Publications

Preprints

Bramon Mora, B. & Cirtwill, A.R., & Stouffer, D.B. (2018) pymfinder: a tool for the motif analysis of binary and quantitative complex networks. bioRxiv: doi: https://doi.org/10.1101/364703     pdf

This preprint introduces pymfinder, a python package for calculating the frequencies of motifs (unique patterns of interactions among small groups of species) in complex networks. Includes functions to describe network structure overall as well as functions to define the roles of species or links in terms of their participation in different motifs.

2019

Albouy, C., Archambault, P., Appeltans, W., Araújo, M.B., Beauchesne, D., Cazelles, K., Cirtwill, A.R., Fortin, M.J., Galiana, N., Leroux, S., Pellissier, L., Poisot, T., Stouffer, D.B., Wood, S.A., & Gravel, D. (2019) The marine fish food web is globally connected. Nature Ecology and Evolution: in press.

This paper examines how spatial turnover in marine fish community composition affects the structure of the fish food web. We found that the network was generally highly connected and did not show strong spatial modules, but the expected increase in species richness towards the tropics did result in changes to network structure. The high spatial connectivity may help marine food webs to resist perturbations, but could also allow the effects of disturbances to spread rapidly.

Cirtwill, A.R., Eklöf, A., Roslin, T., Wootton, K., & Gravel, D. (2019) A quantitative framework for investigating the reliability of empirical network construction. Methods in Ecology and Evolution: 10, 902-911.
doi: 10.1111/2041-210X.13180     preprint doi: https://doi.org/10.1101/332536     submitted pdf

This paper begins by describing the nested layers of uncertainty which affect the assembly of empirical ecological networks (e.g., due to true variation in interactions between sites, variation in interactions due to changes in abundances, or variation in the detectability of different interactions). To address the uncertainty inherent in empirical networks, we propose a simple and adaptable Bayesian framework. Using this framework makes the assumptions used to build the network explicit and can account for different levels of information about different interactions.

Baiser, B., Gravel, D., Cirtwill, A.R., Dunne, J.A., Fahimipour, A.K., Gilarranz, L.J., Grochow, J.A., Li, D., Martinez, N.D., McGrew, A., Poisot, T., Romnuk, T.N., Stouffer, D.B., Trotta, L.B., Valdovinos, F.S., Williams, R.J., Wood, S.A., & Yeakel, J.D. (2019) Ecogeographical rules and the macroecology of food webs. Global Ecology and Biogeography: online early view. doi: https://doi.org/10.1111/geb.12925

This paper summarizes several well-known ecological rules (Rapoport's rule, Bergmann's Rule, etc.) and their potential relationships with food-web structure. These relationships have different levels of support, and we aim to promote further study about the trends which are currently under-studied.

Simmons, B.I., Cirtwill, A.R., Baker, N., Dicks, L.V., Stouffer, D.B., & Sutherland, W.J. (2019) Motifs in bipartite ecological networks: uncovering indirect interactions. Oikos: 128, 154-170.
https://doi.org/10.1111/oik.05670     open-access early view edition

This paper demonstrates that motifs (unique patterns of interaction among small groups of species) can explain variation in the structure of bipartite networks such as plant-pollinator networks that is masked by other measures of structure such as connectance, nestedness, and modularity. Bipartite motifs can be calculated using the software introduced in Simmons et al., 2019.

2018

Cirtwill, A.R., Dalla Riva, G.V., Gaiarsa, M.P., Bimler, M.D., Cagua E.F., Coux, C., & Dehling, D.M. (2018) A review of species role concepts in food webs. Food Webs: 16, e00093.
doi: 10.1016/j.fooweb.2018.e00093

This paper reviews several major concepts of species roles in food webs, including centrality, trophic position, and motif roles. We use Eltonian niches as a framework to relate these role concepts to each other and to the broader ecological context.

Cirtwill, A.R. & Eklöf, A. (2018) Feeding environment and other traits shape species' roles in marine food webs. Ecology Letters: 21(6), 875-884. doi: 10.1111/ele.12955.
pre-publication main text     pre-publication SI
Dryad data repository

This paper identifies the motif positions which explain the most variation in species' roles in marine food webs. We then relate the frequencies of these positions to species traits such as body mass and feeding environment. We found that positions in motifs describing apparent and direct competition and the three-species food chain explained the most variation and were related to feeding environment, body mass, trophic level, and other traits.

Cirtwill, A.R., Roslin, T., Rasmussen, C., Olesen, J.M., & Stouffer, D.B. (2018) Between-year changes in community composition shape species' roles in an Arctic plant-pollinator network. Oikos: 127(8), 1163-1176. doi:10.1111/oik.05074.
pre-publication main text     pre-publication SI
Dryad data repository

This paper describes changes in the structure of an Arctic plant-pollinator network over two decades and relates changes to network structure and species' motif roles to changes in community composition. We found that networks with greater turnover in composition tended to include species with different roles.

2017

Cirtwill, A.R., Lagrue, C., Poulin, R., & Stouffer, D.B. (2017) Host taxonomy constrains the properties of trophic transmission routes for parasites in lake food webs. Ecology: 98(9), 2401–2412. doi:10.1002/ecy.1927
pre-publication version     pre-publication SI

This paper explores how links' roles (e.g., centrality, proportion of predator's diet contributed, and prey abundance) and host taxonomies relate to their use as parasite transmission routes. Host taxonomy plays a major role, as most parasites are restricted to small numbers of hosts. Nevertheless, we found that transmission routes generally involved intermediate prey with high local biomasses, while links between intermediate and definitive hosts tend to be dynamically weak.

2016

Cirtwill, A.R., Stouffer, D.B., Poulin, R., & Lagrue, C. (2016) Are parasite diversity and abundance linked to individual diet range and feeding preferences in fish hosts? Parasitology: 143(1), 75-86. doi:10.1017/S003118201500150X

Poisot, T., Cirtwill, A., Gravel, D., Fortin, M.-J., & Stouffer, D.B. (2016) The structure of probabilistic networks. Methods in Ecology and Evolution: 7(3), 303-312. doi: 10.1111/2041-210X.12468
preprint

Poisot, T., Gravel, D., Leroux, S., Wood, S.A., Fortin, M.-J., Baiser, B., Cirtwill, A.R., Araujo, M.B., & Stouffer, D.B. (2016) Synthetic datasets and community tools for the rapid testing of ecological hypotheses. Ecography: 39(4), 402-408. doi: 10.1111/ecog.01941
preprint

Cirtwill, A.R. & Stouffer, D.B. (2016) Knowledge of predator-prey interactions improves predictions of immigration and extinction in island biogeography. Global Ecology and Biogeography: 25(7), 900-911. doi: 10.1111/geb.12332
pre-publication version     pre-publication SI

Cirtwill, A. 2016. Species roles and link roles: a richer perspective on network ecology. University of Canterbury [PhD Thesis].

2015

Cirtwill, A.R., Stouffer, D.B., & Romanuk, T.N. (2015) Latitudinal gradients in biotic niche breadth vary across ecosystem types. Proceedings of the Royal Society B: 282(1819), 20151589. doi: 10.1098/rspb.2015.1589
pre-publication version

Cirtwill, A.R. & Stouffer, D.B. (2015) Concomitant predation on parasites is highly variable but constrains the ways in which parasites contribute to food web structure. Journal of Animal Ecology: 84(3), 734-744. doi: 10.1111/1365-2656.12323
full text

2014

Stouffer, D.B., Cirtwill, A.R., & Bascompte, J. (2014) How exotic plants integrate into pollination networks. Journal of Ecology: 102(6), 1442-1450. doi: 10.1111/1365-2745.12310
full text

2012

Cirtwill, A. 2012. Latitude, temperature, and productivity affect ecological network structure. Dalhousie University [Honours Thesis].