Biology subjects

Tysklind, N.

Publications and source records attributed to Tysklind, N..

7 recordsLinked to original sources

bioRxiv2026

Complementary evidence from historical and contemporary gene dispersal reveals contrasting population dynamics in a tropical tree species

Gene flow shapes the demographic stability and evolutionary potential of tropical forest trees, yet its dynamics may differ depending on the temporal scale at which it is assessed. We combined spatial genetic structure (SGS), parentage analyses, and reproductive success metrics to investigate historical and contemporary gene dispersal in four populations of Dicorynia guianensis across French Guiana, encompassing sites differing in environment and management history. A total of 1,528 individuals were genotyped using 66 nuclear and 23 plastid microsatellite markers, enabling high-resolution inference of biparental and maternal gene dispersal. Historical mating and dispersal parameters inferred from SGS revealed marked contrasts among populations. Some populations exhibited high historical gene dispersal distances and weak spatial genetic structure, whereas others showed stronger SGS and long-term aggregative dispersal patterns. Contemporary parentage analyses further highlighted differences in seed and pollen dispersal distances, parent assignment rates, and reproductive skew. In certain populations, pronounced reproductive inequality and reduced effective connectivity were observed, while others displayed more balanced reproductive contributions. By jointly evaluating long-term dispersal legacies and present-day reproductive patterns, our study demonstrates the value of combining indirect and direct genetic approaches to assess population dynamics and conservation status in tropical forest trees. This multi-temporal perspective provides a comprehensive basis for long-term monitoring and sustainable management in heterogeneous tropical landscapes.

ecology↗

bioRxiv2025

Impact of selective logging on the population dynamics and genetic diversity in the neotropical timber tree Dicorynia guianensis

Selective logging is a widely applied forest management strategy in the tropics, yet it is insufficiently documented how it affects the genetic and demographic processes of seedling recruitment in timber species in the Guiana Shield. Our study investigates how selective logging influences genetic diversity, gene dispersal, and seedling establishment in Dicorynia guianensis by comparing a logged and an unlogged forest plot in French Guiana. We genotyped 703 individuals using 66 nuclear SSR markers and applied parentage analyses to infer dispersal patterns and reproductive success. We analyzed genetic diversity and spatial genetic structure across life stages, and tested whether seedling recruitment was associated with logging-related canopy openings. Genetic diversity indices were broadly similar between logged and unlogged plots, with no evidence of genetic erosion in adults or seedlings. Seedling establishment was associated with logging-induced canopy openings. Parentage analyses revealed shorter mean dispersal distances in the logged plot but substantial long-distance pollen flow, ensuring admixture and inter-plot connectivity. Reproductive success was more evenly distributed among mothers, whereas male contributions were skewed in the logged plot. Selective logging did not cause immediate genetic erosion but altered dispersal dynamics and reproductive patterns. These findings underline the resilience of D. guianensis under current management practices, while emphasizing the need for long-term monitoring of regeneration to ensure sustainable recruitment and evolutionary resilience across logging cycles.

ecology↗

bioRxiv2024

Adaptive trade-offs between vertebrate defense and insect predation drive ant venom evolution

Stinging ants have diversified into various ecological niches, and several evolutionary drivers may have contributed to shape the composition of their venom. To comprehend the drivers underlying venom variation in ants, we selected 15 Neotropical species and recorded a range of traits, including ecology, morphology, and venom bioactivity. Principal component analysis of both morphological and venom bioactivity traits revealed that stinging ants display two functional strategies. Additionally, phylogenetic comparative analysis indicated that venom function (predatory, defensive, or both) and mandible morphology significantly correlate with venom bioactivity and amount, while pain-inducing activity trades off with insect paralysis. Further analysis of the venom biochemistry of the 15 species revealed switches between cytotoxic and neurotoxic venom compositions in some species. This study highlights the fact that ant venoms are not homogenous, and for some species, there are major shifts in venom composition associated with the diversification of venom ecological functions. SignificanceVenoms are under severe evolutionary pressures, exerted either on the innovation of toxins or the reduction of the metabolic cost of production (1). To reduce the metabolic costs associated with venom secretion, some venomous animals can regulate venom expenditure by metering the amount of venom injected and by switching between offensive and defensive compositions (2-2). Many ants use venom for subduing a wide range of arthropod prey, as well as for defensive purposes against invertebrates and vertebrates, but are unable to adapt venom composition to stimuli (5, 6). Consequently, the expression of venom genes directly affects the ability of ants to interact with the biotic environment, and the venom composition may be fine-tuned to the ecology of each species. A previous study showed that defensive traits in ants exhibit an evolutionary trade-off in which the presence of a sting is negatively correlated with several other defensive traits, further supporting that trade-offs in defensive traits significantly constrain trait evolution and influence species diversification in ants (7). However, the sting is not used for the same purpose depending on the ant species. Our study supports an evolutionary trade-off between the ability of venom to deter vertebrates and to paralyze insects which are correlated with different life history strategies among Formicidae.

ecology↗

bioRxiv2023

Plant mutations: slaying beautiful hypotheses by surprising evidence

Somatic mutations potentially play a role in plant evolution, but common expectations pertaining to plant somatic mutations remain insufficiently tested. Unlike in most animals, the plant germline is assumed to be set aside late in development, leading to the expectation that plants accumulate somatic mutations along growth. Therefore, several predictions were made on the fate of somatic mutations: mutations have generally low frequency in plant tissues; mutations at high frequency have a higher chance of intergenerational transmission; branching topology of the tree dictates mutation distribution; and, exposure to UV radiation increases mutagenesis. To provide new insights into mutation accumulation and transmission in plants, we produced two high-quality reference genomes and a unique dataset of 60 high-coverage whole-genome sequences of two tropical tree species, Dicorynia guianensis (Fabaceae) and Sextonia rubra (Lauraceae). We identified 15,066 de novo somatic mutations in D. guianensis and 3,208 in S. rubra, surprisingly almost all found at low frequency. We demonstrate that: 1) low-frequency mutations can be transmitted to the next generation; 2) mutation phylogenies deviate from the branching topology of the tree; and 3) mutation rates and mutation spectra are not demonstrably affected by differences in UV exposure. Altogether, our results suggest far more complex links between plant growth, ageing, UV exposure, and mutation rates than commonly thought. Significance StatementThe origin and fate of new mutations have received less attention in plants than in animals. Similarly to animals, plant mutations are expected to accumulate with growth and time, and under exposure to UV light. However, contrary to animals, plant reproductive organs form late in an individuals development, allowing the transmission to the progeny of mutations accumulated along growth. Here, we resequenced DNA from different branches differentially exposed to sunlight of two tropical tree species. We showed that new mutations are generally rare in plant tissues and do not mimic branching patterns but can nevertheless be transmitted to the progeny. Our findings provide a new perspective on heritable plant mutation and its pivotal role as the engine of evolution.

genomics↗

bioRxiv2021

Somatic mutation detection in plants: a critical evaluation through simulations and reanalyses

AO_SCPLOWBSTRACTC_SCPLOWO_LIMutation, the source of genetic diversity, is the raw material of evolution; however, the mutation process remains understudied, especially in plants. Using both a simulation and reanalysis framework, we set out to explore and demonstrate the improved performance of variant callers developed for cancer research compared to single nucleotide polymorphism (SNP) callers in detecting de novo somatic mutations. C_LIO_LIIn an in silico experiment, we generated Illumina-like sequence reads spiked with simulated mutations at different allelic fractions to compare the performance of seven commonly-used variant callers to recall them. More empirically, we then reanalyzed two of the largest datasets available for plants, both developed for identifying within-individual variation in long-lived pedunculate oaks. C_LIO_LIBased on the in silico experiment, variant callers developed for cancer research outperform SNP callers regarding plant mutation recall and precision, especially at low allele frequency. Such variants at low allelic fractions are typically expected for within-individual de novo plant mutations, which initially appear in single cells. Reanalysis of published oak data with Strelka2, the best-performing caller based on our simulations, identified up to 3.4x more candidate somatic mutations than reported in the original studies. C_LIO_LIOur results advocate the use of cancer research callers to boost de novo mutation research in plants, and to reconcile empirical reports with theoretical expectations. C_LI This version of the article has been peer-reviewed and recommended by Peer Community in Genomics https://doi.org/10.24072/pci.genomics.100024

plant biology↗

bioRxiv2021

Screening of the antimicrobial activity of marine sponge extracts from Martinique.

Marine sponges are known for their antimicrobial, antifungal, and cytotoxic activity. In this study, the activity of aqueous and ethanoic extracts of 3 sponges from Martinique were tested on 5 bacterial strains: Bascillus cereus (CIP 783), Echerichia coli (CIP 54127), Pseudomonas aeruginosa (CIP A22), Staphylococcus aureus (CIP 67.8) and Staphylococcus saprophyticus (CIP 76125). The antimicrobial activity of Agelas clathrodes, Desmapsamma anchorata, and Verongula rigida, was demonstrated using the disc diffusion method and by determining the minimum inhibitory concentration and the minimum bactericidal concentration. The ethanoic extract of Agelas clathrodes had an inhibitory activity specifically on Staphylococcus aureus and Staphylococcus saprophyticus. No activity was observed for the other extracts. Further chemical analyses will be carried out in order to identify the active molecules of these sponges.

microbiology↗

bioRxiv2018

Low functional but large soil-related variations in growth trajectories characterise the widespread Neotropical tree Cecropia obtusa Trecul (Urticaceae)

AO_SCPLOWBSTRACTC_SCPLOWO_LITrait-environment relationships have been described at the community level across tree species. However, whether interspecific trait-environment relationships are consistent at the intraspecific level is yet unknown. Moreover, we do not know how consistent is the response between organ vs. whole-tree level. C_LIO_LIWe examined phenotypic variability for 16 functional leaf (dimensions, nutrient, chlorophyll) and wood traits (density) across two soil types, Ferralitic Soil (FS) vs. White Sands (WS), on two sites for 70 adult trees of Cecropia obtusa Trecul (Urticaceae) in French Guiana. Cecropia is a widespread pioneer Neotropical genus that generally dominates early successional forest stages. To understand how soil types impact resource-use through the processes of growth and branching, we examined the architectural development with a retrospective analysis of growth trajectories. We expect soil types to affect both, functional traits in relation to resource acquisition strategy as already described at the interspecific level, and growth strategies due to resource limitations with reduced growth on poor soils. C_LIO_LIFunctional traits were not involved in the soil response, as only two traits-leaf residual water content and K content-showed significant differences across soil types. Soil effects were stronger on growth trajectories, with WS trees having the slowest growth trajectories and less numerous branches across their lifespan. C_LIO_LIThe analysis of growth trajectories based on architectural analysis improved our ability to characterise the response of trees with soil types. The intraspecific variability is higher for growth trajectories than functional traits for C. obtusa, revealing the complementarity of the architectural approach with the functional approach to gain insights on the way trees manage their resources over their lifetime. Soil-related responses of Cecropia functional traits are not the same as those at the interspecific level, suggesting that the effects of the acting ecological processes are different between the two levels. Apart from soil differences, much variation was found across sites, which calls for further investigation of the factors shaping growth trajectories in tropical forests. C_LI

ecology↗