Biology subjects

Gravendeel, B.

Publications and source records attributed to Gravendeel, B..

8 recordsLinked to original sources

bioRxiv2025

Universal Hyb-Seq kits capture considerable intraspecific variation: Less is more in herbarium-inclusive molecular ecology

Target capture sequencing has enhanced the study of plant evolution and molecular ecology, particularly through the access to degraded DNA from herbarium specimens. Universal "off-the-shelf" kits, such as Angiosperms-353, are cheap and readily available but are considered to expose insufficient variation below the species level, because they are designed to target highly conserved regions. However, this remains to be tested in a direct comparison with customised approaches below the species level. In this study, near-identical genotypes from both herbarium and fresh material of the common dandelion (apomictic lineages in Taraxacum officinale F.H.Wigg.) are characterised with customised and universal approaches of target capture sequencing. An RNA-bait panel was designed to capture (i) highly variable loci normally obtained with a Genotyping-by-Sequencing (GBS) approach customised for dandelions; (ii) custom selected genes with potential for environmental adaptation, likely to harbour intraspecific genetic variation; (iii) conserved exons from universal kits (Angiosperms-353; Compositae-COS). Although exons from universal kits yield considerably less intraspecific genetic variation than both customised approaches, they still provided sufficient genetic variation to discriminate between near-identical genotypes of the same apomictic lineage. Given that universal kits save time, money, and the need for genomic reference data, this approach is recommended to increase the number of samples under budgetary constraints while still capturing considerable levels of intraspecific genetic variation.

genomics↗

bioRxiv2024

Data-centric AI approach for automated wildflower monitoring

Both researchers and policy makers are in need of standards and tools that help understanding and assessing natural capital. Wildflowers are a major component of our natural capital; they play an essential role in ecosystems, improve soil health, supply food and medicines, and curb climate change. In this paper, we present the Eindhoven Wildflower Dataset (EWD) as well as a PyTorch object detection model that is able to identify and count wildflowers. EWD, collected over two entire flowering seasons and expert annotated, contains 2002 top-view images of flowering plants captured in the wild in five different landscape types (roadsides, urban green spaces, cropland, weed-rich grassland, marshland). It holds a total of 65571 annotations for 160 species belonging to 31 different families of flowering plants and serves as a reference dataset for automating wildflower monitoring. To ensure consistent annotations, we define specific floral count units (largely based on inflorescences) and provide extensive annotation guidelines. With a 0.82 mAP (@IoU > 0.50) score the presented baseline model, trained with a balanced subset of EWD, is to the best of our knowledge superior in its class. Our approach empowers automated quantification of wildflower richness and abundance and encourages the development of standards for AI-based wildflower monitoring. The annotated EWD dataset is publicly available on the DataverseNL research data repository, and the code to train and run the baseline model is supplied as supplementary material.

bioinformatics↗

bioRxiv2023

The Origin And Speciation Of Orchids

Orchids constitute one of the most spectacular radiations of flowering plants. However, their geographical origin, historical spread across the globe, and hotspots of speciation remain uncertain due to the lack of a broad phylogenomic framework. We present a new Orchidaceae phylogeny based on high-throughput and Sanger sequencing datasets, covering all five subfamilies, 17/22 tribes, 40/49 subtribes, 285/736 genera, and [~]7% (1,921) of the currently 29,524 accepted species. We then use it to infer geographic range evolution, diversity, and speciation patterns by adding curated geographical distribution data through the World Checklist of Vascular Plants. Orchids most recent common ancestor is traced back to the Late Cretaceous in Laurasia. The modern Southeast Asian range of subfamily Apostasioideae is interpreted as relictual, matching the history of numerous clades that went extinct at higher latitudes following the global climate cooled during the Oligocene. Despite their ancient origins, modern orchid species diversity mainly originated over the last 5 Ma, with the fastest speciation rates found in south-eastern Central America. Our results substantially alter our understanding of the geographic origin of orchids, previously proposed as Australian, and further pinpoint the role of Central American as a region of recent and explosive speciation.

evolutionary biology↗

bioRxiv2023

Some like it hot: adaptation to the urban heat island in common dandelion.

The Urban Heat Island Effect (UHIE) is a globally consistent pressure on species living in cities. Rapid adaptation to the UHIE may be necessary for urban wild flora to persist in cities, but experimental evidence is lacking. Here, we report the first evidence of genetic differentiation in a plant species in response to the UHIE. We collected seeds from common dandelion (Taraxacum officinale) individuals along an urban-rural gradient in the city of Amsterdam (The Netherlands). In common-environment greenhouse experiments, we assessed the effect of elevated temperatures on plant growth and the effect of vernalisation treatments on flowering phenology. We found that urban plants accumulate more biomass at higher temperatures and require shorter vernalisation to induce flowering compared to rural plants. Differentiation was also observed between different intra-urban subhabitats, with park plants displaying a higher vernalisation requirement than street plants. Our results show strong differentiation between urban and rural dandelions in temperature-dependent growth and phenology, consistent with adaptive divergence in response to the UHIE. Rapid adaptation to the UHIE may be a potential explanation for the widespread success of dandelions in urban environments. Summary statementThe urban heat island effect (UHIE) is the most prominent and globally consistent characteristic of environmental change due to urbanisation, severely impacting human populations in cities as well as the cohabiting wildlife. Despite the profoundly mitigating effect of vegetation on urban heat, evidence for plant adaptation to the UHIE has been lacking. Here we provide the first experimental evidence to date, demonstrating adaptation in urban dandelions in response to elevated temperatures, similar to the UHIE. We furthermore show an urban-rural differentiation in flowering response to shorter vernalisation times (cold winter period to activate the onset of flowering in early spring). Given the predominantly asexual apomictic mode of reproduction in dandelions, this evolution is likely the result of environmental filtering on a diverse population of clonal genotypes. We conclude that plant adaptation to the UHIE exists and recommend future studies to contrast our findings with those in outcrossing sexual plant systems. Studies of urban heat adaptation can bring impactful contributions to building climate change-resilient environments and plants should be an integral part of this research.

plant biology↗

bioRxiv2022

A TOMATO GENOME FROM THE ITALIAN RENAISSANCE PROVIDES INSIGHTS INTO COLUMBIAN AND PRE-COLUMBIAN EXCHANGE LINKS AND DOMESTICATION

AO_SCPLOWBSTRACTC_SCPLOWThe history of the tomatos interactions with humans spans both a pre-Columbian period of millennia of cultivation and domestication in South and Central America as well as the plants rise to becoming one of the worlds major cash crops following the arrival of Europeans in the Neotropics and the subsequent Columbian Exchange. In the process, the influence of successive regimes of artificial selection gave rise to an entangled species complex comprised of a wild ancestor and numerous cultivars exhibiting a great diversity of fruit phenotypes (often sorted in cherry and big types). Here, we provide a snapshot into these dynamics by presenting the ancient nuclear and plastid genomes of one of the oldest tomatoes still in existence: the almost half a millennium old En Tibi specimen from the Italian Renaissance. By placing the genome skimming data obtained from this specimen within the phylogenomic context of wild relatives and Neotropical tomato cultivars and land races, we are able to show that the most likely geographic origins of the specimens immediate ancestors, i.e. whence the exchange of this particular lineage originated, are around the Gulf of Mexico. We also show that this specimen was less inbred than present-day tomatoes, shedding light on the genomic signatures of historical domestication processes. Probing deeper into the ancestry that shaped extant genetic diversity within the complex, we reconstruct multiple ancestral populations with diffuse but distinct signatures in cherry and big tomatoes. The geographic structure of these ancestries within the nearest wild relative of tomatoes and the differential extent to which these ancestries are represented in domesticates points to early cultivation and human-assisted dispersal of tomatoes originating from the northern extreme of the natural range of the species. Our findings illustrate the inferences that can be drawn from ancient DNA extracted from herbarium specimens and historic plant collections. At the same time, we stress that our findings draw on multiple disciplines including ethnobotanical and historical research and on the (agri)cultural contributions of a variety of world cultures.

plant biology↗

bioRxiv2022

Phylotranscriptomics Reveals the Reticulate Evolutionary History of a Widespread Diatom Species Complex

In contrast to surveys based on a few genes that often provide limited taxonomic resolution, transcriptomes provide a wealth of genomic loci that can resolve relationships among taxonomically challenging lineages. Diatoms are a diverse group of aquatic microalgae that includes important bioindicator species and many such lineages. One example is Nitzschia palea, a widespread species complex with several morphologically based taxonomic varieties, some of which are critical pollution indicators. Morphological differences among the varieties are subtle and phylogenetic studies on a few genes fail to resolve their evolutionary relationships. We conducted morphometric and transcriptome analyses of 10 Nitzschia palea strains to resolve the relationships among strains and taxonomic varieties. Nitzschia palea was resolved into three clades, one of which corresponds to a group of strains with narrow linear-lanceolate valves. The other morphological group recovered in the shape outline analysis was not monophyletic and consisted of two clades. Subsequent gene-tree concordance analyses and phylogenetic network estimations revealed patterns of incomplete lineage sorting and gene flow between intraspecific lineages. We detected reticulated evolutionary patterns among lineages with different morphologies and a resulting putative recent hybrid. Our study shows that phylogenomic analyses of many unlinked nuclear loci, complemented with morphometrics, can resolve complex evolutionary histories of recently diverged species complexes.

genomics↗

bioRxiv2020

Archaeogenomics of a ~2,100-year-old Egyptian leaf provides a new timestamp on date palm domestication

O_LIThe date palm (Phoenix dactylifera) has been a cornerstone of Middle Eastern and North African agriculture for millennia. It is presumed that date palms were first domesticated in the Persian Gulf and subsequently introduced into North Africa, where their evolution in the latter region appears to have been influenced by gene flow from the wild relative P. theophrasti, which is restricted to Crete and Turkey. However, the timing of gene flow from P. theophrasti to P. dactylifera remains unknown due to the limited archaeobotanical evidence of P. theophrasti and their exclusion from population genomic studies. C_LIO_LIWe addressed this issue by investigating the relatedness and ancestry of a ~2,100-year-old P. dactylifera leaf from Saqqara (Egypt), combining genome sequencing of this ancient specimen with a broad sample of date palm cultivars and closely related species. C_LIO_LIThe ancient Saqqara date palm shares close genetic ancestry with North African date palm populations. We find clear genomic admixture between the Saqqara date palm, P. theophrasti and the closest known relative P. sylvestris. C_LIO_LIOur study highlights that gene flow from P. theophrasti and P. sylvestris to North African date palms had already occurred at least ~2,100 years ago, providing a minimum timestamp for hybridisation between species. C_LI

evolutionary biology↗

bioRxiv2020

Hundreds of nuclear and plastid loci yield insights into orchid relationships

Premise of the studyEvolutionary relationships in the species-rich Orchidaceae have historically relied on organellar DNA sequences and limited taxon sampling. Previous studies provided a robust plastid-maternal phylogenetic framework, from which multiple hypotheses on the drivers of orchid diversification have been derived. However, the extent to which the maternal evolutionary history of orchids is congruent with that of the nuclear genome has remained uninvestigated. MethodsWe inferred phylogenetic relationships from 294 low-copy nuclear genes sequenced/obtained using the Angiosperms353 universal probe set from 75 species representing 69 genera, 16 tribes and 24 subtribes. To test for topological incongruence between nuclear and plastid genomes, we constructed a tree from 78 plastid genes, representing 117 genera, 18 tribes and 28 subtribes and compared them using a co-phylogenetic approach. The phylogenetic informativeness and support of the Angiosperms353 loci were compared with those of the 78 plastid genes. Key ResultsPhylogenetic inferences of nuclear datasets produced highly congruent and robustly supported orchid relationships. Comparisons of nuclear gene trees and plastid gene trees using the latest co-phylogenetic tools revealed strongly supported phylogenetic incongruence in both shallow and deep time. Phylogenetic informativeness analyses showed that the Angiosperms353 genes were in general more informative than most plastid genes. ConclusionsOur study provides the first robust nuclear phylogenomic framework for Orchidaceae plus an assessment of intragenomic nuclear discordance, plastid-nuclear tree incongruence, and phylogenetic informativeness across the family. Our results also demonstrate what has long been known but rarely documented: nuclear and plastid phylogenetic trees are not fully congruent and therefore should not be considered interchangeable.

evolutionary biology↗