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# Warmer host conditions can select for more virulent parasites over just ten passages
- URL: https://intelligence.wildlandseco.com/2026-09-14-warming-parasite-virulence-evolution/
- Published: 2026-09-14T12:03:59.000Z
- Updated: 2026-09-14T12:03:59.000Z
- Description: A short experimental-evolution study found temperature left both phenotypic and genomic signatures on a bacterial parasite—but this remains a laboratory warning signal, not a field forecast.
- Author: Benjamin Worlund
- Tags: parasite virulence, experimental evolution, thermal mismatch, heatwave, Disease ecology, One Health, Climate, Methods, #ecological-intelligence, #brief-2026-09-14, #weak-signal, #peer-reviewed, #geo-africa

Evidence

Peer-reviewed

Geography

Cabo Verde isolate; laboratory host–parasite system

System

Experimental host–parasite system

## WHAT THE EVIDENCE SAYS

Researchers experimentally evolved the bacterial parasite Leucobacter musarum for ten passages in Caenorhabditis elegans across 20–35°C. At 25°C, host-mediated selection favored higher virulence and genomic diversification; parasites evolved at hotter temperatures maintained virulence and showed a latent increase in lethality when hosts later experienced heatwave conditions.

## WHY IT MATTERS / OUR READ

The weak signal is evolutionary: climate stress may alter not only disease exposure or transmission but also which parasite traits are selected. If similar dynamics occur in natural systems, temperature could change pathogen evolution on management-relevant timescales.

## CAVEATS / UNCERTAINTY

This is a short laboratory experimental-evolution study using one bacterium–nematode system. It does not establish that warming generally increases virulence in wildlife, livestock or human pathogens in the field.

## SOURCE

Global Change Biology · Original evidence  
[View original evidence ↗](https://onlinelibrary.wiley.com/doi/10.1111/gcb.71082?ref=intelligence.wildlandseco.com)

From the Morning Brief · 2026-09-14

[Read the full Morning Brief →](https://intelligence.wildlandseco.com/morning-brief-2026-09-14/)