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Character evolution is the process by which a 
Natural Selection is the process by which organisms that are better adapted to their environment are selected to survive and reproduce more offspring. Natural selection selects for the phenotype or the characteristics of an organism that gives the organism a reproductive advantage in which it becomes the gene pool of a population. In addition, mutations also arise in the genome of an individual organism and offspring(s) can inherit such mutations. This genetic variation allows more organisms to adapt to a changing environment.
Lamarck is best known for his ''Theory of Inheritance of Acquired Characteristics'' in 1801. His theory states that the characteristics an organism acquires throughout its life in order to adapt to its environment are passed down to its offspring. For example, Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves of a tree. Their offspring and later generations inherited the resulting long necks.
Character Evolution research group
of
character
Character or Characters may refer to:
Arts, entertainment, and media Literature
* ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk
* ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...
or trait
Trait may refer to:
* Phenotypic trait in biology, which involve genes and characteristics of organisms
* Genotypic trait, sometimes but not always presenting as a phenotypic trait
* Trait (computer programming)
In computer programming, a tra ...
(a certain body part or property of an organism) evolves along the branches of an evolutionary tree. Character evolution usually refers to single changes within a lineage that make this lineage unique from others. These changes are called character state changes and they are often used in the study of evolution to provide a record of common ancestry. Character state changes can be phenotypic changes, nucleotide
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecul ...
substitutions, or amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
substitutions. These small changes in a species can be identifying features of when exactly a new lineage diverged from an old one.
Phylogenetics
In the study ofphylogenetics
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...
or cladistics
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived ch ...
, researchers can look at the characters shared by a collection of species and then group them into what is called a clade. The term clade was coined in 1957 by the biologist Julian Huxley
Sir Julian Sorell Huxley (22 June 1887 – 14 February 1975) was an English evolutionary biologist, eugenicist, and internationalist. He was a proponent of natural selection, and a leading figure in the mid-twentieth century modern synthes ...
to refer to the result of cladogenesis
Cladogenesis is an evolutionary splitting of a parent species into two distinct species, forming a clade.
This event usually occurs when a few organisms end up in new, often distant areas or when environmental changes cause several extinctions ...
, a concept Huxley borrowed from Bernhard Rensch
Bernhard Rensch (21 January 1900 – 4 April 1990) was a German evolutionary biologist and ornithologist who did field work in Indonesia and India. Starting his scientific career with pro-Lamarckian views, he shifted to selectionism and became on ...
. A clade is by definition monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...
, meaning it contains one ancestor (which can be an organism, a population
Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using ...
, or a species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
) and all its descendants.
Natural selection
Natural Selection is the process by which organisms that are better adapted to their environment are selected to survive and reproduce more offspring. Natural selection selects for the phenotype or the characteristics of an organism that gives the organism a reproductive advantage in which it becomes the gene pool of a population. In addition, mutations also arise in the genome of an individual organism and offspring(s) can inherit such mutations. This genetic variation allows more organisms to adapt to a changing environment.
Maximum parsimony
It is often the case in the study of phylogenies that the vast majority of organisms of interest are long extinct. It is therefore a matter of speculation to reconstruct what ancestral organisms existed long before the present time, and how the evolutionary process led from one organism to another, and which present-day organisms are most closely related. Character evolution and the character state changes that drive this type of evolution are what help researchers construct these trees in a fashion referred to asmaximum parsimony
In phylogenetics, maximum parsimony is an optimality criterion under which the phylogenetic tree that minimizes the total number of character-state changes (or miminizes the cost of differentially weighted character-state changes) is preferred. ...
. When talking about phylogenetics, maximum parsimony refers to a method of inferring a phylogenetic tree in a way that minimizes the number of implied character state transformations in the observed data (hence ''maximally parsimonious''). The basic ideas were presented by James S. Farris
James is a common English language surname and given name:
*James (name), the typically masculine first name James
* James (surname), various people with the last name James
James or James City may also refer to:
People
* King James (disambigua ...
Farris, J. S. (1970). Methods for computing Wagner trees. ''Systematic Zoology'' 19, 83-92. in 1970.
Although fairly effective, maximum parsimony (like any method of phylogenetic inference) may not recover the true course of evolution for a given feature. For a number of reasons, two organisms can possess a trait not present in their last common ancestor. The phenomena of convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
, parallel evolution
Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure.Zhang, J. and Kumar, S. 1997Detection of convergent and paral ...
, and evolutionary reversals (collectively termed ''homoplasy'') are evolutionary forces that may disrupt the effectiveness of the maximum parsimony method of inferring phylogenetic relationships. However, Rindal and Brower Rindal, E. and Brower A.V.Z. (2010) Do model‐based phylogenetic analyses perform better than parsimony? A test with empirical data. ''Cladistics'' 27, 331-334. showed that the vast majority of the time, parsimony and model-based phylogenetic analyses of the same data sets gave results that were not significantly different from one another, implying that if parsimony is producing false hypotheses of relationships due to homoplasy, then the Maximum Likelihood or Bayesian methods are doing so as well.
Theory of Inheritance of Acquired Characteristics
Lamarck is best known for his ''Theory of Inheritance of Acquired Characteristics'' in 1801. His theory states that the characteristics an organism acquires throughout its life in order to adapt to its environment are passed down to its offspring. For example, Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves of a tree. Their offspring and later generations inherited the resulting long necks.
References
{{reflistExternal links
Character Evolution research group
of
Naturalis Biodiversity Center
Naturalis Biodiversity Center ( nl, Nederlands Centrum voor Biodiversiteit Naturalis) is a national museum of natural history and a research center on biodiversity in Leiden, Netherlands. It was named the European Museum of the Year 2021.
Alt ...
Evolution