Rebecca Yahr is an American lichenologist who works at the Royal Botanic Garden Edinburgh in Scotland. She was President of the British Lichen Society from 2019 until 2021.^[1]

Rebecca Yahr was born in the United States and grew up near the Appalachian Mountains.^[2] She studied botany at University of California, Davis for her B. Sc. degree, awarded in 1994.^[2] She gained her doctorate from Duke University in 2004 for research into how the relationship between the fungi and algae within a lichen evolve over time.^[2]

From 1991 until 1998 Yahr worked as a botanical research scientist, firstly for the California Native Plant Society and then at Archbold Biological Station in Florida, USA, where she began to be interested in lichens.^[2][3] In 2005 she took up a research fellowship at the University of St Andrews in Scotland, UK and from 2006 has worked at the Royal Botanic Gardens, Edinburgh in Scotland.^[4] Her research concerns the evolution of lichens. She uses historical data and specimens, biogeography and molecular biology.^[1] She also studies the processes that underlie the lichen symbiosis.^[1]

She has served on the editorial boards of The Lichenologist and the Edinburgh Journal of Botany since 2010.^[1][5]

From 2019 until 2022 she was President of the British Lichen Society, having served as Vice President from 2018 until 2019.^[2]

Since 2020 she has been the co-chair of the International Union for Conservation of Nature (IUCN) Lichen Specialist Group.^[6] She contributes samples to the Darwin Tree of Life Project.^[2]

Yahr collaborated in the characterisation of Opegrapha viridipruinosa Coppins & Yahr (renamed Alyxoria viridipruinosa (Coppins & Yahr) Ertz)^[7] and Phaeographis illitoraticola Lendemer, R.C. Harris & Yahr (now Phaeographis atromaculata (A.W.Archer) A.W.Archer).^[8]

She is the author or co-author of over 45 scientific publications and several book chapters. These include:

• Gregory M. Mueller; Kelmer Martins Cunha; Tom May; Jessica Allen; James R. S. Westrip; Cátia Canteiro; Diogo Henrique Costa-Rezende; Drechsler-Santos; Aida Vasco-Palacios; Antony Martyn Ainsworth and others. (2022) What do the first 597 global fungal red list assessments tell us about the threat status of fungi? Diversity 14 (9), 736
• Steinová, J., Skaloud, P., Yahr, R., Bestová, H., Muggia, L. (2019) Reproductive and dispersal strategies shape the diversity of mycobiont-photobiont association in lichen symbioses. Molecular Phylogenetics and Evolution 134 226-237.
• Yahr, R., Schoch, C. L., Dentinger, B. T. M. (2016) Scaling up discovery of hidden diversity in fungi: impacts of barcoding approaches. Philosophical Transactions of the Royal Society, Series B 371 (1702), 20150336
• Ellis, C.J., Yahr, R., Belinchón, R. & Coppins, B.J. (2014) Archaeobotanical evidence for climate as a driver of ecological community change across the anthropocene boundary. Global Change Biology 20 2211-2220.
• Yahr, R., Coppins, B.J., Coppins, A.M. (2013) Transient population dynamics in the conservation priority species, Cladonia botrytes. Lichenologist 45 265-276.
• Schoch, C.L., Seifert, K.A., Huhndorf, S., Robert. V., Spouge, J.L., Levesque, C.A., … and Fungal Barcoding Consortium. (2012) Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for Fungi. Proceedings of the National Academy of Sciences 109 6241-6246.
• James TY, F Kauff, CL Schoch, PB Matheny, V Hofstetter, CJ Cox, … and R Vilgalys.( 2006) Reconstructing the early evolution of Fungi using a six-gene phylogeny. Nature 443 818-822.
• Dolan, R.W., Yahr, R., Menges, E.S. & Halfhill, M.D. (1999) Conservation implications of genetic variation in three rare species endemic to Florida rosemary scrub. American Journal of Botany 86 1556-1562.

In 1994 she was awarded a Young Botanist Award from the Botanical Society of America.^[9]

The lichen species Gyalectidium yahriae was named after her in 2000.^[10]

In October 2023 the Systematics Association invited Yahr to give the society's annual Founders Lecture.^[11]

Yahr is married to ecologist Chris Ellis and they have two children together.^[2]