Diversity and flexibility of algal symbiont community in globally distributed larger benthic foraminifera of the genus Amphistegina

Martina Prazeres,Christiane Schmidt,Willem Renema,Marleen Stuhr,Shadrina Fildzah Ramadhani,T Edward Roberts,Steve S Doo

doi:10.1186/s12866-021-02299-8

Abstract

BackgroundUnderstanding the specificity and flexibility of the algal symbiosis-host association is fundamental for predicting how species occupy a diverse range of habitats. Here we assessed the algal symbiosis diversity of three species of larger benthic foraminifera from the genus Amphistegina and investigated the role of habitat and species identity in shaping the associated algal community.ResultsWe used next-generation sequencing to identify the associated algal community, and DNA barcoding to identify the diatom endosymbionts associated with species of A. lobifera, A. lessonii, and A. radiata, collected from shallow habitats (< 15 m) in 16 sites, ranging from the Mediterranean Sea to French Polynesia. Next-generation sequencing results showed the consistent presence of Ochrophyta as the main algal phylum associated with all species and sites analysed. A significant proportion of phylotypes were classified as Chlorophyta and Myzozoa. We uncovered unprecedented diversity of algal phylotypes found in low abundance, especially of the class Bacillariophyta (i.e., diatoms). We found a significant influence of sites rather than host identity in shaping algal communities in all species. DNA barcoding revealed the consistent presence of phylotypes classified within the order Fragilariales as the diatoms associated with A. lobifera and A. lessonii, while A. radiata specimens host predominately diatoms of the order Triceratiales.ConclusionsWe show that local habitat is the main factor influencing the overall composition of the algal symbiont community. However, host identity and the phylogenetic relationship among hosts is relevant in shaping the specific endosymbiont diatom community, suggesting that the relationship between diatom endosymbiont and hosts plays a crucial role in the evolutionary history of the genus Amphistegina. The capacity of Amphistegina species to associate with a diverse array of diatoms, and possibly other algal groups, likely underpins the ecological success of these crucial calcifying organisms across their extensive geographic range.

Highlights

Understanding the specificity and flexibility of the algal symbiosis-host association is fundamental for predicting how species occupy a diverse range of habitats
We found that A. radiata specimens host phylotypes belonging to the diatom order Triceratiales, which was absent in A. lobifera and A. lessonii
Our results further suggest that while the presence of an algal symbiont community is crucial to the host, the identity of species within the community is not, and that the nature of the symbiont community is primarily shaped and evolutionarily reinforced by local habitat

Summary

Introduction

Understanding the specificity and flexibility of the algal symbiosis-host association is fundamental for predicting how species occupy a diverse range of habitats. We assessed the algal symbiosis diversity of three species of larger benthic foraminifera from the genus Amphistegina and investigated the role of habitat and species identity in shaping the associated algal community. Algal symbiosis drives the normal functioning of coral reef ecosystems [1]. It plays an important role in facilitating the adaptation or acclimatisation of organisms to environmental change, and their capacity to successfully expand into new habitats [2]. Symbiosis is influenced by complex interactions between the host, the symbionts, and the local environment [9], which shapes the fitness of the holobiont (i.e., host-symbiont complex and associated microbiome) [10]

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Conclusion