On May 8, Ashley Shaw presented her PhD thesis on “Trophic relationships in soil communities: How abiotic stress affects biotic interactions in the McMurdo Dry Valleys, Antarctica”. Ashley has been in the Wall lab since 2011, first as a MSc student, then as a PhD student and graduate research assistant. The research she presented casts new light on how carbon and nutrient availability and abiotic constraints such as salinity and moisture control soil food webs, in the Antarctic Dry Valleys and beyond.
Her contributions to scientific knowledge include: demonstrating the presence of up to 3 trophic levels in the food webs of the Dry Valleys, including an omnivore-predator; proving that the dominant microbial-feeding invertebrate of the Dry Valleys can exert top-down control on soil microbial abundance when it is not constrained by high abiotic stress (salinity); showing that variation of soil food web complexity across the Dry Valleys’ landscape can be explained by soil age and resource availability; and presenting evidence that pulses of water availability in the Dry Valleys result in a flow of recent carbon in the soil food web. Ashley has been an integral member of the Wall lab for more than six years and a great person to work with. The lab congratulates her on a brilliant public defense and wishes her all the best in her future career.