Conclusions and future studies
This study showed that maternal effects manifested as gene expression
differences in interspecific hybrids of the coral A.tenuis and A. loripes . We also showed that maternal
effects can persist to at least seven months of age in coral and were
likely responsible for the phenotypes of F1 hybrids. However, the
pathways and mechanisms responsible for the phenotypic differences were
unknown and exposure to elevated temperature andp CO2 conditions did not result in differential
coral gene expression. Although the composition of bacterial and
microalgal endosymbiont communities of these corals was similar under
ambient and elevated conditions and between hybrids and purebreds,
these microbes may have expressed
different genes and contributed to holobiont phenotypic differences.
Future studies will benefit from examining the gene expression of these
microbial communities alongside the host. Other less studied members of
the coral holobiont, such as viruses and fungi (that were not examined),
may also have contributed to coral survival and size differences between
offspring groups and treatment conditions. Further, post-transcriptional
and epigenetic regulation (e.g., DNA methylation) may have varied
between treatments and hybrid and purebreds and may have resulted in
phenotypic differences (Dimond et al., 2017). Future studies should
consider adopting a multi-omics approach and assessing other members of
the coral-associated microbiome to explore other mechanisms that
underpin the phenotype of the coral holobiont.
Acknowledgements. We thank P. Buerger, C. Kenkel and P. Laffy
for fruitful discussions, and support from the National Sea Simulator
team of AIMS. This research was funded by the Paul G. Allen Family
Foundation and the Australian Institute of Marine Science (AIMS). WYC
acknowledges the University of Melbourne International Research
Scholarship and Fee Remission Scholarship. MvO acknowledges Australian
Research Council Laureate Fellowship FL180100036.
Author’s ontribution. W.Y.C., M.J.H.O., L.P. and A.H. designed
the study. W.Y.C. and
L.P. conducted the experiment. L.P. carried out the laboratory work.
J.C., W.Y.C. and A.H. undertook bioinformatic and statistical analyses.
W.Y.C. and M.J.H.O. wrote much of the manuscript and all authors
contributed to the final edited version of the manuscript.
Data Availability Statement
Raw sequences are available in GenBank (SRR12695232 to SRR12695253,
project accession no.: PRJNA665083) and the R scripts for statistical
analyses are available as Appendix S1.