Like other sessile invertebrates (such as corals), sponges represent
important components of the Great Barrier Reef in terms of biomass production,
diversity levels and pelagic processes. Like corals however, sponges have
specific eco-physiological windows for survival, characterized by rigorous
temperature optima. In other words, sponge populations suffer seriously thermal stress
associated with increases in sea surface temperature, a consequence of climate
change.
Larvae of the sponge Rhopaloeides
odorabile in the GBR show a remarkable thermal tolerance compared to adults.
Rhopaloeides larvae are capable of surviving
and metamorphosing in seawater temperatures even 9 oC above the
annual maxima. This suggests that the chances for Rhopaloeides to survive global warming are great given the capacity
of the species to relocate towards more suitable habitats via larval dispersal.
But the question is, how?
In this new paper we make us of a Multiplex Reverse-Transcription
Quantitative PCR assay, designed for a total of 26 genes selected on the basis
of their known involvement in cell-stress responses and cellular homeostasis-related processes. Our aim is to understand the molecular events, at the transcriptomic
level, responsible for adaptive advantages in each of the sponges’ life stages.
Despite larvae and adults share the same genome, they exhibit a remarkable degree of
ecological, physiological and morphological differentiation within the species
heteromorphic life cycle. Different selective forces may expose beneficial
adaptations in each of the two life stages; the observed differences in gene expresion and thermal
resistance can likely be attributed to epigenetic alterations occurring in response to
particular environmental cues.
Relevant
literature
- N Webster, R Pantile, E Botté, D Abdo, N Andreakis, S Whalan (2013) A complex life cycle in a warming planet: gene expression in thermally stressed sponges. Molecular Ecology. DOI: 10.1111/mec.12213.
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