進化の法則を破る「ハルクトカゲ」 ― 数百万年続いた色多様性が消滅 (‘Hulk’ wall lizards cause millions of years of color diversity to disappear)

2026-01-09 マックス・プランク研究所

ドイツ・マックスプランク進化生物学研究所らの研究で、特定の「Hulk」壁トカゲ(wall lizard)系統の急速な拡大が、何百万年も維持されてきた色彩多型(スリーモードの喉色)を消しつつあることが明らかになった。地中海周辺の220集団を調べた結果、元来白・黄・オレンジの3色喉色が混在していた集団は、緑黒色の「Hulk」型が侵入・拡大する地域では黄色やオレンジの形質が失われ、白一色に固定される傾向が見られた。ゲノム解析により、単なる遺伝的連鎖ではなく、「Hulk」型の高い攻撃性や社会的優位性によって行動的・繁殖戦略のバランスが崩れ、多型が維持できなくなっていることが示唆された。この研究は、長年進化生物学の教科書的例として扱われてきた多型維持モデルが、新たな形質の出現によって崩壊し得ることを示し、進化の規則性には例外があることを実証している。

進化の法則を破る「ハルクトカゲ」 ― 数百万年続いた色多様性が消滅 (‘Hulk’ wall lizards cause millions of years of color diversity to disappear)
Comparisons of  common wall lizard heads showing the nigriventris white, ancestral white, yellow and orange throat coloration (from top to bottom).© Roberto Garcia-Roa

<関連情報>

性選択症候群の適応的拡散により、壁トカゲにおける古代の色の多型性が排除される Adaptive spread of a sexually selected syndrome eliminates an ancient color polymorphism in wall lizards

Tobias Uller, Nathalie Feiner, Roberto Sacchi, Marco Zuffi, […] , and Geoffrey M. While
Science  Published:1 Jan 2026
DOI:https://doi.org/10.1126/science.adx3708

Editor’s summary

Many animal species exhibit different physical characteristics between individuals, especially when it comes to males. Lizards are particularly interesting examples, because many species have multiple versions of males. Studying these species can inform understanding of how such polymorphism evolves and operates. Uller et al. found that a recently emerged white throated morph of European wall lizards was highly preferred over an earlier three-color system, which has led to disruption of a million-year balance across the morphs (see the Perspective by Gopalan and Castoe). In related work on side-blotched lizards in the United States, Corl et al. found that a well-known morphological triad of males was generated by a two-allele system, with phenotypic plasticity at one of the alleles and a rock-paper-scissors dynamic. —Sacha Vignieri

Abstract

Genetically determined color morphs are found in many animals. Polymorphism can be maintained by social selection if competitive interactions allow each morph to increase in frequency when rare. This reliance on negative frequency–dependent selection should make color polymorphism vulnerable to the appearance of novel phenotypes that disrupt competitive interactions among morphs. We show that the origin and adaptive spread of a sexually selected syndrome in common wall lizards (Podarcis muralis) selectively eliminates alleles coding for alternative color morphs that have been maintained for millions of years. The results demonstrate how the arrival of a novel phenotype can disrupt balancing selection, providing a link between rapid phenotypic evolution and the loss of color polymorphisms.

1903自然環境保全
ad
ad
Follow
ad
タイトルとURLをコピーしました