Evolutionary origins of intracellular symbionts in arthropods
Abstrakt
Intracellular symbionts are widespread among arthropods, particularly within insects. Obligate
symbiotic associations are known to have originated multiple times between the arthropods feeding on
nutrient-poor diets and bacteria from various groups. However, exact phylogenetic positions and
relationships among these symbiotic lineages are mostly unclear or vague. This thesis consists of an
exemplary case study on the most symbiont-rich bacterial group, Enterobacteriaceae, already published
in BMC Biology. It uses advanced phylogenetic tools and extended taxonomic sample to establish
phylogenetic relationships among individual symbiotic lineages and their phylogenetic affinity to freeliving
relatives. To provide it with broader background, the publication is accompanied by a review on
general evolutionary forces influencing origin and maintenance of intracellular symbiosis in
arthropods. Apart from overviewing the current known diversity of the symbiotic bacteria, it also points
out specific drawbacks in inferring symbionts phylogeny and consequences that can phylogeny have on
our understanding of intracellular symbiosis.