Biology subjects

Vallejo-Marin, M.

Publications and source records attributed to Vallejo-Marin, M..

23 records · Page 2Linked to original sources

bioRxiv2019

Invasion but not hybridisation is associated with ecological niche shift in monkeyflowers

BackgroundThe ecological niche occupied by novel hybrids can influence their establishment as well as the potential to coexist with their parents. Hybridisation generates new phenotypic combinations, which, in some cases, may allow them to occupy ecological niches outside the environmental envelope of parental taxa. In other cases, hybrids may retain similar ecological niches to their parents, resulting in competition and affecting their coexistence. To date, few studies have quantitatively assessed niche shifts associated with hybridisation in recently introduced populations while simultaneously characterising the niche of parental species in both native and introduced ranges.\n\nAimsIn this study, we compared the ecological niche of a novel hybrid plant with the niches of its two parental taxa in the non-native geographic range. We also characterised and compared the parental taxas ecological niche of native and introduced populations in order to assess potential niche changes during the invasion process independent of hybridisation.\n\nMethodsWe studied monkeyflowers (Mimulus spp., Phrymaceae) that were introduced from the Americas to Europe and New Zealand in the last 200 years. We focused on a novel hybrid, triploid, asexual taxon (M. x robertsii) that occurs only in the British Isles where its two parents (M. guttatus and M. luteus) come into secondary contact. We assembled more than 12,000 geo-referenced occurrence records and eight environmental variables of the three taxa across native and introduced ranges, and conducted ecological niche model analysis using maximum entropy, principal component and niche dynamics analysis.\n\nResultsWe found no evidence of niche shift in the hybrid, M. x robertsii compared to introduced populations of both of their parental taxa. The hybrid had a niche more similar to M. luteus, which is also the rarest of the parental taxa on the introduced range. Among parental monkeyflowers, M. guttatus showed niche conservatism in introduced populations in Europe, but a niche shift in New Zealand, while M. luteus showed a niche shift in Europe. However, the evidence of niche shift should be treated with caution due to the occurence of non-analog climatic conditions, small population size and unfilling niche dynamics.\n\nConclusionsOur results suggest that hybridisation in non-native monkyeflowers did not result in a shift in ecological niche. This niche conservation could create competition between parental and derived taxa, the outcome of which will depend on relative competitive abilities. Further work is needed to establish if the expansion of the hybrid in the introduced range is causally related to the apparent rarity of one of the parents (M.luteus). Finally, the comparison of native and non-native populations of parental taxa, suggest that whether invasions result in niche shifts or not depends on both taxon and geographic region, highlighting the idiosyncratic nature of biological invasions.

ecology↗

bioRxiv2019

A test of the evolution of increased competitive ability in two invaded regions

O_LIFinding patterns that predict and explain the success of non-native species has been an important focus in invasion ecology. The evolution of increased competitive ability (EICA) hypothesis has been a frequently used framework to understand invasion success. Evolution of increased competitive ability predicts that 1. Non-native populations will escape from coevolved specialist herbivores and this release from specialist herbivores should result in relaxed selection pressure on specialist-related defense traits, 2. There will be a trade-off between allocation of resources for resistance against specialist herbivores and allocation to traits related to competitive ability and 3. This shift will allow more allocation to competitive ability traits.\nC_LIO_LIWe tested the predictions of EICA in the model plant Mimulus guttatus, a native of western North America (WNA). We compared how well the predictions of EICA fit patterns in two non-native regions, the United Kingdom (UK) and eastern North America (ENA). Coupled with extensive herbivore surveys we quantified genetic variation for herbivore resistance traits and fitness/ competitive ability traits to test adherence to the predictions of EICA in a common greenhouse environment.\nC_LIO_LIHerbivore communities differed significantly between WNA, UK, and ENA populations with evidence of specialist herbivore escape in the UK, but not necessarily the ENA plants. Compared to native plants, resistance traits were lower in non-native UK plants with the exception of trichome density, while the non-native ENA plants had equivalent or higher levels of herbivore resistance traits. The UK plants had increased competitive traits than native plants while the ENA plants had equivalent competitive traits to native plants. The UK plants, but not the ENA plants, showed some signs of tradeoffs between resistance traits and fitness/ competitive ability.\nC_LIO_LISynthesis. Plants from the UK conformed to predictions of EICA more closely than those from ENA. The UK invasion is an older, more successful invasion, suggesting that support for EICA may be highest in more successful invasions. The lack of comprehensive conformity of either non-native region to the predictions of EICA also leaves room for other hypotheses that may add to our mechanistic understanding of the success of non-native plant invasions.\nC_LI

ecology↗

bioRxiv2018

Bee and floral traits affect the characteristics of the vibrations experienced by flowers during buzz-pollination

During buzz pollination, bees use their indirect flight muscles to produce vibrations that are transmitted to the flowers and result in pollen release. Although buzz pollination has been known for >100 years, we are still in the early stages of understanding how bee and floral characteristics affect the production and transmission of floral vibrations. Here we analysed floral vibrations produced by four closely related bumblebee taxa (Bombus spp.) on two buzz-pollinated plants species (Solanum spp.). We measured floral vibrations transmitted to the flower to establish the extent to which the mechanical properties of floral vibrations depend on bee and plant characteristics. By comparing four bee taxa visiting the same plant species, we found that peak acceleration (PA), root mean-squared acceleration (RMS) and frequency varies between bee taxa, but that neither bee size (intertegular distance) or flower biomass (dry weight) affect PA, RMS or frequency. A comparison of floral vibrations of two bee taxa visiting flowers of two plant species, showed that, while bee species affects PA, RMS and frequency, plant species affects acceleration (PA and RMS) but not frequency. When accounting for differences in the transmission of vibrations across the two types of flowers, using a species-specific \"coupling factor\", we found that RMS acceleration and peak displacement does not differ between plant species. This suggests that bees produce the same initial acceleration in different plants but that transmission of these vibrations through the flower is affected by floral characteristics.\n\nSummary statementWe show that buzz-pollinating bumblebees differ in the type of vibrations produced while visiting the same flower, and that floral species affects the transmission properties of those vibrations.

biophysics↗

bioRxiv2018

Mechanisms driving endosperm-based hybrid incompatibilities: insights from hybrid monkeyflowers

Angiosperm endosperm requires genomic and epigenomic interactions between maternal and paternal genomes for proper seed development. Genomic imprinting, an epigenetic phenomenon where the expression of certain genes is predominantly contributed by one parent, is an essential part of this process and unique to endosperm. Perturbation of imprinting can be fatal to developing seeds, and can be caused by interspecific or interploidy hybridization. However, underlying mechanisms driving these endosperm-based hybridization barriers are not well understood or described. Here we investigate the consequences of genomic imprinting in a naturally occurring interploidy and interspecies hybrid between the diploid, Mimulus guttatus, and the allotetraploid (with two subgenomes), M. luteus (Phrymaceae). We find that the two parental species differ in patterns of DNA methylation, gene expression, and imprinting. Hybrid crosses in both directions, which suffer from endosperm abnormalities and decreased germination rates, display altered methylation patterns compared to parent endosperm. Furthermore, imprinting and expression patterns appear perturbed in hybrid endosperm, where we observe global expression dominance of each of the two M. luteus subgenomes, which share similar expression patterns, over the M. guttatus genome, regardless of crossing direction. We suggest that epigenetic repatterning within the hybrid may drive global shifts in expression patterns and be the result of diverged epigenetic/regulatory landscapes between parental genomes. This may either establish or exacerbate dosage-based epistatic incompatibilities between the specific imprinting patterns that have diverged between parental species, thus driving potentially rapid endosperm-based hybridization barriers.

evolutionary biology↗

bioRxiv2016

Subgenome dominance in an interspecific hybrid, synthetic allopolyploid, and a 140 year old naturally established neo-allopolyploid monkeyflower.

The importance and applications of polyploidy have long been recognized, from shaping the evolutionary success of flowering plants to improving agricultural productivity. Recent studies have shown that one of the parental subgenomes in ancient polyploids is generally more dominant - having both retained more genes and being more highly expressed - a phenomenon termed subgenome dominance. How quickly one subgenome dominates within a newly formed polyploid, if immediate or after millions of years, and the genomic features that determine which genome dominates remain poorly understood. To investigate the rate of subgenome dominance emergence, we examined gene expression, gene methylation, and transposable element (TE) methylation in a natural less than 140 year old allopolyploid (Mimulus peregrinus), a resynthesized interspecies triploid hybrid (M. robertsii), a resynthesized allopolyploid (M. peregrinus), and diploid progenitors (M. guttatus and M. luteus). We show that subgenome expression dominance occurs instantly following the hybridization of two divergent genomes and that subgenome expression dominance significantly increases over generations. Additionally, CHH methylation levels are significantly reduced in regions near genes and within transposons in the first generation hybrid, intermediate in the resynthesized allopolyploid, and are repatterned differently between the dominant and submissive subgenomes in the natural allopolyploid. Our analyses reveal that the subgenome differences in levels of TE methylation mirror the increase in expression bias observed over the generations following the hybridization. These findings not only provide important insights into genomic and epigenomic shock that occurs following hybridization and polyploid events, but may also contribute to uncovering the mechanistic basis of heterosis and subgenomic dominance.

genomics↗