Eelgrass Zostera capensis populations in KwaZulu-Natal, South Africa, harbour distinct genomic signals despite limited geographical distance
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Date
Authors
Smit, S. Engela
Henriques, Romina
Jackson, Megan
Taylor, Ricky
Vivier, Leon
Von der Heyden, Sophie
Journal Title
Journal ISSN
Volume Title
Publisher
NISC (Pty) Ltd and Informa UK Limited (trading as Taylor and Francis Group)
Abstract
Seagrasses are threatened by anthropogenic stressors and climate change, with numerous population declines reported. In South Africa, the eelgrass Zostera capensis is restricted to estuarine environments and has a disjunct distribution and declining status. With the majority of the distribution of Z. capensis on the west and southwest coasts of South Africa, the isolated easternmost populations in KwaZulu-Natal Province (KZN) are of particular interest. Following the extirpation of Z. capensis at Durban and St Lucia, only five populations remain, of which three (in the Amatikulu, Mlalazi and Mhlatuze estuaries) are situated <50 km apart. Previous molecular analyses showed strong population structure between Z. capensis populations, but the geographically close populations on the east coast were not included. In this study, using single nucleotide polymorphisms (SNPs) isolated from 31 individual sampled plants collected from three northern KZN estuaries, we provide evidence for distinct population clusters, with unique evolutionary signals. Zostera capensis in the Mlalazi Estuary has a low level of genomic diversity, likely as a result of a small, dynamic population unable to withstand prolonged freshwater exposure. Our results suggest that conservation efforts need to consider unique population signals even among geographically close populations, in particular within the context of restoration, where genomic compatibility may determine the persistence of restored populations.
Description
DATA AVAILABILITY : Raw reads and associated code are
available via Data Dryad at https://datadryad.org/stash/share/
nTww7slTPVNzFSxUPosVvsDz343fggcZ3T2ObBSjwpo.
SUPPLEMENTARY MATERIAL : summary of the difference between the sequence alignment and balanced sampling methods; a graph showing the number of clusters (K) and cross-entropy criterion; and clustering PCoA plots indicating population differentiation.
SUPPLEMENTARY MATERIAL : summary of the difference between the sequence alignment and balanced sampling methods; a graph showing the number of clusters (K) and cross-entropy criterion; and clustering PCoA plots indicating population differentiation.
Keywords
Eelgrass (Zostera capensis), Seagrasses, KwaZulu-Natal (KZN), Amatikulu Estuary, Conservation, Evolutionary dynamics, Mhlatuze Estuary, Mlalazi Estuary, Population differentiation, Seagrass persistence, Seagrass restoration, SDG-14: Life below water
Sustainable Development Goals
SDG-14:Life below water
Citation
S.E. Smit, R. Henriques, M. Jackson, R. Taylor, L. Vivier & S. von der Heyden (2023) Eelgrass Zostera capensis populations in KwaZulu-Natal, South Africa, harbour distinct genomic signals despite limited geographical distance, African Journal of Marine Science, 45:4, 259-264, DOI: 10.2989/1814232X.2023.2263503.