Faculty and Staff Publications

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Mapping of historical design values and their future-projected changes over Canada
(New Horizons in Green Civil Engineering (NHICE), 2022-04-27) Curry, Charles L.; Annau, Nicolaas J.; Zwiers, Francis W.; Anslow, Faron; Glover, Rod; Hiebert, James
Climate change has the potential to affect buildings and infrastructure by changing the conditions to which they are exposed. To better quantify and prepare for these changes, Infrastructure Canada and the National Research Council (NRC) recently supported a collaboration between the Pacific Climate Impacts Consortium (PCIC) and Environment and Climate Change Canada (ECCC) to develop updated guidance to the engineering community. One facet of this work was the provision of standard climatic design values based on up-to-date historical observations at meteorological stations. Climatic data for infrastructure design are often required at locations not co-located with stations, necessitating some sort of interpolation. Purely mathematical or statistical interpolation tends to oversmooth spatial structure in station-poor areas and, depending on the technique, can exaggerate station measurement error in station-rich areas. Nor is physical consistency of the underlying climatic field in space guaranteed. We developed an approach that uses historical regional climate model (RCM) simulations as a spatial interpolator of station observations. RCMs can adequately reproduce the observed spatial patterns and probability distributions of many climate variables, with the benefit of spatiotemporal consistency—albeit in a "model world" and at spatial scales resolved by the RCM. The mapping method has been implemented as an online tool (the Design Value Explorer, or DVE) for general users to explore design value variations across Canada. The seamless transition from historical to future climate states in the RCM further allows the tool to provide projected changes to design values indexed to different levels of global warming. In this short paper, we review the development of the Design Value Explorer online tool, and showcase its main features.
Juvenile smokescreens: Softening the harm of zoos, aquaria, and prisons through (human) children
(Cambridge University Press, 2022) Deckha, Maneesha
This chapter explores how human children soften the abusive edge of carceral spaces. Prisons, immigration detention centres, and zoos and aquaria are institutions that attract sustained public scrutiny from prisoner rights, migrant rights, anti-racist, and animal rights movements. Critics and scholars note the entwined nature of race, gender, and species logics that shape and unite these spaces and object to the shortand long-term incarceration these institutions make possible as well as the conditions residents confined within experience. Prisoner rights, migrant rights, and animal rights critics also contest the messaging that these institutions and their proponents use to assure the public of the need for confinement and the ethical acceptability of the conditions captive animals and humans experience. These discourses, depending on the specific institution, highlight the larger public “law and order” interests of safety and border control, but also “progressive” interests of rehabilitation, conservation, and education. In highlighting these latter “progressive” interests, carceral institutions seek to humanize themselves and their work to bolster their social credibility. This “humane-washing” occurs through long-standing rationales about rehabilitation for offenders in the prison context, and more recent rationales about the conservation of nature and conservation education in the zoo and aquarium context. It also, I will argue, occurs through a specific type of marshaling of the human child. I seek to add to the literature on “humane-washing”4 as well as contestations and uses of “childhood” and “family” narratives in general in this analysis. I apply a multispecies lens to consider how the real and imagined human child in the zoo and aquaria context, and narratives about what is in the best interests of human children in the immigration and prison context, figure into characterizing such carceral institutions as legally and socially legitimate spaces. The argument acknowledges that these carceral spaces can yield positive benefits for some, such as rehabilitation or rescue of a specific individual or even conservation of a specific species. However, it accepts the existing critical scholarly literature against such spaces overall to focus on the question of how carceral spaces mask their problematic and oppressive nature by integrating the presence of human children.
Animalization and dehumanization concerns: Another psychological barrier to animal law reform
(Psychology of Human-Animal Intergroup Relations, 2023) Deckha, Maneesha
Legal systems across the world classify animals as property. There is growing global momentum asking courts in anthropocentric legal systems to revisit this position through test-case litigation. This has resulted in a few discrete victories for animals, but not much more. An ongoing issue is general legal conservatism and the belief in human exceptionalism that judges exhibit in these and related cases. In addition to general human exceptionalism, this article argues that a further psychological block for judges can arise from concerns about exacerbating racism and other intra-human prejudices given histories and legacies of animalizing and dehumanizing certain human groups. The first aim of this study is to illustrate this psychological phenomenon impacting judicial decision-making in relation to race. The article discusses the 2022 decision by the New York Court of Appeals with respect to the ongoing captivity of Happy, an elephant at the Bronx Zoo. This decision is selected given its recent and landmark status in North America. The second aim of the study is to outline why the dissociation of humans from animals is counterproductive to eliminating racism and other intra-human prejudices and inequities. The third aim of the study is to explain why affirming human proximity and kinship to animals—and thus putting a positive spin on animalization—in the legal system would be a more effective anti-racist and decolonizing gesture.
Human children, nonhuman animals, and a plant-based vegan future
(Koninklijke Brill NV, 2023) Deckha, Maneesha
Conservative estimates indicate that humans eat approximately 65 billion land-based animals annually (FAO 2020a), and that wild-caught fishing and aquaculture entail the death of nearly a trillion (and quite possibly more) fish per year. The enormity of this scale of animal consumption is unprecedented in human society. Yet, most people are unaware of the scale of animal farming, trawling, and slaughter or the brutalities it involves as these activities take place away from public view, typically in windowless concentrated animal feeding operations or in gigantic trawler nets in the middle of the ocean (Bisgould 2011, 162–163). Media coverage discussing the phenomena, even in affluent countries with the highest levels of animal consumption per capita, is sparse with national governments also remaining silent on farmed animal suffering (Arcari 2017, 77–82). In fact, meat, dairy, and animal-based food lobbies enjoy elevated levels of political influence (Kemmerer 2006), and legislation may also exist in certain jurisdictions to illegalise whistleblowing or undercover investigations in these spaces. All of these forces combine to minimise public awareness of the scale of these industries and the torturous conditions in which animals are raised, slaughtered, and otherwise processed.
Supplanting anthropocentric legalities: Can the rule of law tolerate intensive animal agriculture?
(Routledge, 2023) Deckha, Maneesha
The rule of law is a concept in motion. Whether adopted as foundational to the constitutional backdrop of nation-states or circulating as a higher-order international law general principle of law, the now-transnational concept defies a fixed meaning and has been subject to multiple interpretations. Its open-endedness permits it to attend to pressing social problems and matters of justice heretofore unseen or undertheorized and which exceed its normal liberal legal parameters and colonial formation. In this contribution, I suggest that the rule of law is deployable against the planetary scourge of animal-based food systems (ABFS) and the more-than-human violence ABFS occasion. Drawing on posthuman feminist theory, the chapter contributes to the growing field of global animal law that explores animal law issues through international law and transnational law frameworks (Blattner 2019; Cao et al 2016; Peters 2020, 2017, 2016: 3–4; Stucki 2017), by highlighting the potential of the rule of law to challenge the legitimacy of at least some forms or portion of ABFS.
Accelerating animal replacement: How universities can lead — results of a one-day expert workshop in Zurich, Switzerland
(Alternatives to Laboratory Animals, 2025) Deckha, Maneesha; Michel, Margot; Azilagbetor, David; Blattner, Charlotte; Morales, Rosa M. C.; Davies, Gail; Elger, Bernice; Faizee, Sara; Fox, Marie; Gerritsen, Vanessa; Heuss, Adrian; Kämpfen, Laura; Louis-Maerten, Edwin; Lüthi, Nicole; Milford, Aoife; Müller, Nico D.; Persson, Kirsten; Ritskes-Hoitinga, Merel; Rothen-Rutishauser, Barbara; Rüttimann, Andreas; Stoykova, Katerina; Stucki, Saskia; Zemanova, Miriam A.
This report is a result of an interdisciplinary workshop held at the Collegium Helveticum in Zurich, Switzerland in February 2024, in which ideas for accelerating NAMs (New Approach Methodologies) in Swiss universities were shared and discussed. Due to regional differences in university organisation and funding structures, not all recommendations will be transferable to all regions worldwide. All participants were qualified to contribute to the discussion, due to their knowledge and experience of the Three Rs, in particular with regard to their implementation. The workshop participants believed that universities, which play a pioneering role in so many other areas, should also exploit their innovative potential in the field of animal-free research. The workshop uncovered four areas that would need to be addressed in order to achieve a significant change in university science culture and do more justice to the Three Rs, namely: language — innovative framing (pro-replacement framing in official university statements); knowledge transfer—communicating innovative findings in teaching (redirecting curriculum); change of values within science faculties; and structured implementation and well-coordinated planning of the transformation (establishment of a ‘transition unit’). Specific strategies for implementing these four areas are outlined. In addition, we discuss why the replacement of animal testing should be an essential goal for universities, why this goal has not yet been achieved, and why concerted efforts toward change are required.
Editorial for special issue
(LEOH - Journal of Animal Law Ethics and One Health, 2025) Deckha, Maneesha
Animal experimentation has long been a topic of bioethical, philosphical, and legal debate.1 The vast majority of argumentation against the practice proceeds through deontological and utilitarian premises that may be characterized as largely liberal in theoretical orientation.2 These accounts highlight harms to animals through a methodology of rational argumentation and with a substantive focus on the interests of animals. Argumentation against experimenting on animals rooted in critical theoretical perspectives, i.e. theories that challenge or supplement these classic liberal theories such as ecofeminist and feminist care approaches,3 are considerably less prominent in the scholarship contesting animal experimentation.4
A child’s right to non-anthropocentric education
(VerfBlog, 2025) Deckha, Maneesha
The European Charter on Fundamental Human Rights (“the Charter”) is not concerned about the core topic of contemporary animal law: animal rights. But although the Charter is silentabout animals, it is possible to connect certain human rights it enshrines to animals in amanner that can foment animal rights. The protection of a healthy environment in Article 37 is an obvious choice inasmuch it is backed up by Article 191 of the Treaty on the Functioning of the European Union (TFEU) and the European Green Deal’s commitment to net zero greenhouse gas emissions by 2050. Indeed, there is a growing body of work aimed at harnessing environmental support for the rights of nature in favour of animal rights. In this contribution, I want to suggest a lesser theorized human right in the Charter that similarly has considerable potential to benefit animals: the right to education under Article 14.
Taxonomic utility of isolated ankylosaurian dinosaur teeth using traditional and geometric morphometrics with implications for ankylosaur paleoecology
(Journal of Paleontology, 2025) Cross, Emily; Fraass, Andrew J.; Arbour, Victoria M.
The presence of a basal cingulum, fluting, and overall size have been used to differentiate nodosaurid and ankylosaurid teeth for decades. The taxonomic utility of tooth morphology in ankylosaurs, however, has not been quantitatively tested. In addition, new phylogenetic hypotheses recognize four ankylosaur families (Panoplosauridae, Polacanthidae, Struthiosauridae, and Ankylosauridae), rather than the traditional nodosaurid–ankylosaurid dichotomy. Understanding ankylosaur tooth variation could better help identify taxa with ambiguous phylogenetic affinities or allow isolated teeth to test paleoecological questions such as a potential extirpation of mid-Cretaceous ankylosaurids from Laramidia. We analyzed a large sample of ankylosaur teeth using traditional and geometric morphometrics and investigated the utility of size and the presence of a cingulum and fluting for differentiating ankylosaur teeth. Morphometric analyses show that “nodosaurids” had the greatest variation in tooth shape and size. Panoplosauridae and Struthiosauridae account for a large amount of “nodosaurid” variation, whereas basal ankylosaurs, Polacanthidae, and Ankylosauridae share a similar restricted morphospace. Teeth with a crown base length or height over 10 mm are found only in panoplosaurids, struthiosaurids, and Peloroplites, but smaller sizes are found in all clades. A basal cingulum and fluting are associated with Ankylosauridae and Panoplosauridae. Linear discriminant analyses could accurately identify only between 50% and 75% of the teeth in our sample; thus, they should be used in conjunction with size and discrete traits when identifying isolated teeth. With these findings, caution should be used when attempting to use isolated ankylosaur teeth in broader paleoecological questions, and reclassification of museum collections should be undertaken.
Record of foraminifera test composition throughout the Phanerozoic
(Proceedings of the Royal Society B Biological Sciences, 2025) Faulkner, Katherine; Lowery, Christopher; Martindale, Rowan Claire; Simpson, Carl; Fraass, Andrew J.
Marine calcifiers produce calcareous structures (e.g. shells, skeletons or tests) and are therefore sensitive to ocean chemistry. Nevertheless, the long-term evolutionary consequences of marine carbonate changes are not well understood. This article compares calcareous and non-calcareous responses to ocean chemistry changes throughout the Phanerozoic Eon (541 million years ago to present). To accomplish this, we calculated proportional wall-type diversity, origination rates and extinction rates for 2282 benthic foraminiferal genera. Calcareous origination and extinction rates fluctuated throughout the Palaeozoic Era (541–251.9 million years ago), but during the Mesozoic Era (251.9–66 million years ago), calcareous origination and extinction rates stabilized following the evolution of pelagic calcifiers. Despite variations in Cenozoic Era (66–0 million years ago) foraminifera diversity, calcareous wall types maintained around 77% proportional diversity. Although calcareous wall-type extinction rates decline during the Mesozoic and Cenozoic, Phanerozoic foraminifera wall-type changes during individual events are largely contingent upon contemporaneous conditions rather than overarching trends. Of the Big Five mass extinction events, calcareous wall-type proportions only decreased at the end-Permian (73% to 26% diversity) and end-Triassic (56% to 50% diversity). These results suggest long-term ocean chemistry changes were not the main driver of foraminiferal wall-type diversity through time.
Canadian natural science graduate stipends lie below the poverty line
(PLoS ONE, 2025) Fraass, Andrew J.; Bailey, Thomas J.; Karunakumar, Kayona; Wishart, Andrea E.
Despite the critical role of graduate students in the Canadian research ecosystem, students report high levels of financial stress. As a case study, we collected graduate minimum stipends and tuition data from all university graduate programs in Canada in Ecological Sciences/Biology and Physics, along with cost of living measures for the cities in which they reside. These data are heterogeneous, complex, and in many cases simply not publicly available, making it challenging for potential graduate students to understand what support they should expect. We find Canadian minimum stipends are at values almost exclusively below the poverty threshold. Only two of 140 degree programs offered stipends which meet cost of living measures after subtracting tuition and fees. For graduate programs which offered a minimum guaranteed stipend, the average minimum domestic stipend is short ~Can$9,584 (international ~Can$16,953) of the poverty threshold after accounting for payment of tuition and fees. On average, approximately 33% of a minimum stipend is returned to the university in tuition and fees by a domestic Canadian student and 76% (59% median) by an international student, though there are important caveats with the international student comparison. While international comparison is difficult, the highest Canadian minimum stipend found is roughly equivalent or lower than the lowest stipend within the largest dataset of United States of America (US) Biology stipends, and lower than the United Kingdom (UK) stipend. University endowment correlates with minimum stipend amount but intra- and inter-institutional differences suggest it is not solely institutional wealth associated with graduate pay. We observe Canada is behind comparable countries in minimum funding levels for the next generation of scientists.
Diversity dynamics of microfossils from the Cretaceous to the Neogene show mixed responses to events
(Palaeontology, 2022) Jamson, Katie M.; Moon, Benjamin C.; Fraass, Andrew J.
Microfossils have a ubiquitous and well-studied fossil record with temporally and spatially fluctuating diversity, but how this arises and how major events affect speciation and extinction is uncertain. We present one of the first applications of PyRate to a micropalaeontological global occurrence dataset, reconstructing diversification rates within a Bayesian framework from the Mesozoic to the Neogene in four microfossil groups: planktic foraminiferans, calcareous nannofossils, radiolarians and diatoms. Calcareous and siliceous groups demonstrate opposed but inconsistent responses in diversification. Radiolarian origination increases from c. 104 Ma, maintaining high rates into the Cenozoic. Calcareous microfossil diversification rates significantly declines across the Cretaceous–Palaeogene boundary, while rates in siliceous microfossil groups remain stable until the Paleocene–Eocene transition. Diversification rates in the Cenozoic are largely stable in calcareous groups, whereas the Palaeogene is a turbulent time for diatoms. Diversification fluctuations are driven by climate change and fluctuations in sea surface temperatures, leading to different responses in the groups generating calcareous or siliceous microfossils. Extinctions are apparently induced by changes in anoxia, acidification and stratification; speciation tends to be associated with upwelling, productivity and ocean circulation. These results invite further micropalaeontological quantitative analysis and study of the effects of major transitions in the fossil record. Despite extensive occurrence data, regional diversification events were not recovered; neither were some global events. These unexpected results show the need to consider multiple spatiotemporal levels of diversity and diversification analyses and imply that occurrence datasets of different clades may be more appropriate for testing some hypotheses than others.
Time Scavengers: An educational website to communicate climate change and evolutionary theory to the public through blogs, web pages, and social media platforms
(The Journal of STEM Outreach, 2019) Lam, Adriane; Bauer, Jennifer E.; Fraass, Susanna; Sheffield, Sarah; Limbeck, Maggie R.; Borden, Rose M.; Thompson-Munson, Megan E.; Fraass, Andrew J.; Hills, Michael; Muskelly, Cameron E.; Hartshorn, Kyle R.; Bryant, Raquel
Climate change and evolution are topics at the forefront of political discussions, debates, and the public sphere. Regardless of evidence on both topics, the public as a whole still believes they are under debate. It is imperative that the public have access to correct and easy-to-digest information on these topics to make informed environmental and ecological decisions. To date, scientifically accurate digital platforms aimed at informing the public on these topics are overly complex and jargon-ridden. Time Scavengers (www.timescavengers.blog) was created to address these issues and is maintained by a group of academics, graduate students, avocational scientists, and educators. The site includes many informational pages about geology, climate change, and evolution, all written for the public with useful descriptions and figures. To make the process of science more transparent, the site includes blogs to provide insight into data collection and interpretation, field work, and public outreach. The site also includes additional pages with links to relevant content and activities appropriate for K-12 classrooms. The overarching goals of the site are to bridge the gap between scientists and the public through engaging, informational pages and personal experiences and to increase science literacy through easy-to-digest content.
The Extending Ocean Drilling Pursuits (EODP) Project: Synthesizing scientific ocean drilling data
(Geochemistry, Geophysics, Geosystems, 2023) Sessa, Jocelyn A.; Fraass, Andrew J.; LeVay, Leah J.; Jamson, Katie M.; Peters, Shanan E.
For over 50 years, cores recovered from ocean basins have generated fossil, lithologic, and chemical archives that have revolutionized fields within the earth sciences. Although scientific ocean drilling (SOD) data are openly available following each expedition, the formats for these data are heterogeneous. Furthermore, lithological, chronological, and paleobiological data are typically separated into different repositories, limiting researchers' abilities to discover and analyze integrated SOD data sets. Emphasis within Earth Sciences on Findable, Accessible, Interoperable, and Reusable (FAIR) Data Principles and the establishment of community-led databases provide a pathway to unite SOD data and further harness the scientific potential of the investments made in offshore drilling. Here, we describe a workflow for compiling, cleaning, and standardizing key SOD records, and importing them into the Paleobiology Database and Macrostrat, systems with versatile, open data distribution mechanisms. These efforts are being carried out by the extending Ocean Drilling Pursuits (eODP) project. eODP has processed all of the lithological, chronological, and paleobiological data from one SOD repository, along with numerous other data sets that were never deposited in a database; these were manually transcribed from original reports. This compiled data set contains over 79,899 lithological units from 1,125 drilling holes from 422 sites. Over 26,000 fossil-bearing samples, with 5,378 taxonomic entries from 13 biological groups, are placed within this lithologic spatiotemporal framework. All information is available via GitHub and Macrostrat's application programming interface, which renders data retrievable by a variety of parameters, including age, site, and lithology.
Phonon hydrodynamics revisited
(Springer, 2025) Struchtrup, Henning
The equations of phonon hydrodynamics are re-considered in the framework of expansions of the phonon kinetic equation for large frequency of momentum conserving N-processes. Specifically, the Chapman-Enskog expansion provides a sound derivation of non-linear transport equations that fulfill all necessary compatibility requirements. The celebrated Guyer-Krumhansl equations can only be derived under the more restrictive condition of slow processes, and are affected by compatibility problems. The impact of different energy-temperature relations on the structure of equations is discussed.
Sur les routes de « l’Amérique française » : métissage et auto-autochtonisation discursive dans Volkswagen Blues de Jacques Poulin
(Revue d’études autochtones, 2023) Lak, Zishan; Landry, Pierre-Luc
This article examines discursive and narrative strategies of métissage and self-indigenization in Volkswagen Blues, a transculturalist novel published in 1984 by Quebecois writer Jacques Poulin. Claims to indigeneity and métissage in the novels do not appear directly, but through the myth of French America; settler colonialism is concealed, Indigenous peoples are relegated to a prehistoric past, and French settler past is implicitly foregrounded as the origin of North America.
An introduction to legal research of Indigenous legal orders
(Emond Montgomery Publications, 2024) Asch, Jessica; Williamson, Tara
This chapter has been written with various audiences in mind, but with the overarching premise that if a reader is accessing this text, it is in the spirit of being a student of Indigenous law. This includes students of law or other disciplines, and legal educators, lawyers, and researchers. The authors come from a practice rooted in community-led research and partnership, so considerable emphasis is placed on ethical relationship-building and community engagement, which are cornerstones of their practice. The purpose of this research and writing may dictate the extent to which some of these practices will be relevant or the amount of attention they will require. For example, a student drafting a paper for a class may not engage in much primary research or embedded learning. Still, understanding the history, context, and importance of rigorous, ethical research in Indigenous law is imperative for responsible scholarship in the field.
Intraspecific trait variation in urban stream ecosystems: Toward understanding the mechanisms shaping urban stream communities
(Freshwater Science, 2019) Marques, Piatã S.; Manna, Luisa R.; Mazzoni, Rosana; El-Sabaawi, Rana
The rapid expansion of urban centers is a critical threat to stream ecosystems, yet we currently lack mechanistic understanding of the effects of urbanization on stream communities. Here we explore how an intraspecific trait perspective can unveil mechanisms of change in urban stream communities. Intraspecific trait approaches are rarely used in urban aquatic ecosystems though their potential has been widely demonstrated in terrestrial systems. We begin by identifying several biotic and abiotic agents that can drive intraspecific trait changes in life history, behavior, morphology, and feeding in a range of urban stream organisms. We then propose that intraspecific trait-based approaches in urban streams can help explain the mechanisms underlying species persistence, biodiversity responses, functionality, and evolution and how they can potentially improve biomonitoring in urban streams. This trait-based information is essential to better understand, predict, and manage the impacts of urbanization on stream biota.
Urbanization can increase the invasive potential of alien species
(Journal of Animal Ecology, 2020) Santana Marques, Piatã; Resende Manna, Luisa; Clara Frauendorf, Therese; Zandonà, Eugenia; Mazzoni, Rosana; El-Sabaawi, Rana
Alien species often flourish and become invasive in urban ecosystems. How and why invaders succeed in urban systems is an important, yet poorly understood, question. We investigate whether the success of urban invaders is related to changes in species traits that enhance invasive potential. We also explore whether a trophic mechanism helps explain the success of invaders in urban systems. We use the guppy Poecilia reticulata, a globally distributed alien species that has invaded both urban and non-urban systems, as our model. We first characterize the effect of urbanization on streams where guppies are present. We measure guppy invasion success using their population density and size-frequency. Then we assess how traits that are related to the potential of guppies to invade (life history and condition) respond to urbanization. Next, we explore how urbanization affects the availability of food for guppies and their diets. We also test if the presence of other fish species grants biological resistance to invasion by dampening guppy invasive potential. We find that urban streams have high concentrations of ammonium and faecal coliforms, indicating contamination from sewage. On average, guppy populations from urban streams have 26? higher density and larger body sizes than non-urban populations. Urban guppies are in better condition and have on average five more offspring than non-urban guppies. Urbanization increases the availability and consumption of highly nutritious food (chironomid larvae) by guppies. We find a positive relationship between the consumption of chironomids and both fecundity and condition. The presence of other fish species in urban streams often has a negative but small effect on guppy traits and density. Our data suggest a relaxation of trade-offs that shape life-history traits which is related to increased food resources in urban streams. These indicate that urbanization enhances the invasive potential of guppies through a trophic mechanism that simultaneously increases reproduction and somatic investment. Such mechanism is likely widespread because chironomids are often highly abundant in urban systems. Thus, not only guppies but also other invasive species can take advantage of such a resource to invest in traits that enhance invasion success.
Using fish to understand how cities affect sexual selection before and after mating
(Frontiers in Ecology and Evolution, 2022) Marques, Piatã; Zandonà, Eugenia; Amaral, Jeferson; Selhorst, Yasmin; El-Sabaawi, Rana; Mazzoni, Rosana; Castro, Letícia; Pilastro, Andrea
Urbanization transforms natural and agricultural areas into built landscapes. Such profound habitat alteration imposes strong pressure for phenotypic trait changes through processes related to natural and/or sexual selection. Evidence for how natural selection drives changes to traits in urban biota is increasing, but little is known about the role of sexual selection. In this study, we assess the effect of urbanization on the expression and interaction of males` pre-mating traits (body size and color) and a post-mating trait (sperm load). We used a widespread invasive species, the guppy (Poecilia reticulata), which is a well-known model for studying sexual selection, but has never been studied in urban systems for this purpose. We found that urbanization did not affect mean body size or condition, but it resulted in size-dependent reductions in the expression of orange and iridescent colors, as well as sperm load. Orange color was reduced in small urban guppies, while the iridescent colors were reduced in large urban guppies compared to non-urban guppies. Difference in sperm load was only found in large males, with lower sperm load in urban guppies. The relationship between orange color and sperm load was positive in urban guppies but negative in non-urban guppies, while the association between iridescent color and sperm load followed the opposite pattern. Our findings suggest that sexual selection on pre- and post-mating traits is weaker in urban than non-urban systems and that interactions between such traits are context dependent. These responses can be related to the pollution and altered visual environment of urban systems and provide an opportunity to advance our understanding of the mechanisms determining adaptation in cities.

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