Population structure of the 128 L. infantum strains inferred by STRUCTURE analysis. Population structure is based on the MLMT data observed for each analysed strain at 14 microsatellite markers. Each population is represented by different colour and differently coloured segments in the vertical bar correspond to the membership of each strain to different populations. The length of each coloured segment is proportional to the estimated membership coefficient of each strain per population. The percentage of strains enclosed per population/subpopulation based on their geographical origin (TR, Turkey; CY, Cyprus; BG, Bulgaria; GR, Greece; AL, Albania; HR, Croatia; FR, France; ES, Spain; PT, Portugal) and L. infantum zymodeme (MON-1, MON-98), is demonstrated by large and small pie-charts, respectively. A. The likelihood of population number was calculated by STRUCTURE HARVESTER  implementing the Evanno method . The major peak at K = 4 at the ΔK graph indicates the existence of four populations (populations 1–4) for the total strain set, which were constantly observed in all independent simulations (10 runs). Population subdivision was investigated by re-analyzing separately each population at K = 4; subdivision of populations 1 and 2 is not shown. B. Three geographically determined subpopulations (subs 3A, 3B1 and 3B2) were observed upon re-analysis of population 3. Bar plots for both K = 2 and K = 3 are shown. C. Four stable subpopulations (subs 4A, 4B, 4C1 and 4C2) based on both geographical origin and zymodeme type, were identified for population 4. Bar plots for both K = 3 and K = 4 are shown.