Biology subjects

Sivess, L.

Publications and source records attributed to Sivess, L..

3 recordsLinked to original sources

bioRxiv2026

Metagenomic analysis of the effects of European bison Bison bonasus (Linnaeus, 1758) presence on soil community structure and function in West Blean and Thornden Woods, Kent

The reintroduction of extinct or endangered species to restore ecosystem function is an essential aspect of rewilding. The Wilder Blean Project at West Blean and Thornden Woods in Canterbury, UK, is committed to rewilding natural processes and enhancing biodiversity in one of England's oldest and largest areas of ancient woodland. The introduction of European bison (Bison bonasus) is an important part of the project. However, how the reintroduction of large herbivores influences local biodiversity and ecosystem functions during the early stages of rewilding remains poorly understood. Soil samples were collected from the same sampling sites before and two years after bison were reintroduced and profiled by metagenomic sequencing using Oxford Nanopore Technologies sequencing platforms. The results showed that the alpha diversity of soil organisms did not change significantly before and after the introduction of European bison, while beta diversity showed modest shifts in community composition. The relative abundance of some nitrogen-fixing and photosynthetic microbial genera showed declines in the 2024 Bison Area, while the mycorrhizal fungus genus Rhizophagus was significantly less abundant than in the 2024 Control Area. Despite relatively stable taxonomic diversity, functional composition differed significantly between the 2022 and 2024 Bison areas and among the 2024 rewilding treatments, revealing a decoupling between taxonomic diversity and functional composition. Amino acid synthesis pathways and carbon metabolism pathways were significantly enriched. These findings highlight the potential of long-read Oxford Nanopore metagenomics to reveal functional shifts that may not be apparent from taxonomic diversity alone. Although these early-stage responses cannot yet predict long-term rewilding trajectories, continued longitudinal monitoring integrating microbial, soil physicochemical, and ecosystem-level measurements will be essential to determine the persistence and ecological significance of these functional shifts.

ecology↗

bioRxiv2026

Warming-induced sex bias fuels deceptive conservation success in sea turtles

Global warming threatens species with temperature-dependent sex determination (TSD) by risking extreme offspring sex-ratio bias. In sea turtles, warmer incubation conditions produce more females. Such biases can transiently inflate apparent population growth before male scarcity undermines reproduction, possibly leading to population extinction. Here, we combine 15 years of field monitoring, drone-based sex-ratio surveys, Argos telemetry, and eco-physiological modelling to test whether rising temperatures underpin the rapid increase in loggerhead (Caretta caretta) nesting in Cabo Verde, one of the worlds largest populations. Historical air temperature, lagged by one generation, predicts current nest counts, consistent with a climate-driven, female-biased population. Drone surveys reveal an approximately 9:1 female-to-male breeding sex ratio across two consecutive breeding seasons, and simulations reproduce observed nesting trajectories under historical warming but not under null (no-warming) scenarios. Extending the analysis to 28 global loggerhead populations reveals consistent links between temperatures, latitude, and nesting trends. Our results identify warming-induced sex ratio bias as a key, yet deceptive, driver of apparent recovery, highlighting the need to reassess conservation success through the lens of demography of TSD species.

ecology↗

bioRxiv2022

Comparing the accuracy and efficiency of third generation DNA barcode sequencing: Oxford Nanopore Technologies versus Pacific Biosciences

At times of drastic decrease in biodiversity and loss of species, sometimes referred to as the "sixth mass extinction" or "Holocene extinction", there is a high demand on the development of effective tools for studying and monitoring biodiversity. In the past decade, new promising technologies, such as third generation sequencing (TGS), enabled massive, rapid, and cost-effective data analysis of non-model organisms, accelerating taxonomic identification studies and contributing to conservation applications. Here, we focus on the comparison of the two main TGS providers, Pacific Biosciences (PacBio), and Oxford Nanopore Technologies (ONT), for the purpose of DNA barcoding. For ONT, we also tested selected combinations of different types of flow cells and ligation sequencing kits. Out of five tested combinations (PacBio, ONT Flongle flow cell & SQK-LSK110 kit, R9 flow cell & SQK-LSK109 kit, R9 & SQK-LSK100 kit, and R10 flow cell & Q20+ chemistry kit), ONTs Flongle turned out to be most variable in returning the results, but at the same time the most cost efficient. The highest numbers of successfully sequenced samples were achieved with the ONTs R10 & Q20+ chemistry combination. In terms of library preparation time, ONT protocols are the quickest, whereas regarding cost effectiveness - using Sanger pricing per sample as a cut-off - various technologies become affordable depending on the number of samples used. Although both tested platforms are suitable for DNA barcoding, we further discuss their limitations and applicability to different studies, with a special focus on the price and the number of samples. The pipeline we developed, from whole specimens to final DNA barcode consensuses, can aid planning and budgeting biodiversity studies, maximising the number of specimens sequenced in one run and speeding up the sample processing time.

molecular biology↗