Biology subjects

Gotthard, K.

Publications and source records attributed to Gotthard, K..

7 recordsLinked to original sources

bioRxiv2026

upSPLAT: Early-Barcoded Library Preparation for Cost-Effective Population-Scale Genomics

Advances in high-throughput sequencing have substantially reduced sequencing costs, yet library preparation remains a major financial and logistical bottleneck, particularly for high-throughput applications or low-quality DNA inputs. Here, we introduce upscaled Splinted Ligation Adapter Tagging (upSPLAT), a library preparation strategy that combines early sample barcoding with single-stranded splinted ligation to enable highly multiplexed pooled sequencing at substancially reduced cost. upSPLAT supports flexible high-plex pooling and reduces per-sample library preparation costs by approximately 10-fold compared to conventional workflows. By leveraging single-strand ligation, upSPLAT is compatible with a wide range of DNA inputs, including degraded, damaged or denatured double stranded DNA, bisulfite or enzymatically converted DNA, and viral single-stranded DNA. We present two complementary workflows and evaluate their performance across multiple species and DNA qualities, demonstrating robust demultiplexing, uniform sample representation, and low barcode cross-assignment. Together, upSPLAT provides a scalable, cost-effective solution for sequencing-based studies requiring large sample numbers while preserving individual-level information.

genomics↗

bioRxiv2026

Timing of reproduction modulates fitness effects of local seasonal adaptation in a range expanding butterfly

Local seasonal adaptation across latitudes is ubiquitous, but its fitness consequences are rarely estimated in the field. Using a common-garden field experiment at the northern range margin of the butterfly Lasiommata megera, we show that fitness consequences of among-population, genetic differences in photoperiodism for diapause (dormancy) timing depend on when during the adult flight period eggs are laid. In early-developing cohorts, individuals from southern populations were more likely to avert diapause than locally adapted northern range margin populations, and this non-diapause development was strongly disfavoured by natural selection. However, for all populations, virtually all eggs laid only one week later entered diapause, limiting overall among-population phenotypic differences. This demonstrates how evolved genetic differences for a reaction norm interact with phenology to shape the developmental decisions of caterpillars in the wild. Rapid local adaptation of photoperiodism has likely occurred through natural selection acting on a limited part of each autumn generation, implying a smooth fitness landscape where mildly locally maladapted populations can establish and subsequently evolve towards the local fitness peak. Thus, latitudinal differences in daylength are unlikely to restrict climate change-driven range expansions.

ecology↗

bioRxiv2025

Life history evolution of insects in response to climate variation: seasonal timing versus thermal physiology

Climate adaptation in insects can proceed via responses in life history traits and their thermal plasticity, and through phenological shifts mediated by responses to photoperiodic cues ("photoperiodism"). While, experimental studies demonstrate evolutionary potential for both modes of adaptation, it remains unclear how evolution will unfold in natural populations, limiting our ability to predict how insects will respond to climate change. Here we review the literature and perform an analysis of published studies revealing that photoperiodism for diapause induction evolves predictably along latitude, with high-latitude populations entering diapause earlier. In contrast, although a few species showed clinal variation in life history and thermal plasticity, the direction of these clines were not consistent across taxa. This suggests that while insect life history and physiological adaptation to temperature can evolve, phenological shifts via evolution of photoperiodism is likely to be a more common and predictable response to future climate change.

ecology↗

bioRxiv2022

Evolution of seasonal plasticity in response to climate change differs between life-stages of a butterfly

Climate change alters seasonal environments without altering photoperiod, creating a cue-environment mismatch for organisms that rely on photoperiod as a cue for seasonal plasticity and phenology. Evolution can potentially correct for this mismatch by altering the photoperiodic reaction norm, but often phenology depends on multiple plastic decisions made at different life stages and times of year. We tested whether seasonal plasticity in different life stages evolves independently or in concert under climate change using Pararge aegeria (Speckled wood butterfly). This butterfly uses day length as a cue for life history plasticity in two different life stages: larval development time and pupal diapause. Photoperiodic reaction norms for plasticity in these traits were first measured over 30 years ago for two different Swedish populations. In this study, we replicated historic experiments that measured these reaction norms using the contemporary populations. We found evidence for evolution of the reaction norm for larval development time, but in opposite directions in the two populations. In contrast, we found no evidence for evolution of the reaction norm for pupal diapause. These results show that different life stages can evolve differently in response to climate change and only studying one part of the life cycle will not always be enough to fully understand how climate change impacts phenotypic plasticity and phenology.

evolutionary biology↗

bioRxiv2020

Analyzing the neutral and adaptive background of butterfly voltinism reveals structural variation in a core circadian gene

Many insects exhibit geographic variation in voltinism, the number of generations produced per year. This includes high-latitude species in previously glaciated areas, implying divergent selection on life cycle traits during or shortly after recent colonization. Here, we use a whole-genome approach to genetically characterize a set of populations of the butterfly Pararge aegeria that differ in voltinism. We construct a high-quality de novo genome for P. aegeria, and assess genome-wide genetic diversity and differentiation between populations. We then use the inferred phylogeographic relationships as the basis for a scan for loci showing signs of divergent selection associated with voltinism differences. The genic outliers detected include population-specific mutations of circadian loci, most notably a locally fixed 97-amino acid deletion in the circadian gene timeless. Variation in timeless has previously been implicated as underlying variation in life cycle regulation in wild populations in our study species, as well as in other insects. These results add to a growing body of research framing circadian gene variation as a mechanism for generating local adaptation of life cycles.

evolutionary biology↗

bioRxiv2020

Variation in developmental rates is not linked to environmental unpredictability in annual killifishes

Comparative evidence suggests that adaptive plasticity may evolve as a response to predictable environmental variation. However, less attention has been placed on unpredictable environmental variation, which is considered to affect evolutionary trajectories by increasing phenotypic variation (or bet-hedging). Here, we examine the occurrence of bet-hedging in egg developmental rates in seven species of annual killifish, which originate from a gradient of variation in precipitation rates, under three treatment incubation temperatures (21{degrees}C, 23{degrees}C, and 25{degrees}C). In the wild, these species survive regular and seasonal habitat desiccation, as dormant eggs buried in the soil. At the onset of the rainy season, embryos must be sufficiently developed in order to hatch and complete their life-cycle. We found substantial differences among species in both the mean and variation of egg development rates, as well as species-specific plastic responses to incubation temperature. Yet, there was no clear relationship between variation in egg development time and variation in precipitation rate (environmental predictability). The exact cause of these differences therefore remains enigmatic, possibly depending on differences in other natural environmental conditions in addition to precipitation predictability. Hence, if species-specific variances are adaptive, the relationship between development and variation in precipitation is complex, and does not diverge in accordance with simple linear relationships.

evolutionary biology↗

bioRxiv2019

Developmental plasticity in metabolism but not in energy reserve accumulation in a seasonally polyphenic butterfly

The evolution of seasonal polyphenisms (discrete phenotypes in different annual generations) associated with alternative developmental pathways of diapause (overwintering) and direct development is favoured in temperate insects. Seasonal life history polyphenisms are common and include faster growth and development under direct development than diapause. However, the physiological underpinnings of this difference remain poorly known despite its significance for understanding the evolution of polyphenisms. We measured respiration and metabolic rates through the penultimate and final larval instars in the butterfly Pieris napi and show that directly developing larvae grew and developed faster and had a higher metabolic rate than larvae entering pupal diapause. The metabolic divergence appeared only in the final instar, that is, after the induction of developmental pathway that takes place in the penultimate instar in P. napi. The accumulation of fat reserves during the final larval instar was similar under diapause and direct development, which was unexpected as diapause is predicted to select for exaggerated reserve accumulation. This suggests that overwinter survival may be more dependent on metabolic suppression during diapause than the size of energy reserves. The results, nevertheless, demonstrate that physiological changes coincide with the divergence of life histories between the alternative developmental pathways, thus elucidating the proximate basis of seasonal life history polyphenisms. Summary statementThe switch between diapause and direct development results in developmental pre-diapause plasticity in life history and metabolism but not in reserve accumulation in a seasonally polyphenic butterfly.

evolutionary biology↗