# Functional and evolutionary diversification of luciferase genes in Metridia lucens Boeck 1865

## TL;DR

This paper explores the evolution of luciferase genes in the copepod Metridia lucens, revealing unexpected genetic diversity and multiple gene lineages involved in bioluminescence.

## Contribution

The study identifies three distinct luciferase gene lineages in M. lucens, expanding understanding of marine bioluminescence evolution.

## Key findings

- M. lucens luciferase genes show high genetic diversity within and between specimens.
- Three distinct luciferase gene lineages were identified, each with multiple copies.
- The findings suggest an extended gene family contributing to bioluminescence in this copepod.

## Abstract

Bioluminescent organisms have developed extraordinary adaptations to produce light using a luciferin-luciferase reaction, fulfilling various ecological functions such as predator evasion, prey attraction, and intraspecies communication. Although the earliest record in the marine environment dates back some 540 million years, the evolutionary origins of this phenomenon remain largely unknown in most species. In Metridinidae copepods, light production capability is facilitated by a luciferase gene duplication. This study focuses on characterizing the luciferase genes of Metridia lucens, a copepod widely distributed throughout global oceans, excluding the high Arctic. Despite being the first species described in this genus, the genomic sequences of its luciferase genes remained unknown prior to this investigation. Here, using an integrated approach combining molecular cloning and high-throughput sequencing, we isolated and characterized M. lucens luciferase genes. Our results revealed an unexpectedly high genetic diversity both within and between specimens, consistent with the presence of an extended gene family in this copepod’s genome. We identified three distinct luciferase gene lineages, each represented by several copies, expanding our knowledge of marine bioluminescence evolution.

The online version contains supplementary material available at 10.1038/s41598-026-36319-2.