Saving the harlequin toads: Genetic structure and historical demography of the populations of Atelopus (Anura: Bufonidae) from the Sierra Nevada de Santa Marta.

Harlequin toads (Atelopus) are considered the most endangered vertebrate genus in the world, with approximately 87% of species classified as endangered, critically endangered, or extinct in the wild (Frost, 2013; Della Togna et al. ., 2017).

Among the causes that have generated their population reductions or extinctions are the transformation and loss of habitat, pollution, change
climate change and trade in exotic species (De Sá, 2005).

However, these factors do not explain the population declines observed in pristine habitats or in conserved areas (Lips, 1998), where the main cause of mass mortality events and population reduction is the disease called chytridiomycosis, produced by the Batrachochytrium fungus. dendrobatidis (Bd) (Longcore et al., 1999).

In Sierra Nevada de Santa Marta there are four species of harlequin toads (Atelopus laetissimus, A.nahumae, A, carrikeri, A. arsyecue, which are categorized as endangered according to IUCN criteria due to the different emerging threats in their territories, such as habitat loss and degradation, contamination of water resources, presence of invasive species, emerging diseases and climate change (Granda-Rodríguez et al., 2012).

These species probably represent some of the last of their genus with stable and abundant populations (Granda et al., 2012; Rueda-Solano et al., 2016), a situation that stands in stark contrast to the dramatic declines and extinctions documented in more than 75 % of upland species (La Marca et al., 2005; Lotters, 2007).

However, in the first place, the historical population trend of the species during the years in which population declines were reported in Colombia is unknown (Lynch and Grant 1998); therefore, it is possible that the current populations of both species have faced declines that were not documented.

Secondly, the spatial heterogeneity determined by the SNSM massif (Forero et al., 2011) can affect functional connectivity, that is, the movement between individuals of different populations, which can have implications for flow, diversity and their genetic structure (Watts et al., 2015); in this case, amphibians are particularly susceptible to genetic isolation due to their low dispersal potential (Gómez-Rodríguez et al., 2009).

Third, connectivity between populations may also be determined by environmental features within and between habitat patches, whereby landscape condition may create resistance to gene flow, leading to an increased effect of genetic drift. and risk of suffering from local extinctions due to the limited ability to respond to abrupt changes in the environment (Premoli et al., 2011; Tammone, 2016); likewise, it is crucial to take into account that the coverages in which the populations of the species under study are found are contrasting, due to
because the town of San Pedro de la Sierra presents notable agricultural and livestock activities that have transformed and degraded the habitat of the harlequin toads; in comparison with the localities of San Lorenzo, Rio ancho, Páramo de cebolletas and Sogrome, which present better conservation conditions because they are protected areas and indigenous reservations respectively.

Therefore, in this project we pose the following research question: What is the genetic structure and historical demography of Atelopus species in contrasting environments as a result of anthropic intervention in the Sierra Nevada de Santa Marta?

Phylogeography, Populations, Amphibians, Conservation.