An overlooked pink species of land iguana in the Galapagos - PubMed (original) (raw)

An overlooked pink species of land iguana in the Galapagos

Gabriele Gentile et al. Proc Natl Acad Sci U S A. 2009.

Abstract

Despite the attention given to them, the Galápagos have not yet finished offering evolutionary novelties. When Darwin visited the Galápagos, he observed both marine (Amblyrhynchus) and land (Conolophus) iguanas but did not encounter a rare pink black-striped land iguana (herein referred to as "rosada," meaning "pink" in Spanish), which, surprisingly, remained unseen until 1986. Here, we show that substantial genetic isolation exists between the rosada and syntopic yellow forms and that the rosada is basal to extant taxonomically recognized Galápagos land iguanas. The rosada, whose present distribution is a conundrum, is a relict lineage whose origin dates back to a period when at least some of the present-day islands had not yet formed. So far, this species is the only evidence of ancient diversification along the Galápagos land iguana lineage and documents one of the oldest events of divergence ever recorded in the Galápagos. Conservation efforts are needed to prevent this form, identified by us as a good species, from extinction.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.

Fig. 1.

Galápagos Islands. The islands where land iguanas occur or have occurred in historic times are in gray. The locations of sampling sites are reported in Materials and Methods.

Fig. 2.

Fig. 2.

Adult male iguanas of the yellow (A, Sierra Negra; D, Volcan Wolf) and rosada (B and C, Volcan Wolf) forms (photograph by G.G.)

Fig. 3.

Fig. 3.

ML phylogenetic tree. The tree is rooted at the midpoint. The branches subtending the node A and the genus Amblyrhynchus have been equally shortened. The asterisk denotes a terminal node. Numbers at the nodes indicate statistical support as follows (from top): MP, ML, Bayesian analysis. For MP and ML, only bootstrap values higher than 70 are shown. For Bayesian analysis numbers indicate posterior probability values. The number of individuals examined is reported inside each terminal triangle.

Fig. 4.

Fig. 4.

STRUCTURE analyses. (A) ΔK values are shown for K ranging between 2 and 6. Maximum value is observed when K = 2. (B) Results after the first analysis indicate individuals WA7 and WA11 (yellow morphotypes) as possible hybrids. The second analysis, which was more refined, indicates WA11 as a possible second-generation hybrid (see text).

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References

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