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Postdoctoral Work
Seascape genomics and genomic offset in the purple sea urchin
Seascape genomics and genomic offset in the purple sea urchin
I use the purple urchin as a model to detect genomic regions of selection in a latitudinally broad (from Alaska to Baja California) marine species, with extremely high gene flow and untangle which envrionmental variables are driving local adaptation. Additionally, I use genomic forecasting techniques (genomic offset) to predict (mal)adaptation under global change, and how that may influence community dynamics in the intertidal and kelp forest ecosystems of the West Coast of America.
Thermal tolerance of multiple urchin species
Thermal tolerance of multiple urchin species
To understand the role of thermal tolerance across populations and between species, we used CTmax, developing a novel assay involving adhesion loss across three species of urchin. We used the latitudinally broad purple, the circumpolar green. and the tropical variegated sea urchin and showed suprising resilience to elevated thermal stress.
Identifying structural variants in the purple sea urchin
Structural variants are becoming increasingly studied, and their role in evolutionary processes are becoming evident. In this project we identify putative inversions in a crucial model organism for the first time as well as identifying associations of inversions and local adaptation in the population.
PhD Work
Recovery dynamics of an overharvested population
Fisheries often induce a moratorium when stocks are low to halt fishing, aiming to reduce the effects of overharvesting. There is evidence this recovery period increases population size, and we even show these populations can phenotypcially recover (i.e., reach their orginal size and fecundity before harvesting commenced) see van Dijk, Sadler et al., 2024 Biol. Lett. However, what is the role of the underlying genomic structure? and how has a legacy of overharvesting influenced genetic diversity and putattively adaptive alleles?
Size-selective fisheries and their effect on evolutionary trajectories
Fisheries are often size-selective, harvesting the largest, most economically valuable individuals. Such size-selection has phenotypic consequences (e.g., changes in growth rate and fecundity). However, it also drives genomic changes, I looked at how genomic architecture shifts and genetic diversity declines after five generations of size-selective harvesting in the zebrafish. Research published as Sadler et al., 2024, J. Fish. Biol. Our results help us understand how adaptive potential is potentially shifting in response to harvesting stress.
Vulnerability of overharvested fish to climate change warming
Wild populations experience multiple stressors potnetially having synergistic or antagonistic effects on population fitness. Two key anthropogenics stressors for fish populations are overharvesting and long term temperature change. For this project I looked at populations that had experienced a history of size-selected overharvesting and exposed them to elevated, ambient and lowered temperature over 250 days to understand changes in fitness components including fecundity, growth, behaviour, microbiota and genetic markers of stress. This work can be found in Sadler et al., 2024 Ecol. Evol., Sadler et al., 2024 Sci. Rep., Sadler et al., J. Therm. Biol. We show evidence across different fitness components that random selected (i.e., no directional selection) perform better under thermal stress.
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