65059 2025 eng poster 0 -- -- -- Termites challenge long-standing assumptions about insect social evolution. One important difference compared to the social ants, bees and wasps lies in their chromosomes: termites are diploid, with X/Y sex differentiation observed in most species and males playing active roles across all castes and life stages. Adding to their uniqueness, termites exhibit multivalent chromosome chains during male meiosis—an intriguing and seldom seen feature of eukaryote evolution. These chains, in addition to other chromosomal formations, such as bivalent rings and rods, may serve to suppress recombination, thereby mitigating against the potentially harmful effects of inbreeding. Again, this positions termites as an important contrasting study system to other social insect groups, where recombination rates tend to be elevated. Multivalent chromosome chains may also play a significant role in speciation processes by increasing the likelihood of chromosomal translocations and promoting genomic islands of divergence. In European Reticulitermes, variability in chain length and stability both between and within species provides a compelling model system for studying the evolutionary importance of multivalent chromosome chains at intra- and interspecific levels and at different evolutionary time scales. To investigate these dynamics, we collected over 200 colonies of Reticulitermes species across the Mediterranean, generating de novo reference genomes, comprehensive population genomic as well as karyotypic data from three recently diverged species. Our findings shed light on the intricate relationship between chromosomal architecture and evolutionary mechanisms in termites, offering new insight into how genome structure shapes species evolution. ESEB 2025 Congress Barcelona, Spain 17.08.2025 publish false true Mara Jean Julseth eng uncontrolled Termites eng uncontrolled Chromosome evolution Sanitär- und Kommunaltechnik; Umwelttechnik 4 Material und Umwelt Umwelt Umwelt-Material-Interaktionen Datei im Netzwerk der BAM verfügbar ("Closed Access") Präsentation 4.3 Molekulare und angewandte Entomologie