Biology subjects

Mikhail V Matz

Publications and source records attributed to Mikhail V Matz.

6 recordsLinked to original sources

bioRxiv2016

Coral life history differences determine the refugium potential of a remote Caribbean reef

Remote populations can influence connectivity and may serve as refugia from climate change. Here, we investigated two reef-building corals (Pseudodiploria strigosa and Orbicella franksi) from the Flower Garden Banks (FGB) - the most isolated, high-latitude Caribbean reef system that retains high coral cover. We characterized coral size frequency distributions, quantified larval mortality rates and onset of competence, estimated larval production, and created detailed biophysical models incorporating these parameters to evaluate source-sink dynamics from 2009 to 2012. Mortality rates were similar across species but competency differed dramatically: P. strigosa was capable of metamorphosis within 2.5 days post fertilization (dpf), while O. franksi were not competent until >20dpf and remained competent up to 120dpf Despite these differences, models demonstrated that larvae of both types were similarly successful in reseeding the FGB. Nevertheless, corals with shorter pelagic larval durations (PLD), such as P. strigosa, were highly isolated from the rest of the Caribbean, while long PLD corals, such as O. franksi, could export larvae to distant northern Caribbean reefs. These results suggest that FGB coral populations are self-sustaining and highlight the potential of long PLD corals, such as endangered Orbicella, to act as larval sources for other degraded Caribbean reefs.

Ecology↗

bioRxiv2016

Enhanced gene expression plasticity as a mechanism of adaptation to a variable environment in a reef-building coral

Local adaptation is ubiquitous1, but the molecular mechanisms giving rise to this ecological phenomenon remain largely unknown2. A year-long reciprocal transplant of mustard hill coral (Porites astreoides) between a highly environmentally variable inshore habitat and more stable offshore habitat3 demonstrated that both inshore and offshore populations exhibit elevated growth, protein and lipid content in their home reef environment, indicative of local adaptation 4 Here, we characterized the genomic basis of this adaptation in both coral hosts and their intracellular algal symbionts (Symbiodinium sp.) using genome-wide gene expression profiling5,6 and gene coexpression network analysis7. Inshore and offshore coral populations differ primarily in their capacity for gene expression pla ...

Genomics↗

bioRxiv2016

Evolutionary consequences of DNA methylation in a basal metazoan

Gene body methylation (gbM) is an ancestral and widespread feature in Eukarya, yet its adaptive value and evolutionary implications remain unresolved. The occurrence of gbM within protein coding sequences is particularly puzzling, because methylation causes cytosine hypermutability and hence is likely to produce deleterious amino acid substitutions. We investigate this enigma using an evolutionarily basal group of Metazoa, the stony corals (order Scleractinia, class Anthozoa, phylum Cnidaria). We show that gbM correlates with breadth and abundance of transcription and with slow sequence evolution. We also show a strong correlation between gbM and codon bias due to systematic replacement of CpG bearing codons. We suggest that the ancestral function of gene body methylation is tied to selective pressure for accurate and stable gene expression, and that mutation caused by gbM may be a previously unrecognized driver of adaptive codon evolution.

Evolutionary Biology↗

bioRxiv2016

Ecological factors rather than barriers to dispersal shape genetic structure of algal symbionts in horizontally-transmitting corals

Many reef-building corals acquire their algal symbionts (Symbiodinium sp.) from the local environment upon recruitment. This horizontal transmission strategy where hosts pair with locally available symbionts could serve to increase coral fitness across diverse environments, as long as hosts maintain high promiscuity and symbionts adapt locally. Here, we tested this hypothesis in two coral species by comparing host and symbiont genetic structures across different spatial scales in Micronesia. Each host species associated with two genetically distinct Symbiodinium lineages, confirming high promiscuity in broadly dispersing hosts. However, contrary to our initial expectation, symbiont genetic structure was independent of physical barriers to dispersal between islands, unlike genetic structure of their hosts that was nearly perfectly explained by ocean currents. Instead, Symbiodinium consistently demonstrated genetic divergence among local reefs and between the two host species at each island, although not necessarily between distant islands. These observations indicate that Symbiodinium lineages disperse much more broadly than previously thought and continuously adapt to specific hosts and reef environments across their range, following the classical Baas Beckings hypothesis: \"Everything is everywhere, but the environment selects\". Overall, our findings confirm that horizontal transmission could be a mechanism for broadly dispersing coral species to enhance their local fitness by associating with locally adapted symbionts. Dramatic differences in factors driving the genetic structures of horizontally-transmitting corals and their Symbiodinium imply that viewing their combined genomes as a single entity ( hologenome) would not be useful in the context of their evolution and adaptation.

Ecology↗

bioRxiv2015

The design and analysis of binary variable traits in common garden genetic experiments of highly fecund species to assess heritability

Many biologically important traits are binomially distributed, with their key phenotypes being presence or absence. Despite their prevalence, estimating the heritability of binomial traits presents both experimental and statistical challenges. Here we develop both an empirical and computational methodology for estimating the narrow-sense heritability of binary traits for highly fecund species. Our experimental approach controls for undesirable culturing effects, while minimizing culture numbers, increasing feasibility in the field. Our statistical approach accounts for known issues with model-selection by using a permutation test to calculate significance values and includes both fitting and power calculation methods. We illustrate our methodology by estimating the narrow-sense heritability for larval settlement, a key life-history trait, in the reef-building coral Orbicella faveolata. The experimental, statistical and computational methods, along with all of the data from this study, were deployed in the R package multiDimBio.

Evolutionary Biology↗

bioRxiv2014

Gene expression associated with white syndromes in a reef building coral, Acropora hyacinthus.

BackgroundCorals are capable of launching diverse immune defenses at the site of direct contact with pathogens, but the molecular mechanisms of this activity and the colony-wide effects of such stressors remain poorly understood. Here we compared gene expression profiles in eight healthy Acropora hyacinthus colonies against eight colonies exhibiting tissue loss commonly associated with white syndromes, all collected from a natural reef environment near Palau. Two types of tissues were sampled from diseased corals: visibly affected and apparently healthy.\n\nResultsTag-based RNA-Seq followed by weighted gene co-expression network analysis identified groups of co-regulated differentially expressed genes between all health states (disease lesion, apparently healthy tissues of diseased colonies, and fully healthy). Differences between healthy and diseased tissues indicate activation of several innate immunity and tissue repair pathways accompanied by reduced calcification and the switch towards metabolic reliance on stored lipids. Unaffected parts of diseased colonies, although displaying a trend towards these changes, were not significantly different from fully healthy samples. Still, network analysis identified a group of genes, suggestive of altered immunity state, that were specifically up-regulated in unaffected parts of diseased colonies.\n\nConclusionsSimilarity of fully healthy samples to apparently healthy parts of diseased colonies indicates that systemic effects of white syndromes on A. hyacinthus are weak, which implies that the coral colony is largely able to sustain its physiological performance despite disease. The genes specifically up-regulated in unaffected parts of diseased colonies, instead of being the consequence of disease, might be related to the originally higher susceptibility of these colonies to naturally occurring white syndromes.

Genomics↗