Key finding from my PhD. A: Showcasing differences in evolutionary history among populations of V. microstatchys in response to invasive species B. hordeaceus. B: Key finding that intraspecific competition evolves in response to an invader.

See Sakarchi & Germain (2023)

in The American Naturalist

Understanding competition is central to understanding when and how species can persist together. This is typically treated as an ecological question, but sometimes species have the capacity to evolve in response to competition by becoming more competitive or through differentiating into different niches. How and when this occurs as remains an open question.

Competitive and other interactions are most often examined between separate species. Yet, little is known how competition within-species occurs and its consequences. For example, can we observe similar competitive differences within-species? If so, what are the possible consequences of within-species competition?

Key finding from my PhD. Differences between within-species niche and competitive differences of lineages of S. polyrhiza (green) vs. between-species S. polyrhiza x S. intermedia (orange). Shaded region in blue represents domain of ecological coexistence, where both competitors can invade when rare.

See Sakarchi et al. (bioRxiv) 

Submitted to Nature Ecology & Evolution

Example of how resource breadth can define how strong species compete and how we observe realized niche overlap. (A) When resource availability is wide, competition may be weak and observed niche overlap is low. (B) When resource availability is narrow, observed niche overlap may be high.

See Sakarchi & Germain (2025) 

in The American Naturalist

Competition is especially environment dependent, but often how the environment and competitive dynamics relate is not predictable. This has made it challenging to translate results from one biological system to another. Here I make progress by trying to understand which and what conditions precipitate or preclude coexistence before measuring competitive interactions.