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Map showing sample localities and current taxonomic status with Iguana: Inset shows the Lesser Antilles. Further geographic details for each lineage can be found in Table 1. ‘aff.’ indicates the uncertain taxonomic status, which is undergoing assessment (van den Burg et al. in prep)
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Biodiversity and wild populations are globally threatened by a wide range of actors. The genus Iguana, widely distributed throughout the Americas, is under threat by invasive species, hybridization, the global pet trade, and habitat destruction. This holds especially true for the insular lineages, with the Critically Endangered I. delicatissima hav...
Citations
... Currently, I. delicatissima is confined to only a few populations, which either remain pure and inhabit small islets of <2 km 2 or remain present on larger islands were hybridization has or is occurring (Vuillaume et al., 2015;Angin, 2017;van den Burg et al., 2018b;Pounder et al., 2020). Stakeholders throughout the region are trying to conserve these last remaining populations, a process that is extremely challenging given the number of regionally established non-native green iguana populations that have differing, but only marginally studied (though see Vuillaume et al., 2015;van den Burg et al., 2018b;Pounder et al., 2020) geographic origins from throughout the highly variable I. iguana complex (Stephen et al. 2013;van den Burg et al., 2021). ...
... Compared to I. delicatissima, intraspecific variation is more evident within green iguanas (Day & Thorpe, 1996;Breuil, 2013;Stephen et al., 2013;van den Burg et al., 2021;van den Burg et al., in prep.), although a full range-wide assessment has not been performed. Established non-native Iguana populations within the Lesser Antilles have different, and often multiple, geographic origins (Vuillaume et al., 2015;Pounder et al., 2020;De Jesús Villanueva et al., 2021;Breuil et al., in prep.). ...
Invasive alien species severely impact native and endemic species, disproportionately affecting insular species, and this is especially true for Caribbean reptiles. The Lesser Antillean iguana (Iguana delicatissima) experienced a drastic range decline strongly driven by hybridization with non-native green iguanas (NNGI, Iguana iguana species complex). With numerous NNGI populations within the Lesser Antilles, it is a matter of time before these arrive on the last I. delicatisisma inhabited islands, whereupon rapid in-situ identification of non-native and hybrid animals is essential. However, only a few scale and coloration characters allow in-situ identification of NNGI, which are compromised by introgression. Here we assessed the differentiating power of an additional 20 scale and length-dependent characteristics between the I. delicatissima population on St. Eustatius and the established NNGI population on St. Maarten, the main source of arriving stowaway iguanas on St. Eustatius. We identified 14 length-dependent characteristics that significantly differ between I. delicatissima and NNGI’s, with multi-variate analysis showing clear morphospace separation and high assignment accuracy of predictive models (>91%). Additionally, the number of femorals and supra digital scales significantly differs between these iguanas. Morphospace knowledge of St. Eustatius’ I. delicatissima now allows rapid identification of any divergent iguanas using easy to obtain measurements and meristics. Given intraspecific variation in I. delicatissima and green iguanas, we recommend that these characteristics are assessed and validated for other populations, including hybrid individuals. Our work demonstrates the urgent need to invest in baseline morphometric datasets to aid rapid in-situ conservation efforts once NNGI arrive and start to hybridize with I. delicatissima.
... samples from the IguanaBase dataset analyzed at the GenIndexe Animal Genetics Lab in France, were also genotyped and compared to their original GenIndexe scores [38]. A total of 17 microsatellite markers were evaluated (based on van den Burg et al. [39]), and polymerase chain reaction (PCR) protocols specified by Schuelke [40] were used to amplify DNA segments at the specific marker sites. A 1% agarose gel was used to verify successful PCR amplification. ...
Lizards within the Iguana iguana species complex are among the most common reptilian
pets, with the widest natural geographic range among iguanids. Deep phylogenetic divergence distinguishes multiple mitochondrial clades, and several taxonomic changes have recently been proposed. These small populations, typically island endemics, are threatened by numerous factors, including the international pet trade. Recent investigations reveal the absence of required CITES permits for lawful export of animals, providing evidence of ongoing illegal trade. Additional monitoring of trade in iguanas can be achieved through the application of forensic molecular techniques. In this study, two captive melanistic iguanas were genotyped for molecular markers for which geographic distributions of alleles have been established. Mitochondrial sequencing indicates that both animals carry a haplotype known to originate from the islands of Saba and Montserrat, populations taxonomically proposed to be Iguana melanoderma. Genotypes at 15 microsatellite loci are equally consistent with this origin, given the results of a principal component analysis. This first forensic genetic assessment within the extensive I. iguana pet trade highlights the presence of illegal activity. The need for additional forensic assessments of pet‐trade iguanas is evident, especially given that their value is driven by variety and rarity, which is further intensified by recent taxonomic changes.
... Non-native presence and potential hybridization in native Iguana populations are mostly assessed using microsatellite and sequence data in conjunction with genetic databases for native populations (e.g., Vuillaime et al. 2015; van den Burg et al. 2018bvan den Burg et al. , 2021bPounder et al. 2020), especially for hatchling and juvenile iguanas given their high morphological similarity between island populations. Although some comparisons on scale and coloration patterns can also be used (Breuil 2013), the data underlying this reference dataset only covers a small part of the Iguana iguana complex and numerous characteristics are not informative. ...
... Microsatellite laboratory procedures at Labofarm-GenIndexe (France) using identical methodologies as presented in Valette et al. (2013) were used to amplify 17 microsatellite loci (see van den Burg et al. 2021b). Then, PCR product analyses and allele scoring were performed following van den Burg et al. ...
Invasive alien species are among the main drivers of the ongoing sixth mass extinction wave, especially affecting island populations. Although the Caribbean is well-known for its high species richness and endemism, also for reptiles, equally important is the regional contribution of non-native species to island biodiversity. The Lesser Antilles encompass high genetic diversity in Iguana , though most native populations either have gone extinct or are declining following competitive hybridization with invasive non-native iguanas. Here we assessed non-native presence in two poorly-studied native melanistic Iguana iguana populations using available genetic tools, and explored utilizing size-dependent body measurements to discriminate between native and non-native iguanas. Genetic samples from Saba and Montserrat were genotyped across 17 microsatellite loci with STRUCTURE and multivariate analyses indicating non-native iguanas presence only on Saba. This was corroborated by mtDNA and nDNA sequences, highlighting a non-native origin in Central America and the ABC islands. We identified preliminary evidence suggestive of hybridization. Morphological variation among size-dependent characteristics showed that non-native iguanas have significantly larger subtympanic plates than native iguanas. Non-native individuals also differed in scalation and coloration patterns. Overall, our findings demonstrate the need for continuous monitoring for non-native iguanas within remaining native Iguana populations in the Lesser Antilles, with those not directly threatened by non-native iguanas restricted to only 8.7% of the historic range. Although genetic data allows for identification of non-native or hybrid iguana presence, this field-to-lab workflow is time consuming. Rapid in-situ identification of non-native individuals is crucial for conservation management, and besides scale and coloration patterns, we have highlighted the utility of size-dependent variables for rapid diagnosis. We urge regional partners to build morphometric databases for native Iguana populations that will help to quickly detect future incursions of non-native iguanas and allow the rapid implementation of effective countermeasures during the early phase of invasion.
... A further challenge is that most juvenile specimens in this genus look very similar to the untrained eye, which has enabled traders to export rare iguanas under the guise of ordinary captive-bred I. iguana [5]. While it is now possible to use genetic techniques to accurately determine the geographic origin of any individual iguana and identify whether it is a hybrid ( [17][18][19][20]), there is currently almost no capacity in the Caribbean region to perform such tests. ...
Lizards in the Neotropical genus Iguana are heavily traded for the international pet trade, with unusual colour morphs and rare species commanding high prices. Recent research aimed to understand the taxonomy and phenotypic variation of Iguana in the Lesser Antilles, with those populations now severely threatened by this trade. Although the entire Iguana genus has been on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix II since 1977, current levels of trade regulation are proving to be inadequate for the Caribbean Iguana populations, which are declining. This paper presents the case for immediately halting regional commercial trade to safeguard the most vulnerable island populations. We further provide recommendations for trade regulations of other species complexes where the nomenclature used in legislation and the trade industry fall temporarily out of step with new taxonomic changes.
Invasive alien species are among the main drivers of the ongoing sixth mass extinction wave, especially affecting island populations. Although the Caribbean is well‐known for its high species richness and endemism, also for reptiles, equally important is the regional contribution of non‐native species to island biodiversity. The Lesser Antilles encompass high genetic diversity in Iguana, though most native populations either have gone extinct or are declining following competitive hybridization with invasive non‐native green iguanas. Here, we assessed non‐native presence in two poorly‐studied native melanistic Iguana iguana populations using available genetic tools and explored utilizing size‐dependent body measurements to discriminate between native and non‐native iguanas. Genetic samples from Saba and Montserrat were genotyped across 17 microsatellite loci with STRUCTURE, and multivariate analyses indicating non‐native iguana presence only on Saba. This was corroborated by mtDNA and nDNA sequences, highlighting a non‐native origin in Central America and the ABC islands. We identified preliminary evidence suggestive of hybridization. Morphological variation among size‐dependent characteristics showed that non‐native iguanas have significantly larger subtympanic plates than native iguanas. Non‐native individuals also differed in scalation and coloration patterns. Overall, our findings demonstrate the need for continuous monitoring of non‐native iguanas within remaining native Iguana populations in the Lesser Antilles, as those not directly threatened by non‐native green iguanas are restricted to only 8.7% of the historic range. Although genetic data allow for the identification of non‐native or hybrid iguana presence, this field‐to‐lab workflow is time‐consuming. Rapid in‐situ identification of non‐native individuals is crucial for conservation management. In addition to patterns of scalation and coloration, we have highlighted the utility of size‐dependent variables for rapid diagnosis. We urge regional partners to build morphometric databases for native Iguana populations allowing the quick detection of future incursions of non‐native green iguanas and the rapid implementation of effective countermeasures during the early phase of invasion.
Intraspecific diversity is among the most important biological variables, although still poorly understood for most species. Iguana iguana is a Neotropical lizard known from Central and South America, including from numerous Caribbean islands. Despite the presence of native melanistic I. iguana populations in the Lesser Antilles, these have received surprisingly little research attention. Here we assessed population size, distribution, degree of melanism, and additional morphological and natural history characteristics for the melanistic iguanas of Saba, Caribbean Netherlands based on a one-month fieldwork visit. Using Distance sampling from a 38-transect dataset we estimate the population size at 8233 ±2205 iguanas. Iguanas mainly occurred on the southern and eastern sides of the island, between 180-390 m (max altitude 530 m), with highest densities both in residential and certain natural areas. Historically, iguanas were relatively more common at higher altitudes, probably due to more extensive forest clearing for agricultural reasons. No relationship was found between the degree of melanism and elevation, and few animals were completely melanistic. Furthermore, we found that body-ratio data collection through photographs is biased and requires physical measuring instead. Although the population size appears larger than previously surmised, the limited nesting sites and extremely low presence of juvenile and hatchling iguanas (2.4%), is similarly worrying as the situation for I. delicatissima on neighboring St. Eustatius. The island's feral cat and large goat population are suspected to impact nest site quality, nest success, and hatchling survival. These aspects require urgent future research to guide necessary conservation management.
The newly described horned iguana Iguana insularis from the southern Lesser Antilles is separated in two easily recognized subspecies: I. insularis sanctaluciae from St. Lucia and I. insularis insularis from the
Grenadines. Its former description is completed by the use of 38 new samples for genetic and morphological analysis. Seventeen microsatellites were used to estimate genetic diversity, population structure and the level of introgression with other Iguana species over nearly the whole range of the species. ND4 and PAC sequences were also used to better characterize hybridization and to complete the description of this lineage. The I. insularis population of St. Vincent shows a high level of introgression from I. iguana whereas in the Grenadines, most islands present pure insularis populations but several show evidence of introgressions. Of the two remaining populations of I. insularis sanctaluciae, only one is still purebred. The recent identification of this and other distinct insular species and subspecies in the eastern Caribbean, and evaluation of where hybridization has occurred, are timely and important because the native iguanas are in urgent need of conservation action. Among the greatest threats is the ongoing human-mediated spread of invasive iguanas from Central and South America, which are destroying the endemic insular lineages through multiple diachronic introgression events.
