Editing Macroevolution (section)

=== Evolution of viviparity in lizards ===
[[File:Zootoca vivipara. 3epo.Post.jpg|thumb|The European Common Lizard (''[[Viviparous lizard|Zootoca vivipara]]'') consists of populations that are egg-laying or live-bearing, demonstrating that this dramatic difference can even evolve within a species.]]
Most lizards are egg-laying and thus need an environment that is warm enough to incubate their eggs. However, some species have evolved [[viviparity]], that is, they give birth to live young, as almost all [[mammal]]s do. In several clades of lizards, egg-laying (oviparous) species have evolved into live-bearing ones, apparently with very little genetic change. For instance, a European common lizard, [[Viviparous lizard|''Zootoca vivipara'']], is viviparous throughout most of its range, but oviparous in the extreme southwest portion.<ref>{{Cite journal |last=Heulin |first=Benoît |date=1990-05-01 |title=Étude comparative de la membrane coquillère chez les souches ovipare et vivipare du lézard Lacerta vivipara |url=http://www.nrcresearchpress.com/doi/10.1139/z90-147 |journal=Canadian Journal of Zoology |language=en |volume=68 |issue=5 |pages=1015–1019 |doi=10.1139/z90-147 |bibcode=1990CaJZ...68.1015H |issn=0008-4301}}</ref><ref>{{Cite journal |last1=Arrayago |first1=Maria-Jesus |last2=Bea |first2=Antonio |last3=Heulin |first3=Benoit |date=1996 |title=Hybridization Experiment between Oviparous and Viviparous Strains of Lacerta vivipara: A New Insight into the Evolution of Viviparity in Reptiles |url=https://www.jstor.org/stable/3892653 |journal=Herpetologica |volume=52 |issue=3 |pages=333–342 |jstor=3892653 |issn=0018-0831}}</ref> That is, within a single species, a radical change in reproductive behavior has happened. Similar cases are known from South American lizards of the genus ''[[Liolaemus]]'' which have egg-laying species at lower altitudes, but closely related viviparous species at higher altitudes, suggesting that the switch from oviparous to viviparous reproduction does not require many genetic changes.<ref>{{Cite journal |last1=Ii |first1=James A. Schulte |last2=Macey |first2=J. Robert |last3=Espinoza |first3=Robert E. |last4=Larson |first4=Allan |date=January 2000 |title=Phylogenetic relationships in the iguanid lizard genus Liolaemus: multiple origins of viviparous reproduction and evidence for recurring Andean vicariance and dispersal |journal=Biological Journal of the Linnean Society |language=en |volume=69 |issue=1 |pages=75–102 |doi=10.1111/j.1095-8312.2000.tb01670.x|doi-access=free }}</ref>