This Fall will be remote for the majority of academic activities. The 8.0 credit honours thesis program is approximately 8mos in duration. The student leads an independent research project. As a team, we would like to work with two individuals on one of the following projects. Each student will work with a graduate student or postdoc and Chris Lortie.

a. Each project is individually implemented by the student safely.
b. Zoom calls with Chris and the co-mentor to ideate, solve, and plan will be used to collaborate in addition to editing datasheets and docs.
c. It will be beneficial for the student to have experience in R and be able to work independently.
d. The pre-reqs are listed online for BIOL4000 are here and currently include students their final year with a BIOL GPA of at least 6.0.

Tree forest dynamics at YorkU

(1) Subway effects on trees and woodlots. A census of tree forest dynamics and individual tree changes on YorkU campus. Jenna Braun, Mike Belanger, and I dug through census records compiled by the YorkU master gardener in 2012 and 2013. Over 5000 trees were tagged on campus and their size and health were recorded. The data are here. This is a fantastic project and opportunity to revisit a superb dataset in R and also resample some or many of the trees. We now have a subway rumbling away underneath campus, and we can check trees near and far from the line and test the hypothesis that disturbance belowground influences tree growth and health.

(2) Other ecological hypotheses relevant to urban forest dynamics (disturbance, new buildings, edge or center of campus etc). There are at least two projects here. The students can work independently and still split up the work of testing more than question or hypothesis. One individual can (re)sample trees from 2012 and 2013 near/far subway lines, and a second student can examine any other ecological question with disturbance, new buildings, or how sets of trees are doing in different ecological contexts on a university campus.

Desert ecology data analyses

We have many open datasets ready to go for deep analysis work if you are competent in R (or Python but we work in R in the lab). Many spatial questions, niche questions, or use or plant and animal survey data and join them to new data on climate or downscaled remote data if you are game for that adventure. Here are a few examples.

Vegetation under shrubs and in the open in the Central California Deserts.

Desert arthropod diversity patterns in California.

Camera traps and birds of the deserts.

In each instance, the workflow will include a few Zooms to plan analyses and additional data lookups, then the student researcher digs in!

To apply

If you meet the pre-reqs and are in your final year in YorkU Biology, please email lortieatyorkudotca, and we will set up an interview with you for the team!

Bromus ecotypic contrast experiment up and running in Israel for winter growing season 2020

York Science Fellow Dr. Jacob Lucero and international collaborator Dr Merav Seifan are launching into 2020 with an ambitious experiment in Israel and California. The purpose is to explore the relative importance of provenance of a highly invasive species of bromus in the deserts of California by comparing performance and key interactions in its home range, Israel, and in its introduced range, California. This is a new direction from previous work published in NeoBiota entitled ‘The dark side of facilitation: native shrubs facilitate exotic annuals more strongly than native annuals’ that demonstrated a very significant effect of bromus on local plant community dynamics.

Setup in Israel was a positive adventure!

Potential study species

The reproductive biology of Cactaceae is not well known – only approximately 2% of the 2000 or so species have been studied (Mandujano et al, 2010). Consequently, how they interact with neighbouring plants of different species for pollinators or what this means in a community context are both virtually unknown. In one of the few published experiments that explicitly tested these interactions, researchers focused on the highly invasive prickly-pear Opuntia stricta in coastal shrublands in Catalonia (Bartomeus 2008). Cacti in the Opuntia genus are primarily bee-pollinated; they have large, colourful bowl-shaped flowers and many species are rich in pollen and nectar (Mandujano et al, 2010), suggesting they are very attractive to pollinators. Plants that exhibit these characteristics can interact with other plants in two notable ways for pollinators – they may act as a magnet plant, increasing local abundances of shared pollinators and thus facilitating the pollination of their neighbours, or conversely, they may steal pollinators and reduce the fitness of their neighbours.

To determine the effects of the invasion on the native plant community, the researchers created plant-pollinator interaction networks for both invaded and uninvaded sites. They found that O. stricta acted as a super-generalist in its new range. It was visited by 31% of the insect taxa in the invaded sites and was outcompeting native plants for pollination services. Within the same study, they found that Carpobrotus, an invasive succulent, had the opposite interaction with the surrounding plant community; it facilitated the pollination of the native plants in the system. This highlights the species-specific and context-dependent aspects of these interactions. There are a few species of Opuntia common in the Mojave Desert, and I hope to discover if and how they are interacting with other plants, particularly shrubs and their annual understory.

Attribution Stan Shebs [GFDL (, CC BY-SA 3.0 ( or CC BY-SA 2.5 (], via Wikimedia Commons

Bartomeus, I., Vilà, M., & Santamaría, L. (2008). Contrasting effects of invasive plants in plant–pollinator networks. Oecologia, 155(4), 761-770.

del Carmen Mandujano, M., Carrillo-Angeles, I., Martínez-Peralta, C., & Golubov, J. (2010). Reproductive biology of Cactaceae. In Desert plants (pp. 197-230). Springer Berlin Heidelberg.