Robidart, J. | Search bioRxiv

bioRxiv2020

Consistent marine biogeographic boundaries across the tree of life despite centuries of human impacts

Over millennia, ecological and evolutionary mechanisms have shaped macroecological distributions across the tree of life. Research describing patterns of regional and global biogeography has traditionally focussed on the study of conspicuous species. Consequently, there is limited understanding of cross-phyla biogeographic structuring, and an escalating need to understand the macroecology of both microscopic and macroscopic organisms. Here we used environmental DNA (eDNA) metabarcoding to explore the biodiversity of marine metazoans, micro-eukaryotes and prokaryotes along an extensive and highly heterogeneous coastline. Our results showed remarkably consistent biogeographic structure across the kingdoms of life, which were underpinned by environmental and anthropogenic influence. Additionally, metazoan communities displayed biographic patterns that suggest regional biotic homogenisation of conspicuous species. Against the backdrop of global pervasive anthropogenic environmental change, our work highlights the importance of considering multiple domains of life to understand the maintenance and drivers of marine biodiversity across broad taxonomic, ecological and geographical scales.

ecology↗

bioRxiv2018

The detection of novel and resident marine non-indigenous species using environmental DNA metabarcoding of seawater and sediment

Environmental DNA (eDNA) surveys are increasingly being used for biodiversity monitoring, principally because they are sensitive and can provide high resolution community composition data. Despite considerable progress in recent years, eDNA studies examining how different environmental sample types can affect species detectability remain rare. Comparisons of environmental samples are especially important for providing best practice guidance on early detection and subsequent mitigation of non-indigenous species. Here we used eDNA metabarcoding of COI (cytochrome c oxidase subunit I) and 18S (nuclear small subunit ribosomal DNA) genes to compare community composition between sediment and water samples in artificial coastal sites across the United Kingdom. We first detected markedly different communities and a consistently greater number of distinct operational taxonomic units in sediment compared to water. We then compared our eDNA datasets with previously published rapid assessment biodiversity surveys and found excellent concordance among the different survey techniques. Finally, our eDNA surveys detected many non-indigenous species, including several newly introduced species, highlighting the utility of eDNA metabarcoding for both early detection and temporal / spatial monitoring of non-indigenous species. We conclude that careful consideration on environmental sample type is needed when conducting eDNA surveys, especially for studies assessing community change.

molecular biology↗