Gonzalo Rivas-Torres

The introduction of invasive plant species has become a major threat to the unique biodiversity and ecological integrity of the Galápagos Islands. One of the most aggressive invaders is Syzygium jambos (Myrtaceae), which forms dense tree stands that suppress native vegetation and alter ecosystem functioning. Remarkably, populations of this invasive rose apple tree have undergone a pronounced decline on San Cristóbal Island in recent years. In this study, we combined remote sensing with pathogen identification to investigate this phenomenon. Spectral and spatial analyses revealed an approximate 73% reduction in S. jambos tree cover between 2018 and 2024. Concurrently, symptomatic leaves were examined using morphological characterization and molecular diagnostics. Nested PCR amplification followed by internal transcribed spacer (ITS) region sequencing confirmed the presence of Austropuccinia psidii , a myrtle rust fungus known to infect members of the Myrtaceae family, in symptomatic S. jambos leaves. This study combines morphological and molecular identification of A. psidii infecting S. jambos in the Galápagos Islands with a landscape-scale assessment of the invasive host’s decline. Our findings document an ecological paradox in which an invasive fungal pathogen infects an invasive tree, potentially contributing to its decline while posing a risk to native and endemic Myrtaceae. This interaction highlights how associations among non-native species may influence invasion dynamics, with potentially contrasting consequences for biodiversity conservation in vulnerable island ecosystems.

Background: Monitoring wildlife in remote areas is a key challenge in conservation, with traditional methods proving increasingly inadequate in the face of accelerating biodiversity loss. Uncrewed Aerial Vehicles (UAVs) or drones help bridge data gaps, but methods require careful development and validation to ensure protocols are appropriate, accessible, reproducible, and generate reliable data. Herein, we develop detailed UAV-based protocols for surveying the endangered marine iguana ( Amblyrhynchus cristatus ), a lizard that is endemic to the coastlines of the Galápagos Islands, Ecuador. We outline steps from image collection and processing, through locating and counting animals, before validating results against traditional methods. Results: We find that UAV-based surveys outperform traditional ground-based surveys in terms of count reliability and effort in the field in different types of terrain and various population densities. Moreover, we show that consumer-level drones can be used effectively — even by newly trained pilots — and describe a standardised manual flying protocol that mimics automated flying whilst maintaining flexibility in the field. Finally, we recommend the use of orthomosaics (geometrically corrected, high-resolution aerial image maps) for surveys on flat terrains and 3D models (digital representations of the surface in three dimensions) for cliffs and compare several common image-processing platforms in terms of success to reconstruct marine iguanas. Conclusion: Our protocols advance the effective monitoring of Galápagos marine iguanas. Whilst they were specifically developed for this species, we postulate that these could be applicable for other species across the archipelago, or in coastal and open landscapes worldwide.

Scalesia gordilloi is a critically endangered species endemic to San Cristobal Island in the Galapagos archipelago and represents one of the most unique and vulnerable lineages within the adaptive radiation of the genus Scalesia. Despite its evolutionary distinctiveness and conservation importance, no genomic resources have been available for this species. Here, we present the first high-quality reference genome of S. gordilloi, generated using Oxford Nanopore long-read sequencing. Across three PromethION R10.4.1 flow cells, we obtained 80.5 Gb of long reads (~25X coverage), which enabled a highly contiguous 3.61 Gb assembly composed of only 549 contigs and an N50 of 106.6 Mb. BUSCO completeness reached 98.6%, with assembly metrics comparable to other high-quality Asteraceae genomes. Repeat annotation revealed that 76.2% of the genome is composed of interspersed elements, dominated by LTR retrotransposons. Structural annotation resulted in 47,913 high-confidence protein-coding genes, consistent with expectations for large, repetitive Asteraceae genomes. This genome provides a critical foundation for conservation genomics, enabling assessments of genetic diversity, inbreeding, and adaptive potential in the species. It further establishes a framework for comparative genomics across the Scalesia radiation and supports future efforts to protect and restore one of the most threatened plant lineages of the Galapagos Islands.

Devil’s gardens are among the most striking ant–plant mutualisms in Amazonian forests. In this system, the tree Duroia hirsuta is associated with the ant Myrmelachista schumanni , which actively removes neighboring vegetation and maintains nearly monodominant patches of the host plant. Despite the apparent efficiency of this system, repeated field observations at the Tiputini Biodiversity Station, Yasuní Biosphere Reserve, revealed that individuals of Palicourea alba recurrently occur within active devil’s gardens. Palicourea alba closely resembles dead plant material, exhibiting leaf morphology and coloration that strongly mimic the surrounding litter layer, and appears to be uncommon outside these gardens. To our knowledge, this “dead-leaf” masquerade has not been previously documented in this intensively studied system, making it a particularly striking and unexpected observation. To evaluate whether this masquerade facilitates persistence within devil’s gardens, we surveyed 35 gardens and recorded P. alba in 19 (52.8%). When present, P. alba covered on average 27% of plot area, while mean herbivory across sampled leaves remained low (8.6%). Generalized linear mixed models showed that P. alba cover decreased significantly with increasing herbivory (F = 8.09, p = 0.0159), whereas herbivory increased with leaf-litter cover (F = 8.73, p = 0.0120). Field observations further revealed that many individuals are nearly indistinguishable from dry leaf litter, suggesting a role for visual crypsis or masquerade. Together, these results indicate initially, that the persistence of P. alba within devil’s gardens is mediated by a multi-layered ecological filtering process. First, masquerade likely reduces detection by M. schumanni , allowing seedlings to escape ant-mediated removal. Second, low herbivory suggests either enemy avoidance or reduced apparency to herbivores within the simplified understory. Third, spatial heterogeneity in leaf-litter cover may create microhabitats where both ant activity and herbivore pressure are modulated, reinforcing establishment success. This system thus represents a previously undocumented mechanism in which plant–litter resemblance enables persistence within a highly structured, biotically filtered habitat, highlighting how subtle trait-mediated interactions may modulate outcomes in otherwise strongly deterministic mutualisms.

Aim of study: Dialogue among stakeholders is key for implementing sustainable forest management in tropical forests. However, in such multi-actor processes, the role and interest of a key stakeholder such as scientists is often overlooked. Hence, the aim of this work was to analyse the topics that forest scientists have related the most to the concept of “tropical timber species” during the last four decades. Area of study: World´s tropical forests. Material and methods: Scientometric analyses (co-word analysis), using Bibliometrix and Biblioshiny R packages with Web of Science (WoS) and Scopus databases. Main results: A total of 35,204 documents were identified that used the “tropical timber species” concept. Scientific productivity grew from one occurrence in 1980 to 31,457 occurrences by 2023, with 40% of all relevant scientific productivity generated in the 2018-2023 period. Dominant research themes were related to basic science on ecological structure (topics such as taxonomy and biodiversity, with 4,682 and 4,359 occurrences, respectively). However, climate change is quickly growing in importance (575 occurrences in 2018-2023). In fact, climate change has become a basic research topic, while applied themes such as ecosystem fragmentation, deforestation, forest management and remote sensing have become the themes more prevalent (as niche, motor or basic themes) in the last two years studied (2022-2023). Research highlights: Scientists are increasingly showing interest in applied topics related to management of tropical timber species. However, forest scientists are also mostly interested in research related to biodiversity, conservation and climate change when studying tropical timber species. Hence, such issues should be taken into account in multi-actor dialogues on sustainable tropical forest management.

Scalesia (Asteraceae) is the largest endemic plant genus of the Galápagos archipelago and an example of adaptive radiation. While Scalesia species are highly varied in habit and morphology, most remarkable is their variety of leaf shapes, especially in the differential presence of leaf lobing/serration, a derived trait that evolved multiple times as a likely adaptation to the islands’ hot and dry equatorial climate. Using population-level genomic data from 396 individuals representing all 15 recognized Scalesia species, we characterize this young radiation (around 1 million years ago), and reveal that their substantial morphological divergence and ecological specialization are primarily based on shared genetic variation. To further elucidate the repeated adaptive evolution of leaf lobing in Scalesia , we integrate genomic and leaf morphometric data, with transcriptomes from different developmental stages, and conclude that leaf lobing evolved through diversifying selection. Natural selection occurs independently on different regulators in the pathway controlling development of adaxial-abaxial leaf polarity, highlighting the importance of the founder populations’ high genetic diversity maintained via allopolyploidy. Finally, our findings have implications for the conservation of Scalesia ’s threatened biodiversity, as unexpectedly high intra-specific genetic structure and long-term isolation among populations indicate widespread nascent speciation.

Aim: Forests support the majority of the planet's terrestrial biodiversity, and in recent years the characterisation of soundscapes has emerged as a powerful tool for understanding forest ecosystems, both in terms of ecology and for the purpose of conservation. But it is still poorly understood to what extent generalisations can be made about soundscapes in different parts of the world, and to what extent we should expect soundscapes to differ regionally. Here, we characterise the dominant acoustic features of forest soundscapes on a global scale and establish baseline expectations for how acoustic indices vary among biogeographic realms and biomes. Location: Forests in Brunei, Ecuador, Gabon, Germany, Peru, Singapore, Sierra Leone and the USA, a dataset spanning two biomes and five out of six global biogeographic realms where forests occur. Time Period: Two to five weeks of continuous audio data from each site collected between 2020 and 2024. Major Taxa: Birds, amphibians, insects and mammals. Methods: Stratifying data by time and frequency, we calculated four acoustic indices. Principal components analysis was used to compare the similarity of soundscapes across sites. Results: Temperate and tropical forest soundscapes clustered separately in principal component analysis. Temperate forests had soundscapes which were uniformly loud during the day across all frequencies and were generally quiet at night. In contrast, all tropical locations had complex soundscapes during both day and night and had banding patterns suggestive of a high diversity of soniferous insects. These banding patterns were created by the unique soniferous community at each site, causing the ‘acoustic fingerprint’ of each site to be most similar to other sites in the same ecoregion and in the same biogeographic realm. The ‘acoustic fingerprints’ of temperate forest differentiated between ecoregions only when dawn was considered separately. Main Conclusions: Our results stress the importance of using regional specific baseline data, as soundscapes are not necessarily comparable. Ecoacoustics is growing in popularity as an ecosystem monitoring tool, and understanding how forest soundscapes vary naturally across the globe can provide much needed context for studies that seek to understand factors that may disrupt or alter those soundscapes.

The Amazon rainforest, the most biodiverse biome on Earth, represents a critical natural laboratory for studying species interactions, ecosystem functioning, and vulnerability to climate change. High-quality datasets are crucial for advancing a detailed understanding of this complex biome; however, open-access uncrewed aerial system (UAS) datasets for this region remain notably scarce. Here, we present UAS-derived high-resolution products that seamlessly cover over 700 hectares of the upper and hyperdiverse Amazon. To the best of our knowledge, this is the first large-scale, comprehensive, open, and seamless UAS dataset of the Amazon, integrating multispectral imagery and lidar (light detection and ranging) data collected during a single mission, ensuring temporal consistency. The dataset provides complementary spectral and structural information from the Tiputini Biodiversity Station, one of the regions with the highest tree species richness per unit area on Earth. This resource supports diverse applications such as biodiversity and forest-structure analyses and establishes a methodological reference for future large-scale UAS research in the Amazon.

Climate and atmospheric changes are impacting forest function and structure worldwide, but their effects on tropical forest diversity are unclear. Nowhere is the scientific challenge greater than in the Andes and the Amazon, which together include the world’s most diverse forests. Here, using 406 permanent plots spanning four decades of intact lowland and montane forest dynamics, we test for long-term change in species richness and assess the influence of climate and other variables. We show that, at a continental scale, species richness appears stable, but this masks substantial regional variation. Species richness increased in Northern Andean and Western Amazon plots, yet declined in the Central Andes, Guyana Shield and Central-Eastern Amazon. Overall, warmer, drier and more seasonal forests lost species, while those at higher elevations, in less fragmented areas and with faster rates of tree turnover experienced increases. Region-specific drivers, particularly precipitation seasonality and demographic factors, modulated these trends. The results highlight the diverse ways in which Amazon–Andes forests are changing and underscore the critical need to preserve large-scale ecosystem integrity to maintain local tree diversity. By doing so, Northern Andean forests in particular could serve as an important refuge for species increasingly displaced by climate change.