Heather J. Alexander, PhD

I am currently the Research Manager for Dr. Dan Bolnick’s Lab (University of Connecticut), based out of BMSC, studying the evolutionary immunology of the threespine stickleback.

The primary focus of the research is to understand the genetic basis of host adaptation to spatially varying parasites, and the corresponding immunological traits. This work includes field surveys of parasite communities, field experiments testing for local adaptation and immunological plasticity, and experimental infection assays in the lab coupled with immunological study (multiple ongoing studies).

In the Bolnick Lab at BMSC, I will be managing the field and lab work, sampling lakes in the area to determine Schistocephalus solidus abundance in the water, copepods, stickleback and birds, throughout the year.

I earned my PhD from Simon Fraser University in evolutionary ecology (sexual selection & phylogeography in Poecilia reticulata), MSc from University of Calgary (sex change in intertidal copepods), and BSc from University of Victoria. Following completion of my PhD, I was a Research Associate with Dr. Brad Anholt, (UVIC) (sex determining mechanisms in Tigriopus californicus), and most recently was Bamfield Marine Sciences Center’s Communications Manager and University Programs Coordinator.  I have extensive experience in field work on the west coast of Vancouver Island and in South America, with many laboratory skills acquired throughout my academic career.

Phone: 250-720-7721


June 2007 – Department of Biological Sciences. Simon Fraser University, Burnaby, BC, Canada<
Dissertation Title: Population Differentiation and Sexual Isolation among Poecilia reticulata populations

December 1994 – Department of Biology, University of Calgary, Calgary, AB, Canada
Thesis Title: Population Dynamics and Comparative Ecophysiology of the Intertidal Isopods Gnorimosphaeroma luteum and G. oregonense.

May 1990 – Department of Biology, University of Victoria, Victoria, BC, Canada; First Class standing


Research: Polygenic sex determination in Tigriopus californicus.
Principal Ivenstigator: Dr. Brad Anholt, University of Victoria.

The harpacticoid copepod, Tigriopus californicus inhabits high intertidal splash pools along the west coast of North America from Baja California to Alaska. Although its habitat provides refuge from a diverse predator fauna, the high intertidal pools are characterized by extreme fluctuations in temperature and salinity. Clutch sex ratios (proportion of males in a brood) from natural populations of T. californicus often deviate from the binomial distribution. We have been accumulating corroborative evidence in support of the hypothesis of a polygenic sex determination mechanism. Under this model, variation in sex ratio is a consequence of an underlying trait, the value of which is determined by the additive effect of many alleles at multiple loci .

PhD Research: Population Differentiation and Sexual Isolation among Poecilia reticulata (the guppy) populations
Advisor: Dr. Felix Breden, Simon Fraser University
Committee: Dr. Bernard Crespi, Dr. Arne Mooers

Phylogeography and phenotypic/genotypic associations
Understanding the relative roles of contemporary selection versus historical processes in determining the mechanisms driving population differentiation and ultimately speciation may be best achieved by examining well-studied model systems. For my PhD dissertation I examined patterns of morphological and molecular divergence among Poecilia reticulata (the guppy) populations across the entire range of this species,a model system for the study of evolution, testing whether patterns of neutral genetic differentiation (mtDNA and a nuclear locus – Xsrc) are associated with vicariant events, and whether patterns of morphological divergence are correlated to neutral genetic divergence, or have arisen as a consequence of selection. In particular, I examined whether parallel evolution observed among Trinidad populations are persistent across the natural range.

Sexual selection and speciation
Theory predicts that sexual selection can promote the evolution of reproductive isolation and speciation. We examined a highly divergent group of P. reticulata populations occurring in Cumaná, Venezuela. Our study suggest that the Cumaná guppy has most likely differentiated from other guppy populations due to divergent sexual selection, and may be the first documented case of incipient speciation in the guppy.

Differentiation in male secondary sexual characters maintained in the Cumaná guppy despite mtDNA and nuclear introgression.
In the phylogeographic study of Poecilia reticulata Peter (the guppy) across the entire natural range, two highly divergent mtDNA lineages were inferred for the morphologically divergent Cumaná guppy. In this study microsatellite loci were used to test whether these divergent mtDNA lineages would also be observed in data from nuclear loci (nDNA). Shared haplotypes and microsatellite alleles between upstream guppy-morph and downstream Cumaná morph males suggest partial introgression from upstream into downstream populations. Despite introgression via downstream migration, the distinctive Cumaná male morphotype is maintained, suggesting sexual selection by female choice has imposed differential rates of introgression among genes that do or do not code for characters related to biological divergence.

MSc research: Protogynous sex change in the intertidal isopod Gnorimosphaeroma luteum and G. oregonense.
Advisor: Dr. R. Davies, University of Calgary, BMSC

In Crustacea, the dominant pattern of sequential hermaphroditism is protandry (sex change from male to female). In the study I provide the first evidence from external morphology and population structure that G. oregonense and G. luteum, abundant, sexually dimorphic intertidal isopods, undergo protogynous (female to male) sex change. In the field, females had rudimentary penes, suggesting sex change, and laboratory growth experiments confirmed that females produced one brood of juveniles, then passed through a variable number of molts as immature males before becoming sexually mature males. Contrary to reports for other protogynous Crustacea, this study suggests that sex change is not socially mediated, although it may be facultative, because a large percentage of laboratory-reared juvenile isopods developed directly into males.


Peer Reviewed:

Richardson, J.M.L., Alexander, H.J., and B.R. Anholt. 2023. Variance Components of Sex Determination in the copepod Tigriopus californicus estimated from a pedigree analysis. Ecology and Evolution. DOI: https://doi.org/10.1002/ece3.9997

Davies, H.L. Robb, H., Cox, K.D., Covernton, G.A., Eastham,T.M., Alexander, H.J., and Juanes, F. 2021. A preliminary analysis of ingestion and egestion of microplastic fibres in the acorn barnacle Balanus glandula. Journal of Experimental Marine Biology and Ecology. doi: 10.1016/j.jembe.2021.151589

Alexander, H.J., Richarson, J.M.L., Edmands, S., and B.R. Anholt. 2015. Sex without sex chromosomes; genetic architecture of multiple loci independently segregating to determine sex ratios in the copepod Tigriopus californicus. J. Evol. Biol. 2015 Dec; 28(12): 2196-207. doi: 10.1111/jeb.12743.

Alexander, H.J., Richardson, J.M.L. and Anholt, B.R. 2014. Multi-generational response to artificial selection for biased clutch sex ratios in Tigriopus californicus populations. J Evol Biol. 27 (9): 1921-1929. doi.org/10.1111/jeb.12449

Herdegen, M., Alexander, H. J., Babik, W., Mavarez, J., Breden, F. and Radwan, J. 2014. Population structure of guppies in north-eastern Venezuela, the area of putative incipient speciation. Bmc Evolutionary Biology 14. doi.org/10.1186/1471-2148-14-28

Alexander, H.J., J. Taylor, S. Wu, and F. Breden. 2006. Parallel evolution and vicariance in the guppy (Poecilia reticulata) over multiple spatial and temporal scales. Evolution 60:2352-2369. doi.org/10.1111/j.0014-3820.2006.tb01870.x

Lindholm, A.K., F. Breden, H.J. Alexander, W-K. Chan, S.G. Thakurta, and R. Brooks. 2005. Invasion success and genetic diversity of introduced populations of guppies Poecilia reticulata in Australia. Molecular Ecology 14: 3671-3682. Ecology and Evolution doi.org/10.1111/j.1365-294X.2005.02697.x

Alexander, H.J. and F. Breden. 2004. Sexual isolation and extreme morphological divergence in the Cumaná guppy: a possible case of incipient speciation. Journal of Evolutionary Biology 17: 1238-1254. doi: 10.1111/j.1420-9101.2004.00788.x

Brook (Alexander), H.J., T.A. Rawlings and R.W. Davies. 1994. Protogyny in the Intertidal Isopod, Gnorimosphaeroma oregonense. Biological Bulletin 187: 99-111. doi.org/10.2307/1542169

Seminars & talks

H.J. Alexander, J. Richardson, B. Foley, S. Edmands, T. Tai, Mackeracher & B. Anholt. 2014, 2015. Extraordinary sex ratios in Tigriopus californicus. BMSC Fall Program Seminar.

H.J. Alexander, J. Richardson & B. Anholt, 2013. Extraordinary sex ratios in Tigriopus californicus; a QTL analysis. University of Würzburg

H.J. Alexander, J. Richardson & B. Anholt, 2012. Extraordinary sex ratios in Tigriopus californicus; a QTL analysis. Society for the Study of Evolution meetings. Ottawa, ON (Talk)

Richardson, J., Alexander, H.J. & B. Anholt, 2012. Heritability and response to selection of brood sex ratio in the marine copepod Tigriopus californicus. Society for the Study of Evolution meetings. Ottawa, ON (Poster)

H.J. Alexander & B. Anholt, 2010. Extraordinary sex ratios in Tigriopus californicus. Bamfield Marine Sciences Centre (seminar)

H.J. Alexander & B. Anholt, 2010. Extraordinary sex ratios in Tigriopus californicus. Fall Program Seminar Series, Bamfield Marine Sciences Centre.

H.J. Alexander & B. Anholt, 2010. Implications of sex ratio variation among marine copepod (Tigriopus californicus) populations. Society for the Study of Evolution meetings. Portland, OR. (Talk)

H.J. Alexander, 2006. The Cumaná guppy: multiple lineages or introgression? Society for the Study of Evolution meetings. Stony Brook, NY. (Talk)

H.J. Alexander, 2004. Evolutionary history of Poecilia reticulata. Society for the Study of Evolution meetings. Colorado State University, Fort Collins, CO. (Poster)

H.J. Alexander, 2003. Pre-mating isolation between morphologically diverged guppy populations. Society for the Study of Evolution meetings. California State University, Chico, CA (Talk)

H.J. Alexander, 2002. Population divergence and reproductive isolation between Poecilia reticulata (the guppy) and “Endler’s Livebearer”. Society for the Study of Evolution meetings. University of Illinois at Urbana-Champaign, IL.
American Society of Naturalists meetings, Banff, Alberta – July 2002 (Talk)

H.J. Alexander, and F. Breden, 2002. Population divergence and reproductive isolation between Poecilia reticulata (the guppy) and “Endler’s Livebearer”. Pacific Ecology and Evolution Retreat, Brackendale, BC. (Poster)

H.J. Alexander. 1999. Pre-existing bias; a model for sexual selection? Simon Fraser University (Talk)

H.J. Brook and R.W. Davies. 1993. Implications of Sex Change for the Population Ecology of Gnorimosphaeroma luteum. American Zoologist 33(5): 299 (Abstract). American Society of Zoologists Annual Meeting, Los Angeles, CA. – December 1993 (Talk)

H.J. Brook, T.A. Rawlings and R.W. Davies. Protogyny in the Intertidal Isopod Gnorimosphaeroma oregonense and G. luteum. Pacific Ecology Conference, Bamfield Marine Station, Bamfield, B.C. – March 1993 (Talk)

H.J. Brook (Alexander), T.A. Rawlings and R.W. Davies. Protogyny in the Intertidal Isopod Gnorimosphaeroma oregonense. Western Society of Naturalists, Newport, OR. – January 1993. (received honourable mention for Best Student Paper Award) American Society of Zoologists, Vancouver, B.C. – December 1992 (Talk)

Research, teaching & employment history

Research, teaching & employment history

May 1 –
Research Manager at BMSC
Dr. Dan Bolnick, University of Connecticut

May 2019 – April 2023
University Programs Coordinator / Communications
Bamfield Marine Sciences Centre, Bamfield, B.C.

September – December 2019
Associate Director, Education (Acting)
Bamfield Marine Sciences Centre, Bamfield, B.C.

August 2018 – April 2019
Graduate Program Administrator
Division of Medical Sciences, University of Victoria

February 2018 – June 2018
University Programs Coordinator
Bamfield Marine Sciences Centre, Bamfield, B.C.

January 2009 – June 2018
Communications Manager
Project Manager – BMSC Branding
Bamfield Marine Sciences Centre, Bamfield, B.C.

January 2009 – 2017
Research Associate, Dr. Brad Anholt (UVic, BMSC)
Bamfield Marine Sciences Centre, Bamfield, B.C.

February 2008 – January 2009
University Programs Coordinator
Bamfield Marine Sciences Centre, Bamfield, B.C.
‘OceanLink’ Website development

September 1999 – June 2007
PhD, Simon Fraser University
Phylogeography; evolutionary biology (molecular techniques; DNA extraction, PCR, automated sequencing, nuclear, mtDNA and microsatellite sequence analyses). Behavioural and morphometric studies in Poecilia reticulata. Field work conducted primarily in Venezuela.

May 1996 – September 1999
University Programs Coordinator
Bamfield Marine Sciences Centre, Bamfield, B.C.
Provide technical and administrative support to visiting and resident students and researchers with computing, microscopy, photography, SCUBA, general equipment, chemicals.

March – June 1994
Research Technician – Dr. Don Levitan, Florida State University (at BMSC)
Fertilization success in Strongylocentrotus spp. Laboratory experiments included energetic content assays, fertilization assays, counting sperm and eggs. Field-work was conducted by SCUBA, and examined the effects of wave exposure and mass spawning events on fertilization success (see Nature 1996, 382:153-155)

December 1993 – February 1994
Research Technician – Dr. Fu-Shiang Chia, University of Alberta (at BMSC)
Independent project, “The effects of maternal diet on embryonic development in isopods.”

September 1991 – December 1994
MSc, University of Calgary
Marine ecology, population dynamics, intertidal sampling, experimental design, controlled laboratory experiments, statistical analyses, fresh water analyses and aquatic ecology, scanning electron and light microscopy.

September 1991 – December 1994
Parks Canada, West Coast Trail, Pacific Rim National Park Reserve


Directed Studies in Marine Science, BMSC, Fall 2017
Seminars and Papers in Marine Science, BMSC, Fall 2003, 2008, 2012
Directed Studies in Marine Science, BMSC, Fall 2003

Teaching Assistant
Molecular Ecology and Evolution in the Intertidal, BMSC Summer 2007
Evolution and Adaptation in the Intertidal, BMSC, Summer 2002, 2006
Marine Invertebrate Zoology, BMSC, Summer 1992, 1993, 2004, 2005
Sturcture and Function in Animals, BMSC, Fall 2004
Life History Strategies of Marine Organisms, BMSC, Summer 2000
Evolution, SFU, Winter 2000
Instroductory Biology, SFU, Fall 1999
Human Physiology, UCalgary, Fall 1991

Guest Lectures
Population Genetics – undergraduate lecture on population genetics of Poecilia reticulata, SFU
Evolution and Adaptation in the Intertidal – undergraduate lecture on PhD research, focusing on colour and morphological analysis methodology, BMSC
Biology of Marine Fishes – undergraduate lecture, BMSC

Academic Services
Manuscript reviewer: Journal of Evolutionary Biology, Evolution, Heredity, Molecular Ecology, Journal of Visualized Experiments