Biology subjects

Loaiza, J. R.

Publications and source records attributed to Loaiza, J. R..

7 recordsLinked to original sources

bioRxiv2026

The Taxonomic Status and Phylogenetic Relationships of Toxorhynchites (Diptera: Culicidae) Species from Panama

Mosquitoes in the Toxorhynchites genus (Theobald, 1901) are specialized predators of container-breeding mosquito larvae, including major Aedes disease vectors. Despite their biological control potential, species boundaries and phylogenetic relationships remain poorly understood. Utilizing country-wide sampling across Panama, we evaluated the taxonomic status and diversity of local Toxorhynchites species. We collected 147 specimens from artificial and natural containers, yielding 97 cytochrome c oxidase subunit I barcodes from 101 sequenced individuals. A Panama-only Neighbor-Joining analysis revealed four distinct, well-supported clusters (I - IV) exhibiting high mean inter-cluster genetic divergence (4.8 - 20.2%), alongside morphological and ecological segregation. A subsequent global Neighbor-Joining analysis incorporating BOLD and GenBank sequences recovered Toxorhynchites as a strongly supported monophyletic group (99.0% bootstrap support) and revealed deep phylogenetic divergence separating Old World Toxorhynchites (Toxorhynchites) (Clades A and B) from New World Toxorhynchites (Lynchiella) (Clades C - G) lineages. Panamanian Clusters I and II formed two distinct groupings within Clade G, nesting as sisters to Subclade G1 characterized by severe taxonomic discordance involving sequences labeled as Tx. moctezuma, Tx. theobaldi, and Tx. rutilus. Cluster III nested within Tx. hypoptes (1.5% divergence) in Clade E, whereas Cluster IV associated with Tx. haemorrhoidalis s.l. (>5.0% divergence) in Clade C. The high degree of taxonomic uncertainty or cryptic diversity uncovered within Clades C, D, and G underscores an urgent need for formal taxonomic revision to accurately delimit species boundaries. Due to its widespread peri-urban distribution, Cluster I (within the Tx. moctezuma s.l. complex) shows the greatest promise for mass-rearing and Aedes biocontrol applications in Panama.

evolutionary biology↗

bioRxiv2026

Invasion history of Aedes (Stegomyia) albopictus into Mesoamerica based on mitogenomes and Wolbachia symbionts: Multiple introductions with temperate origins.

The global invasion of the Asian tiger mosquito Aedes albopictus has led to an increase in arboviral disease, including within Mesoamerica. Understanding vector invasion routes is important for public health because it directs biosecurity and identifies sources of adaptive allele spread. Panama is an important hub of global trade with opportunities for Aedes introduction through both maritime and overland routes but dispersal into the Isthmus has not yet been investigated. We therefore sought to investigate the population structure and invasion history of Ae. albopictus into Panama, targeting both its mitogenome and associated Wolbachia. Historical demographic analysis with Bayesian phylogeographic diffusion models and estimates of divergence revealed that Panamanian Ae. albopictus and its associated Wolbachia have a convergent evolutionary history resulting from multiple introductions. Both could be traced to Asian-derived lineages introduced via the Americas, with invasion primarily through the maritime trade of the Panama Canal rather than overland dispersal from neighboring Costa Rica. An investigation of the relative density of Wolbachia in Panama revealed that both the strains wAlbB and wAlbA were at a notably lower density compared to other worldwide locations. This finding has implications for arbovirus transmission and raises important questions about how Wolbachia density is impacted by the environment and impacts on population control. Overall, the Panama Canal is a key route for vector introductions into Mesoamerica.

evolutionary biology↗

bioRxiv2023

Comparative phylogeography reveals widespread cryptic diversity driven by ecology in Panamanian birds

Widespread species often harbor unrecognized genetic diversity, and investigating the factors associated with such cryptic variation can help us better understand the forces driving diversification. Here, we identify potential cryptic species based on a comprehensive dataset of COI mitochondrial DNA barcodes from 2,333 individual Panamanian birds across 429 species, representing 391 (59%) of the 659 resident landbird species of the country, as well as opportunistically sampled waterbirds. We complement this dataset with additional publicly available mitochondrial loci, such as ND2 and cytochrome b, obtained from whole mitochondrial genomes from 20 taxa. Using barcode identification numbers (BINs), we find putative cryptic species in 19% of landbird species, highlighting hidden diversity in the relatively well-described avifauna of Panama. Whereas some of these mitochondrial divergence events corresponded with recognized geographic features that likely isolated populations, such as the Cordillera Central highlands, the majority (74%) of lowland splits were between eastern and western populations. The timing of these splits are not temporally coincident across taxa, suggesting that historical events, such as the formation of the Isthmus of Panama and Pleistocene climatic cycles, were not the primary drivers of cryptic diversification. Rather, we observed that forest species, understory species, insectivores, and strongly territorial species--all traits associated with lower dispersal ability--were all more likely to have multiple BINs in Panama, suggesting strong ecological associations with cryptic divergence. Additionally, hand-wing index, a proxy for dispersal capability, was significantly lower in species with multiple BINs, indicating that dispersal ability plays an important role in generating diversity in Neotropical birds. Together, these results underscore the need for evolutionary studies of tropical bird communities to consider ecological factors along with geographic explanations, and that even in areas with well-known avifauna, avian diversity may be substantially underestimated. LAY SUMMARY- What factors are common among bird species with cryptic diversity in Panama? What role do geography, ecology, phylogeographic history, and other factors play in generating bird diversity? - 19% of widely-sampled bird species form two or more distinct DNA barcode clades, suggesting widespread unrecognized diversity. - Traits associated with reduced dispersal ability, such as use of forest understory, high territoriality, low hand-wing index, and insectivory, were more common in taxa with cryptic diversity. Filogeografia comparada revela amplia diversidad criptica causada por la ecologia en las aves de Panama RESUMENEspecies extendidas frecuentemente tiene diversidad genetica no reconocida, y investigando los factores asociados con esta variacion criptica puede ayudarnos a entender las fuerzas que impulsan la diversificacion. Aqui, identificamos especies cripticas potenciales basadas en un conjunto de datos de codigos de barras de ADN mitocondrial de 2,333 individuos de aves de Panama en 429 especies, representando 391 (59%) de las 659 especies de aves terrestres residentes del pais, ademas de algunas aves acuaticas muestreada de manera oportunista. Adicionalmente, complementamos estos datos con secuencias mitocondriales disponibles publicamente de otros loci, tal como ND2 o citocroma b, obtenidos de los genomas mitocondriales completos de 20 taxones. Utilizando los numeros de identificacion de codigo de barras (en ingles: BINs), un sistema taxonomico numerico que proporcina una estimacion imparcial de la diversidad potencial a nivel de especie, encontramos especies cripticas putativas en 19% de las especies de aves terrestres, lo que destaca la diversidad oculta en la avifauna bien descrita de Panama. Aunque algunos de estos eventos de divergencia conciden con caracteristicas geograficas que probablemente aislaron las poblaciones, la mayoria (74%) de la divergencia en las tierras bajas se encuentra entre las poblaciones orientales y occidentales. El tiempo de esta divergencia no coincidio entre los taxones, sugiriendo que eventos historicos tales como la formacion del Istmo de Panama y los ciclos climaticos del pleistoceno, no fueron los principales impulsores de la especiacion. En cambio, observamos asociaciones fuertes entre las caracteristicas ecologicas y la divergencia mitocondriale: las especies del bosque, sotobosque, con una dieta insectivora, y con territorialidad fuerte mostraton multiple BINs probables. Adicionalmente, el indice mano-ala, que esta asociado a la capacidad de dispersion, fue significativamente menor en las especies con BINs multiples, sugiriendo que la capacidad de dispersion tiene un rol importamente en la generacion de la diversidad de las aves neotropicales. Estos resultos demonstran la necesidad de que estudios evolutivos de las comunidades de aves tropicales consideren los factores ecologicos en conjunto con las explicaciones geograficos. Palabras clave: biodiversidad tropical, biogeografia, codigos de barras, dispersion, especies cripticas

evolutionary biology↗

bioRxiv2020

Proteomic fingerprint identification of Neotropical hard tick species (Acari: Ixodidae) using a self-curated mass spectra reference library

Matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry is an analytical method that detects macromolecules that can be used as biomarkers for taxonomic identification in arthropods. The conventional MALDI approach uses fresh laboratory-reared arthropod specimens to build a reference mass spectra library with high-quality standards required to achieve reliable identification. However, this may not be possible to accomplish in some arthropod groups that are difficult to rear under laboratory conditions, or for which only alcohol preserved samples are available. Here, we generated MALDI mass spectra of highly abundant proteins from the legs of 18 Neotropical species of adult field-collected hard ticks, several of which had not been analyzed by mass spectrometry before. We then used their mass spectra as fingerprints to identify each tick species by applying machine learning and pattern recognition algorithms that combined unsupervised and supervised clustering approaches. Both principal component analysis (PCA) and linear discriminant analysis (LDA) classification algorithms were able to identify spectra from different tick species, with LDA achieving the best performance when applied to field-collected specimens that did have an existing entry in a reference library of arthropod protein spectra. These findings contribute to the growing literature that ascertains mass spectrometry as a rapid and effective method for taxonomic identification of disease vectors, which is the first step to predict and manage arthropod-borne pathogens.Author Summary Hard ticks (Ixodidae) are external parasites that feed on the blood of almost every species of terrestrial vertebrate on earth, including humans. Due to a complete dependency on blood, both sexes and even immature stages, are capable of transmitting disease agents to their hosts, causing distress and sometimes death. Despite the public health significance of ixodid ticks, accurate species identification remains problematic. Vector species identification is core to developing effective vector control schemes. Herein, we provide the first report of MALDI identification of several species of field-collected Neotropical tick specimens preserved in ethanol for up to four years. Our methodology shows that identification does not depend on a commercial reference library of lab-reared samples, but with the help of machine learning it can rely on a self-curated reference library. In addition, our approach offers greater accuracy and lower cost per sample than conventional and modern identification approaches such as morphology and molecular barcoding.Competing Interest StatementThe authors have declared no competing interest.List of abbreviationsMALDImatrix-assisted laser desorption/ionizationPCAprincipal component analysisLDAlinear discriminant analysisDNAdeoxyribonucleic acidINDICASATInstitute for Scientific Research and High Technology ServicesSTRISmithsonian Tropical Research InstituteSNINational System of InvestigationUTPTechnological University of PanamaTOFtime-of-flightMiAmbienteMinistry of Environment.View Full Text

zoology↗

bioRxiv2019

The impact of local adaptation and biological invasion on the geographical distribution of Aedes aegypti in Panama

Local adaptation is an important consideration when predicting arthropod-borne disease risk because it can impact on vector population fitness and persistence. However, the extent that vector populations are adapted to local environmental conditions and whether this can impact on species distributions generally remains unknown. Here we find that the geographic distribution of Ae. aegypti across Panama is rapidly changing as a consequence of the recent invasion by its ecological competitor, Aedes albopictus. Although Ae. albopictus has displaced Ae. aegypti in some areas, species coexist across many areas, raising the question: What biological and environmental factors permit population persistence?. Despite low population structure and high gene flow in Ae. aegypti across Panama, excepting the province of Bocas del Toro, we identify 128 candidate SNPs, clustered within 17 genes, which show a strong genetic signal of local adaptation. This putatively adaptive variation occurs across relatively fine geographic scales with the composition and frequency of candidate adaptive loci differing between populations in wet tropical environments along the Caribbean coast and the dry tropical conditions typical of the Pacific coast of Panama. Temperature and vegetation were important predictors of adaptive genomic variation in Ae. aegypti with potential areas of local adaptation occurring within the Caribbean region of Bocas del Toro, the Pacific coastal areas of Herrera and Panama City and the eastern Azuero Peninsula. Interestingly, several of these locations coincide with areas where Ae. aegypti and Ae. albopictus co-exist, suggesting that Ae. aegypti could have an adaptive edge under local environmental conditions that impacts on inter-specific competition with Ae. albopictus. Our results guide future experimental work by suggesting that locally adapted Ae. aegypti are able to persist on invasion by Ae. albopictus and, as a consequence, may fundamentally alter future arborviral disease risk and efforts to control mosquito populations. Author SummaryLocal environmental adaptation of mosquito vectors can alter the landscape of arthropod-borne disease by impacting on life history traits that increase their relative fitness thus promoting population persistence. We have identified a number of genomic loci in Ae. aegypti from Panama that exhibit a signal of natural selection associated with variation in the environment. Loci with a signal of local adaptation are predominately partitioned between wet and dry tropical environments with variation largely impacted by temperature and vegetation indices. Local adaptation in tandem with changes in the geographic distribution of Ae. aegypti due to the recent invasion of its ecological competitor, Ae. albopictus, has the potential to alter the landscape of arborviral disease.

evolutionary biology↗

bioRxiv2019

Detecting space-time clusters of dengue fever in Panama after adjusting for vector surveillance data

Long term surveillance of vectors and arboviruses is an integral aspect of disease prevention and control systems in countries affected by increasing risk. Yet, little effort has been made to adjust space-time risk estimation by integrating disease case counts with vector surveillance data, which may result in inaccurate risk projection when several vector species are present, and little is known about their likely role in local transmission. Here, we integrate 13 years of dengue case surveillance and associated Aedes occurrence data across 462 localities in 63 districts to estimate the risk of infection in the Republic of Panama. Our space-time modelling approach detected the presence of five clusters, which varied by duration, relative risk, and spatial extent after incorporating vector species as covariates. Dengue prevalence (n = 49,910) was predicted by the presence of resident Aedes aegypti alone, while all other covariates exhibited insignificant statistical relationships with it, including the presence and absence of invasive Aedes albopictus. Furthermore, the Ae. aegypti model contained the highest number of districts with more dengue cases than would be expected given baseline population levels. This implies that arbovirus case surveillance coupled with entomological surveillance can affect cluster detection and risk estimation, improving efforts to understand outbreak dynamics at national scales. Author SummaryDengue cases have increased in tropical regions worldwide owing to climate change, urbanization, and globalization facilitating the spread of Aedes mosquito vectors. National surveillance programs monitor trends in dengue fever and inform the public about epidemiological scenarios where outbreak preventive actions are most needed. Yet, most estimations of dengue risk so far derive only from disease case data, ignoring Aedes occurrence as a key aspect of dengue transmission dynamic. Here we illustrate how incorporating vector presence and absence as a model covariate can considerably alter the characteristics of space-time cluster estimations of dengue cases. We further show that Ae. aegypti has likely been a greater driver of dengue infection in high risk districts of Panama than Ae. albopictus, and provide a discussion of possible public health implications of both spatial and non-spatial model outcomes.

epidemiology↗

bioRxiv2018

Mitochondrial genomes and phylogenetic analysis of Central American weakly-electric fishes: Apteronotus rostratus, Brachyhypopomus occidentalis and Sternopygus dariensis

Electric fishes are a diverse group of freshwater organisms with the ability to generate electric organ discharges (EODs) that are used for communication and electrolocation. Over 200 species have originated in South America, but of these, only a few have managed to colonize the Central American Isthmus. Here, we assembled two complete and one nearly complete mitochondrial genomes (mitogenomes) for three Central American Gymnotiformes: Sternopygus dariensis, Brachyhypopomus occidentalis and Apteronotus rostratus. We then explored the three species phylogenetic position in the context of South American electric fishes. Mitogenomes were organized in the standard fish mitogenome order, and presented sizes of 16,600, 16,540 and 15,940 base pairs (bp) (nearly complete) for S. dariensis, B. occidentalis and A. rostratus, respectively. We uncovered a novel 60 bp intergenic spacer (IGS) located between the COII and tRNALys genes, which appears to be unique to the Apteronotidae. Furthermore, phylogenetic relationships supported the traditional monophyly of Gymnotiformes, with the three species positioned within their respective family. In addition, the genus Apteronotus was placed as the basal taxon of the order. Finally, we found high sequence divergence (13.3%) between our B. occidentalis specimen and a sequence previously reported in GenBank, suggesting that the prior mitogenome of B. occidentalis represents a different South American species that was misidentified. Indeed, phylogenetic analyses using Cytochrome b gene across the genus placed the previously reported individual within B. bennetti. Our study provides novel mitogenome resources that will advance our understanding of the diversity and phylogenetic history of Neotropical fishes.

evolutionary biology↗