Multivalent Myteries: How Termite Chromosome Chains Shape Evolution
- 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
promotingTermites 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.…

