Decrypting Corals: Does Regulatory Evolution Underlie Environmental Specialisation of Coral Cryptic Lineages?

Area of Science:

• Marine biology
• Genomics
• Coral reef ecology

Background:

• Two Caribbean coral species, Montastraea cavernosa and Siderastrea siderea, exhibit genetically distinct lineages in the Florida Keys.
• These lineages display specialization to specific depths and nearshore/offshore habitats.

Purpose of the Study:

• To investigate if regulatory evolution, marked by gene expression modules, underlies coral lineage specialization.
• To determine if genes within these modules show greater genetic divergence between lineages.

Main Methods:

• Genome-wide gene coexpression network analysis was used to compare gene expression patterns.
• Genetic divergence was assessed between coral lineages and habitats.

Main Results:

• Coral lineages showed minimal differences in gene expression responses to environmental variation at the genome-wide level.
• No identified gene expression modules exhibited elevated genetic divergence between lineages.
• Gene expression differences were greater between habitats than between lineages.

Conclusions:

• Contrary to hypotheses, regulatory evolution does not appear to be the primary driver of coral lineage specialization.
• Algal symbionts, microbiome, or spatially varying selection may explain the observed gene expression patterns.
• Further research is needed to differentiate between these potential adaptive mechanisms.