Important terms in evolution
This post is dedicated to some important terms which we come across quite often while studying any article or chapter related to evolution
What is phylogeny?
The term phylogeny refers to the evolution or historical development of a plant or animal species, or even a human tribe or similar group. (or) Phylogeny represents the historical pattern of relationships among organisms which has resulted from the actions of many different evolutionary processes.
What is a phylogenetic tree?
A phylogenetic tree is a graphical representation of the evolutionary relationship between taxonomic groups.
(or) Cladograms or phylogenetic trees are branching diagrams depicting phylogenetic relationships among different taxonomic groups.
What is Tree of life ?
The number of species of animals present on our planet earth ranges in millions. Based on the evidence from fossils, morphological, biochemical, and gene sequence data, It is universally agreed that all organisms ,from the smallest micro organism to the largest plants and animal are related to each other by descent (It means that different species arise from previous forms). The relationships among living things can be represented in the form of a huge evolutionary tree, called as “the Tree of Life”.
The living organisms represent leaves of the huge tree and by tracing the history by going down the branches of tree of life ,we will be able to find the common ancestors , which have gone extinct million years ago.
What is Natural selection ?
According to Darwin’s theory of evolution, only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated. (or )
According to Ryan Gregory Natural selection can be defined as ( its rather lengthy sentence but sounds effective)
Natural selection is a non-random difference in reproductive output among replicating entities, often due indirectly to differences in survival in a particular environment, leading to an increase in the proportion of beneficial, heritable characteristics within a population from one generation to the next.
This reminds me of a new article by Ryan Gregory in Evolution: Education and Outreach (Natural selection issue )
Understanding natural selection: essential concepts and common misconceptions
T. Ryan Gregory
To download click here
To see how natural selection works Click here for an example.
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…Phylogenetic trees
Cladograms and phylogenetic trees are not strictly the same. Both are tree representations of evolutionary relationships between taxonomic groups. But in the phylogenetic tree the branch length is proportional to the evolutionary time since the branching event between related organisms. In cladograms the branch length does not signify evolutionary time between related groups or sequences.
Thanks for pointing out the difference between the two!!!!
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