Biology subjects

Strader, M.

Publications and source records attributed to Strader, M..

5 recordsLinked to original sources

bioRxiv2025

Selective breeding enhances coral heat tolerance even over small spatial scales

Coral reefs globally are experiencing escalating mass bleaching and mortality. Reefs along the western Indian Ocean have been relatively unimpacted. We assessed heat tolerance baselines in two widespread reef-building Acropora species and used selective breeding from two thermally distinct (present day and stress histories) northern (Mean Monthly Maximum 27.9 {degrees}C) and southern (26.6 {degrees}C) reefs along the Ningaloo World Heritage Reef. Fitness responses were measured in control and heat stress temperatures (adults = 31.0 {degrees}C, larvae = 35.5 {degrees}C), including survival, tissue necrosis, bleaching, and photosynthesis. Larvae with one parent from the warmer population exhibited >2.2-fold higher survival under heat stress, while those with both parents from the warmer population survived 1.6-fold better (compared to control larvae with two parents from the cooler population). Photosynthesis was maintained in both species and both populations, suggesting heat responses were host driven. Adults from both populations from one species (A. tenuis) exhibited similar responses to heat, while the other (A. millepora) was more variable. These findings are the first to demonstrate that selective breeding can provide heat tolerance enhancement for corals in the Indian Ocean and will be critical to preparing for future marine heatwaves.

ecology↗

bioRxiv2024

Genomic signatures of coral adaptation and recovery following a mass mortality event

Globally, corals face an increased frequency of mass mortality events (MMEs) as populations experience repeated marine heatwaves which disrupt their obligate algal symbiosis. Despite greater occurrences of MMEs, the relative roles of the environment, host, and symbiont genetic variation in survival and recovery remain unresolved. We explore these roles using high-resolution temporal and spatial whole genome sequencing of corals before, after, and several years following a MME. We show that host genetics has an impact on bleaching and mortality and that selected alleles important for adaptation persist through the next generation. We also demonstrate that survival for the bleaching event was highly polygenic and that allele frequency shifts have reef habitat specificity. This study reveals how MMEs reshape the genomic landscape and the spatial and temporal distribution of genomic diversity within coral populations facing severe threats from global change. SIGNIFICANCEInvestigations of natural selection in coral genomes following bleaching events have primarily relied on indirect inference, using contemporary populations to explore signatures of past selective pressures, or failed to link these events to the subsequent generation. This has left an open question about the ability of a coral population to adapt from host standing genetic variation in the face of a bleaching event. We demonstrate rapid evolution in a Moorean coral population following an MME from a marine heatwave by capturing allele frequency shifts through time. However, the complex polygenic architecture of bleaching survival shows strong habitat specificity, complicating the path towards a genomic prediction of bleaching.

evolutionary biology↗

bioRxiv2018

Epigenetic factors coordinate intestinal development

Intestinal epithelium development depends on epigenetic modifications, but whether that is also the case for other intestinal tract cell types remains unclear. We found that functional loss of a DNA methylation machinery component, ubiquitin-like protein containing PHD and RING finger domains 1 (uhrf1), leads to reduced enteric neuron number, changes in neuronal morphology, and severe intestinal smooth muscle disruption. Genetic chimeras revealed that Uhrf1 functions both cell-autonomously in enteric neuron progenitors and cell-non-autonomously in surrounding intestinal cells. Uhrf1 recruits the DNA methyltransferase Dnmt1 to unmethylated DNA during replication. Dnmt1 is also expressed in enteric neuron and smooth muscle progenitors. dnmt1 mutants show a strong reduction in enteric neuron number and disrupted intestinal smooth muscle. Because dnmt1;uhrf1 double mutants have a similar phenotype to dnmt1 and uhrf1 single mutants, Dnmt1 and Uhrf1 must function together during enteric neuron and intestinal muscle development. This work shows that genes controlling epigenetic modifications are important in coordinating intestinal tract development, provides the first demonstration that these genes are important in ENS development, and advances uhrf1 and dnmt1 as potential new Hirschsprung disease candidates.\n\nSummaryThis work provides evidence that DNA methylation factors are important in all cell types that contribute to development of a functional intestine.

developmental biology↗

bioRxiv2018

Effects of thermal stress on amount, composition, and antibacterial properties of coral mucus

The surface mucus layer of reef-building corals supports several essential functions including feeding, sediment clearing, and protection from pathogenic invaders. For the reef ecosystem, coral mucus provides energy to support heterotrophic benthic communities. Mucus production represents a substantial metabolic investment on behalf of the coral: as much as half of the fixed carbon supplied by the corals algal symbionts is incorporated into expelled mucus. In this study, we examined if bleaching (disruption of the coral-algal symbiosis) has the potential to indirectly disturb reef ecosystem function by impacting the nutritional composition of coral mucus. In a controlled laboratory thermal stress challenge, visibly paled corals produced mucus with higher protein and lipid content and increased antibacterial activity relative to healthy corals. These results are likely explained by the expelled symbionts in the mucus of bleached individuals. This study illuminates how the immediate effects of coral bleaching could impact the reef-ecosystem indirectly through modulation of available nutrients within the ecosystem.

molecular biology↗

bioRxiv2018

Relationship between Acropora millepora juvenile fluorescence and composition of newly established Symbiodinium assemblage

Coral-dinoflagellate symbiosis is the key biological interaction enabling existence of modern-type coral reefs, but the mechanisms regulating initial host-symbiont attraction, recognition and symbiont proliferation thus far remain largely unclear. A common reef-building coral, Acropora millepora, displays conspicuous fluorescent polymorphism during all phases of its life cycle, due to the differential expression of fluorescent proteins (FPs) of the green fluorescent protein family. In this study, we examine whether fluorescent variation in young coral juveniles exposed to natural sediments is associated with the uptake of disparate Symbiodinium assemblages determined using ITS-2 deep sequencing. We found that Symbiodinium assemblages varied significantly when redness values varied, specifically in regards to abundances of clades A and C. Whether fluorescence was quantified as a categorical or continuous trait, clade A was found at higher abundances in redder juveniles. These preliminary results suggest juvenile fluorescence may be associated with Symbiodinium uptake, potentially acting as either as an attractant to ecologically specific types or as a mechanism to modulate the internal light environment to control Symbiodinium physiology within the host.

ecology↗