Population size shapes trade-off dilution and adaptation to a marginal niche unconstrained by sympatric habitual conditions
Author:
Chavhan Yashraj1,
Malusare Sarthak1,
Dey Sutirth1ORCID
Affiliation:
1. Biology Division, Indian Institute of Science Education and Research (IISER) Pune , Pune, Maharashtra , India
Abstract
Abstract
How does niche expansion occur when the habitual (high-productivity) and marginal (low-productivity) niches are simultaneously available? Without spatial structuring, such conditions should impose fitness maintenance in the former while adapting to the latter. Hence, adaptation to a given marginal niche should be influenced by the identity of the simultaneously available habitual niche. This hypothesis remains untested. Similarly, it is unknown if larger populations, which can access greater variation and undergo more efficient selection, are generally better at niche expansion. We tested these hypotheses using a large-scale evolution experiment with Escherichia coli. While we observed widespread niche expansion, larger populations consistently adapted to a greater extent to both marginal and habitual niches. Owing to diverse selection pressures in different habitual niches (constant vs. fluctuating environments; environmental fluctuations varying in both predictability and speed), fitness in habitual niches was significantly shaped by their identities. Surprisingly, despite this diversity in habitual selection pressures, adaptation to the marginal niche was unconstrained by the habitual niche’s identity. We show that in terms of fitness, two negatively correlated habitual niches can still have positive correlations with the marginal niche. This allows the marginal niche to dilute fitness trade-offs across habitual niches, thereby allowing costless niche expansion. Our results provide fundamental insights into the sympatric niche expansion.
Funder
Indian Institute of Science Education and Research Pune
Council for Scientific and Industrial Research (CSIR), Government of India
Wenner-Gren Foundations
Department of Science and Technology (DST) of the Government of India
Department of Biotechnology, Government of India
Publisher
Oxford University Press (OUP)
Subject
General Agricultural and Biological Sciences,Genetics,Ecology, Evolution, Behavior and Systematics
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