Biology subjects

Chiles, E. N.

Publications and source records attributed to Chiles, E. N..

3 recordsLinked to original sources

bioRxiv2021

Ploidy variation and its implications for reproduction and population dynamics in two sympatric Hawaiian coral species

Standing genetic variation is a major driver of fitness and resilience, and therefore of fundamental importance for threatened species such as stony corals. We analyzed RNA- seq data generated from 132 Montipora capitata and 119 Pocillopora acuta coral colonies collected from K[a]neohe Bay, Oahu, Hawaii. Our goals were to determine the extent of colony genetic variation and to study reproductive strategies in these two sympatric species. Surprisingly, we found that 63% of the P. acuta colonies were triploid, with putative independent origins of the different triploid clades. These corals have spread primarily via asexual reproduction and are descended from a small number of genotypes, whose diploid ancestor invaded the bay. In contrast, all M. capitata colonies are diploid, outbreeding, with almost all colonies genetically distinct. Only two cases of asexual reproduction, likely via fragmentation, were identified in this species. We report two distinct strategies in sympatric coral species that inhabit the largest sheltered body of water in the main Hawaiian Islands. These data highlight divergence in reproductive behavior and genome biology, both of which contribute to coral resilience and persistence. Significance StatementGiven the threat posed to coral reef ecosystems by human caused climate change, there is a growing focus on developing strategies for the protection and restoration of these critical marine habitats. These efforts are however limited by our understanding of the diversity of coral survival and reproductive strategies. Our analysis of data from two coral species inhabiting the same Hawaiian bay found that one is a strict sexual outbreeder, whereas the other reproduces predominantly asexually (i.e., clonally) and includes both diploids and triploids. These results broaden our understanding of coral biology, adaptability, and evolution, and underpin future research into the mechanisms of coral resilience that can inform restoration activities.

genomics↗

bioRxiv2021

Multi-omic characterization of the thermal stress phenome in the stony coral Montipora capitata

We used network methods to analyze transcriptomic and polar metabolomic data generated from the stress resistant stony coral Montipora capitata. Corals were exposed to ambient or thermal stress conditions over a five-week period that coincided with a mass spawning event of this species. Gene co-expression networks showed that the early thermal stress response involves downregulation of growth and DNA replication, whereas signaling and the immune response are strongly upregulated. Later stages are dominated by suppression of metabolite transport and biomineralization and enhanced expression of transcriptional regulators. Integration of gene-metabolite data demonstrates that the major outcome of the thermal treatment is activation of animal redox stress pathways with detoxification of reactive oxygen species being dominant. Differential regulation of the highly conserved cytochrome P450 gene family was of particular interest with downregulation of CYP1A1, involved in progesterone metabolism, potentially explaining the attenuated mass spawning observed during the sampling period.

genomics↗

bioRxiv2020

Metabolome shift associated with thermal stress in coral holobionts

Coral reef systems are under global threat due to warming and acidifying oceans1. Understanding the response of the coral holobiont to environmental change is crucial to aid conservation efforts. The most pressing problem is "coral bleaching", usually precipitated by prolonged thermal stress that disrupts the algal symbiosis sustaining the holobiont2,3. We used metabolomics to understand how the coral holobiont metabolome responds to heat stress with the goal of identifying diagnostic markers prior to bleaching onset. We studied the heat tolerant Montipora capitata and heat sensitive Pocillopora acuta coral species from the Hawaiian reef system in K[a]neohe Bay, Oahu. Untargeted LC-MS analysis uncovered both known and novel metabolites that accumulate during heat stress. Among those showing the highest differential accumulation were a variety of co-regulated dipeptides present in both species. The structures of four of these compounds were determined (Arginine-Glutamine, Lysine-Glutamine, Arginine-Valine, and Arginine-Alanine). These dipeptides also showed differential accumulation in symbiotic and aposymbiotic (alga free) individuals of the sea anemone model Aiptasia4, suggesting their animal provenance and algal symbiont related function. Our results identify a suite of metabolites associated with thermal stress that can be used to diagnose coral health in wild samples.

evolutionary biology↗