Population dynamics of interacting species

Tuesday, June 15 at 09:30am (PDT)
Tuesday, June 15 at 05:30pm (BST)
Wednesday, June 16 01:30am (KST)

SMB2021 SMB2021 Follow Tuesday (Wednesday) during the "MS07" time block.
Note: this minisymposia has multiple sessions. The second session is MS08-ECOP (click here).

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Rebecca Tyson (University of British Columbia, Canada), Maria Martignoni (Memorial University of Newfoundland, Canada), Frithjof Lutscher (University of Ottawa, Canada)


A clear understanding of the dynamics of interacting species is of crucial importance as researchers try to predict the effects of invasive species and climate change on population persistence, diversity, and spread. Without such understanding, it is easy for managers to implement actions that may seem appropriate based on past knowledge, but that turn out to be potentially disastrous given new, emerging understanding of interacting populations. For example, the use of mycorrhizae as a biofertilizer is seen to be of high benefit to growers, but field studies have generated conflicting results. Recent mathematical work shows that the fungi can ultimately be detrimental or beneficial, depending on the nature of the nonlinear interactions between plant and fungi. This example is an illustration of the importance of mathematical work on the nonlinear interactions between species in order to untangle the population dynamics that result. This mini-symposium will gather together talks covering a wide range of interacting species models, creating an environment where there is maximum likelihood that ideas from one speaker will be entirely novel to another speaker, and generate new ideas for future research and collaboration.

Jimmy Garnier

(CNRS - Universite de Savoie-Mont Blanc, France)
"Genetic diversity in age-structured populations"
In many population, the individuals behavior might differ according to their age. The emerging structure have profound influence on the population dynamics as well as its genetic diversity. I will investigate the dynamics of the genetic diversity in metapopulations. I show that the duration of the juvenile stage or the reproduction strategy might have profound influence on the local diversity of sub--population composing the metapopulation.

Maria Martignoni

(Memorial University of Newfoundland, Canada)
"Mechanisms for coexistence and competitive exclusion among mutualist guilds."
Mutualistic interactions are gaining increasing attention in the scientific literature, especially as pollination and plant-microbe symbioses play a key role in agricultural productivity. In particular, the widespread symbiosis between plants and arbuscular mycorrhizal (AM) fungi, offers a promising sustainable alternative for maintaining productivity in farmland. Despite the potential benefits for soil quality and crop yield associated with the use of AM fungi, experiments assessing the effective establishment of the fungi in the field have given inconsistent results. Additionally, it is not clear whether the introduction of commercial AM fungi could lead to a biodiversity loss in the native fungal community, and ultimately have a negative impact on plant growth. We developed a series of mathematical models for plant and AM fungal growth to assess the establishment, spread and impact of an introduced species of AM fungi on the native fungal community and on plant productivity. Our models provide a theoretical framework to determine the circumstances under which the inoculated fungal species can coexist with the native fungal community and effectively boost productivity, versus when inoculation constitutes a biodiversity risk and, ultimately, a detriment to crop yield. Overall, our results show that diversity within mutualistic communities promotes productivity and reduces the risk of invasion and biodiversity loss posed by the introduction of a less mutualistic, or even parasitic, species. Although my analysis focuses on plant-fungal interactions, my findings provide valuable criteria to assess the impact of species introduction in mutualistic communities in general, such as other beneficial microbes or pollinator communities.

Frithjof Lutscher

(University of Ottawa, Canada)
"A seasonal hybrid model for the evolution of flowering onset in plants"
In temperate climates with strong seasonal changes, plants need to decide how to allocate resources to vegetative growth or to reproduction during a potentially short favorable season. Many plants switch from mostly vegetative growth early in the season to mostly reproduction late in the season. The onset of flowering marks the transition between the two phases. Later onset of flowering typically implies a larger size at maturity and higher reproductive capacity. At the same time, it limits the remaining time in the favorable season for pollination and seed development. Hence, plants face a trade-off for some optimal flowering onset. In this talk, I will present a seasonal hybrid model for the density of a plant population, structured by onset of flowering as a trait. I will apply two complementary approaches to analyze the system. Overall, I find that evolution favours some intermediate flowering times.

Kelsey Marcinko

(Whitworth University, USA)
"Host-Parasitoid Dynamics and Climate-Driven Range Shifts"
Climate change has created new and evolving environmental conditions that cause the habitat ranges of many species to shift upward in elevation and/or towards the poles. To investigate the impact of climate-driven range shifts on host and parasitoid insect species, I consider an integrodifference equation (IDE) model. Using this IDE model, I determine criteria for coexistence of the host and parasitoid species as the habitat shifts spatially. I compare several methods of determining the critical habitat speed, beyond which the parasitoid cannot survive. To make the analysis tractable, I determine the critical speed from a spatially-implicit model that uses an approximation of the dominant eigenvalue of an integral operator. Because the kernel is asymmetric, classical methods for determining the dominant eigenvalue perform poorly. Instead, I approximate the dominant eigenvalue with a method known as geometric symmetrization. The critical speed for parasitoid survival, as computed from the spatially-implicit model, is a good lower bound for the critical speed as determined from simulations of the full IDE model. This framework allows for further exploration of how biological factors impact the coexistence of the host and parasitoid species.

Hosted by SMB2021 Follow
Virtual conference of the Society for Mathematical Biology, 2021.