A pilot study to estimate the population size of endangered Galápagos marine iguanas using drones.

BACKGROUND: Large-scale species monitoring remains a significant conservation challenge. Given the ongoing biodiversity crisis, the need for reliable and efficient methods has never been greater. Drone-based techniques have much to offer in this regard: they allow access to otherwise unreachable areas and enable the rapid collection of non-invasive field data. Herein, we describe the development of a drone-based method for the estimation of population size in Galápagos marine iguanas, Amblyrhynchus cristatus. As a large-bodied lizard that occurs in open coastal terrain, this endemic species is an ideal candidate for drone surveys. Almost all Amblyrhynchus subspecies are Endangered or Critically Endangered according to the IUCN yet since several colonies are inaccessible by foot, ground- based methods are unable to address the critical need for better census data. In order to establish a drone-based approach to estimate population size of marine iguanas, we surveyed in January 2021 four colonies on three focal islands (San Cristobal, Santa Fe and Espanola) using three techniques: simple counts (the standard method currently used by conservation managers), capture mark-resight (CMR), and drone-based counts. The surveys were performed within a 4-day window under similar ambient conditions. We then compared the approaches in terms of feasibility, outcome and effort. RESULTS: The highest population-size estimates were obtained using CMR, and drone-based counts were on average 14% closer to CMR estimates-and 17-35% higher-than those obtained by simple counts. In terms of field-time, drone-surveys can be faster than simple counts, but image analyses were highly time consuming. CONCLUSION: Though CMR likely produces superior estimates, it cannot be performed in most cases due to lack of access and knowledge regarding colonies. Drone-based surveys outperformed ground-based simple counts in terms of outcome and this approach is therefore suitable for use across the range of the species. Moreover, the aerial approach is currently the only credible solution for accessing and surveying marine iguanas at highly remote colonies. The application of citizen science and other aids such as machine learning will alleviate the issue regarding time needed to analyze the images.

Three new species of frogs of the genus Pristimantis (Anura, Strabomantidae) with a redefinition of the P. lacrimosus species group.

A new phylogeny for the Pristimantis lacrimosus species group is presented, its species content reviewed, and three new species described from the eastern slopes of the Ecuadorian Andes. Our phylogeny includes, for the first time, samples of P. aureolineatus, P. bromeliaceus, and P. lacrimosus. The morphology of hyperdistal subarticular tubercles is also assessed among 21 species of Pristimantis. The P. lacrimosus species group is composed of 36 species distributed in the Chocó, Guiana, and Amazon regions of tropical South America with a single species reaching Central America. Ancestral area reconstruction indicates that, despite its high diversity in the Amazon region, the P. lacrimosus group originated in the Pacific basin, Chocó region of Ecuador and Colombia. Pristimantis amaguanae sp. nov. is most closely related to P. bromeliaceus. It differs from P. bromeliaceus by being smaller, having transversal dark bands in the hindlimbs (absent or faint in P. bromeliaceus) and the absence of discoidal fold (present in P. bromeliaceus). Pristimantis nankints sp. nov. and P. romeroae sp. nov. are part of a clade of predominantly light-green frogs that includes P. acuminatus, P. enigmaticus, P. limoncochensis, and P. omeviridis. Pristimantis nankints sp. nov. and P. romeroae sp. nov. can be distinguished from all of them by the presence of a dark dorsolateral stripe that borders a light green band on a green background. Hyperdistal tubercles are present in all examined species of the P. lacrimosus species group and its sister clade. Species with hyperdistal tubercles are characterized by having relatively long terminal phalanges and narrow T-shaped expansion at the end of the terminal phalange. We discuss the phylogenetic distribution of these characters and their potential diagnostic significance.

Analysis of ultraconserved elements supports African origins of narrow-mouthed frogs.

Narrow-mouthed frogs (Anura: Microhylidae) are globally distributed and molecular data suggest the rapid evolution of multiple subfamilies shortly after their origin. Despite recent progress, several subfamilial relationships remain unexplored using phylogenomic data. We analysed 1,796 nuclear ultraconserved elements, a total matrix of 400,664 nucleotides, from representatives of most microhylid subfamilies. Summary method species-tree and maximum likelihood analyses unambiguously supported Hoplophryninae as the earliest diverging microhylid and confirm Chaperininae as a junior synonym of Microhylinae. Given the emerging consensus that subfamilies from mainland Africa diverged early, microhylids have likely occupied the continent for more than 66 million years.

A new treefrog from Cordillera del Cóndor with comments on the biogeographic affinity between Cordillera del Cóndor and the Guianan Tepuis (Anura, Hylidae, Hyloscirtus).

The Hyloscirtuslarinopygion group is a clade of 16 species of large hylids that inhabit cascading Andean streams. They have brown coloration that, in most species, contrasts with bright marks. Herein morphological and genetic evidence is used to describe a new species of the group from Cordillera del Cóndor, a sub-Andean mountain chain that has phytogeographic affinities with the Guianan Tepuis. The new species is characterized by dark-brown coloration with contrasting bright orange flecks and by the presence of an enlarged and curved prepollex protruding as a spine. The new species is closely related to H.tapichalaca and an undescribed species from the southern Andes of Ecuador. The genetic distance between H.hillisi sp. n. and its closest relative, H.tapichalaca, is 2.9% (gene 16S mtDNA). Our phylogeny and a review of recently published phylogenies show that amphibians from Cordillera del Cóndor have close relationships with either Andean or Amazonian species. Amphibians do not show the Condor-Guianan Tepuis biogeographic link that has been documented in plants.