Molecular biogeography of prickly lettuce (lactuca serriola l.) shows traces of recent range expansion

Prickly lettuce (Lactuca serriola L., Asteraceae), a wild relative of cultivated lettuce, is an autogamous species which greatly expanded throughout Western and Northern Europe during the last 2 centuries. Here, we present a large-scale biogeographic genetic analysis performed on a dataset represented by 2622 individuals from 110 wild European populations. Thirty-two maternally inherited chloroplast RFLP-markers and 10 nuclear microsatellite loci were used. Microsatellites revealed low genetic variation and high inbreeding coefficients within populations, as well as strong genetic differentiation between populations, which was in accordance with the autogamous breeding system. Analysis of molecular variance based clustering indicated the presence of 3 population clusters, which showed strong geographical patterns. One cluster occupied United Kingdom and part of Northern Europe, and characterized populations with a single predominant genotype. The second mostly combined populations from Northern Europe, while the third cluster grouped populations particularly from Southern Europe. Kriging of gene diversity for L. serriola corroborated northwards and westwards spread from Central (Eastern) Europe. Significant lower genetic diversity characterized the newly colonized parts of the range compared to the historical ones, confirming the importance of founder effects. Stronger pattern of isolation by distance was assessed in the newly colonized areas than in the historical areas (Mantel’s r = 0.20). In the newly colonized areas, populations at short geographic distances were genetically more similar than those in the historical areas. Our results corroborate the species’ recent and rapid northward and westward colonization from Eastern Europe, as well as a decrease of genetic diversity in recently established populations

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Over de toekomst van Valkruid (Arnica montana) in Nederland: wat is er aan de hand in kleine populaties?

Een groot aantal plantensoorten is de laatste tientallen jaren drastisch in verspreiding achteruitgegaan door verslechtering en vernietiging van hun habitat. Populaties van deze soorten worden steeds kleiner en groeien steeds meer van elkaar geïsoleerd in natuurreservaten. Onafhankelijk van de kwaliteit van de groeiplaats is er een aantal risico’s verbonden aan het kleiner worden van de populatie en een toenemende mate van isolatie, zoals het verlies van genetische variatie, de vermindering van voortplantingssucces, en de vermindering van genetische uitwisseling tussen populaties. Daardoor kan het gebeuren dat populaties niettegenstaande een (oecologisch) juist beheer alsnog uitsterven. Het is daarom noodzakelijk dat we meer inzicht krijgen in het belang van deze processen voor de levensvatbaarheid van (kleine) geïsoleerde populaties van zeldzame soorten. Een aantal van deze risico’s wordt thans onderzocht bij een serie populaties van Arnica, voornamelijk in Drenthe. Arnica montana (Valkruid) is een kenmerkende soort van heischrale graslanden van het verbond Violion caninae. Veel soorten van deze levensgemeenschap zijn de laatste jaren achteruit gegaan of zelfs geheel verdwenen. Valkruid is een overblijvende plant die zich zowel sexueel via zaden als vegetatief met korte ondergrondse uitlopers vermeerdert

Bumblebee pollination of understorey shrub species in a tropical montane forest in Costa Rica

This study addresses the pollination ecology of shrub species in an upper montane forest in Costa Rica, where the diversity of insect visitors is much below that of the well-studied tropical forests of lower elevations. Data are presented on visitation rates by the tropical bumblebee Bombus ephippiatus to flowers of three species, pollen loads on bumblebee bodies, and pollen loads on stigmas of two of` the species. High visitation rates to flowers of Palicourea brenesii were found, a species which produces copious amounts of nectar. Visitation rates to nectarless Leandra subseriata and Deppea grandiflora were much lower. Conspecific pollen comprised on average 90% of the pollen load on stigmas of Leandra, while Palicourea stigmas carried only 26 to 55% conspecific pollen, With only two ovules per flower, fruit and seed set in Palicourea were not limited by a shortage of conspecific pollen. In Leandra, 20-25% of the flowers received too few conspecific pollen grains for maximum seed set among 440 ovules per flower. Individual bumblebees showed no constancy in plant choice, judging from the high number of different pollen types (6-12) on their bodies. Workers returned frequently to the same Palicourea patch without visiting nearby Palicourea plants, which suggests the use of foraging paths