation of natural selection makes peak higher and narrower.b. If peak shifts to right directionc. If two peaks are formed instead.OR By taking industrial melanism as an example, explain the concept of natural selection by evolution. What is the role of variation in evolution?
Answers
Missing link between birds & reptiles called. Archaeopteryx showed that “Birds have evolved from reptiles”. These are organisms which show the characters of both birds (e.g. presence of wings & feathers in the body) as well as of reptiles (e.g.gong tail & jaws with identical teeth).
Theory of natural selection states that due to survival of fittest, the species change readily owing to preservation & transmission of minute variation & gradually give rise to new forms.
In a collection of moths in 1850 before the advent of industrialization, it was observed that there were more white winged moths on trees than dark winged one or melanised moths. However, in 1920, the population of dark winged ones increased and white winged ones reduced.
The explanation put forth for this observation was that predators could spot a moth against a contrasting background. During post industrialization period, the tree trunks became dark due to industrial smoke and soot. Under this condition, white moths did not survive due to predators but dark winged or melanised moths survived.
Before industrialization, white coloured lichens grew thickly and covered the trees. In that background, the white winged moths survived but dark ones were picked up by the predators. Hence, moths that were able to camouflage in both the backgrounds were able to survive. No variant was wiped out completely.
Answer:
Missing link between birds & reptiles called. Archaeopteryx showed that “Birds have evolved from reptiles”. These are organisms which show the characters of both birds (e.g. presence of wings & feathers in the body) as well as of reptiles (e.g.gong tail & jaws with identical teeth).
Theory of natural selection states that due to survival of fittest, the species change readily owing to preservation & transmission of minute variation & gradually give rise to new forms.
In a collection of moths in 1850 before the advent of industrialization, it was observed that there were more white winged moths on trees than dark winged one or melanised moths. However, in 1920, the population of dark winged ones increased and white winged ones reduced.
The explanation put forth for this observation was that predators could spot a moth against a contrasting background. During post industrialization period, the tree trunks became dark due to industrial smoke and soot. Under this condition, white moths did not survive due to predators but dark winged or melanised moths survived.
Before industrialization, white coloured lichens grew thickly and covered the trees. In that background, the white winged moths survived but dark ones were picked up by the predators. Hence, moths that were able to camouflage in both the backgrounds were able to survive. No variant was wiped out completely.