Evolution of longevity improves immunity in Drosophila

Area of Science:

• Evolutionary biology
• Genetics of aging
• Immunology

Background:

• Studies in model organisms identified insulin signaling as a key longevity regulator.
• Little is known about naturally occurring genetic variations influencing lifespan and fitness.

Purpose of the Study:

• Investigate genetic changes associated with selection for longevity and postponed reproduction in Drosophila melanogaster.
• Identify candidate genes and pathways involved in the evolution of longevity.

Main Methods:

• Genomic analysis of Drosophila melanogaster lines selected for longevity over 35 years.
• Functional experiments including gene knockdown (RNAi) and infection survival assays.

Main Results:

• Selection identified candidate loci, but canonical longevity genes were not overrepresented.
• Immunity genes, particularly in the Toll pathway, were enriched.
• Long-lived flies showed improved survival against infections and altered immune responses with age.
• Modulating Toll pathway genes (Toll receptor, cactus) directly impacted lifespan.

Conclusions:

• Evolutionary changes in immune function, specifically age-dependent immune homeostasis, may contribute to longevity.
• Findings challenge the sole focus on insulin signaling and highlight the role of immunity in aging.