Painted black: Iguana melanoderma (Reptilia, Squamata, Iguanidae) a new melanistic endemic species from Saba and Montserrat islands (Lesser Antilles)

The complete mitochondrial genome of the Critically Endangered Saba Green Iguana, Iguana iguana (Squamata: Iguanidae)

The populations of native iguanas in the Caribbean Lesser Antilles are threatened by the wide occurrence and spread of non-native iguanas. Until recently, competitive hybridization was not believed to threaten the Saba Green Iguana, a subpopulation of Iguana iguana (Linnaeus, 1758) from the island of Saba. However, the arrival of non-native iguanas has put the native population at risk, leading to a change in the conservation status of the Saba Green Iguana to Critically Endangered, according to guidelines from the International Union for the Conservation of Nature. Here, we generated the complete mitogenome of the Saba Green Iguana using Oxford Nanopore long-read technology. The mitogenome is 16,626 bp long and has 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region (1194 bp). Noteworthy, this is only the second published mitogenome for the Iguana iguana species complex, despite the known high intraspecific genetic variation.

Forensic Genetic Analyses of Melanistic Iguanas Highlight the Need to Monitor the Iguanid Trade

Simple Summary

The illegal pet trade remains an ongoing, substantial threat to wild populations, especially small insular populations, and can even lead to extinction. Fraudulent activity within the global reptile trade is known to occur, but its identification through forensic applications depends on knowledge of diversity within wild populations. In this study, we assessed the geographic origin of melanistic iguanas (Iguana iguana), which are only found in nations that have never authorized legal export of live animals. Analysis of genetic data from two pet iguanas in the USA flag these as originating from Saba or Montserrat, from which no export permits have ever been issued, confirming their illegal origin. Despite the international trade in I. iguana, in which tens- if not hundreds of thousands of specimens are traded each year, only a handful of individuals have been genetically assessed. Our work highlights the utility of applying forensic genetic techniques to this trade in order to track and discourage illegal activity.

Abstract

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.

Urgent International Action Needed to Tackle Illegal Pet Trade in Caribbean Iguana Populations

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.

Iguanainsularis (Iguanidae) from the southern Lesser Antilles: An endemic lineage endangered by hybridization

The newly described horned iguanaIguanainsularis from the southern Lesser Antilles is separated in two easily recognized subspecies: I.insularissanctaluciae from St. Lucia and I.insularisinsularis 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.insularissanctaluciae, 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.

Gastroesophageal tube of the Iguana iguana (Iguanidae): histological description, histochemical and immunohistochemical analysis of 5-HT and SS cells

The work aims were to describe the histological and histochemical structure of the gastroesophageal tube of Iguana iguana and verify the occurrence and distribution of immunoreactive serotonin (5-HT) and somatostatin (SS) cells. Fragments of the gastrointestinal tract (GIT) of five iguanas were which underwent standard histological and immunohistochemistry technique. Immunoreactive cells for 5-HT and SS were quantified using the STEPanizer. The oesophagus has ciliated columnar pseudostratified epithelium with staining Alcian blue (AB) + and goblet cells highly reactive to periodic acid Schiff (PAS). In the cervical oesophagus, the numerical density of 5-HT cells per unit area (QA [5-HT cells]/µm2) was 4.6x10-2 ± 2.0 and celomatic oesophagus presented QA = 4.0x10-2 ± 1.0. The epithelium of the stomach is simple columnar, PAS and AB +. The cranial and middle regions of the stomach presented (QA [5-HT cells]/µm2) = 6.18x10-2 ± 3.2 and the caudal region, QA = 0.6x10-2 ± 0.2. The SS cells were only observed in the caudal stomach, with numerical density (QA [SS cells]/µm2) = 1.4x10-2 ± 0.9 In I. iguana, variation was observed in terms of the distribution of mucus secretions and the pattern of occurrence of serotonin and somatostatin-secreting enteroendocrine cells in the TGI, which possibly will result in an interspecific adaptive response.

Population increase and changes in behavior and morphology in the Critically Endangered Redonda ground lizard (Pholidoscelis atratus) following the successful removal of alien rats and goats

Redonda is a small volcanic Caribbean island that is home to at least 4 endemic lizard species, including the Critically Endangered ground lizard (Pholidoscelis atratus). Black rats (Rattus rattus) and domestic goats (Capra hircus) were introduced to the island at some time after its discovery by Europeans in the late 1500s. They had a devastating effect on the island, resulting in the loss of nearly all trees and most of the ground vegetation. Point count surveys of P. atratus in 2012 indicated low densities, and the invasive rats were observed hunting and preying on the lizards. Both populations of rats and goats were successfully removed in 2017 as part of an ecological restoration program, and native vegetation and invertebrate populations have increased rapidly since. Population surveys in 2017, 2018, and 2019 show the lizard population has increased by more than sixfold. In 2017, as rats and goats were being removed, we evaluated the morphology and escape behavior of this species and repeated these measurements 1 year later. We observed that P. atratus had become bolder, with a reduced flight distance. We also detected changes in limb morphology related to locomotion and suggest possible explanations that will need to be further investigated in the future. These results show how the removal of invasive species can rapidly affect lizard population recovery and behavior, potentially restoring island ecosystems to their pre‐human interference dynamics.