Difference between revisions of "3. Evolution; CSCG, phylogenetic tree, Convergent evolution -YJ code: 130629"
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<p><span style="font-size:18px"><span style="font-family:times new roman,times,serif">A phylogenetic tree or evolutionary tree is a branching diagram. I</span><span style="font-family:times new roman,times,serif">t is showing the inferred evolutionary relationships among various biological speciese or other entities based upon similarities and differences in their physical or genetic characteristics. Phylogenetic trees are central to the field of phylogenetics. </span><span style="font-family:times new roman,times,serif">In a rooted phylogenetic tree, each node with descendants represents the inferred most recent common ancestor of the descendants, and the edge lengths in some trees may be interpreted as time estimates. Each node is called a taxonomic unit. Internal nodes are generally called hypothetical taxonomic units, as they cannot be directly observed. Unrooted trees illustrate only the relatedness of the leaf nodes and do not require the ancestral root to be known or inferred.</span></span></p> | <p><span style="font-size:18px"><span style="font-family:times new roman,times,serif">A phylogenetic tree or evolutionary tree is a branching diagram. I</span><span style="font-family:times new roman,times,serif">t is showing the inferred evolutionary relationships among various biological speciese or other entities based upon similarities and differences in their physical or genetic characteristics. Phylogenetic trees are central to the field of phylogenetics. </span><span style="font-family:times new roman,times,serif">In a rooted phylogenetic tree, each node with descendants represents the inferred most recent common ancestor of the descendants, and the edge lengths in some trees may be interpreted as time estimates. Each node is called a taxonomic unit. Internal nodes are generally called hypothetical taxonomic units, as they cannot be directly observed. Unrooted trees illustrate only the relatedness of the leaf nodes and do not require the ancestral root to be known or inferred.</span></span></p> | ||
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| + | <p><span style="font-size:26px"><em><span style="font-family:times new roman,times,serif">What is the 'Convergent evolution'?</span></em></span></p> | ||
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| − | <p style="text-align: justify | + | <p style="text-align:justify"><span style="font-size:16px"><span style="font-family:times new roman,times,serif">Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example of convergent evolution. Flying insects, birds and bats have all evolved the capacity of flight independently. They have "converged" on this useful trait. Convergent evolution is similar to but different from parallel evolution. Parallel evolution occurs when two independent but similar species evolve in the same direction and thus independently acquire similar characteristics</span></span></p> |
Revision as of 22:48, 5 December 2016
What is the phylogenetic tree?
A phylogenetic tree or evolutionary tree is a branching diagram. It is showing the inferred evolutionary relationships among various biological speciese or other entities based upon similarities and differences in their physical or genetic characteristics. Phylogenetic trees are central to the field of phylogenetics. In a rooted phylogenetic tree, each node with descendants represents the inferred most recent common ancestor of the descendants, and the edge lengths in some trees may be interpreted as time estimates. Each node is called a taxonomic unit. Internal nodes are generally called hypothetical taxonomic units, as they cannot be directly observed. Unrooted trees illustrate only the relatedness of the leaf nodes and do not require the ancestral root to be known or inferred.
What is the 'Convergent evolution'?
Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example of convergent evolution. Flying insects, birds and bats have all evolved the capacity of flight independently. They have "converged" on this useful trait. Convergent evolution is similar to but different from parallel evolution. Parallel evolution occurs when two independent but similar species evolve in the same direction and thus independently acquire similar characteristics
