Biology subjects

Smith, L. L.

Publications and source records attributed to Smith, L. L..

3 recordsLinked to original sources

bioRxiv2026

Climate stress priming of juvenile Southern California giant kelp (Macrocystis pyrifera) to thermal extremes

Climate change threatens food production across the globe, creating challenges for food systems. Aquaculture, including seaweed production, is expanding while being threatened by global climate stressors, including increasing extreme events. Marine aquaculture is especially vulnerable to heatwaves, which can rapidly raise temperatures above the physiological limits of some organisms. While several interventions to increase resilience to climate impacts are being explored, priming has emerged as a possible adaptation for seaweeds that maintains genetic diversity but hardens individuals to stressors later in life. California has a developing seaweed sector while also experiencing some of the most extreme marine heatwave conditions on record. We explore temperature impacts and priming - exposing an earlier stage of an organism to a mild stressor to prepare the individual for future stress - on giant kelp Macrocystis pyrifera, an important foundation species along the West Coast of the United States. Our experiments focused on the juvenile sporophyte stage on miniaturized spools, from approximately one week before outplanting size to one week after. First, we determined the reaction norms of M. pyrifera in waters ranging from 5 to 30{degrees}C at the outplanting stage. Next, we explored how priming (heat + or - nutrients) in a hatchery setting prepares M. pyrifera for outplanting to a marine heatwave. To assess experimental outcomes, we took measures of growth, survival, photosynthetic function (Fv/Fm), and carbon and nitrogen assimilation via isotopes. We found temperatures above 20{degrees}C had significant negative impacts on all metrics of performance during the juvenile sporophyte stage. Further, we determined heat priming in conjunction with hatchery level (+) nutrients resulted in overall increased performance when exposed to a marine heatwave. These findings support the continued exploration of priming as a tool for climate resilience and can inform current hatchery practices for aquaculture practitioners looking to improve crop outcomes for this species.

physiology↗

bioRxiv2024

Evolution and Diversification of the Aposematic Poison Frog, Oophaga pumilio, in Bocas del Toro

The aposematic strawberry poison frog, Oophaga pumilio, is an iconic model system for studying the evolution and maintenance of color variation. Through most of its range, this frog is red with blue limbs. However, frogs from the Bocas del Toro Province, Panama, show striking variance in color and pattern, both sympatrically and allopatrically. This observation contradicts standard models of the evolution of aposematism and has led to substantial speculation about its evolutionary and molecular causes. Since the enigma of O. pumilio phenotypic variation is partly unresolved because of its large, [~] 6.7 Gb genome, we here sequence exomes from 347 individuals from ten populations and map a number of genetic factors responsible for the color and pattern variation. The kit gene is the primary candidate underlying the blue-red polymorphism in Dolphin Bay, where an increase in melanosomes is correlated with blue coloration. Additionally, the ttc39b gene, a known enhancer of yellow-to-red carotenoid conversion in birds, is the primary factor behind the yellow-red polymorphism in the Bastimentos West area. The causal genetic regions show evidence of selective sweeps acting locally to spread the rare phenotype. Our analyses suggest an evolutionary model in which selection is driving the formation of new morphs in a dynamic system resulting from a trade-off between predation avoidance, intraspecific competition, and mate choice.

evolutionary biology↗

bioRxiv2020

Early-life mitochondrial DNA damage results in lifelong deficits in energy production mediated by redox signaling in Caenorhabditis elegans

The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mtDNA is more susceptible to damage than nuclear DNA (nucDNA), and many environmental toxicants target the mitochondria. Reports from the toxicological literature suggest that exposure to early-life mitochondrial damage could lead to deleterious consequences later in life (the "Developmental Origins of Health and Disease" paradigm) but reports from other fields often report beneficial ("mitohormetic") responses to such damage. Here, we test the effects of low (causing no change in lifespan) levels of ultraviolet C (UVC)-induced, irreparable mtDNA damage during early development in Caenorhabditis elegans. This exposure led to life-long reductions in mtDNA copy number and steady-state ATP levels, accompanied by increased oxygen consumption and altered metabolite profiles, suggesting inefficient mitochondrial function. Exposed nematodes were also developmentally delayed, reached smaller adult size, and were rendered more susceptible to subsequent exposure to chemical mitotoxicants. Metabolomic and genetic analysis of key signaling and metabolic pathways supported redox signaling during early development as a mechanism for establishing these persistent alterations. Our results highlight the importance of early-life exposures to environmental pollutants, especially in the context of exposure to chemicals that target mitochondria.

cell biology↗