View source for Biology:Convergent evolution

{{Short description|Independent evolution of similar features}}
{{multiple image
|align=right|total_width=400|footer=Two [[Biology:Succulent plant|succulent plant]] genera, ''[[Biology:Euphorbia|Euphorbia]]'' and ''[[Biology:Astrophytum|Astrophytum]]'', are only distantly related, but the species within each have converged on a similar body form.
|width1=800|height1=700|image1=E_obesa_symmetrica_ies.jpg|alt1=
|width2=500|height2=495|image2=Astrophytum_asterias1.jpg|alt2=
}}
{{Evolutionary biology}}

'''Convergent evolution''' is the independent [[Biology:Evolution|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 common ancestor of those groups. The cladistic term for the same phenomenon is [[Biology:Cladogram#Measuring homoplasy|homoplasy]]. The [[Biology:Recurrent evolution|recurrent evolution]] of flight is a classic example, as flying [[Biology:Pterygota|insect]]s, [[Biology:Bird|bird]]s, pterosaurs, and [[Biology:Bat|bat]]s have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''[[Biology:Homology|homologous]]'' structures or traits have a common origin but can have dissimilar functions.  Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions.

The opposite of convergence is [[Biology:Divergent evolution|divergent evolution]], where related species evolve different traits. Convergent evolution is similar to [[Biology:Parallel evolution|parallel evolution]], which occurs when two independent species evolve in the same direction and thus independently acquire similar characteristics; for instance, [[Biology:Flying frog|gliding frog]]s have evolved in parallel from multiple types of [[Biology:Tree frog|tree frog]].

Many instances of convergent evolution are known in [[Biology:Plant|plant]]s, including the repeated development of C<sub>4</sub> photosynthesis, [[Earth:Seed dispersal|seed dispersal]] by fleshy [[Biology:Fruit|fruit]]s adapted to be eaten by animals, and carnivory.

==Overview==
[[File:Analogous & Homologous Structures.svg|thumb|upright=1.5|[[Biology:Homology|Homology]] and analogy in mammals and insects: on the horizontal axis, the structures are homologous in morphology, but different in function due to differences in habitat. On the vertical axis, the structures are analogous in function due to similar lifestyles but anatomically different with different phylogeny.{{efn|However, evolutionary developmental biology has identified deep homology between insect and mammal body plans, to the surprise of many biologists.}}]]
{{Further|Biology:List of examples of convergent evolution}}

In morphology, analogous traits arise when different species live in similar ways and/or a similar environment, and so face the same environmental factors. When occupying similar [[Biology:Ecological niche|ecological niche]]s (that is, a distinctive way of life) similar problems can lead to similar solutions.<ref>{{cite book |last=Kirk |first=John Thomas Osmond |title=Science & Certainty |url=https://books.google.com/books?id=kTr5BTxMpFYC&pg=PA79 |year=2007 |publisher=Csiro Publishing |isbn=978-0-643-09391-1 |page=79 |quote=evolutionary convergence, which, quoting .. Simon Conway Morris .. is the 'recurring tendency of biological organization to arrive at the same "solution" to a particular "need". .. the 'Tasmanian tiger' .. looked and behaved like a wolf and occupied a similar ecological niche, but was in fact a marsupial not a placental mammal.|access-date=2017-01-23 |archive-url=https://web.archive.org/web/20170215051246/https://books.google.com/books?id=kTr5BTxMpFYC&pg=PA79|archive-date=2017-02-15|url-status=live}}</ref><ref name="Reece et al">{{cite book |last=Reece |first=J. |author2=Meyers, N. |author3=Urry, L. |author4=Cain, M. |author5=Wasserman, S. |author6=Minorsky, P. |author7=Jackson, R. |author8=Cooke, B. |title=Cambell Biology, 9th Edition |publisher=Pearson |isbn=978-1-4425-3176-5 |page=586|date=2011-09-05 }}</ref><ref name=BerkeleyHomologyAnalogy/> The British anatomist Richard Owen was the first to identify the fundamental difference between analogies and [[Biology:Homology|homologies]].<ref>{{cite book |last=Thunstad |first=Erik |title=Darwins teori, evolusjon gjennom 400 år |year=2009 |publisher=Humanist forlag |location=Oslo, Norway |isbn=978-82-92622-53-7 |page=404 |language=no}}</ref>

In biochemistry, physical and chemical constraints on mechanisms have caused some [[Biology:Active site|active site]] arrangements such as the [[Biology:Catalytic triad|catalytic triad]] to evolve independently in separate enzyme superfamilies.<ref name="Buller&Townsend_2013">{{cite journal |last=Buller |first=A. R. |author2=Townsend, C. A. |title=Intrinsic evolutionary constraints on protease structure, enzyme acylation, and the identity of the catalytic triad.|journal=Proceedings of the National Academy of Sciences of the United States of America|date=19 Feb 2013 |volume=110 |issue=8 |pages=E653–61 |pmid=23382230|doi=10.1073/pnas.1221050110 |bibcode=2013PNAS..110E.653B |pmc=3581919|doi-access=free }}</ref>

In his 1989 book ''Wonderful Life'', [[Biography:Stephen Jay Gould|Stephen Jay Gould]] argued that if one could "rewind the tape of life [and] the same conditions were encountered again, evolution could take a very different course."<ref name="wonderfullife">{{cite book| title=Wonderful Life: The Burgess Shale and the Nature of History| author=Gould, S.J.|  year=1989| publisher=W.W. Norton |pages=[https://archive.org/details/wonderfullifebur00goul/page/282 282–285] |isbn=978-0-09-174271-3| title-link=Wonderful Life (book)}}</ref> [[Biography:Simon Conway Morris|Simon Conway Morris]] disputes this conclusion, arguing that convergence is a dominant force in evolution, and given that the same environmental and physical constraints are at work, life will inevitably evolve toward an "optimum" body plan, and at some point, evolution is bound to stumble upon intelligence, a trait presently identified with at least [[Biology:Primates|primates]], corvids, and cetaceans.<ref name=SCM2005/>

== Distinctions ==

===Cladistics===
{{Main|Biology:Cladistics}}
In cladistics, a homoplasy is a trait shared by two or more [[Biology:Taxon|taxa]] for any reason other than that they share a common ancestry. Taxa which do share ancestry are part of the same [[Biology:Clade|clade]]; cladistics seeks to arrange them according to their degree of relatedness to describe their [[Biology:Phylogeny|phylogeny]]. Homoplastic traits caused by convergence are therefore, from the point of view of cladistics, confounding factors which could lead to an incorrect analysis.<ref>{{Cite journal |last1=Chirat |first1=R. |last2=Moulton |first2=D. E. |last3=Goriely |first3=A. |doi=10.1073/pnas.1220443110 |title=Mechanical basis of morphogenesis and convergent evolution of spiny seashells |journal=Proceedings of the National Academy of Sciences |volume=110 |issue=15 |pages=6015–6020 |year=2013 |bibcode= 2013PNAS..110.6015C|pmid=23530223 |pmc=3625336|doi-access=free }}</ref><ref name="Lomolino et al">{{cite book|author1=Lomolino, M |author2=Riddle, B |author3=Whittaker, R |author4=Brown, J |title=Biogeography, Fourth Edition |publisher=Sinauer Associates |isbn=978-0-87893-494-2 |page=426|year=2010 }}</ref><ref name=West-Eberhard>{{cite book |last=West-Eberhard |first=Mary Jane |title=Developmental Plasticity and Evolution |pages=353–376 |year=2003 |publisher=Oxford University Press |isbn=978-0-19-512235-0}}</ref><ref>{{cite book |last1=Sanderson |first1=Michael J. |last2=Hufford |first2=Larry |title=Homoplasy: The Recurrence of Similarity in Evolution |url=https://books.google.com/books?id=WWGNzeNmRUYC&pg=PA330 |year=1996 |publisher=Academic Press |isbn=978-0-08-053411-4 |pages=330, and passim |access-date=2017-01-21 |archive-url=https://web.archive.org/web/20170214233633/https://books.google.com/books?id=WWGNzeNmRUYC&pg=PA330 |archive-date=2017-02-14 |url-status=live }}</ref>

===Atavism===
{{Main|Biology:Atavism}}

In some cases, it is difficult to tell whether a trait has been lost and then re-evolved convergently, or whether a gene has simply been switched off and then re-enabled later. Such a re-emerged trait is called an [[Biology:Atavism|atavism]]. From a mathematical standpoint, an unused gene ([[Biology:Genetic drift|selectively neutral]]) has a steadily decreasing [[Probability|probability]] of retaining potential functionality over time. The time scale of this process varies greatly in different phylogenies; in mammals and birds, there is a reasonable probability of remaining in the genome in a potentially functional state for around 6 million years.<ref>{{Cite journal| last1=Collin | first1=R.| last2=Cipriani | first2=R.| year=2003| title=Dollo's law and the re-evolution of shell coiling| journal=Proceedings of the Royal Society B| volume=270 | issue=1533 | pages=2551–2555| doi=10.1098/rspb.2003.2517| pmc=1691546| pmid=14728776}}</ref>

===Parallel vs. convergent evolution===

[[File:Evolutionary trends.svg|thumb|upright=1.5|Evolution at an amino acid position. In each case, the left-hand species changes from having alanine (A) at a specific position in a protein in a hypothetical ancestor, and now has serine (S) there. The right-hand species may undergo divergent, parallel, or convergent evolution at this amino acid position relative to the first species.]]

When two species are similar in a particular character, evolution is defined as parallel if the ancestors were also similar, and convergent if they were not.{{efn|However, all organisms share a common ancestor more or less recently, so the question of how far back to look in evolutionary time and how similar the ancestors need to be for one to consider parallel evolution to have taken place is not entirely resolved within evolutionary biology.}} Some scientists have argued that there is a continuum between parallel and convergent evolution,<ref>{{cite journal|last=Arendt |first=J |author2=Reznick, D |title=Convergence and parallelism reconsidered: what have we learned about the genetics of adaptation?|journal=Trends in Ecology & Evolution|date=January 2008|volume=23|issue=1 |pages=26–32 |doi=10.1016/j.tree.2007.09.011|pmid=18022278}}</ref><ref>{{cite journal |last1=Waters |first1=Jonathan M. |last2=McCulloch |first2=Graham A. |title=Reinventing the wheel? Reassessing the roles of gene flow, sorting and convergence in repeated evolution |journal=Molecular Ecology |date=2021 |volume=30 |issue=17 |pages=4162–4172 |doi=10.1111/mec.16018 |pmid=34133810 |s2cid=235460165 | issn=1365-294X}}</ref> while others maintain that despite some overlap, there are still important distinctions between the two.<ref>{{cite journal |last=Pearce |first=T. |title=Convergence and Parallelism in Evolution: A Neo-Gouldian Account |journal=The British Journal for the Philosophy of Science |date=10 November 2011 |volume=63 |issue=2 |pages=429–448 |doi=10.1093/bjps/axr046|doi-access=free }}</ref><ref name="Zhang">{{cite journal | last1=Zhang | first1=J. | last2=Kumar | first2=S. | year=1997 | title=Detection of convergent and parallel evolution at the amino acid sequence level | journal=Mol. Biol. Evol. | volume=14 | issue=5| pages=527–36 | doi=10.1093/oxfordjournals.molbev.a025789| pmid=9159930 | doi-access=free }}</ref>

When the ancestral forms are unspecified or unknown, or the range of traits considered is not clearly specified, the distinction between parallel and convergent evolution becomes more subjective.  For instance, the striking example of similar placental and marsupial forms is described by [[Biography:Richard Dawkins|Richard Dawkins]] in ''The Blind Watchmaker'' as a case of convergent evolution, because mammals on each continent had a long evolutionary history prior to the extinction of the dinosaurs under which to accumulate relevant differences.<ref>{{cite book|last=Dawkins|first=Richard|year=1986|title=The Blind Watchmaker|publisher=W. W. Norton|isbn=978-0-393-31570-7|pages=[https://archive.org/details/blindwatchmaker00rich/page/100 100–106]|title-link=The Blind Watchmaker}}</ref>

==At molecular level==
[[File:Triad convergence ser cys.svg|thumb|upright=1.5|Evolutionary convergence of [[Biology:Serine protease|serine]] and cysteine protease towards the same catalytic triads organisation of acid-base-nucleophile in different protease superfamilies. Shown are the triads of subtilisin, prolyl oligopeptidase, TEV protease, and papain.]]

===Proteins===

====Protease active sites====
{{Main|Biology:Catalytic triad}}
The [[Biology:Enzymology|enzymology]] of proteases provides some of the clearest examples of convergent evolution. These examples reflect the intrinsic chemical constraints on enzymes, leading evolution to converge on equivalent solutions independently and repeatedly.<ref name="Buller&Townsend_2013"/><ref>{{cite journal |last=Dodson |first=G. |author2=Wlodawer, A. |title=Catalytic triads and their relatives |journal=Trends in Biochemical Sciences |date=September 1998 |volume=23 |issue=9 |pages=347–52 |pmid=9787641 |doi=10.1016/S0968-0004(98)01254-7}}</ref>

Serine and cysteine proteases use different amino acid functional groups (alcohol or thiol) as a [[Chemistry:Nucleophile|nucleophile]]. In order to activate that nucleophile, they orient an acidic and a basic residue in a [[Biology:Catalytic triad|catalytic triad]]. The chemical and physical constraints on [[Biology:Enzyme catalysis|enzyme catalysis]] have caused identical triad arrangements to evolve independently more than 20 times in different enzyme superfamilies.<ref name="Buller&Townsend_2013"/>

[[Biology:Threonine protease|Threonine protease]]s use the amino acid threonine as their catalytic [[Chemistry:Nucleophile|nucleophile]]. Unlike cysteine and serine, threonine is a secondary alcohol (i.e. has a methyl group). The methyl group of threonine greatly restricts the possible orientations of triad and substrate, as the methyl clashes with either the enzyme backbone or the histidine base. Consequently, most threonine proteases use an N-terminal threonine in order to avoid such steric clashes.
Several evolutionarily independent enzyme superfamilies with different protein folds use the N-terminal residue as a nucleophile. This commonality of [[Biology:Active site|active site]] but difference of protein fold indicates that the active site evolved convergently in those families.<ref name="Buller&Townsend_2013"/><ref>{{cite journal |last=Ekici|first=O. D. |author2=Paetzel, M. |author3=Dalbey, R. E. |title=Unconventional serine proteases: variations on the catalytic Ser/His/Asp triad configuration |journal=Protein Science |date=December 2008 |volume=17 |issue=12 |pages=2023–37 |pmid=18824507 |doi=10.1110/ps.035436.108 |pmc=2590910}}</ref>

====Cone snail and fish insulin, fish-like bacterial copper/zinc superoxide dismutase====

''[[Biology:Conus geographus|Conus geographus]]'' produces a distinct form of [[Biology:Insulin|insulin]] that is more similar to fish insulin protein sequences than to insulin from more closely related molluscs, suggesting convergent evolution.<ref>{{cite journal |last1=Safavi-Hemami |first1=Helena |last2=Gajewiak |first2=Joanna |last3=Karanth |first3=Santhosh |last4=Robinson |first4=Samuel D. |last5=Ueberheide |first5=Beatrix |last6=Douglass |first6=Adam D. |last7=Schlegel |first7=Amnon |last8=Imperial |first8=Julita S. |last9=Watkins |first9=Maren |last10=Bandyopadhyay |first10=Pradip K. |last11=Yandell |first11=Mark |last12=Li |first12=Qing |last13=Purcell |first13=Anthony W. |last14=Norton |first14=Raymond S. |last15=Ellgaard |first15=Lars |last16=Olivera |first16=Baldomero M. |title=Specialized insulin is used for chemical warfare by fish-hunting cone snails |journal=Proceedings of the National Academy of Sciences |date=10 February 2015 |volume=112 |issue=6 |pages=1743–1748 |doi=10.1073/pnas.1423857112|pmid=25605914 |pmc=4330763 |bibcode=2015PNAS..112.1743S |doi-access=free }}</ref> Although convergent evolution is not impossible in this example, the possibility of [[Biology:Horizontal gene transfer|horizontal gene transfer]] cannot be ignored, and it provides the only reasonable explanation of the fish-like copper/zinc [[Biology:Superoxide dismutase|superoxide dismutase]] of ''[[Biology:Photobacterium leiognathi|Photobacterium leiognathi]]''.<ref>{{cite journal  | title = Evidence for a natural gene-transfer from the ponyfish to its bioluminescent bacterial symbiont ''Photobacter leiognathi'' — the close relationship between bacteriocuprein and the copper-zinc superoxide-dismutase of teleost fishes  | last1 = Martin  | first1 = J P | last2 = Fridovich  | first2 = I  | journal = J. Biol. Chem.  | year = 1981 |  volume = 256 | issue = 12  |  pages = 6080–6089| doi = 10.1016/S0021-9258(19)69131-3 | pmid = 6787049 | doi-access = free }}</ref>

==== Ferrous iron uptake via protein transporters in land plants and chlorophytes ====

Distant homologues of the metal ion transporters ZIP in land plants and chlorophytes have converged in structure, likely to take up Fe<sup>2+</sup> efficiently. The IRT1 proteins from ''[[Biology:Arabidopsis thaliana|Arabidopsis thaliana]]'' and [[Biology:Rice|rice]] have extremely different amino acid sequences from ''[[Biology:Chlamydomonas|Chlamydomonas]]''{{'}}s IRT1, but their three-dimensional structures are similar, suggesting convergent evolution.<ref>{{Cite journal |last1=Rodrigues |first1=Wenderson Felipe Costa |last2=Lisboa |first2=Ayrton Breno P. |last3=Lima |first3=Joni Esrom |last4=Ricachenevsky |first4=Felipe Klein |last5=Del‐Bem |first5=Luiz‐Eduardo |date=2023-01-10 |title=Ferrous iron uptake via IRT1 / ZIP evolved at least twice in green plants |url=https://onlinelibrary.wiley.com/doi/10.1111/nph.18661 |journal=New Phytologist |volume=237 |issue=6 |pages=1951–1961 |doi=10.1111/nph.18661|pmid=36626937 }}</ref>

====Na<sup>+</sup>,K<sup>+</sup>-ATPase and Insect resistance to cardiotonic steroids ====

Many examples of convergent evolution exist in insects in terms of developing resistance at a molecular level to toxins. One well-characterized example is the evolution of resistance to cardiotonic steroids (CTSs) via amino acid substitutions at well-defined positions of the α-subunit of Na<sup>+</sup>,K<sup>+</sup>-ATPase (ATPalpha). Variation in ATPalpha has been surveyed in various CTS-adapted species spanning six insect orders.<ref name="Zhen_et_al_2012">{{cite journal|last1=Zhen|first1=Ying|last2=Aardema|first2=Matthew L.|last3=Medina|first3=Edgar M.|last4=Schumer|first4=Molly|last5=Andolfatto|first5=Peter|date=2012-09-28|title=Parallel Molecular Evolution in an Herbivore Community|url= |journal=Science|language=en|volume=337|issue=6102|pages=1634–1637|doi=10.1126/science.1226630|issn=0036-8075|pmid=23019645|pmc=3770729|bibcode=2012Sci...337.1634Z}}</ref><ref>Dobler, S., Dalla, S., Wagschal, V., & Agrawal, A. A. (2012). Community-wide convergent evolution in insect adaptation to toxic cardenolides by substitutions in the Na,K-ATPase. Proceedings of the National Academy of Sciences, 109(32), 13040–13045. https://doi.org/10.1073/pnas.1202111109</ref><ref name="Yang_et_al_2019">{{cite journal |last1=Yang|first1=L|last2=Ravikanthachari|first2=N|last3=Mariño-Pérez|first3=R|last4=Deshmukh|first4=R|last5=Wu|first5=M|last6=Rosenstein|first6=A|last7=Kunte|first7=K|last8=Song|first8=H|last9=Andolfatto|first9=P.|title=Predictability in the evolution of Orthopteran cardenolide insensitivity.|journal=Philosophical Transactions of the Royal Society of London, Series B|date=2019 |volume=374 |issue=1777|pages=20180246 |doi=10.1098/rstb.2018.0246|pmid=31154978|pmc=6560278}}</ref> Among 21 CTS-adapted species, 58 (76%) of 76 amino acid substitutions at sites implicated in CTS resistance occur in parallel in at least two lineages.<ref name="Yang_et_al_2019"/> 30 of these substitutions (40%) occur at just two sites in the protein (positions 111 and 122). CTS-adapted species have also recurrently evolved [[Biology:Neofunctionalization|neo-functionalized]] duplications of ATPalpha, with convergent tissue-specific expression patterns.<ref name="Zhen_et_al_2012"/><ref name="Yang_et_al_2019"/>

===Nucleic acids===
Convergence occurs at the level of [[Biology:DNA|DNA]] and the [[Chemistry:Amino acid|amino acid]] sequences produced by [[Biology:Translation|translating]] [[Biology:Structural gene|structural gene]]s into [[Biology:Protein|protein]]s. Studies have found convergence in amino acid sequences in echolocating bats and the dolphin;<!--<ref name="Parkeretal2013">{{cite journal | doi=10.1038/nature12511 | last1=Parker | first1=J. | last2=Tsagkogeorga | first2=G | last3=Cotton | first3=J. A. | last4=Liu | first4=Y. | last5=Provero | first5=P. | last6=Stupka | first6=E. | last7= Rossiter | first7=S. J. | year=2013 | title=Genome-wide signatures of convergent evolution in echolocating mammals | journal=Nature | volume=502 | pages=228–231 | issue=7470 |bibcode=2013Natur.502..228P | pmc=3836225 | pmid=24005325}}</ref> may be unreliable per talk page--><ref name="LiuQi2014">{{cite journal |last1=Liu |first1=Zhen |last2=Qi |first2=Fei-Yan |last3=Zhou |first3=Xin |last4=Ren |first4=Hai-Qing |last5=Shi |first5=Peng |title=Parallel Sites Implicate Functional Convergence of the Hearing Gene Prestin among Echolocating Mammals |journal=Molecular Biology and Evolution |volume=31 |issue=9 |year=2014 |pages=2415–2424 |issn=1537-1719 |doi=10.1093/molbev/msu194|pmid=24951728 |doi-access=free }}</ref> among marine mammals;<ref>{{Cite journal |last1=Foote |first1=Andrew D. |last2=Liu |first2=Yue |last3=Thomas |first3=Gregg W. C. |last4=Vinař |first4=Tomáš |last5=Alföldi |first5=Jessica |last6=Deng |first6=Jixin |last7=Dugan |first7=Shannon |last8=Elk |first8=Cornelis E. van |last9=Hunter |first9=Margaret E. |date=March 2015 |title=Convergent evolution of the genomes of marine mammals |journal=Nature Genetics |volume=47 |issue=3 |pages=272–275 |doi=10.1038/ng.3198|pmid=25621460 |pmc=4644735 }}</ref> between giant and red pandas;<ref>{{Cite journal |last1=Hu |first1=Yibo |last2=Wu |first2=Qi |last3=Ma |first3=Shuai |last4=Ma |first4=Tianxiao |last5=Shan |first5=Lei |last6=Wang |first6=Xiao |last7=Nie |first7=Yonggang |last8=Ning |first8=Zemin |last9=Yan |first9=Li |date=January 2017 |title=Comparative genomics reveals convergent evolution between the bamboo-eating giant and red pandas |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=114 |issue=5 |pages=1081–1086 |doi=10.1073/pnas.1613870114 |pmc=5293045 |pmid=28096377|bibcode=2017PNAS..114.1081H |doi-access=free }}</ref> and between the thylacine and canids.<ref>{{Cite journal |last1=Feigin |first1=Charles Y. |last2=Newton |first2=Axel H. |last3=Doronina |first3=Liliya |last4=Schmitz |first4=Jürgen |last5=Hipsley |first5=Christy A. |last6=Mitchell |first6=Kieren J. |last7=Gower |first7=Graham |last8=Llamas |first8=Bastien |last9=Soubrier |first9=Julien |date=January 2018 |title=Genome of the Tasmanian tiger provides insights into the evolution and demography of an extinct marsupial carnivore |journal=Nature Ecology & Evolution |volume=2 |issue=1 |pages=182–192 |doi=10.1038/s41559-017-0417-y|pmid=29230027 |doi-access=free }}</ref> Convergence has also been detected in a type of [[Biology:Non-coding DNA|non-coding DNA]], [[Biology:Cis-regulatory element|cis-regulatory element]]s, such as in their rates of evolution; this could indicate either positive selection or relaxed [[Biology:Negative selection (natural selection)|purifying selection]].<ref>{{Cite journal |last1=Partha |first1=Raghavendran |last2=Chauhan |first2=Bharesh K |last3=Ferreira |first3=Zelia |last4=Robinson |first4=Joseph D |last5=Lathrop |first5=Kira |last6=Nischal |first6=Ken K. |last7=Chikina |first7=Maria |last8=Clark |first8=Nathan L. |date=October 2017 |title=Subterranean mammals show convergent regression in ocular genes and enhancers, along with adaptation to tunneling |journal=eLife |volume=6 |doi=10.7554/eLife.25884|pmid=29035697 |pmc=5643096 }}</ref><ref>{{cite journal |last1=Sackton |first1=TB |last2=Grayson |first2=P |last3=Cloutier |first3=A |last4=Hu |first4=Z |last5=Liu |first5=JS |last6=Wheeler |first6=NE |last7=Gardner |first7=PP |last8=Clarke |first8=JA |last9=Baker |first9=AJ |last10=Clamp |first10=M |last11=Edwards |first11=SV |title=Convergent regulatory evolution and loss of flight in paleognathous birds. |journal=Science |date=5 April 2019 |volume=364 |issue=6435 |pages=74–78 |doi=10.1126/science.aat7244 |pmid=30948549|bibcode=2019Sci...364...74S |s2cid=96435050 |url=http://nrs.harvard.edu/urn-3:HUL.InstRepos:39865637 |doi-access=free }}</ref>

==In animal morphology==
[[File:Ichthyosaur vs dolphin.svg|thumb|upright=1.5|Dolphins and ichthyosaurs converged on many adaptations for fast swimming.]]

===Bodyplans ===

Swimming animals including [[Biology:Fish|fish]] such as [[Biology:Herring|herring]]s, marine mammals such as dolphins, and [[Biology:Ichthyosaur|ichthyosaur]]s (of the Mesozoic) all converged on the same streamlined shape.<ref>{{cite web |title=How do analogies evolve? |url=http://evolution.berkeley.edu/evolibrary/article/similarity_ms_08 |publisher=University of California Berkeley |access-date=2017-01-26 |archive-url=https://web.archive.org/web/20170402153740/http://evolution.berkeley.edu/evolibrary/article/similarity_ms_08 |archive-date=2017-04-02 |url-status=live }}</ref><ref>{{cite book |last1=Selden |first1=Paul |last2=Nudds |first2=John |edition=2nd |title=Evolution of Fossil Ecosystems |url=https://books.google.com/books?id=LgdL9ZP2ftgC&pg=PA133 |year=2012 |publisher=CRC Press |isbn=978-1-84076-623-3 |page=133 |access-date=2017-01-26 |archive-url=https://web.archive.org/web/20170215082234/https://books.google.com/books?id=LgdL9ZP2ftgC&pg=PA133 |archive-date=2017-02-15 |url-status=live }}</ref> A similar shape and swimming adaptations are even present in molluscs, such as ''[[Biology:Phylliroe|Phylliroe]]''.<ref>{{Cite web|url=http://www.deepseanews.com/2015/11/meet-the-sea-slug-that-looks-like-a-fish-lives-in-the-deep-sea-and-glows/|title=Meet Phylliroe: the sea slug that looks and swims like a fish|last=Helm|first=R. R.|date=2015-11-18|website=Deep Sea News|language=en-US|access-date=2019-07-26|archive-url=https://web.archive.org/web/20190726003554/http://www.deepseanews.com/2015/11/meet-the-sea-slug-that-looks-like-a-fish-lives-in-the-deep-sea-and-glows/|archive-date=2019-07-26|url-status=live}}</ref> The fusiform bodyshape (a tube tapered at both ends) adopted by many aquatic animals is an adaptation to enable them to [[Biology:Animal locomotion|travel at high speed]] in a high [[Physics:Drag|drag]] environment.<ref>{{Cite web |url=http://cetus.ucsd.edu/sio133/PDF/Marine%20Environment%20&%20Secondary%20Marine%20Forms2016.pdf |title=The Marine Environment as a Selective Force for Secondary Marine Forms |last=Ballance |first=Lisa |year=2016 |publisher=UCSD |access-date=2019-09-19 |archive-url=https://web.archive.org/web/20170202025138/http://cetus.ucsd.edu/sio133/PDF/Marine%20Environment%20%26%20Secondary%20Marine%20Forms2016.pdf |archive-date=2017-02-02 |url-status=live }}</ref> Similar body shapes are found in the [[Biology:Earless seal|earless seal]]s and the eared seals: they still have four legs, but these are strongly modified for swimming.<ref>{{cite journal | author1=Lento, G. M. | author2=Hickson, R. E. | author3=Chambers, G. K. | author4=Penny, D. | date=1995 | title=Use of spectral analysis to test hypotheses on the origin of pinnipeds | journal=Molecular Biology and Evolution | volume=12 | issue=1 | pages=28–52 | pmid=7877495 | doi=10.1093/oxfordjournals.molbev.a040189 | doi-access=free }}</ref>

The marsupial fauna of Australia and the placental mammals of the Old World have several strikingly similar forms, developed in two clades, isolated from each other.<ref name=SCM2005>{{Cite book | last=Conway Morris | first=Simon | year=2005 | title=Life's solution: inevitable humans in a lonely universe | isbn=978-0-521-60325-6 | oclc=156902715 | publisher=Cambridge University Press | pages=[https://archive.org/details/lifessolutionine01conw/page/164 164, 167, 170 and 235] | url=https://archive.org/details/lifessolutionine01conw/page/164 }}</ref> The body and especially the skull shape of the [[Biology:Thylacine|thylacine]] (Tasmanian tiger or Tasmanian wolf) converged with those of [[Biology:Canidae|Canidae]] such as the red fox, ''Vulpes vulpes''.<ref>{{cite journal |journal=Australian Journal of Zoology|volume=34 |issue=2 |year=1986 |pages=109–117 |title=Comparison of Skull Shape in Marsupial and Placental Carnivores |last=Werdelin |first=L. |doi=10.1071/ZO9860109}}</ref>{{clear}}

<gallery heights="150px" mode="packed" caption="Convergence of [[Biology:Marsupial|marsupial]] and placental mammals">
File:Vulpes vulpes skeleton.JPG|[[Biology:Red fox|Red fox]] skeleton
File:Beutelwolf fg01.jpg|Skulls of  [[Biology:Thylacine|thylacine]] (left),  timber wolf (right)
File:Beutelwolfskelett brehm.png|[[Biology:Thylacine|Thylacine]] skeleton
</gallery>

=== Echolocation ===

As a sensory adaptation, [[Philosophy:Animal echolocation|echolocation]] has evolved separately in cetaceans (dolphins and whales) and bats, but from the same genetic mutations.<ref>{{Cite journal |last1=Liu |first1=Yang |last2=Cotton |first2=James A. |last3=Shen |first3=Bin |last4=Han |first4=Xiuqun |last5=Rossiter |first5=Stephen J. |last6=Zhang |first6=Shuyi |date=2010-01-01 |title=Convergent sequence evolution between echolocating bats and dolphins |journal=Current Biology |volume=20 |issue=2 |pages=R53–R54 |doi=10.1016/j.cub.2009.11.058 |pmid=20129036 |s2cid=16117978 |doi-access=free }}</ref>

=== Electric fishes ===

The [[Biology:Gymnotiformes|Gymnotiformes]] of South America and the [[Biology:Mormyridae|Mormyridae]] of Africa independently evolved [[Philosophy:Electroreception and electrogenesis|passive electroreception]] (around 119 and 110 million years ago, respectively). Around 20 million years after acquiring that ability, both groups evolved active [[Biology:Electric fish|electrogenesis]], producing weak electric fields to help them detect prey.<ref name="Lavoué Miya 2012">{{cite journal |last1=Lavoué |first1=Sébastien |last2=Miya |first2=Masaki |last3=Arnegard |first3=Matthew E. |last4=Sullivan |first4=John P. |last5=Hopkins |first5=Carl D. |last6=Nishida |first6=Mutsumi |title=Comparable Ages for the Independent Origins of Electrogenesis in African and South American Weakly Electric Fishes |journal=PLOS ONE |volume=7 |issue=5 |date=14 May 2012 |doi=10.1371/journal.pone.0036287 |page=e36287|pmid=22606250 |pmc=3351409 |bibcode=2012PLoSO...736287L |doi-access=free }}</ref>

===Eyes===
[[File:Evolution eye.svg|thumb|The camera eyes of vertebrates (left) and cephalopods (right) developed independently and are wired differently; for instance, optic nerve <sup>(3)</sup> fibres <sup>(2)</sup> reach the vertebrate retina <sup>(1)</sup> from the front, creating a blind spot <sup>(4)</sup>.<ref>{{cite book|last=Roberts|first=M.B.V.|date=1986|url= https://books.google.com/books?id=ASADBUVAiDUC&pg=PA574|title=Biology: A Functional Approach|url-status=live|archive-url= https://web.archive.org/web/20160912091025/https://books.google.com/books?id=ASADBUVAiDUC&pg=PA574|archive-date=2016-09-12|publisher=Nelson Thornes|page=274|isbn=978-0-17-448019-8}}</ref>]]

One of the best-known examples of convergent evolution is the camera eye of cephalopods (such as squid and octopus), [[Biology:Vertebrate|vertebrate]]s (including mammals) and [[Biology:Cnidaria|cnidaria]] (such as jellyfish).<ref name="Kozmik2008">{{cite journal|last=Kozmik|first=Z |author2=Ruzickova, J |author3=Jonasova, K |author4=Matsumoto, Y. |author5=Vopalensky, P. |author6=Kozmikova, I. |author7=Strnad, H. |author8=Kawamura, S. |author9=Piatigorsky, J. |author10=Paces, V. |author11=Vlcek, C. |title=From the Cover: Assembly of the cnidarian camera-type eye from vertebrate-like components|journal=Proceedings of the National Academy of Sciences |date=1 July 2008 |volume=105|issue=26 |pages=8989–8993|doi=10.1073/pnas.0800388105|pmid=18577593 |pmc=2449352 |bibcode=2008PNAS..105.8989K |doi-access=free }}</ref>  Their last common ancestor had at most a simple photoreceptive spot, but a range of processes led to the [[Biology:Evolution of the eye|progressive refinement of camera eyes]] — with one sharp difference: the cephalopod eye is "wired" in the opposite direction, with blood and nerve vessels entering from the back of the retina, rather than the front as in vertebrates. As a result, cephalopods lack a [[Biology:Blind spot (vision)|blind spot]].<ref name=SCM2005/>

===Flight===
[[File:Homology.jpg|thumb|upright|Vertebrate wings are partly [[Biology:Homology|homologous]] (from forelimbs), but analogous as organs of flight in (1) pterosaurs, (2) bats, (3) birds, evolved separately.]]

Birds and [[Biology:Bat|bat]]s have [[Biology:Homology|homologous]] limbs because they are both ultimately derived from terrestrial [[Biology:Tetrapod|tetrapod]]s, but their flight mechanisms are only analogous, so their wings are examples of functional convergence. The two groups have independently evolved their own means of powered flight.  Their wings differ substantially in construction. The bat wing is a membrane stretched across four extremely elongated fingers and the legs. The airfoil of the bird wing is made of feathers, strongly attached to the forearm (the ulna) and the highly fused bones of the wrist and hand (the [[Biology:Carpometacarpus|carpometacarpus]]), with only tiny remnants of two fingers remaining, each anchoring a single feather. So, while the wings of bats and birds are functionally convergent, they are not anatomically convergent.<ref name=BerkeleyHomologyAnalogy>{{cite web |title=Homologies and analogies |url=http://evolution.berkeley.edu/evolibrary/article/evo_09 |publisher=University of California Berkeley |access-date=2017-01-10 |archive-url=https://web.archive.org/web/20161119095845/http://evolution.berkeley.edu/evolibrary/article/evo_09 |archive-date=2016-11-19 |url-status=live }}</ref><ref>{{cite web |title=Plant and Animal Evolution |url=http://sci.waikato.ac.nz/evolution/Homology.shtml |publisher=University of Waikato |access-date=2017-01-10 |archive-url=https://web.archive.org/web/20170318123517/http://sci.waikato.ac.nz/evolution/Homology.shtml |archive-date=2017-03-18 |url-status=live }}</ref> Birds and bats also share a high concentration of [[Biology:Cerebroside|cerebroside]]s in the skin of their wings. This improves skin flexibility, a trait useful for flying animals; other mammals have a far lower concentration.<ref>{{Cite journal |last1=Ben-Hamo |first1=Miriam |last2=Muñoz-Garcia |first2=Agustí |last3=Larrain |first3=Paloma |last4=Pinshow |first4=Berry |last5=Korine |first5=Carmi |last6=Williams |first6=Joseph B. |date=June 2016 |title=The cutaneous lipid composition of bat wing and tail membranes: a case of convergent evolution with birds |journal=Proc. R. Soc. B |volume=283 |issue=1833 |page=20160636 |doi=10.1098/rspb.2016.0636 |pmid=27335420 |pmc=4936036 }}</ref> The extinct [[Biology:Pterosaur|pterosaur]]s independently evolved wings from their fore- and hindlimbs, while [[Biology:Insect|insect]]s have [[Biology:Insect wing|wings]] that evolved separately from different organs.<ref>{{cite book |last=Alexander |first=David E. |title=On the Wing: Insects, Pterosaurs, Birds, Bats and the Evolution of Animal Flight |url=https://books.google.com/books?id=H6xUCgAAQBAJ&pg=PT28 |year=2015 |publisher=Oxford University Press |isbn=978-0-19-999679-7 |page=28 |access-date=2017-01-21 |archive-url=https://web.archive.org/web/20170214224338/https://books.google.com/books?id=H6xUCgAAQBAJ&pg=PT28 |archive-date=2017-02-14 |url-status=live }}</ref>

Flying squirrels and [[Biology:Sugar glider|sugar glider]]s are much alike in their body plans, with gliding wings stretched between their limbs, but flying squirrels are placental mammals while sugar gliders are marsupials, widely separated within the mammal lineage from the placentals.<ref>{{cite web |title=Analogy: Squirrels and Sugar Gliders |url=http://evolution.berkeley.edu/evolibrary/article/analogy_02 |publisher=University of California Berkeley |access-date=2017-01-10 |archive-url=https://web.archive.org/web/20170127120055/http://evolution.berkeley.edu/evolibrary/article/analogy_02 |archive-date=2017-01-27 |url-status=live }}</ref>

[[Biology:Hummingbird hawk-moth|Hummingbird hawk-moth]]s and [[Biology:Hummingbird|hummingbird]]s have evolved similar flight and feeding patterns.<ref name="herrera">
{{cite journal |last1 = Herrera |title = Activity pattern and thermal biology of a day-flying hawkmoth (''Macroglossum stellatarum'') under Mediterranean summer conditions |journal = Ecological Entomology |volume = 17 |pages = 52–56 |year = 1992 |doi = 10.1111/j.1365-2311.1992.tb01038.x |first1 = Carlos M.|hdl = 10261/44693 |s2cid = 85320151 |hdl-access = free }}</ref>

===Insect mouthparts===
Insect mouthparts show many examples of convergent evolution. The mouthparts of different insect groups consist of a set of [[Biology:Homology|homologous]] organs, specialised for the dietary intake of that insect group. Convergent evolution of many groups of insects led from original biting-chewing mouthparts to different, more specialised, derived function types. These include, for example, the [[Biology:Proboscis|proboscis]] of flower-visiting insects such as [[Biology:Bee|bee]]s and flower beetles,<ref name="Krenn-2005">{{cite journal |last1=Krenn |first1=Harald W. |last2=Plant |first2=John D. |last3=Szucsich |first3=Nikolaus U. |year=2005 |title=Mouthparts of flower-visiting insects |journal=Arthropod Structure & Development |volume=34 |issue=1 |pages=1–40 |doi=10.1016/j.asd.2004.10.002}}</ref><ref name="Krenn-2011">{{cite journal |last1=Bauder |first1=Julia A.S. |last2=Lieskonig |first2=Nora R. |last3=Krenn |first3=Harald W. |year=2011 |title=The extremely long-tongued Neotropical butterfly Eurybia lycisca (Riodinidae): Proboscis morphology and flower handling |journal=Arthropod Structure & Development |volume=40 |issue=2 |pages=122–7 |doi=10.1016/j.asd.2010.11.002|pmid=21115131 |pmc=3062012 }}</ref><ref name="Krenn-2012-1">{{cite journal |last1=Wilhelmi |first1=Andreas P. |last2=Krenn |first2=Harald W. |year=2012 |title=Elongated mouthparts of nectar-feeding Meloidae (Coleoptera) |journal=Zoomorphology |volume=131 |issue=4 |pages=325–37 |doi=10.1007/s00435-012-0162-3|s2cid=9194699 }}</ref> or the biting-sucking mouthparts of blood-sucking insects such as fleas and [[Biology:Mosquito|mosquito]]s.

===Opposable thumbs===
Opposable thumbs allowing the grasping of objects are most often associated with [[Biology:Primates|primates]], like humans, monkeys, apes, and lemurs. Opposable thumbs also evolved in giant pandas, but these are completely different in structure, having six fingers including the thumb, which develops from a wrist bone entirely separately from other fingers.<ref>{{cite web|title=When is a thumb a thumb?|url=http://evolution.berkeley.edu/evolibrary/article/analogy_06|website=Understanding Evolution|access-date=2015-08-14|archive-url=https://web.archive.org/web/20151016133905/http://evolution.berkeley.edu/evolibrary/article/analogy_06|archive-date=2015-10-16|url-status=live}}</ref>

===Primates===

{| style="border-collapse: collapse" class="floatleft" width=222px
|- 
|style="padding:0;margin:0"| {{CSS image crop|Image=Veronika Loncká.jpg|bSize=73|cWidth = 74|cHeight = 65|oTop = 0|oLeft =0}}
|style="padding:0;margin:0"| {{CSS image crop|Image=Angela Bassett by Gage Skidmoe.jpg|bSize=84|cWidth = 74|cHeight = 65|oTop = 10|oLeft =0}}
|style="padding:0;margin:0"| {{CSS image crop|Image=(미쓰와이프) 제작기영상 엄정화 3m3s.jpg|bSize=104|cWidth = 74|cHeight = 65|oTop = 17|oLeft =17}}
|-
|colspan=3 style="padding:0;margin:0"|[[File:Convergent evolution human skin color map.svg|222px]] {{resize|90%|Despite the similar lightening of skin colour after moving out of Africa, different genes were involved in European (left) and East-Asian (right) lineages.}}
|}

Convergent evolution in humans includes blue eye colour and light skin colour.<ref name="Edwards 2010"/> When humans migrated out of Africa, they moved to more northern latitudes with less intense sunlight.<ref name="Edwards 2010"/> It was beneficial to them to reduce their skin pigmentation.<ref name="Edwards 2010"/> It appears certain that there was some lightening of skin colour ''before'' European and East Asian lineages diverged, as there are some skin-lightening genetic differences that are common to both groups.<ref name="Edwards 2010"/> However, after the lineages diverged and became genetically isolated, the skin of both groups lightened more, and that additional lightening was due to ''different'' genetic changes.<ref name="Edwards 2010">{{cite journal |last1=Edwards |first1=M. |display-authors=0 |title=Association of the OCA2 Polymorphism His615Arg with Melanin Content in East Asian Populations: Further Evidence of Convergent Evolution of Skin Pigmentation |journal=PLOS Genetics |date=2010 |doi=10.1371/journal.pgen.1000867 |volume=6 |issue=3 |pages=e1000867 |pmid=20221248 |pmc=2832666}}</ref>

{| style="border-collapse: collapse" class="floatright"  width=220px
|-
! colspan=2|Humans
! colspan=2|Lemurs
|- 
|style="padding:0;margin:0"| {{CSS image crop|Image=A_blue_eye.jpg|bSize=100|cWidth = 50|cHeight = 50|oTop = 25|oLeft =25}}
|style="padding:0;margin:0"| {{CSS image crop|Image=Eye_See_You_(2346693372).jpg|bSize=130|cWidth = 50|cHeight = 50|oTop = 8|oLeft =53}}
|style="padding:0;margin:0"| {{CSS image crop|Image=Eulemur_mongoz_(male_-_face).jpg |bSize=400|cWidth = 50|cHeight = 50|oTop = 130|oLeft =150}}
|style="padding:0;margin:0"| {{CSS image crop|Image=Blue-eyed_black_lemur.jpg|bSize=400|cWidth = 50|cHeight = 50|oTop = 100|oLeft =133}}
|-
|colspan=4 style="padding:0;margin:0"|{{resize|90%|Despite the similarity of appearance, the genetic basis of blue eyes is different in humans and lemurs.}}
|}

Lemurs and [[Humans|humans]] are both primates. Ancestral primates had brown eyes, as most primates do today. The genetic basis of blue eyes in humans has been studied in detail and much is known about it. It is not the case that one gene locus is responsible, say with brown dominant to blue eye colour. However, a single locus is responsible for about 80% of the variation. In lemurs, the differences between blue and brown eyes are not completely known, but the same gene locus is not involved.<ref>{{cite journal |last1=Meyer |first1=W. K.| display-authors=0 |title=The convergent evolution of blue iris pigmentation in primates took distinct molecular paths |journal=American Journal of Physical Anthropology |date=2013 |volume=151 |issue=3|pages=398–407 |doi=10.1002/ajpa.22280 |pmid=23640739 |pmc=3746105}}</ref>{{clear left}}

==In plants==
[[File:Chelidonium majus seeds.jpg|thumb|right|In myrmecochory, seeds such as those of ''Chelidonium majus'' have a hard coating and an attached oil body, an elaiosome, for dispersal by ants.]]

===Carbon fixation===

While convergent evolution is often illustrated with animal examples, it has often occurred in [[Biology:Plant|plant]] evolution. For instance, C<sub>4</sub> photosynthesis, one of the three major carbon-fixing biochemical processes, has [[Biology:Evolutionary history of plants#Evolution of photosynthetic pathways|arisen independently up to 40 times]].<ref name="williamsjohnston">{{cite journal |author1=Williams, B. P. |author2=Johnston, I. G. |author3=Covshoff, S. |author4=Hibberd, J. M.  | title=Phenotypic landscape inference reveals multiple evolutionary paths to C4 photosynthesis | journal=eLife | volume=2 | pages=e00961 |date=September 2013 | doi=10.7554/eLife.00961 | pmid=24082995 | pmc=3786385}}</ref><ref name=Osborne2006>{{cite journal |author=Osborne, C. P. |author2=Beerling, D. J. |year=2006 |title=Nature's green revolution: the remarkable evolutionary rise of {{C4}} plants |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=361 |issue=1465 |pages=173–194 |doi=10.1098/rstb.2005.1737 |pmid=16553316 |pmc=1626541}}</ref> About 7,600 plant species of [[Biology:Angiosperm|angiosperm]]s use {{c4}} carbon fixation, with many monocots including 46% of grasses such as [[Biology:Zea mays|maize]] and sugar cane,<ref>{{cite book |last=Sage |first=Rowan |author2=Russell Monson |title=C4 Plant Biology |year=1999 |pages=551–580 |chapter=16 |isbn=978-0-12-614440-6 |chapter-url=https://books.google.com/books?id=H7Wv9ZImW-QC&pg=PA551}}</ref><ref>{{cite journal |author1=Zhu, X. G. |author2=Long, S. P. |author3=Ort, D. R. |title=What is the maximum efficiency with which photosynthesis can convert solar energy into biomass? |year=2008 |journal=Current Opinion in Biotechnology |volume=19 |pages=153–159 |doi=10.1016/j.copbio.2008.02.004 |pmid=18374559 |issue=2 |url=https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=36097&content=PDF |access-date=2018-12-29 |archive-url=https://web.archive.org/web/20190401014953/https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=36097&content=PDF |archive-date=2019-04-01 |url-status=live }}</ref> and dicots including several species in the Chenopodiaceae and the [[Biology:Amaranthaceae|Amaranthaceae]].<ref>{{cite book |last=Sage |first=Rowan |author2=Russell Monson |title=C4 Plant Biology |year=1999 |pages=228–229 |chapter=7 |isbn=978-0-12-614440-6 |chapter-url=https://books.google.com/books?id=H7Wv9ZImW-QC&pg=PA228}}</ref><ref>{{cite journal |author1=Kadereit, G. |author2=Borsch, T. |author3=Weising, K. |author4=Freitag, H |title=Phylogeny of Amaranthaceae and Chenopodiaceae and the Evolution of {{C4}} Photosynthesis |year=2003 |journal=International Journal of Plant Sciences |volume=164 |issue=6 |pages=959–86 |doi=10.1086/378649|s2cid=83564261 }}</ref>

===Fruits===

A good example of convergence in plants is the evolution of edible [[Biology:Fruit|fruit]]s such as [[Biology:Apple|apple]]s. These [[Biology:Pome|pome]]s incorporate (five) carpels and their accessory tissues forming the apple's core, surrounded by structures from outside the botanical fruit, the [[Biology:Receptacle (botany)|receptacle]] or [[Biology:Hypanthium|hypanthium]]. Other edible fruits include other plant tissues;<ref>{{cite journal|last1=Ireland |first1=Hilary, S. | display-authors=0 |title=Apple SEPALLATA1/2 -like genes control fruit flesh development and ripening|journal=The Plant Journal |date=2013 |volume=73 |issue=6 |pages=1044–1056 |doi=10.1111/tpj.12094 |pmid=23236986 |doi-access=free }}</ref> for example, the fleshy part of a [[Biology:Tomato|tomato]] is the walls of the pericarp.<ref>{{cite book |last=Heuvelink |first=Ep |title=Tomatoes |url=https://books.google.com/books?id=qwMnnepN3uIC&pg=PA72 |year=2005 |publisher=CABI |isbn=978-1-84593-149-0 |page=72 |access-date=2016-12-17 |archive-url=https://web.archive.org/web/20190401051807/https://books.google.com/books?id=qwMnnepN3uIC&pg=PA72 |archive-date=2019-04-01 |url-status=live }}</ref> This implies convergent evolution under selective pressure, in this case the competition for seed dispersal by animals through consumption of fleshy fruits.<ref name="evolution_seed">{{cite journal |author1=Lorts, C. |author2=Briggeman, T. |author3=Sang, T.  |title=Evolution of fruit types and seed dispersal: A phylogenetic and ecological snapshot <!--http://www.sciencemeta.com/index.php/JSE/article/view/1580606--> |journal=Journal of Systematics and Evolution |volume=46 |issue=3 |pages=396–404 |year=2008 |doi=10.3724/SP.J.1002.2008.08039 |doi-broken-date=31 December 2022 |url=http://www.plantsystematics.com/qikan/manage/wenzhang/jse08039.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130718025713/http://www.plantsystematics.com/qikan/manage/wenzhang/jse08039.pdf |archive-date=2013-07-18 }}</ref>

Seed dispersal by ants ([[Biology:Myrmecochory|myrmecochory]]) has evolved independently more than 100 times, and is present in more than 11,000 plant species. It is one of the most dramatic examples of convergent evolution in biology.<ref name="myrmecochory">{{cite journal |author1=Lengyel, S. |author2=Gove, A. D. |author3=Latimer, A. M. |author4=Majer, J. D. |author5=Dunn, R. R. | title=Convergent evolution of seed dispersal by ants, and phylogeny and biogeography in flowering plants: a global survey | journal=Perspectives in Plant Ecology, Evolution and Systematics | volume=12 | pages=43–55 | year=2010 | doi=10.1016/j.ppees.2009.08.001 }}</ref>

=== Carnivory ===
[[File:Chitinase4TC.jpg|thumb|upright=1.5|Molecular convergence in carnivorous plants]]

Carnivory has evolved multiple times independently in plants in widely separated groups. In three species studied, ''[[Biology:Cephalotus|Cephalotus follicularis]]'', ''[[Biology:Nepenthes alata|Nepenthes alata]]'' and ''[[Biology:Sarracenia purpurea|Sarracenia purpurea]]'', there has been convergence at the molecular level. Carnivorous plants secrete [[Biology:Enzymes|enzymes]] into the digestive fluid they produce. By studying [[Biology:Purple acid phosphatases|phosphatase]], [[Biology:Glycoside hydrolase family 19|glycoside hydrolase]], [[Biology:Glucanase|glucanase]],  RNAse and [[Biology:Chitinase|chitinase]] [[Biology:Enzyme|enzyme]]s as well as a [[Biology:Pathogenesis-related protein|pathogenesis-related protein]] and a [[Biology:Thaumatin|thaumatin]]-related protein,  the authors found many convergent [[Chemistry:Amino acid|amino acid]] substitutions. These changes were not at the enzymes' catalytic sites, but rather on the exposed surfaces of the proteins, where they might interact with other components of the cell or the digestive fluid. The authors also found that homologous genes in the non-carnivorous plant ''[[Biology:Arabidopsis thaliana|Arabidopsis thaliana]]'' tend to have their expression increased when the plant is stressed, leading the authors to suggest that stress-responsive proteins have often been co-opted{{efn|The prior existence of suitable structures has been called pre-adaptation or [[Biology:Exaptation|exaptation]].}} in the repeated evolution of carnivory.<ref name=Fukushima2017>{{cite journal |last1=Fukushima |first1=K |last2=Fang |first2=X |display-authors=0 |title=Genome of the pitcher plant Cephalotus reveals genetic changes associated with carnivory |journal=Nature Ecology & Evolution |date=2017 |volume=1 |issue=3 |doi=10.1038/s41559-016-0059 |pmid=28812732 |doi-access=free |page=0059}}</ref>

==Methods of inference==
[[File:Phenotypic-landscape-inference-reveals-multiple-evolutionary-paths-toC4-photosynthesis-elife00961fs002.jpg|thumb|upright=1.5|[[Biology:Angiosperm|Angiosperm]] phylogeny of orders based on classification by the Angiosperm Phylogeny Group. The figure shows the number of inferred independent origins of C<sub>3</sub>-C<sub>4</sub> photosynthesis and C<sub>4</sub> photosynthesis in parentheses.]]

Phylogenetic reconstruction and [[Biology:Ancestral reconstruction|ancestral state reconstruction]] proceed by assuming that evolution has occurred without convergence. Convergent patterns may, however, appear at higher levels in a phylogenetic reconstruction, and are sometimes explicitly sought by investigators. The methods applied to infer convergent evolution depend on whether pattern-based or process-based convergence is expected. Pattern-based convergence is the broader term, for when two or more lineages independently evolve patterns of similar traits. Process-based convergence is when the convergence is due to similar forces of [[Biology:Natural selection|natural selection]].<ref name="Stayton2">{{Cite journal |last=Stayton |first=C. Tristan |date=2015 |title=The definition, recognition, and interpretation of convergent evolution, and two new measures for quantifying and assessing the significance of convergence |journal=Evolution |volume=69 |issue=8 |pages=2140–2153 |doi=10.1111/evo.12729|pmid=26177938 |s2cid=3161530 }}</ref>

=== Pattern-based measures ===
Earlier methods for measuring convergence incorporate ratios of phenotypic and phylogenetic distance by simulating evolution with a [[Brownian motion]] model of trait evolution along a phylogeny.<ref>{{cite journal |last=Stayton |first=C. Tristan|title=Is convergence surprising? An examination of the frequency of convergence in simulated datasets |journal=Journal of Theoretical Biology |volume=252 |issue=1 |pages=1–14 |doi=10.1016/j.jtbi.2008.01.008 |pmid=18321532|year=2008|bibcode=2008JThBi.252....1S}}</ref><ref>{{cite journal |last1=Muschick |first1=Moritz |last2=Indermaur |first2=Adrian |last3=Salzburger |first3=Walter |title=Convergent Evolution within an Adaptive Radiation of Cichlid Fishes |journal=Current Biology |volume=22 |issue=24 |pages=2362–2368 |doi=10.1016/j.cub.2012.10.048 |pmid=23159601 |year=2012|doi-access=free }}</ref> More recent methods also quantify the strength of convergence.<ref>{{Cite journal |last1=Arbuckle |first1=Kevin |last2=Bennett |first2=Cheryl M. |last3=Speed |first3=Michael P. |date=July 2014 |title=A simple measure of the strength of convergent evolution |journal=Methods in Ecology and Evolution |volume=5 |issue=7 |pages=685–693 |doi=10.1111/2041-210X.12195|doi-access=free }}</ref> One drawback to keep in mind is that these methods can confuse long-term stasis with convergence due to phenotypic similarities. Stasis occurs when there is little evolutionary change among taxa.<ref name="Stayton2" />

Distance-based measures assess the degree of similarity between lineages over time. Frequency-based measures assess the number of lineages that have evolved in a particular trait space.<ref name="Stayton2" />

=== Process-based measures ===

Methods to infer process-based convergence fit models of selection to a phylogeny and continuous trait data to determine whether the same selective forces have acted upon lineages. This uses the [[Ornstein–Uhlenbeck process|Ornstein–Uhlenbeck (OU) process]] to test different scenarios of selection. Other methods rely on an ''a priori'' specification of where shifts in selection have occurred.<ref>{{Cite journal |last1=Ingram |first1=Travis |last2=Mahler |first2=D. Luke |date=2013-05-01 |title=SURFACE: detecting convergent evolution from comparative data by fitting Ornstein-Uhlenbeck models with stepwise Akaike Information Criterion |journal=Methods in Ecology and Evolution |volume=4 |issue=5 |pages=416–425 |doi=10.1111/2041-210X.12034|s2cid=86382470 }}</ref>

==See also==
* {{annotated link|Biology:Incomplete lineage sorting}}: the presence of multiple alleles in ancestral populations might lead to the impression that convergent evolution has occurred.
* {{annotated link|Biology:Carcinisation}}

==Notes==
{{Notelist}}
{{Clear}}

==References==
{{Reflist|30em}}

==Further reading==

* {{cite book |title=Improbable Destinies: Fate, Chance, and the Future of Evolution |author=Jonathan B. Losos |year=2017 |publisher=Riverhead Books |isbn=978-0399184925 |ref=none}}

{{evo ecol}}

[[Category:Evolutionary biology concepts]]

{{Sourceattribution|Convergent evolution|1}}