Concordia University
Ph.D. candidate
Supervisor: Grant E. Brown
Start: 2026-01-12
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Project

Anthropogenic disturbances and life-history strategies in freshwater fish: field and experimental insights from the guppy (Poecilia reticulata) and the three-spined stickleback (Gasterosteus aculeatus
General objective: Human-induced disturbances (temperature, food availability, eutrophication, and turbidity) are not constant; they vary over time, often unpredictably. This project aims to understand how these anthropogenic disturbances influence reproductive traits in freshwater fish. The central idea is that unpredictable disturbances reduce the reliability of information available to individuals, making behavioural decisions more difficult and potentially altering reproductive strategies over time. Comparative model: Two freshwater prey species with contrasting reproductive strategies will be compared: the Trinidadian guppy (ovoviviparous, with no parental care) and the three-spined stickleback (oviparous, with nest building and paternal care). This contrast will help determine whether responses to environmental disturbances are shared across species or species-specific. Three-chapter structure: 1. Female mate choice:Preference tests will be conducted in the field and laboratory, using methods adapted to each species. 2. Male reproductive strategies: Reproductive tactics will be compared through direct observations and video recordings of behaviour under both stable and fluctuating environmental conditions. 3. Reproductive investment and sexual traits: Fecundity, size at maturity, and sexual coloration will be measured, along with the distribution of reproductive success among males, to determine whether environmental uncertainty promotes the monopolization of reproduction by certain individuals.

Keywords

Ecologie comportementale, traits d'histoire de vie, perturbations humaines, Poecilia reticulata, Gasterosteus aculeatus

Publications

1- The influence of illumination and cast shadows on prey detectability by predators
Cauchi, Lou, Keagan Reynolds, Sami Merilaita, Jennifer Kelley
2025 Royal Society Open Science