CHANGES IN MICROBIAL COMMUNITIES AND THE ROLE OF IMMUNE RESPONSE IN THE RANGE EXPANSION OF THE INVASIVE SIGNAL CRAYFISH Pacifastacus leniusculus (Dana, 1852)

Invazivne strane vrste jedna su od najvećih prijetnji vrlo osjetljivim slatkovodnim ekosustavima, a predviđanje uspjeha invazije predstavlja globalni izazov. Invazivni uspjeh određen je, između ostaloga, i imunosnim sustavom, kojeg oblikuju patogeni i nepatogeni mikrobi domaćina te ekološki procesi koji proizlaze iz širenja areala. Ovo istraživanje ispituje promjene u sastavu mikrobnih zajednica i ulogu imunosnog odgovora tijekom širenja areala jedne od najuspješnijih invazivnih stranih vrsta slatkovodnih beskralježnjaka u Europi, signalnoga raka. Mikrobi u različitim tkivima jedinki duž invazivnog areala detektirani su analizom metagenoma (sekvenciranjem nove generacije), dok su razlike u imunosnom odgovoru jedinki ispitane analizom nekoliko standardnih imunosnih parametara. Navedene analize pokazale su da se mikrobne zajednice i imunosni odgovor signalnoga raka značajno mijenjaju tijekom širenja invazivnog areala te da su oblikovani, u različitoj mjeri, okolišnim čimbenicima i karakteristikama populacije. Ovo istraživanje također ukazuje na vrlo slabu istraženost patogena slatkovodnih deseteronožnih rakova te ističe potrebu za standardizacijom eksperimentalnih metoda prilikom ispitivanja patogenosti. Invasive alien species are among the largest threats to sensitive freshwater ecosystems, and predicting the success of an invasion represents a global challenge. Invasive success is determined, among other things, by the immune system, which is shaped by pathogenic and non-pathogenic host microbes and ecological processes arising from range expansion. This study examines changes in microbial communities and the role of immune response during range expansion of one of the most successful invasive alien species of freshwater invertebrates in Europe, the signal crayfish. Microbes in different tissues of individuals along the invasion range were detected by metagenome analysis (next generation sequencing), while differences in the immune response of individuals were examined by analysis of several standard immune parameters. These analyses have shown that microbial communities and the immune response of signal crayfish change significantly during range expansion and that they are shaped, to varying degrees, by environmental factors and population characteristics. This study also highlights a gap of knowledge regarding crayfish pathogens and underlines the need for standardization of experimental methods when testing pathogenicity.