Evolutionary Systematics

Question 1

Briefly explain the development of the Earth.

Answer 1

Earth is about 4.6 billion years old. At first, the Earth was glowing and liquid due to radioactive processes. The subsequent cooling allowed the formation of a crust and an atmosphere. Once the lower part of the ancient atmosphere cooled down below 100 degrees, water vapour could condensate, liquid water was formed and the ancient oceans arose.

Question 2

What did the ancient atmosphere mainly consisted of?

Answer 2

Water vapour (H2O)
Carbon dioxide (CO2)
Methane (CH4)
Ammonia (NH3)
Hydrogen sulphide (H2S)
Nitrogen (N2)
Hydrogen (H2)

Question 3

What are the two hypotheses concerning the first organic molecules on Earth?

Answer 3

Once the liquid water was present on Earth, organic compounds could be formed from inorganic materials. All living matter is organic, as are the building blocks of life, such as sugars (carbohydrates) and amino acids (proteins). There are two general hypotheses about the way life-supporting molecules appeared on early Earth:

Miller-Urey experiment: In 1953, Stanley Miller and Harold Urey designed an experiment to demonstrate that organic compounds could be made by passing an electrical current, to simulate lightning, through a mixture of gases. This experiment produced a variety of organic compounds, such as amino acids.

Meteorite hypothesis: Analysis of a meteorite that fell near Murchison, Australia, in 1969 revealed that organic molecules can be found in space. This evidence suggests that amino acids could have been present when Earth formed, or that these organic molecules may have arrived on Earth through meteorite or asteroid impacts.

Question 4

What can we say about the evolution of life on Earth?

Answer 4

All existing animals are the product of long phylogenetic history. Every living cell has its origin from the last universal common ancestor (LUCA), which lived about 3.6 billion years ago. Due to many diversifying changes of traits, we now have all these species on our planet. To get a better overview, we can divide this long history into four big eras: Proterozoic, Paleozoic, Mesozoic and Cenozoic.

Question 5

How is the phylogenetic tree of life constructed?

Answer 5

Today we can divide life into three big groups: Bacteria, Archaea and Eucarya. Species within these groups all share similarities since they emerge from a common ancestor.

Question 6

Which are the five kingdoms of life?

Answer 6

The five kingdoms of life are Monerans, Protista, Plants, Fungi and Animals.

Question 7

What was Carl Linnaeus famous for?

Answer 7

Carl Linnaeus is the father of taxonomy. He tried to group species by looking at anatomical and physiological traits which were similar. Linnaeus also introduced the binary nomenclature which is still used today.

Question 8

What are the two most important mechanisms concerning the evolution theory of Lamarck?

Answer 8

1. Use and Disuse: Body parts which are heavily used become bigger and stronger and parts which are not used will stunt.
2. Inheritance of acquired traits: The acquired traits which are gained through life will be inherited to the next generation.

Question 9

What are the most important observations concerning the evolution theory of Darwin?

Answer 9

1. Species produce more offspring than necessary to just preserve the species. Nevertheless, population size stays constant over time.
2. The habitat of the species has limited resources.
3. The individuals of one species are not identical, there are small differences between them which make them unique.

Question 10

What are the main differences between the theory of Lamarck and Darwin?

Answer 10

Lamarckism:

1. This theory states that there is an internal vital force in all organisms.
2. It considers that new needs or desire produce new structures and change habits of the organism.
3. According to this theory if an organ is constantly used it would be better developed whereas disuse of organ results in its degeneration.
4. It does not consider struggle for existence.
5. All the acquired characters are inherited to the next generation.
6. Lamarckism does not believe in survival of the fittest.

Darwinism:

1. This theory does not believe in the internal vital force.
2. It contends that needs and/ or desires do not form part of Darwin’s natural selection theory.
3. An organ can develop further or degenerate only due to continuous variations.
4. Struggle for existence is very important in this theory.
5. Only useful variations are transferred to the next generation.
6. Darwin’s natural selection theory is based on survival of the fittest.