Symbiodiniumfunctional diversity and clade specificity under global change stressors

Contrasting heat stress response patterns of coral holobionts across the Red Sea suggest distinct mechanisms of thermal tolerance

“…It is also striking that coral host gene expression patterns were mirrored in the algal symbiont. At large, the level of responsiveness in algal symbionts from GoA corals was unexpected, given the commonly ascribed paucity of regulation at the transcriptional level for Symbiodiniaceae (Baumgarten et al, 2013;Bayer et al, 2012), signified by fixed expression differences between symbiont genera and species (Barshis et al, 2014;Davies et al, 2018;Parkinson et al, 2016). However, the notion that algal symbionts in hospite respond transcriptionally to heat stress is now corroborated by several studies (Bellantuono et al, 2019;Fifer et al, 2021;Studivan et al, 2021) and suggest that differential gene expression analysis may provide further insight with regard to relevant cellular processes.…”

Cladocopiumcommunity divergence in twoAcroporacoral hosts across multiple spatial scales

“…Given that unique MLGs have been shown to exhibit functional variation both in culture (i.e., S. psygmophilum, Parkinson et al, 2016) and in hospite (Davies et al, 2018;Howells et al, 2012), these results are counterintuitive for several reasons. First, it is difficult to imagine how an asexual lineage can disperse across such distances, which was especially evident in C21 (Figure 2e), given that the majority of symbioses in corals involve horizontal transmission (Baird et al, 2009) and free-living Symbiodiniaceae are expected to have low dispersal potential (reviewed in Thornhill et al, 2017).…”

“…The genus Cladocopium (formerly clade C Symbiodinium; LaJeunesse et al, 2018) originated and diversified most recently among Symbiodiniaceae, and has achieved the highest diversity of all lineages (Lesser et al, 2013;Pochon & Gates, 2010;Pochon et al, 2006;Thornhill et al, 2014Thornhill et al, , 2017. This diversity has been associated with functional variation in symbiont thermal performance across reefs (Davies et al, 2018;Howells et al, 2012) as well as with functional differences in gene expression between reef zones (Barfield et al, 2018;Davies et al, 2018), lending support for the potential for reef-specific symbiont communities. In addition, the draft genome of Cladocopium goreaui confirm the divergence of this genus from other Symbiodiniaceae genera and specifically highlight that gene families related to the establishment and maintenance of symbiosis (photosynthesis, host-symbiont interactions, nutrient exchange) were under positive selection (Liu et al, 2018).…”

Nearshore corals on the Mesoamerican Barrier Reef System on pace to cease growing as soon as year 2110

“…If temperature and eutrophication continue to increase, nearshore coral growth rates should continue to decline—with offshore corals potentially following suit as these stressors impact more distal portions of the Belize MBRS. Although there is metagenomic evidence that nearshore S. siderea and possibly P. strigosa have begun acclimatizing to these elevated temperatures[46], the observation that skeletal extension rates have continued declining for both species up to present time in nearshore reefs of the MBRS indicate that such acclimatization within nearshore corals is insufficient for maintaining stable rates of skeletal growth amidst the deteriorating environmental conditions of nearshore environments.…”