Biology subjects

Ahlen, D.

Publications and source records attributed to Ahlen, D..

3 recordsLinked to original sources

bioRxiv2024

Data of the Insect Biome Atlas: a metabarcoding survey of the terrestrial arthropods of Sweden and Madagascar

We present the data from the Insect Biome Atlas project (IBA), characterizing the terrestrial arthropod faunas of Sweden and Madagascar. Over 12 months, weekly Malaise trap samples were collected at 203 locations within 100 sites in Sweden and at 50 locations within 33 sites in Madagascar; this was complemented by soil and litter samples from each site. The field samples comprise 4,749 Malaise trap, 192 soil and 192 litter samples from Sweden and 2,566 Malaise trap and 190 litter samples from Madagascar. Samples were processed using mild lysis or homogenization, followed by DNA metabarcoding of COI (418 bp). The data comprise 698,378 non-chimeric sequence variants from Sweden and 687,866 from Madagascar, representing 33,989 (33,046 Arthropoda) and 77,599 (77,380 Arthropoda) operational taxonomic units, respectively. These are the most comprehensive data presented on these faunas so far, allowing unique analyses of the size, composition, spatial turnover and seasonal dynamics of the sampled communities. They also provide an invaluable baseline against which to gauge future changes.

ecology↗

bioRxiv2024

Biotic and abiotic drivers of ecosystem functioning differ between a temperate and a tropical region

Any single ecosystem will provide many ecosystem functions. Whether these functions tend to increase in concert or trade off against each other is a question of much current interest. Equally topical are the drivers behind ecosystem function rates. Yet, we lack large-scale systematic studies that investigate how abiotic factors can directly or indirectly -- via effects on biodiversity -- drive ecosystem functioning. In this study, we assessed the impact of climate, landscape and biotic community on ecosystem functioning and multifunctioning in the temperate and tropical zone, and investigated potential trade-offs among ecosystem functions in both zones. To achieve this, we measured a diverse set of insect-related ecosystem functions -- including herbivory, seed dispersal, predation, decomposition and pollination -- at 50 sites across Madagascar and 171 sites across Sweden, and characterized the insect community at each site using Malaise traps. We used structural equations models to infer causality of the effects of climate, landscape, and biodiversity on ecosystem functioning. For the temperate zone, we found that abiotic factors were more important than biotic factors in driving ecosystem functioning, while in the tropical zone, effects of biotic drivers were most pronounced. In terms of trade-offs among functions, in the temperate zone, only seed dispersal and predation were positively correlated, while all other functions were uncorrelated. By contrast, in the tropical zone, most ecosystem functions increased in concert, highlighting that tropical ecosystems can simultaneously provide a diverse set of functions. These correlated functions in Madagascar could for the most part be explained by similar responses to local climate, landscape, and biota. Our study suggests that the functioning of temperate and tropical ecosystems differs fundamentally in patterns and drivers. Without a better understanding of these differences, it will be impossible to correctly predict shifts in ecosystem functioning in response to environmental disturbances. To identify global patterns and drivers of ecosystem functioning, we will next need replicate sampling across biomes - as here achieved for two regions, thus paving the road and setting the baseline expectations.

ecology↗

bioRxiv2021

Body size mediates latitudinal population differences in response to Bd infection in two amphibian species.

Populations of the same species may differ in their sensitivity to pathogens but the factors behind this variation are poorly understood. Moreover, infections may cause sub-lethal fitness effects even in species resistant or tolerant to disease. The chytrid fungus Batrachochytrium dendrobatidis (Bd), is a generalist pathogen which has caused amphibian population declines worldwide. In many species, Bd infection causes the disease chytridiomycosis, often leading to high mortality. We investigated how geographical origin affects tolerance to Bd by exposing newly metamorphosed individuals of two North European amphibians (moor frog Rana arvalis, common toad Bufo bufo) from two latitudinal regions to two different BdGPL strains. Bd exposure strongly lowered survival in B. bufo, and in both species survival was lower in the northern region, this difference being much stronger in B. bufo. Northern individuals were smaller in both species, and the survival difference between the regions was size-mediated with smaller individuals being more sensitive to Bd. In both species, Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that even individuals surviving the infection may have reduced fitness mediated by smaller body size. Bd strain affected size-dependent mortality differently in the two regions. We discuss the possible mechanisms how body size and geographical origin can contribute to the present results.

ecology↗