Exposing frog embryos to bacterial isolates Colonization order impacts structure of the tadpole microbiome

January 3 – Febuary 28, 2021

Meeting Abstract

P31-2  Sat Jan 2  Exposing frog embryos to bacterial isolates: Colonization order impacts structure of the tadpole microbiome Jones, KR*; Belden, LK; Hughey, MC; Virginia Tech, Blacksburg, Virginia; Virginia Tech, Blacksburg, Virginia; Vassar College, Poughkeepsie, New York, USA korinrex@gmail.com

Dispersal and colonization are stochastic processes that can impact assembly of ecological communities. Colonization order, often referred to as priority effects, can leave a lasting impact on community composition through time. Embryos that develop in an external environment, such as those of amphibians, experience stochasticity in the arrival order of bacterial colonists. We sought to determine if priority effects during embryo colonization impacted bacterial community composition on newly hatched tadpoles. To answer this question, we selectively inoculated the embryos of lab-raised hourglass tree frogs, Dendropsophus ebraccatus, over two days with two bacteria (Genera: Acinetobacter and Stenotrophomonas) initially isolated from the skin of wild adult D. ebraccatus in Panama. On day one, each egg received an inoculation of one of our chosen isolates or sterile water. On the second day, eggs received either the same isolate, the alternate isolate, or sterile water. By altering the order in which isolates were received, we hoped to elucidate the impact of priority effects on resulting tadpole bacterial communities. Through 16S rRNA gene amplicon sequencing, we observed shifts in the relative abundances of ASVs within the tadpole communities due to priority effects. For the Acinetobacter isolate, the effect of being the first inoculum led to increased relative abundance, which was not the case when the Stenotrophomonas isolate was first. In addition, we observed differences in community composition as a result of our varied treatments. Our results suggest that the initial environmental conditions that embryos are exposed to shape microbial communities at later life stages; however, stochasticity in colonization does not impact all potential colonists in an equal manner.

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