Community assembly and metaphylogeography of soil biodiversity: insights
from haplotype-level community DNA metabarcoding within an oceanic
island
Abstract
Most of our understanding of island diversity comes from the study of
aboveground systems, while the patterns and processes of diversification
and community assembly for belowground biotas remain poorly understood.
Here we take advantage of a relatively young and dynamic oceanic island
to advance our understanding of eco-evolutionary processes driving
community assembly within soil mesofauna. Using whole organism community
DNA (wocDNA) metabarcoding and the recently developed metaMATE pipeline,
we have generated spatially explicit and reliable haplotype-level DNA
sequence data for soil mesofaunal assemblages sampled across the four
main habitats within the island of Tenerife. Community ecological and
metaphylogeographic analyses have been performed at multiple levels of
genetic similarity, from haplotypes to species and supraspecific
groupings. Broadly consistent patterns of local-scale species richness
across different insular habitats have been found, whereas local insular
richness is lower than in continental settings. Our results reveal an
important role for niche conservatism as a driver of insular community
assembly of soil mesofauna, with only limited evidence for habitat
shifts promoting diversification. Furthermore, support is found for a
fundamental role of habitat in the assembly of soil mesofauna, where
habitat specialism is mainly due to colonisation and the establishment
of preadapted species. Hierarchical patterns of distance decay at the
community level and metaphylogeographical analyses support a pattern of
geographic structuring over limited spatial scales, from the level of
haplotypes through to species and lineages, as expected for taxa with
strong dispersal limitations. Our results demonstrate the potential for
wocDNA metabarcoding to advance our understanding of biodiversity.