Nijat Nariman
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nnariman.bsky.social
Nijat Nariman
@nnariman.bsky.social
260 followers 110 following 17 posts
Behavioural & Evolutionary Ecologist | Biological Invasions | Spiders and sometimes beetles | he / him | https://linktr.ee/nnariman
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nnariman.bsky.social
No microbial puppet-masters here. European populations of #MermessusTrilobatus lack Rickettsia/Wolbachia; high-flyers host FEWER bacteria. Dispersal is most likely coded in genome, not microbiome. #Microbiome #Genetics doi.org/10.1007/s002...
A two-panel boxplot comparing bacterial richness (number of observed OTUs) across spider groups. Panel a that high-dispersive spiders (left box) have lower microbial OTU richness (median ≈ 7.5) than low-dispersive spiders (right box; median ≈ 12). Panel b shows similar richness between spiders from the invasion front (Horsens; median ≈ 10.5) and those from the invasion core (Wilgartswiesen; median ≈ 9.8). A two-panel NMDS ordination of microbial community composition (Bray–Curtis dissimilarity) for spider groups. Panel a plots high-dispersive and low-dispersive spiders; points for both overlap, indicating no distinct clustering (stress = 0.17). Panel b plots spiders from Horsens versus Wilgartswiesen; points largely overlap, showing no separation by origin (stress = 0.18).
July 24, 2025 at 9:12 AM
nnariman.bsky.social
The key: highly dispersive spiders accumulate at invasion edge with the most recent spread, mate with each other → super-dispersive offspring → faster spread. Genetic spatial sorting in action or microbial puppets? ⬇️ #EvolutionaryBiology #InvasionGenetics #SpatialSorting doi.org/10.1111/geb....
Three-panel bar chart showing dispersal behaviour frequencies in Mermessus trilobatus offspring. Panel (a) shows tiptoe frequency, panel (b) shows rafting frequency, and panel (c) shows take-off frequency. Each panel displays four bars representing offspring from different locations: W = Wilgartswiesen (core, first found 1981), L = Landau (core, first found 1981), V = Vienna (front, first found 2009), and H = Horsens (front, first found 2018). Error bars show standard error. Statistical differences between locations are marked with letters a and b, where locations sharing the same letter are not significantly different. Generally, offspring from area with the most recent colonisation (Horsens) show twice higher dispersal frequencies than those from long-established populations (Vienna, Wilgartswiesen and Landau).
July 24, 2025 at 9:12 AM
nnariman.bsky.social
Dispersal isn’t random – it’s heritable! Offspring of two high-flying parents show 3× higher dispersal rates in #MermessusTrilobatus. High dispersal is recessive, helping founders race ahead then ‘dial back’ later. #Dispersal #Heritability #Evolution doi.org/10.1016/j.an...
Figure shows three side-by-side bar charts (a, b, c), each comparing the mean frequency (± SE) of a dispersal behaviour in F2 offspring across four parental breeding: HH (both parents high-dispersive), HL (high-dispersive dam, low-dispersive sire), LH (low-dispersive dam, high-dispersive sire), and LL (both parents low-dispersive). Panel (a) plots tiptoe frequency, panel (b) rafting frequency, and panel (c) take-off frequency. In each chart, the HH group bar is about three times taller than the other three bars, which are all similar in height; letters above bars (“a” for HH and “b” for HL, LH, LL) denote that HH differs significantly from the other groups, which do not differ from each other.
July 24, 2025 at 9:12 AM
nnariman.bsky.social
Wait...🤔 They're TERRIBLE at handling disturbance, get eaten more by native predators, yet somehow conquered 1,400km of Europe in 45 years? HOW?! 🤯 The answer in establishment might lie in their reproductive behaviour (work in progress - stay tuned!). But let's look at how they spread so fast! ⬇️
Cartoon illustration of a dark-haired, bearded researcher wearing a white lab coat and a small hoop earring. He scratches his head with a worried expression while standing in front of a presentation board. The board shows a zig-zagging upward line graph, a vertical bar chart, a circular pie chart, and several spider silhouettes, all hinting at invasion data. Three large black question marks hover above his head, emphasizing confusion. The background and chart elements use muted beige and brown tones that match the scientist’s lab coat and overall palette.
July 24, 2025 at 9:12 AM
nnariman.bsky.social
Range expansion is speeding up! We mapped 4,000 records: front advanced from 150 km/decade in the 1980s to 400 km/decade after 2010. #Biogeography #RangeShifts #ClimateChange doi.org/10.1111/geb....
Map of Europe displaying ~4,000 collection records of the invasive spider Mermessus trilobatus. Grey circles mark records from 1981–2001, black circles records from 2002–2021. Red markers highlight four sampling localities: two core sites in south-west Germany (Landau and Wilgartswiesen, red squares), a mid-range site near Vienna, Austria (red rhombus), and a recent-front site near Horsens, Denmark (red triangle). Latitudinal and longitudinal grid lines and a scale bar illustrate spatial spread over 1,300 km from the original 1981 detection. Line scatter-plot showing the progressive expansion distance of Mermessus trilobatus in Europe from 1981 to 2021. Each point represents the furthest yearly record from the 1981 introduction site, with red-filled circles marking years when the invasion front advanced. Distances increase from ~150 km in the 1980s to ~1,350 km by 2021. A quadratic red curve fits the maximum distances, illustrating an accelerating, super-linear expansion rate (r² ≈ 0.98). Horizontal and vertical axes denote calendar year and great-circle distance in kilometres, respectively.
July 24, 2025 at 9:12 AM
nnariman.bsky.social
Prey naïveté vs. enemy release? We pitted #MermessusTrilobatus against a native predator. Result? Invader was eaten 3× more often than local spiders 🕷️🕷️🍽️ – naïveté beats enemy-release here. #PredatorPrey #Behaviour #AlienSpecies doi.org/10.1002/ece3...
Bar chart showing mean predation rate (± SE) of a native ground-hunting spider on two sheet-web prey. The left bar, labelled “Mermessus trilobatus (invasive)”, rises to about 70% consumed; the right bar, “Erigone dentipalpis (native)”, reaches roughly 25% consumed. Error bars illustrate standard errors, highlighting that the invader is eaten around three times more often than the native species.
July 24, 2025 at 9:12 AM
nnariman.bsky.social
Unexpected sensitivity of #MermessusTrilobatus to soil disturbance in grasslands! Contrary to many invaders, ploughing slashes its numbers by ≈90%! ➡️ managing grasslands may rein in its spread. #Biodiversity #Disturbance @biolinvasions.bsky.social doi.org/10.1007/s105...
Bar chart comparing densities (individuals / m²) of eight grass-dwelling linyphiid spiders in disturbed vs. undisturbed hay meadows. For each species, two adjacent bars show mean ± SE; Mermessus trilobatus drops sharply after soil tillage (~90% decline, marked with an asterisk), whereas native species remain stable or, in Oedothorax apicatus, rise markedly. X-axis lists species; Y-axis shows individuals per square metre; significant treatment effects indicated by asterisks.
July 24, 2025 at 9:12 AM
nnariman.bsky.social
Tiny #spiders, huge impact! Meet #MermessusTrilobatus – a North-American dwarf spider that has stormed across #Europe in <50 yrs. We follow every silk thread of its success story 🕸️✨ Swipe through this thread for the highlights! #InvasiveSpecies #Ecology
Two small brown spiders on their webs with white springtails. The smaller male spider is on the left, while the larger female spider on the right has a visible red mating plug that develops after her first mating to ensure paternity. Small white springtails, which serve as food for the spiders, are scattered on the silky webs. Three stereo-microscope views of Mermessus trilobatus (dwarf spider): (a) an unmated female seen from above with a smooth epigynal, (b) a mated female showing the rounded mating plug covering her epigyne, and (c) a male with slender legs and elongated abdomen, all on a neutral background.
July 24, 2025 at 9:12 AM