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An example of convergent evolution is carcinization, which is he convergent evolution of crustaceans to a crab-like body plan. Convergent evolution—the repeated evolution of similar traits in multiple lineages which all ancestrally lack the trait—is rife in nature, as illustrated by the examples below.
The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions.
Because a plesiomorphic character inherited from a common ancestor can appear anywhere in a phylogenetic tree, its presence does not reveal anything about the relationships within the tree. [4] Thus grouping species requires distinguishing ancestral from derived character states. [5]
Homoplasy, especially the type that occurs in more closely related phylogenetic groups, can make phylogenetic analysis more challenging. Phylogenetic trees are often selected by means of parsimony analysis. [21] [22] These analyses can be done with phenotypic characters, as well as DNA sequences. [23]
The results are a phylogenetic tree—a diagram depicting the hypothetical relationships between organisms and their evolutionary history. [4] The tips of a phylogenetic tree can be living taxa or fossils, which represent the present time or "end" of an evolutionary lineage, respectively. A phylogenetic diagram can be rooted or unrooted.
Pseudoplesiomorphy – a trait that cannot be identified as either a plesiomorphy or an apomorphy that is a reversal. [15] Reversal – a loss of derived trait present in ancestor and the reestablishment of a plesiomorphic trait. Convergence – independent evolution of a similar trait in two or more taxa. Apomorphy – a derived trait.
Phylogenetic similarities: These phylogenetic terms are used to describe different patterns of ancestral and derived character or trait states as stated in the above diagram in association with synapomorphies. [1] Homoplasy in biological systematics is when a trait has been
These evolutionary lineages can thereby be portrayed through a phylogenetic tree, or cladogram, where varying relatedness amongst species is evidently depicted. Through this tree, organisms can be categorized by divergence from the common ancestor, and primitive characters, to clades of organisms with shared derived character states.