An overlooked pink species of land iguana in the Galápagos

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 blackstriped 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.genetic isolation ͉ molecular phylogeny ͉ evolution ͉ islands ͉ lizards S ince Darwin's pioneering work in the archipelago, the Galápagos Islands have been a major scientific resource for evolutionary biologists. This archipelago, currently consisting of about a dozen volcanic islands and more than 100 associated islets, is located on the equator, about 1,000 kilometers west of the South-American coast (Fig. 1). Given their volcanic origin, the Galápagos Islands host unique flora and fauna that have evolved over millions of years in geographic isolation, generating a variety of endemic species with unique and varied ecological, morphological, and behavioral adaptations (1, 2).Land iguanas are among the most spectacular representative species of the Galápagos Islands. They once lived in many areas of the Galápagos archipelago (Fig. 1). Currently, many factors contribute to their threatened status (3), one of which may be incomplete taxonomy (4). Two species of Galápagos land iguanas are currently recognized: Conolophus pallidus and Conolophus subcristatus, with the former occurring only on Santa Fe, whereas C. subcristatus occurs on Fernandina, Isabela, Santa Cruz, Plaza Sur, Seymour Norte (a translocated population), and Baltra.Charles Darwin visited the Galápagos in 1835. During the 5 weeks of his stay in the archipelago, he did not explore Volcan Wolf (the northernmost volcano in Isabela). Thus, although he noticed and commented on both marine and land iguanas (5), he did not encounter a distinct form of land iguana that occurs only on that volcano. Perhaps even more surprising, this form (herein referred to as ''rosada,'' † meaning ''pink'' in Spanish) remained unrecorded despite many other scientists having visited Volcan Wolf over the past century. Since it was accidentally seen by some Galápagos National Park rangers in 1986, this form has received no attention. The rosada form is characterized by a distinct phenotype (Fig. 2). It can be clearly distinguished from the syntopic...

Unravelling the peculiarities of island life: vicariance, dispersal and the diversification of the extinct and extant giant Galápagos tortoises

“…In such systems, the biogeography of organisms are fundamentally a product of oceanic dispersal (Cowie & Holland 2006). In the case of Galápagos, the colonization histories of several prominent organisms, estimated using molecular data, indicate the formative role of dispersal in patterns of diversification (Rassmann et al 1997;Sato et al 2001;Benavides et al 2007;Schmitz et al 2007;Parent et al 2008;Sequeira et al 2008;Gentile et al 2009). …”

Science and Conservation in the Galapagos Islands

“…By now, most geologists and biologists working in the Galapagos readily accept that as the Nazca plate moves eastward and the islands travel away from the hot spot, they decrease in altitude-apparently owing to the cooling and contraction of the crustand eventually subside (Geist 2009 ) . Recent evidence about the genetic distance between the marine and land iguanas, and especially the new species of land iguana (Gentile et al 2009 ) , provides further support for the currently drawn Galapagos Islands and an older origin of the archipelago.…”

“…These studies have begun to clarify more accurately several issues that were previously dif fi cult to track, such as the ancestral species and geographical origins of the different native species, especially of those that have radiated. We have still a long way to go, but thanks to molecular genetic studies, at least we have gained a better understanding of the historical evolution of Darwin's fi nches (Petren et al 1999(Petren et al , 2005Sato et al 2001a, b ) , Galapagos mockingbirds (Arbogast et al 2006 ;Hoeck et al 2010 ) , Galapagos hawk (Bollmer et al 2005(Bollmer et al , 2006(Bollmer et al , 2007Whiteman et al 2007 ;Hull et al 2008 ;Parker 2009a, b ) , Galapagos cormorant ( Kennedy et al 2009 ;Duf fi e et al 2009 ) , giant tortoises (Caccone et al 1999(Caccone et al , 2002 , land and marine iguanas (Wyles and Sarich 1983 ;Rassmann 1997 ;Gentile et al 2009 ) , lava lizards (Lopez et al 1992 ;Jordan et al 2002 ;Kizirian et al 2004 ;Jordan and Snell 2008 ) , bulimulid land snails (Parent and Crespi 2006 ;Parent et al 2008 ) , and a few others (Sequeira et al 2000 ;Schmitz et al 2007 ).…”

Cryptic diversity and conservation units in the Bahama parrot

“…Detailed genetic analyses are revealing important new insights into the evolutionary histories of some of the most iconic and threatened species on the planet (Russello et al 2005a;Brown et al 2007;Gentile et al 2009). The present work further demonstrates the importance of applying an evolutionary perspective to conservation management, combining population genetic, phylogenetic and historical DNA analyses of extant and extirpated taxa to resolve taxonomic uncertainty and designate conservation units within the Cuban parrot complex, taxa long-revered by local inhabitants and European explorers and now considered flagships for regional conservation.…”

“…Perhaps surprisingly, unrecognized genetic divisions have been detected in megafauna (Beheregaray and Caccone 2007) which historically constitute some of the most thoroughly studied organisms on the planet. Likewise, these groups are among the most imperiled, so that detection of cryptic diversity contributes immediately and directly to conservation efforts (Russello et al 2005a;Brown et al 2007;Poulakakis et al 2008;Gentile et al 2009). …”