Armando Geraldes

Departments of Botany and Zoology, University of British Columbia, Vancouver Campus

Research Associate - Taylor Lab and Rieseberg Lab (2018 to present)

Contact - geraldes(at)mail(dot)ubc(dot)ca

Topics - population genomics, adaptation, divergence with gene flow, sex chromosomes, conservation, domestication

Research interests

Applied population genomics


There are two described subspecies of Northern Goshawk in British Columbia, Accipiter gentilis laingi and A. g. atricapillus. The former, laingi, is designated by COSEWIC as Threatened, based on a small and declining population (potentially restricted to Haida Gwaii and estimated in 2013 as just over 1000). The latter subspecies, atricapillus, is currently considered not at risk, due to its much larger population that spreads across much of North America. The evidence for the laingi subspecies is scarce and somewhat controversial: it is mostly based on qualitative descriptions of size and plumage coloration in a small number of museum specimens, as described by Taverner in 1940. This project, done in the Irwin Lab, used the power of population genomics to inform conservation decisions. We found that laingi a genetically distinct population and that it is restricted to Haida Gwaii where only a few dozens of breeding pairs remain (Geraldes et al. 2019).

Currently in the Taylor Lab I am using genotyping-by-sequencing (GBS) to generate genome-wide polymorphism data in several projects in conservation genetics in fish species. Namely, we are developing SNP markers to understand patterns of population structure and inform fish management in the Site C Dam area in British Columbia and, developing diagnostic markers for species identification.



Finding the genes involved in adaptation of a species to its habitat is a major endeavor of evolutionary biology. Populus trichocarpa occurs naturally from Alaska to California. It can be found from sea level up to more than 2100 m. It grows on a variety of soils: from moist silts, gravels and sands to rich humus, loams and, occasionally, clays. As so, opportunities for detecting adaptation of different populations to their specific habitat are numerous. The development of a 34K SNP array (Geraldes et al. 2013) with markers ascertained through transcriptome (Geraldes et al. 2010) and genome (Slavov et al. 2012) resequencing allowed for large genotype-phenotype association studies to find genes that are responsible for key adaptive phenotypes (Porth et al. 2013; McKown et al. 2014a; McKown et al. 2014b). In parallel, I used a landscape genomics approach, including detection of genes under diversifying selection and correlations between allele frequencies and environmental variables, to understand how genetic variability is partitioned across the landscape and how that partitioning is a product of the interplay of neutral and adaptive processes (Geraldes et al. 2014).



I am interested in understanding the evolution of reproductive barriers among closely related populations.
For my PhD thesis I used Oryctolagus cuniculus (the European rabbit) as a model. We found that, overall, levels of gene flow among rabbit subspecies in the Iberian Peninsula are high. Despite high levels of gene flow, a few regions of the genome remain highly differentiated and they all are located in regions that likely have low recombination rates (the centromere of the X chromosome, Geraldes et al 2006), or, are non-recombining (the Y chromosome and the mitochondria, Geraldes et al 2008). Recent studies have shown that loci near the centromere of other chromosomes also show high differentiation (Carneiro et al 2009).

For my Post-Doctoral research in the the Nachman Lab at the University of Arizona, I focused on the three subspecies of Mus musculus (house mice). We found that there is gene flow among all subspecies, but that levels of gene flow are highly heterogeneous across the genome. We first contrasted patterns of gene flow between the autosomes, sex chromosomes and mitochondria and inferred that gene flow is reduced on the X chromosome relative to the autosomes, as is gene flow on the Y chromosome between the two European subspecies (M. m. domesticus and M. m. musculus), but not between the eastern European subspecies (M. m. musculus) and the Asian subspecies (M. m. castaneus)(Geraldes et al 2008). We then focused on the autosomes and found that: i) levels of genetic differentiation among subspecies are highly heterogeneous, ii) differences in levels of genetic differentiation are highly correlated with the inferred amount of gene flow and iii) levels of gene flow are correlated with the local recombination rate (Geraldes et al 2011). These findings lend strong empirical support to the idea that regions of low recombination can be very important in the early stages of speciation even in the absence of large chromosomal rearrangements.


For my Post-Doctoral research in the Cronk Lab at UBC, I focused I investigated genomic patterns of divergence between black cottonwood (Populus trichocarpa) and balsam poplar (P. balsamifera) two closely related tree species in North America. These species are extremely similar phenotypically (except in flower and fruit morphology) yet have very different ecological requirements suggesting that they are diverging adaptively. We used genotyping-by-sequencing (GBS) of >300 accessions collected along a North/South (from the Yukon to Southern British Columbia) transect across the hybrid zone and found that variation among the species is clinal with a wide hybrid zone with no F1 hybrids and dominated by advanced bacrosses to P. balsamifera. ONgoing work will apply cline theory uncover genes involved in species differences and adaptation.

Current work at UBC is focusing on the Arctic char Salvelinus spp. complex in the Taylor Lab and sea rockets Cakile maritima and C. edentula in the Rieseberg and Hodgins labs. More to come soon.



Domestication is one of the most important technological innovations in human history. It is achieved by strong selection for traits deemed important by the domesticating species. I am interested in understanding the genomic signatures left by this strong and recurrent selection. We have started by exploring the demographic history of the domestication process in rabbits (Carneiro et al 2011). Our findings support the idea that rabbits were domesticated recently in Southern France from a small pool of individuals (~1200). Despite this domestication bottleneck, domestic rabbits harbor significant amounts of nucleotide variability partitioned among breeds - this provides a unique opportunity to determine the genetic basis of morphological diversity.


Black cottonwood is a tree species currently being domesticated for use as a Biofuels feedstock. Using whole genome and transcriptome polymorphism data, in collaboration with colleagues from the Bioenergy Sciences Centre (USA), I developed a 34K genotyping array (Geraldes et al. 2013) to perform whole genome association analysis (GWAs) to determine the genetic architecture of growth (yield) and wood quality (efficiency of biomass conversion to bioenergy) traits. We have used this data to estimate the heritability of these traits (Porth et al. 2013; Mckown et al. 2014) as well as phenotypic correlations between them. The findings from these studies will provide insight into the species biology and inform poplar breeding programs.

Sex chromosome characterization and evolution


In most species, sex chromosomes arise from autosomes after the acquisition of a sex-determining gene. The suppression of recombination that ensues drives this pair down a unique path that can result in highly heteromorphic sex chromosomes and, sometimes even the loss of one of these. To better understand this unique process, I work with two systems that lie at extreme opposites of the sex chromosome evolution spectrum, the European rabbit and the Black cottonwood.
Mammalian Y chromosomes are old, highly degenerated and their gene content highly variable among species. I have characterized the complete sequence of the sex determining gene (SRY) (Geraldes et al. 2005), and found that this gene is duplicated in the Y chromosome (Geraldes et al. 2006). Recently, I found strong evidence that the two copies are evolving in concert through gene conversion (Geraldes et al. 2010) which could delay the degenerating process of non-recombining Y chromosomes.
Contrary to mammals, most plants are hermaphroditic, but separation of sexes in different individuals (dioecy) evolved independently in several Angiosperms. Members of the genus Populus (poplars, cottonwoods, aspens) are dioecious and dioecy is under strong genetic control. There are no clearly distinct heteromorphic sex chromosomes but previous QTL experiments have mapped gender to chromosome XIX. With collaborators, I performed a genomewide association study in P. trichocarpa and recovered hundreds of SNPs significantly associated with gender. These results were confirmed in an independent mapping association and in closely related species. We have also show that despite their young age, these regions already bear some of the hallmarks of degeneration (Geraldes et al. 2015).


Biology 418 - Evolutionary Ecology at UBC (Winter2011/Spring2013/Winter2016).
Forestry 432 - Molecular Ecology at UBC (Winter2015)


University of British Columbia, Canada. PostDoc (2009-2011: advisor Quentin Cronk)
University of Arizona, USA. PostDoc (2006-2009: advisor Michael Nachman)
Universidade do Porto, Portugal. PhD (2001-2006: advisor Nuno Ferrand)
Universidade do Porto, Portugal. Biology degree (1996-2000).

Research appointments

Research Associate and Co-applicant - Fish Genetics Study: BC Hydro Site Clean Energy Project (2018 to 2025)
Research Associate and Co-applicant - Genome BC project: Genomic differentiation among Northern Goshawks of coastal BC (2016 to 2018: with Darren Irwin)
Research Associate and Co-PI - Genome Canada, POPCAN project: genetic improvement of poplar trees as a Canadian bioenergy feedstock: clean energy from the poplar tree (2011-2014)

Editorial experience

News and Views editor for Molecular Ecology (2010 to 2019)
News and Views editor for Molecular Ecology Resources (2014 to 2019)
Special Issue coordinator for Molecular Ecology and Molecular Ecology Resources (2014 to 2018).
Deputy Managing Editor for Molecular Ecology and Molecular Ecology Resources (2014-2015).


Google Scholar Profile

24. Liu A, Geraldes A, Taylor EB (2023) Development and testing of diagnostic molecular markers to differentiate among three species of Salvelinus: Arctic char, Dolly Varden, and Bull trout. Conservation Genetics Resources 15:83-96.

23. Rosinger HS, Geraldes AM, Nurkowski KA, Battlay P, Cousens RD, Rieseberg LH, Hodgins KA (2021) The tip of the iceberg: genome wide marker analysis reveals hidden hybridization during invasion. Molecular Ecology 30:810-825.

22. Baucom RS, Geraldes AM, Rieseberg LH (2019) Some perspective on Molecular Ecology perspectives: Are women being left out? Molecular Ecology 28:2451-2455.

21. Geraldes A1, Askelson KA1, Nikelski E, Doyle FI, Hawwoer WL, Winker K, Irwin DE (2019) Population genomic analyses reveal a highly differentiated and
endangered genetic cluster of northern goshawks (Accipiter gentilis laingi) in Haida Gwaii. Evolutionary Applications 12:757–772. (
1Geraldes and Askelson have shared first authorship.
Media coverage:
Canadian Press
CBC Radio Victoria and CBC Radio Kelowna


20. Geraldes A1, Hefer CA1, Capron A, Kolosova N, Martinez-Nuñez F, Soolanayakanahally RY, Stanton B, Guy RD, Mansfield SD, Douglas CJ, Cronk QCB (2015) Recent Y chromosome divergence despite ancient origin of dioecy in poplars (Populus). Molecular Ecology 24:3243-3256.
1Geraldes and Hefer have shared first authorship.
This is a Molecular Ecology 'From the Cover' manuscript.
(News and Views in Molecular Ecology about this work: Filatov D. 2015. Homomorphic plant sex chromosomes are coming of age. Molecular Ecology, 24:3217-3219.)

19. Crutsinger GM, Rudman SM, Rodriguez-Cabal MA, McKown AD, Sato T, MacDonald AM, Heavyside J, Geraldes A, Hart EM, LeRoy CJ, El-Sabaawi RW (2014) Testing a “genes-to-ecosystems” approach to understanding aquatic-terrestrial linkages. Molecular Ecology. 23:5888-5903.

18. Geraldes A, Farzaneh N, Grassa CJ, McKown AD, Guy RD, Mansfield SD, Douglas CJ, Cronk QCB (2014) Landscape genomics of Populus trichocarpa: the role of hybridization, limited gene flow and natural selection in shaping patterns of population structure. Evolution, 68(11):3260-3280.

17. McKown AD, Klápšte J, Guy RD, Geraldes A, Porth I, Hannemann J, Friedmann M, Muchero W, Tuskan, GA, Ehlting J, Cronk QCB, El-Kassaby YA, Mansfield SD and Douglas CJ (2014) Genome-wide association implicates numerous genes underlying ecological trait variation in natural populations of Populus trichocarpa. New Phytologist, 203(2):535-553.

16. McKown AD, Guy RD, Klápšte J, Geraldes A, Friedmann M, Cronk QCB, El-Kassaby YA, Mansfield SD and Douglas CJ. (2014) Geographical and environmental gradients shape phenotypic trait variation and genetic structure in Populus trichocarpa. New Phytologist, 201(4):1263–1276.

15. Geraldes A, DiFazio SP, Slavov GT, Ranjan P, Muchero W, Hannemann J, Gunter LE, Wymore AM, Grassa CJ, Farzaneh N, Porth I, Mckown AD, Skyba O, Li E, Fujita M, Klapste J, Martin J, Schackwitz W, Pennacchio C, Rokhsar D, Friedmann MC, Wastenays GO, Guy RD, El-Kassaby YA, Mansfield SD, Cronk QCB, Ehlting J, Douglas CJ, Tuskan GA. 2013. A 34K SNP genotyping array for Populus trichocarpa: Design, application to the study of natural populations and transferability to other Populus species. Molecular Ecology Resources, 13(2):306-23.

14. Porth I, Klápště J, Skyba O, Lai B, Geraldes A, Muchero W, Tuskan GA, Douglas CJ, El-Kassaby YA, Mansfield SD. 2013. Populus trichocarpa cell wall chemistry and ultrastructure trait variation, genetic control, and genetic correlations. New Phytologist, 197:777-90.

13. Slavov GT, DiFazio SP, Martin J, Schackwitz W, Muchero W, Rodgers-Melnick E, Lipphardt MF, Pennacchio CP, Hellsten U, Pennacchio L, Gunter LE, Ranjan P, Vining K, Pomraning KR, Wilhelm LJ, Pellegrini M, Mockler T, Freitag M, Geraldes A, El-Kassaby YA, Mansfield SD, Cronk QCB, Douglas CJ, Strauss SH, Rokhsar D, Tuskan GA. 2012. Genome Resequencing Reveals Multiscale Geographic Structure and Extensive Linkage Disequilibrium in the Forest Tree Populus trichocarpa. New Phytologist, 196:713-25.

12. Wang Z, Hobson N, Galindo L, Zhu S, Shi D, McDill J, Yang L, Hawkins S, Neutelings G, Datla R, Lambert G, Galbraith D, Grassa C, Geraldes A, Cronk Q, Cullis C, Dash P, Kumar P, Cloutier S, Sharpe A, Wong G, Wang J, Deyholos M. 2012. The genome of flax (Linum usitatissimum) assembled de novo from short shotgun sequence reads. The Plant Journal, 72:461-73.

11. Geraldes A, Basset P, Smith K, Nachman MW. 2011. Higher differentiation among subspecies of the house mouse (Mus musculus) in genomic regions with low recombination. Molecular Ecology. Molecular Ecology, 20:4722-4736.

10. Carneiro M, Afonso S, Geraldes A, Garreau H, Bolet G, Boucher S, Tircazes A, Queney G, Nachman MW, Ferrand N. 2011. The Genetic Structure of Domestic Rabbits. Molecular Biology and Evolution. Molecular Biology and Evolution, 28: 1785-1816.

9. Geraldes A, Pang J, Thiessen N, Cezard T, Moore R, Zhao Y, Tam A, Wang S, Friedmann M, Birol I, Jones SJM, Cronk QCB, Douglas CJ. 2011. SNP discovery in black cottonwood (Populus trichocarpa) by population transcriptome resequencing. Molecular Ecology Resources, 11 (Suppl. 1): 81-92.

8. Geraldes A, Rambo T, Wing R, Ferrand N, Nachman, MW. 2010. Extensive gene conversion drives the concerted evolution of paralogous copies of the SRY gene in European rabbits. Molecular Biology and Evolution, 27: 2437-2440.

7. Geraldes A, Kane N. 2010. Pushing north one bottleneck at a time: Site Frequency Spectra tell the history of Sitka spruce. News and Views perspective, Molecular Ecology, 19: 3837-3839.

6. Geraldes A, Basset P, Gibson B, Smith K, Harr B, Yu HT, Bulatova N, Ziv Y, Nachman MW. 2008. Inferring the history of speciation in house mice from autosomal, X-linked, Y-linked and mitochondrial genes. Molecular Ecology, 17: 5349-5363.

5. Geraldes A, Carneiro M, Delibes-Mateos M, Villafuerte R, Nachman MW, Ferrand N. 2008. Reduced introgression of the Y chromosome between subspecies of the European rabbit (Oryctolagus cuniculus) in the Iberian Peninsula. Molecular Ecology, 17: 4489-4499.
(News and Views in Molecular Ecology about this work: Payseur BA. 2009. Y not introgress? Insights into the genetics of speciation in European rabbits. Molecular Ecology, 18:23-24.)

4. Salcedo T, Geraldes A, Nachman MW. 2007. Nucleotide variation in wild and inbred mice. Genetics, 177: 2277-2291.

3. Geraldes A, Ferrand N, Nachman MW. 2006. Contrasting patterns of introgression at X-linked loci across the hybrid zone between subspecies of the European rabbit (Oryctolagus cuniculus). Genetics, 173: 919-933.

2. Geraldes A, Ferrand N. 2006. A 7-bp insertion in the 3' untranslated region suggests the duplication and concerted evolution of the rabbit Sry gene. Genetics Selection and Evolution, 38: 313-320.

1. Geraldes A, Rogel-Gaillard C, Ferrand N. 2005. High levels of nucleotide diversity in the European rabbit (Oryctolagus cuniculus) SRY gene. Animal Genetics, 36: 349-351.

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