What is meant by evolutionary lineages?

An evolutionary lineage is a series of populations of organisms that descend from a common ancestor. Each species in the lineage is the direct consequence of evolutionary change from a common ancestor. A phylogenetic tree is generally used to display lineages visually. Lineages are components of the phylogenetic tree of life. Molecular systematics procedures are widely used to predict lineages.

The importance of evolutionary lineages

All life on Earth is linked by a single phylogenetic tree, inferring a common ancestor. A lineage eventually stretches back through the diverse taxonomic levels, from species to genus, the genus to family, the family to order, and so on. Trees are helpful in biological fields like bioinformatics, systematics, and phylogenetics.

Lineages are important in evolution and development. They are also important in the methodology of phylogenetic restoration. If philosophers want to characterize the entities related to biological theories and practices, they should look into lineages. Lineages are groups of biological entities that are linked by ancestor-descent relationships.

Lineages are evolutionary units that evolve in the manner of accumulating and manifesting evolutionary changes over time. The way biologists describe other evolutionary processes, such as natural selection, lends credence to the idea of lineages as units of evolution. These processes necessitate reproduction and the transmission of traits. Considerable evolutionary changes occur at different generations of a lineage, implying that lineages are the entities that evolve.

Phylogenetic representation of lineages        

Phylogeny is the scientific term for the evolutionary history and relationships of an organism or group of organisms known as taxa (singular: taxon). Phylogenetic relationships reveal common ancestors but not necessarily how organisms are similar or different. Taxonomic classifications generally represent lineages as subgroups of phylogenetic trees.

A lineage is a single line of descendants or sequential chain of taxons inside the tree, whereas a clade is a monophyletic group that includes only one ancestor and all of its descendants. Phylogenetic trees are generally built using information from deoxyribonucleic acid (DNA), ribonucleic acid (RNA), or protein sequences. Aside from that, structural similarities and differences have been and continue to be included in taxonomic studies to develop phylogenetic trees. Sequences from different people are compiled and analyzed to see how similar they are. Individuals are clustered based on their similarities using mathematical techniques.

A phylogenetic tree approximates the authentic comprehensive evolutionary relationships. For example, in a comprehensive tree of life, the whole clade of organisms can be collapsed into a single branch of the tree. However, this is simply a rendering space limitation. However, this is simply a rendering space limitation. An authentic and complete tree for all biological entities or any DNA sequence could theoretically be constructed.

Major prokaryotic lineages

Mutation and lateral transfer are two mechanisms that contribute to genetic diversity in prokaryotic genomes. Their relative strength varies across lineages, but they are both complementary evolutionary influences rather than self-sufficient, separable forces. Because prokaryotes are single-celled organisms, they lack membrane-bound nuclei and organelles. They are divided into identical copies to constitute lineages, and they become genetically distinct due to two mechanisms: lateral gene transfer (LGT) and mutations. Mutations cause genetic differences in DNA through nucleotide insertion or deletion, replication errors, and a variety of other processes. Within a lineage, such genetic variation is then passed down from progenitor to offspring.

Archaea and bacteria are the two different lineages, or lines of descent, of prokaryotes. Today, these lineages are thought to constitute two of the three domains of life. All eukaryotes, including animals, plants, and fungi, are included in the third domain (eukarya). Bacteria and archaea have split into numerous groups and species since splitting apart millions of years ago.

Open and closed lineages of prokaryotes

Prokaryotic genetic diversity results in two forms of prokaryotic lineages. On the one hand, over generations, some lineages retain more variation due to LGT than mutation. The genetic traits in these lineages do not share a common ancestor, and cell differentiation patterns may not reflect gene transmission patterns. These prokaryotic lineages are referred to as open lineages. On the other hand, several lineages acquire more mutational variations than LGT over generations. Most genes in these lineages share a common ancestor, so the pattern of cell divisions reflects the pattern of genetic transmission. These are known as closed lineages. Open and closed lineages coexist along the branches of any prokaryotic tree.

Major lineages of eukaryotes

Eukaryota is divided into six supergroups that include all protists as well as animals, fungi, and plants that evolved from a single common ancestor. The supergroups are thought to be monophyletic, which means that all organisms within each group have evolved from a single common ancestor. Thus all members are more closely linked to one another than organisms external to the group. Excavata, Rhizaria, Chromalveolata, Amoebozoa, Archaeplastida, and Opisthokonta are the six groups.

• Excavata is comprised of the kingdoms of euglenozoans, diplomonads, and parabasalids.
• Chromalveolata includes the alveolate kingdoms of apicomplexans, ciliates, and dinoflagellates, as well as the stramenopile kingdoms, golden algae, diatoms,  oomycetes, and brown algae.
• Cercozoans, radiolarians, and forams are all members of the Rhizaria phylum.
• Land plants, red algae, and two kingdoms of green algae, chlorophytes and charophytes, are all members of the Archaeplastida.
• Entamoebas, slime moulds, and gymnamoebas are all examples of amoebozoa.
• Animals, nucleariids, choanoflagellates, and fungi are all members of the Opisthokonta.

Context and Applications

This topic is significant in the exams at school, graduate, and post-graduate levels, especially for

• Bachelors in Zoology/Botany
• Masters in Zoology/Botany

Practice Problems

Question 1: Phylogenetic trees are useful in the fields of _____.

1. Molecular systematics
2. Molecular biology
3. Bioinformatics
4. All of the above

Answer: Option 4 is correct.

Explanation: Molecular systematics procedures are widely used to predict lineages. A lineage eventually stretches back through the diverse taxonomic levels, from species to genus, the genus to family, the family to order, and so on. Trees are helpful in biological fields like molecular biology, bioinformatics, systematics, and molecular phylogenetics to infer lineages.

Question 2: Which of the following is true about lineages?

1. A group of species that descend from a common ancestor.
2. A lineage eventually extends back through the diverse taxonomic levels: from the taxon species to the genus, from the genus to the family, from the family to the taxon order, etc.
3. Both 1 and 2 are true.
4. Only 2 is correct.

Answer: Option 3 is correct.

Explanation: In ecology, an evolutionary lineage is a group of species that descend from a common ancestor. Each new species in the lineage is the direct result of speciation from an ancestral species. A lineage extends back through the various taxonomic levels, from the species to the genus, to the family and then to the order, etc.

Question 3: Lineages that, over time, accumulate more variations in their genomes by lateral transfer than by mutation are called?

1. Closed lineages
2. Open lineages
3. Both 1 and 2
4. None of the above

Answer: Option 2 is correct.

Explanation: Open evolutionary lineages that accumulate more variations in their genomes by lateral transfer than by mutations over time. In closed lineages, most of the variations are caused by mutation.

Question 4: What are the primary causes of genetic diversity in prokaryotes?

1. Mutations
2. Lateral transfer of genes
3. Both 1 and 2
4. None of the above

Answer: Option 3 is correct.

Explanation: Mutation and lateral transfer are two major mechanisms producing genetic diversity in prokaryotic genomes.

Question 5: Which of the following is not included in the eukaryotic supergroups?

1. Excavata
2. Rhizaria
3. Amoebozoa
4. Archaea

Answer: Option 4 is correct.

Explanation: The six groups of eukaryotes are Excavata, Chromalveolata, Rhizaria, Archaeplastida, Amoebozoa, and Opisthokonta. Bacteria and archaea are the two major lineages of prokaryotes.