Construct a phylogenetic tree covering all four eras (with labeled years) includ
ID: 174512 • Letter: C
Question
Construct a phylogenetic tree covering all four eras (with labeled years) including the evolution of bacteria, protozoan, protists, plants and animals. There needs to be significant evolutionary events for each. Use correct taxonomic names and not common names. Construct a phylogenetic tree covering all four eras (with labeled years) including the evolution of bacteria, protozoan, protists, plants and animals. There needs to be significant evolutionary events for each. Use correct taxonomic names and not common names.Explanation / Answer
It is not possible for anyone to study all the organisms. But if they are grouped in some convenient way the study would become easier as the characters of a particular group or a family would apply to all the individuals of that group. Classification allows us to understand diversity better.
History of Classification In the 3rd and 4th century BC Aristotle and others categorized organisms into plants and animals. They even identified a few thousands or more of living organisms. Hippocrates (460-377 BC), the Father of Medicine listed organisms with medicinal value. Aristotle and his student Theophrastus (370-282 BC) made.
the first attempt to classify organisms without stressing their medicinal value. They tried to classify the plants and animals on the basis of their form and habitat. It was followed by Pliny the Elder (23-79 AD) who introduced the first artificial system of classification in his book ‘Historia Naturalis’. John Ray an English naturalist introduced the term species for the first time for any kind of living things. It was then Carolus Linnaeus the Swedish naturalist of 18th century now known as Father of Taxonomy developed the Binomial System of nomenclature which is the current scientific system of naming the species. In his famous book ‘Species Plantarum’(1753) he described 5,900 species of plants and in “systema Naturae’(1758) he described 4200 species of animals.
Taxonomy and Phylogeny
Taxonomy is the branch of biology that deals with identification and nomenclature (naming) of living organisms and their classification on the basis of their similarities and differences. It was the Swiss-French botanist
AugustinPyramus de Candolle(1778-1841) who coined the word Taxonomy, the science of naming and classifying of organisms.
Species is the basic unit of Classification. It is defined as the group of individuals which resemble in their morphological and reproductive characters and interbreed among themselves and produce fertile offsprings.
Phylogeny The evolutionary history of a particular taxon like species is called phylogeny. The classification based on the basis of evolution is called phylogenetic classification. Phylogenetic classification is not always possible since there are 3 several gaps in the fossil records which form the basis of phylogenetic studies and also evolution is never unidirectional. Classification not explicitly based on evolutionary relationships is called artificial, for example, organisms are grouped according to usefulness (economic plants) size (herbs, shrubs) colour (flowers) ecological role (ground cover) and so-forth. Nevertheless many biologists make use of this non-systematic classification.
The Five Kingdom System of Classification
In order to suggest a better system of classification of living organisms, R.H. Whittaker (1969) an American Taxonomist divided all the organisms into 5 kingdoms based on their phylogenetic relationships. This classification takes into account the following important criteria. 1. Complexity of Cell structure – prokaryote to Eukaryote 2. Mode of nutrition – autotrophs and heterotrophs 3. Body organization -unicellular or multi-cellular 4. Phylogenetic or evolutionary relationship The Five kingdoms are Monera, Protista, Fungi, Plantae and Animalia..
Monera
The Kingdom of Prokaryotes This kingdom includes all prokaryotic organisms i.e. mycoplasma, bacteria, actinomycetes(filamentous bacteria) and cyanobacteria (blue green Algae). They show the following characters.
Kingdom Protista
This kingdom includes eukaryotic unicellular mostly aquatic cells. They show the following characters.
Kingdom Fungi
This kingdom includes moulds, mushrooms, toad stools, puffballs and bracket fungi. They have eukaryotic cell organization. They show the following characteristic.
1. They are either unicellular or multi-cellular organisms.
2. Their mode of nutrition is heterotrophic since they lack the green pigment chlorophyll. Some fungi like Puccinia are parasites while others like Rhizopus are saprotrophic and feed on dead organic matter.
3. Their body is made up of numerous filamentous structures called hyphae. 4. Their cell wall is made up of chitin.
Kingdom Plantae
It includes all multi-cellular plants of land and water. Major groups of Algae, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms belong to this kingdom. It shows the following characteristics.
1. The cells have a rigid cell wall made up of cellulose.
2. They show various modes of nutrition. Most of them are autotrophs since they have chlorophyll. Some plants are heterotrophs. For eg. Cuscuta is a parasite. Nepenthes and Drosera are insectivorous plants.
Kingdom Animalia
This kingdom includes all multi-cellular eukaryotic organisms. They are also referred to as metazoans. They show the following characteristic features.
1. All animals show heterotrophic mode of nutrition. They form the consumers of an ecosystem.
2. They have contractibility of the muscle cells.
3. They can transmit impulses due to the presence of nerve cells.
4. Some groups of animals are parasites eg. tapeworms and roundworms
Merits of the Five Kindom Classification
1. It shows the phylogenetic relationships among the organisms.
2. It is based on the complexity of the cell structure from prokaryotic to eukaryotic cell organization.
3. It is based on the complexity of body organization from unicellular to multicellular.
4. It is based on the modes of nutrition: autotrophic or heterotrophic mode of nutrition.
Demerits of Five Kingdom Classification
1. Chlamydomonas and Chlorella are included under the kingdom Plantae. They should have been included under kingdom Protista since they are unicellular.