Phylogeography of West Indies Coral snakes (Micrurus): Island colonisation and banding patterns

Abstract

In this study, we analyse New World coral snakes in a phylogenetic framework based upon an increased molecular data set, including novel sequences for the only two sympatric species known from an island (Trinidad, West Indies). Their presence in Trinidad and absence in Tobago offers a unique system to study the phylogeography of the region. We assess the tempo and mode of colonisation of Micrurus on the island, in addition to discussing the phylogenetic relationships for the genus Micrurus concerning two phenotypic traits, body and tail banding patterns. These relationships are analysed for the first time on statistical coalescent phylogeographic discrete ancestral reconstruction. We find a robust phylogenetic component in these characteristics, where strongly supported clades are recovered: prior to the onset of the Early Miocene, a triadal and tricolour tail clade composed of species from South America, and a second clade dating to the Middle‐Late‐ Miocene with monadal and bicolour tails widely distributed from North to South America. The divergence between clades dates to the Oligocene and suggests an ancient pre‐isthmus divergence supporting the arrival of the triadal clade into South America, before the connection between Central and South America was established. We find the two coral snakes present in the West Indies, M. diutius and M. circinalis, belong to the triadal and monadal clades, respectively. Guyana and Trinidad Micrurus diutius share the same haplotypes suggesting a Late Pleistocene–Holocene vicariance when sea level rises separated Trinidad from the mainland. A second lineage of diutius‐like snakes is present in Guyana and is confirmed as M. lemniscatus which is assigned as a voucher and restricts the type locality for M. lemniscatus.

Biogeographical patterns of amphibians and reptiles in the northernmost coastal montane complex of South America

“…Furthermore, the PR has likely been colonized from both southern and northern regions, increasing its biodiversity. Some evidence for colonization routes may derive from the low genetic divergence of species between Guyana, French Guiana, and Trinidad (an extension of the PR) from eastern coastal regions, most likely through Pleistocene eustatic sea-level falls [ 72 – 74 ]. Similarly, genetic divergence of Elachistocleis from the southern Lago de Maracaibo basin, a region located between the Cordillera de Mérida and Serranía de Perijá (Western versant Cordillera de Mérida), show high genetic affinities to Trinidad Elachistoclies sp.…”

“…Trinidad’s Northern Range was a connected northeastern extension of the Paria Range until the Pliocene when subsidence associated with the Gulf of Paria (Boca del Dragón) separated these two land-masses [ 93 – 96 ]. Prolonged land bridge connections thereafter, at low sea level stands in the Pliocene and Pleistocene, have however facilitated the exchange of faunas and thus gene flow [ 46 , 74 , 97 ]. Accordingly, Trinidad shares many species with the Paria Range [ 37 , 47 ].…”

The enigmatic biogeography of Tobago's marooned relics: The case study of a fossorial snake (Squamata, Dipsadidae)

“…Several phylogenetic studies in the region suggest that the frequently changing topography facilitated the connections and colonization events between the mainland (Venezuela and Guyana) and the islands of Trinidad and Tobago (Jowers et al, 2011(Jowers et al, , 2015(Jowers et al, , 2020Murphy, Salvi, Santos, et al, 2019). Interestingly, most studies show remarkably low genetic divergence between localities (Jowers et al, 2019;Murphy et al, 2016), suggesting recent colonization of the Lesser Antilles and island extensions plausibly via sea-level drops of 50-120 m (Hansen & Routledge, 2016;Murphy, 1997;Rohling et al, 2014). Most studies have addressed the colonization of Trinidad, as this island has a much greater biodiversity than Tobago, is closer to the mainland, and was historically part of the continental mass.…”

“…Most studies have addressed the colonization of Trinidad, as this island has a much greater biodiversity than Tobago, is closer to the mainland, and was historically part of the continental mass. For example, studies on New World Coral snakes (Micrurus diutius), and the Black-Headed snake (Tantilla melanocephala) from Guyana and Venezuela have shown Pleistocene splits between populations (Jowers et al, 2019(Jowers et al, , 2020, and genetic similarity in the Trinidad Threadsnake (Epictia tenella) indicates possible rafting from Guyana (Murphy et al, 2016). Genetic work on the only other Atractus from Trinidad and Tobago, A. trilineatus, has likewise revealed recent divergence between Guyana, Trinidad and Tobago, again corresponding to likely low sea-level stands .…”

Defensive Tail-curling and Head-mimicking Behavior in a Variable Coralsnake, Micrurus diastema (Squamata: Elapidae) in Cusuco National Park, Honduras

“…In combination with aposematism, widely used defensive strategies in both Micrurus and their mimics include nonlocomotory thrash-and-flash displays (Moore et al 2020) and tail-display behaviors (Green 1973). In the genus Micrurus, many species possess similarly patterned heads and tails to confuse predators (Jowers et al 2019), and when attacked, often place their heads beneath the coils of their bodies while raising and flattening their tail to imitate the head (Green 1973). Tail-flattening behavior, a form of self-mimicry called the Protean effect (Gelbach 1972), was previously reported in M. diastema from Honduras (Talley et al 2013).…”