# Effects of The Rate of Environmental Change on Mutational Patterns and Evolutionary Constraints

> **NIH NIH R16** · SAN JOSE STATE UNIVERSITY · 2024 · $183,125

## Abstract

PROJECT SUMMARY
Populations must be able to adapt in environmental conditions that may change either suddenly
(within one generation) or gradually (over multiple generations). Theoretical models predict that
these differences in the rate of environmental change will fundamentally influence the number
and effect sizes of mutations that fix, but few studies have mechanistically examined the genetics
of adaptation in environments that become more stressful over time. Moreover, the theoretical
models do not always account for well-known phenomena that introduce evolutionary constraints,
such as genotype by environment (GxE) interactions and pleiotropy. The goal of this research is
to compare patterns of genome evolution and effects of mutations in RNA viruses under sudden
or gradual environmental change, and to use these data to evaluate theoretical models of
adaptation in environments that change at different rates. The project uses temperature-resistant
populations of the model bacteriophage ɸ6 Cystovirus that were previously generated through an
evolution experiment in which viral populations were exposed to a heat shock temperature that
was increased either gradually (Gradual populations) or suddenly (Sudden populations). Here,
we propose to use these populations to examine patterns of mutation fixation and to characterize
the role of GxE interactions and pleiotropy in environments that change at different rates.
Specifically, we will 1) evaluate the number of mutations, their times to fixation, and haplotype
diversity of Sudden and Gradual populations; and 2) measure the effects of sequential mutations
from select lineages on both viral thermostability and growth rate, and correlate those effects with
the rate of environmental change experienced by the lineage. Our study will address the central
question in evolutionary biology of how changes to the strength and tempo of selection influence
adaptation, and will illuminate the mechanistic underpinnings of adaptation in different rates of
environmental change. Establishing the selective pressures and constraints at play in changing
environments will give us tools to predict or control viral evolution.

## Key facts

- **NIH application ID:** 10874469
- **Project number:** 5R16GM146706-03
- **Recipient organization:** SAN JOSE STATE UNIVERSITY
- **Principal Investigator:** Sonia Singhal
- **Activity code:** R16 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $183,125
- **Award type:** 5
- **Project period:** 2022-07-15 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10874469

## Citation

> US National Institutes of Health, RePORTER application 10874469, Effects of The Rate of Environmental Change on Mutational Patterns and Evolutionary Constraints (5R16GM146706-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10874469. Licensed CC0.

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