Biology subjects

Espeland, M.

Publications and source records attributed to Espeland, M..

12 recordsLinked to original sources

bioRxiv2026

A meta-analysis of Neotropical butterflies reveals long-term signature of the Pebas wetland on Neotropical biogeography

The palaeogeographic history of the Neotropics has inspired multiple diversification models, emphasizing either the Andes or Amazonia as primary drivers of biodiversity. However, the extensive Pebas wetland system that covered western Amazonia during the Miocene has gained attention as a potential barrier to dispersal and diversification. This system may have contributed to the modern diversity imbalance between the Andes and Amazonia, known as the Gentry pattern. Most evidence for this hypothesis comes from isolated case studies and fossils. Here, we conduct a meta-analysis including 1,361 species of Neotropical butterflies to evaluate the role of the Pebas wetland on the dynamics of dispersal and diversification. We found that Andean- and Amazonian-centred clades show complementary but temporarily distinct biogeographic patterns. High Andean diversity reflects an Andean origin, with early occupancy and diversification occurring within the Andes, followed by post-Pebas dispersal into Amazonia. By contrast, Amazonian-centred clades, reflect an Amazonian origin, with an early diversification in Amazonia and subsequent post-Pebas colonization of the Andes. While several clades show little evidence of Pebas influence, our study suggests that the Pebas wetland did not uniformly restrict diversification, but rather selectively constrained dispersal between the Andes and Amazonia, preventing simultaneous diversification in both regions and thereby creating a diversity imbalance that characterizes the modern Neotropic.

evolutionary biology↗

bioRxiv2026

Long-distance dispersal drives global tropical distributions in a widespread moth lineage (Lepidoptera: Limacodidae)

Understanding how global biodiversity patterns arise is a central theme of biogeography, with contemporary theory recognising the roles of both dispersal and vicariance. Genera that are broadly distributed can provide important systems for disentangling the relative influence of these processes across evolutionary timescales. However, many lesser-studied groups, particularly those in the tropics, lack a densely sampled phylogeny which hinders robust inference of their evolutionary and biogeographic history. This study investigates the global diversification and systematics of the putative pantropical moth genus Parasa Moore (Lepidoptera: Limacodidae), with the aim of assessing the relative importance of dispersal and vicariance in shaping its distribution. Medium-coverage whole genome sequencing of specimens predominantly from museum collections were used to generate a globally sampled time-calibrated phylogeny of Parasa and associated genera (the Parasa-complex). Ancestral range estimation analyses were employed to infer geographical origins and possible dispersal times between bioregions. The Parasa-complex originated in Africa in the late Oligocene ([~]24 Ma) and, through a series of long-distance dispersal events during the early-mid Miocene, expanded into Asia ([~]23 Ma) and the Americas ([~]21 Ma). Across all regions, dispersal was the dominant process shaping present-day distributions, with a limited role of vicariance in some subregions. Phylogenetic analyses further demonstrated that Parasa is not a monophyletic genus, with multiple independent lineages contributing to its apparent pantropical distribution. These findings highlight a central role of long-distance dispersal in generating certain global distributions. The results support a dynamic model of range evolution involving rapid Miocene dispersal and subsequent regional diversification. In addition, the non-monophyly of Parasa requires substantial taxonomic revision, underscoring the importance of robust phylogenetic frameworks for interpreting global biodiversity patterns.

evolutionary biology↗

bioRxiv2026

Mixture Models Unveil the Origin of the Enigmatic Satyrine Butterfly Genera Calisto and Llorenteana (Lepidoptera, Nymphalidae, Satyrinae).

We provide the first comprehensive analysis of the origin of two enigmatic Satyrinae genera of uncertain affinities. Calisto, the only Satyrinae genus from the West Indies and endemic to these islands, has resisted numerous attempts at phylogenetic placement, regardless of the data type or methods used. Llorenteana, a monotypic genus from northwestern Mexico, has never been included in a molecular phylogenetic study, and past authors have placed it in five different genera and subtribes. We used mostly published genomic data, but also newly sequenced whole genome data from museum specimens and old DNA extracts, extracted BUSCO genes and prepared several datasets. These datasets differed in the degree of heterogeneity and saturation, the number of nucleotide positions used (all positions or only the first two), and were analyzed as nucleotides or as amino acids. We employed several methods for phylogenetic reconstruction using both partitioned and mixture models, as well as ASTRAL, and we inferred divergence times and ancestral areas of origin for Calisto and Llorenteana. The phylogenetic placement of Calisto varied among datasets when we used partitioned models and ASTRAL; however, most datasets resulted in the same relationships under mixture models. Our results suggest that Calisto is part of a clade of Old World origin that colonized the New World from north to south, thus sharing ancestry with Nearctic taxa. Llorenteana constitutes one of the earliest splits within the Euptychiina, a subtribe of Neotropical origin, but descending together with the Pronophilina from Nearctic ancestors. We propose the recognition of Erebiina stat. rev. as the only subtribe comprising the former Calistina syn. nov., Callerebiina syn. nov, Maniolina syn. nov., and Ypthimina syn. nov.

evolutionary biology↗

bioRxiv2023

Phylogenomics recovers multiple origins of portable case-making in caddisflies (Insecta: Trichoptera), the world's most common underwater architects

Caddisflies (Trichoptera) are among the most diverse groups of freshwater animals with more than 16,000 described species. They play an outsized role in freshwater ecology and environmental engineering in streams, rivers, and lakes. Because of this, they are frequently used as indicator organisms in biomonitoring programs. Despite their importance, key questions concerning the evolutionary history of caddisflies, such as the timing and origin of larval case-making, have been unanswered due to the lack of a well-resolved phylogenetic tree. To shed light on these questions in Trichoptera, we estimated a phylogenetic tree using a combination of transcriptomes and targeted enrichment data for 206 species, representing 48 of 52 extant families and 174 genera. We calibrated and dated the tree with a set of 33 carefully selected fossils. The first caddisflies originated in the Permian and the major suborders began to diversify in the Triassic. Ancestral state reconstruction and diversification analysis revealed that portable case-making evolved in three separate lineages and shifts in diversification occurred in concert with key evolutionary innovations other than case-making.

evolutionary biology↗

bioRxiv2023

One Method to Sequence Them All? Comparison between Whole-Genome Sequencing (WGS) and Target Enrichment (TE) of museum specimens from the moth families Epicopeiidae and Sematuridae (Lepidoptera)

There are various possibilities for sequencing highly degraded DNA, such as target enrichment (TE), or whole-genome sequencing (WGS). Here we compare TE and WGS methods using old museum specimens of two families of moths in the superfamily Geometroidea: Epicopeiidae and Sematuridae. Until recently, the relationships of these two families were unclear, as few studies had been done. Recently two studies used the TE approach, either on relatively fresh specimens, or on old museum specimens. Here, we aim to increase the sampling of the families Epicopeiidae and Sematuridae from museum specimens using the WGS method. We show that both sequencing methods give comparable results, but, unsurprisingly, WGS recovers more data. By combining TE and WGS data, we confirm that Sematuridae are sister to Pseudobistonidae+Epicopeiidae. Relationships of genera within the families are well supported. With the costs of WGS decreasing, we suggest that using low-coverage whole genome sequencing is becoming an increasingly viable option in the phylogenomics of insects.

evolutionary biology↗

bioRxiv2023

Patterns of speciation in a parapatric pair of Saturnia moths as revealed by Target Capture

The focus of this study is to understand the evolutionary relationships and taxonomy of widely distributed parapatric species pair of wild silk moths, Saturnia pavonia and Saturnia pavoniella (Lepidoptera: Saturniidae) in Europe. To address species delimitation challenges associated with many parapatric taxa, target enrichment and mtDNA sequencing was employed alongside phylogenetic, species delimitation, admixture and introgression analyses. The dataset included individuals from both species, two hybrids generated in the lab, as well as individuals from outside the contact zone. Nuclear markers strongly supported both S. pavonia and S. pavoniella as two distinct species, with the hybrids grouping together as intermediate and separate from both species. However, the maximum likelihood (ML) tree generated from mtDNA sequencing data presented a different picture, showing both taxa to be phylogenetically intermixed. This inconsistency may be attributed to mitonuclear discordance, which can arise from biological factors (e.g., introgressive hybridization or incomplete lineage sorting) or alternatively operational factors (e.g., incorrect species delimitation). We further provide the evidence of past introgression to have taken place, but no evidence of current admixture between the two species. Finally, we discuss our results from evolutionary point of view taking into consideration the past climatic oscillations that has likely shaped the present dynamics between the species. Overall, this study demonstrated the effectiveness of the target enrichment approach in resolving the phylogenetic relationships between closely related parapatric species and providing insights into their taxonomic delimitation.

evolutionary biology↗

bioRxiv2023

Species Delimitation Under Allopatry: Genomic Divergences Within and Across Continents in Lepidoptera

Delimitation of allopatric populations into species remains subjective and largely arbitrary. Many cold-adapted species from the subarctic and Central and Southern European Mountain systems display frequent allopatry with disjunct distributions of their populations. The same concerns Holarctic species which are many and which almost regularly show various degrees of differentiation between the continents. In this study, we analyze high- throughput target enrichment data for ten groups of arctic-alpine and Holarctic lepidopteran species sampled from four main regions across the Holarctic realm - Fennoscandia, North America, Alps and Altai. We first aimed to assess whether the genetic differences in the nuclear genome reflect observed DNA barcode divergences and second, whether the gap between population and species-level differences can be dissected using genomic data. We compared the phylogenetic trees and uncorrected pairwise genetic distances obtained from target enrichment and the mitochondrial cytochrome oxidase I (COI) barcodes for each of the study species. Additionally, we also performed a suite of population genetic and species delimitation analyses to further shed light on patterns of intraspecific variation using a large number of nuclear markers. We observed that in about one half of the cases, DNA barcodes tended to show phylogenetic relationships similar to the target enrichment markers. We report varying levels of nuclear genetic differentiation among the populations analyzed, starting from low differentiation of geographically separated populations to the deeper separation of some Nearctic population and further arctic-alpine disjunction. Given that no single consistent pattern emerged across different case studies, we demonstrate that the delimitation of allopatric populations into species could be done much more efficiently and in a consistent manner if based on a large set of universal genetic loci, which would help in reaching standards for taxonomic delimitation of allopatric populations.

evolutionary biology↗

bioRxiv2022

Diversification is correlated with temperature in white and sulfur butterflies

Temperature is thought to be a key variable explaining global patterns of species richness. However, to investigate this relationship carefully, it is necessary to study clades with broad geographic ranges that are comprised of species inhabiting diverse biomes with well- characterized species ranges. In the present study, we investigate the link between temperature and diversification in the butterfly family Pieridae (sulfurs and whites) by combining Next Generation sequences and published molecular data with fine-grained distribution information. After building the most comprehensive phylogeny of the group, with almost 600 species and all higher taxa (subfamilies, tribes and subtribes), we found strong support for the following relationships within the family: Dismorphiinae + (Coliadinae + (Pseudopontiinae + Pierinae)). With a curated distribution dataset of over 800,000 occurrences, we conducted multiple comparative phylogenetic analyses that provided strong evidence that species in environments with more stable daily temperatures or with cooler maximum temperatures in the warm seasons have higher diversification rates. We also found a positive correlation between speciation and extinction with paleotemperature: as global temperature decreased through geological time, so did diversification rates. Although many studies demonstrate higher diversity in the tropics, we have been able to identify specific climate variables associated with changes in diversification, while also inferring the most robust and well sampled phylogenomic framework for Pieridae to date.

evolutionary biology↗

bioRxiv2022

Genetic, clinical underpinnings of subtle early brain change along Alzheimer's dimensions

Alzheimers disease (AD) is associated with heterogeneous atrophy patterns. We employed a semi-supervised clustering technique known as Surreal-GAN, through which we identified two dominant dimensions of brain atrophy in symptomatic mild cognitive impairment (MCI) and AD patients: the "diffuse-AD" (R1) dimension shows widespread brain atrophy, and the "MTL-AD" (R2) dimension displays focal medial temporal lobe (MTL) atrophy. Critically, only R2 was associated with widely known sporadic AD genetic risk factors (e.g., APOE {varepsilon}4) in MCI and AD patients at baseline. We then independently detected the presence of the two dimensions in the early stages by deploying the trained model in the general population and two cognitively unimpaired cohorts of asymptomatic participants. In the general population, genome-wide association studies found 77 genes unrelated to APOE differentially associated with R1 and R2. Functional analyses revealed that these genes were overrepresented in differentially expressed gene sets in organs beyond the brain (R1 and R2), including the heart (R1) and the pituitary gland, muscle, and kidney (R2). These genes were enriched in biological pathways implicated in dendritic cells (R2), macrophage functions (R1), and cancer (R1 and R2). Several of them were "druggable genes" for cancer (R1), inflammation (R1), cardiovascular diseases (R1), and diseases of the nervous system (R2). The longitudinal progression showed that APOE {varepsilon}4, amyloid, and tau were associated with R2 at early asymptomatic stages, but this longitudinal association occurs only at late symptomatic stages in R1. Our findings deepen our understanding of the multifaceted pathogenesis of AD beyond the brain. In early asymptomatic stages, the two dimensions are associated with diverse pathological mechanisms, including cardiovascular diseases, inflammation, and hormonal dysfunction - driven by genes different from APOE - which may collectively contribute to the early pathogenesis of AD.

bioengineering↗

bioRxiv2022

Delimiting Continuity: Comparison of Target Enrichment and ddRAD for Delineating Admixing Parapatric Melitaea Butterflies

Parapatrically distributed taxa pose a challenge for species delimitation due to the presence of gene flow and inherent arbitrariness of exactly defining the species boundaries in such systems. We tackled the problem of species delimitation in a parapatric species pair of Melitaea butterflies using two popular genomic methods - double digest restriction-site associated DNA sequencing (ddRAD) and target enrichment. The former is mainly applied at shallow phylogenetic scales and the latter at both deep and shallow scales. Although both of these methods have been adequately utilised for species delimitation purposes, there are only a handful of studies that have compared these two genomic approaches in the same study system. We applied phylogenetic, population genetic and species delimitation methods and compared the results obtained from the two approaches. Using a recently developed target enrichment probe kit, we were able to capture 1,743 loci with a low amount of missing data and compared these with already available ddRAD data from a previous study on the same set of specimens. We recovered consistent phylogenetic relationships across the datasets, both demonstrating the presence of a genetically distinct Balkan lineage and paraphyly of Melitaea athalia with respect to Melitaea celadussa. The same relationships were also found in a species tree analysis of the target enrichment dataset using ASTRAL. Population genetic STRUCTURE analyses supported the presence of two species when using ddRAD data, but three species when using target enrichment, while the Bayes factor delimitation analysis found both two and three species scenarios equally decisive in both datasets. From the geographic distribution of genomic admixture, we confirm the patterns observed by a previous study that used ddRAD data. As the results obtained from both methods were largely congruent, we discuss some practical considerations and benefits of target enrichment over RAD sequencing. We conclude that the choice of method of genomic data collection does not influence the results of phylogenetic analyses at alpha taxonomic level, given a sufficient number of loci. Finally, we recommend a solution for delineating species in parapatric scenarios by proposing that parapatric taxa be consistently classified as subspecies or complete species, but not both, to promote taxonomic stability.

evolutionary biology↗

bioRxiv2021

Association between Cognitive Function and Large Optic Nerve Cupping, Accounting for Cup-Disc-Ratio Genetic Risk Score

PurposeTo investigate if accounting for a cup-to-disc ratio (CDR) genetic risk score (GRS) modified the association between large CDR and cognitive function among women. DesignThis was a retrospective study using data from the Womens Health Initiative. MethodsPatients with glaucoma or ocular hypertension were excluded. Large CDR was defined as [≥] 0.6 in either eye. Cognitive function was measured by the Modified Mini-Mental State Examination (3MSE). We used the combined effects from 13 single nucleotide polymorphisms (SNPs) to formulate the GRS for CDR. We used logistic regression to investigate associations between weighted GRS and large CDR, then a linear regression to assess the association between weighted GRS and 3MSE scores, and between weighted GRS, CDR, and 3MSE scores, adjusted for demographic and clinical characteristics. ResultsFinal analyses included 1,196 White women with mean age of 69.60 {+/-} 3.62 years and 7.27% with large CDR. Mean GRS in women with and without large CDR was 1.51 {+/-} 0.31 vs. 1.41 {+/-} 0.36, respectively (p = 0.004). The odds of large CDR for a one unit increase in GRS was 2.30 (95% CI: (1.22, 4.36), p = 0.011). Adding the CDR GRS in the model with CDR and 3MSE, women with large CDR still had statistically significantly lower 3MSE scores than those without large CDR, yielding a predicted mean difference in 3MSE scores of 0.84 (p = 0.007). ConclusionsIndependent of the CDR GRS, women with large CDR had a lower cognitive function.

genetics↗

bioRxiv2021

Standardized nuclear markers advance metazoan taxonomy

Species are the fundamental units of life and their recognition is essential for science and society. DNA barcoding, the use of a single and often mitochondrial gene, has been increasingly employed as a universal approach for the identification of animal species. However, this approach faces several challenges. Here, we demonstrate with empirical data from a number of metazoan animal lineages that multiple nuclear-encoded markers, so called universal single-copy orthologs (USCOs) performs much better than the single barcode gene to discriminate closely related species. Overcoming the general shortcomings of mitochondrial DNA barcodes, USCOs also accurately assign samples to higher taxonomic levels. These loci thus provide a powerful and unifying framework for species delimitation which considerably improves the DNA-based inference of animal species.

molecular biology↗