The genetic diversity and distribution of two endangered pit vipers (Bothriechis marchi and Cerrophidion wilsoni) within Cusuco National Park, Honduras

Abstract

The current extinction rate is being increasingly recognised as an escalating issue, with observations still indicating that humans are the leading cause of a sixth mass extinction. Cloud forests in particular are home to a variety of threatened species, however, many of these forests are highly fragmented resulting in many species and populations existing in isolation. These forests have become centres of endemism for many species, leading to a high representation within global biodiversity hotspots and “irreplaceable” protected areas.

This study primarily investigates the genetic diversity and distribution of two recently re-classified, sympatric pit vipers (Bothriechis marchi and Cerrophidion wilsoni) within Cusuco National Park, Honduras using samples acquired by Operation Wallacea Ltd. Twenty-nine B. marchi samples and forty-two C. wilsoni samples were successfully sequenced for the cytochrome oxidase subunit 1 (CO1), NADH dehydrogenase 4 (ND4), and two segments of the cytochrome b (CytB) gene to reveal eight haplotypes within the B. marchi population (haplotype diversity = 0.697044) compared to only two haplotypes within the C. wilsoni population (haplotype diversity = 0.493612). This low variation of mtDNA haplotype diversity within the C. wilsoni population may leave it vulnerable to future challenges.

The mapping of these haplotypes suggests a partial restriction of gene flow between the west and east of the park. This appears to be a larger issue for B. marchi, however ongoing research is required to confirm the significance and potential impact of this. The results also provide further support regarding the distribution of these species, indicating a higher abundance of B. marchi around the El Corticito camp on the west side of the park compared to a higher abundance of C. wilsoni around Cantiles camp in the centre of the park. At the El Danto camp there is a good likelihood of encountering both species, however, the high levels of deforestation on this side of the park pose a significant threat.

The continuation of this deforestation could result in the loss of approximately 33-55% of all found mtDNA genetic diversity within the B. marchi population and cause significant change within the genetic structure of this population. In addition, 71% of all B. marchi encounters and 33% of C. wilsoni encounters between 2007 and 2018 were recorded on the west side of the park, highlighting a greater vulnerability of B. marchi to the current deforestation on this side of the park and indicating that a large percentage of both populations may be lost due to this deforestation should it continue.