Evolution Test - 2

Germplasm theory was proposed by Weismann (1885). According to which only germplasm goes to next generation whereas the somatoplasm dies with each generation and does not influence the germplasm.

• The cleidoic egg is the type of egg which reptiles and birds lay.
• Cleidoic egg is sometimes called the amniotic egg, because it is characteristic of amniotes.

In Triassic period of Mesozoic era, the primitive amphibians became extinct some of the reptilian groups returned to sea-life and some invaded air. Another important event, which took place late in Triassic period, was the first appearance of mammals, which retained egg-laying habit.

Charles Darwin (1809-1882) was an English naturalist. In 183, Darwin got an opportunity to travel on H.H.S. Beagle (a ship in which Charles Darwin sailed around the world) for a voyage of world exploration. 
Alfred Russel Wallace (1823-1913), another English naturalist, also travelled widely and studied the fauna and flora of South America and South East Asia. Evolutionary ideas similar to those of Darwin developed in Wallace in respect of organic evolution was similar. In 1959, Wallace's paper and summary of Darwin theory together appeared in the Journal of the proceeding of Linnean Society. Finally in 1857, Darwin published his observations and conclusions under the name "Origin of species by Natural Selection".

According to Darwin's concept of natural selection, the organisms, which are provided with favourable variations, would survive because they are fittest to face their surroundings, while the organisms which are unfit for surrounding variations, are destroyed. Prevalence of pesticide resistance insects is due to the adaptability of these insects for the changes in environment (due to the use of pesticides).

Lederberg's replica planting experiment explains mutational theory.

Fixity of species is a term, which means all species remain unchanged throughout the history of earth and it is related to the theory of creationism. Lamarck in 1809 was the first to discard the idea of creationism and fixity of species as he stated that organisms can transmit the acquired characters to the offspring.

Ontogeny recapitulates phylogeny means that during the embryonic development of any organism, its complete evolutionary history is repeated.