Simona Georgieva

Associate Professor, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences

Simona is an evolutionary ecologist whose research focuses on revealing and explaining the origins and evolutionary radiation of parasitic worms – an extremely diverse, abundant and widespread group of organisms. Using various host-parasite systems, her research seeks to elucidate the ecological and evolutionary consequences associated with parasites' life cycles and to address broader ecological and evolutionary questions. She blends traditional and novel approaches to study the relationships between parasite transmission dynamics, host specificity, and environmental factors that drive adaptive divergence and evolutionary innovation.

Simona holds a Ph.D. in Parasitology from the University of South Bohemia (Czechia) and conducted postdoctoral research at the Institute of Parasitology, Czech Academy of Sciences, and at the Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain. Prior to her current position as an Associate Professor at the Bulgarian Academy of Sciences, she was an Outstanding Overseas Researcher of the National Research Foundation of Korea.

Abstract

Title : Convergent Evolution of Parasitism: From Ecology to Comparative Genomics

Parasitism has evolved repeatedly within Metazoa, generating a striking diversity of parasitic lineages across the tree of life. These transitions have sometimes been followed by major radiations and, in other cases, by limited diversification, yet distantly related lineages often converge on similar ways of exploiting hosts. In this talk, I will first summarise evidence that, at the phenotypic level, metazoan parasites converge on a number of broad life-history strategies, reflecting strong ecological constraints on the evolution of parasitism. I will then review evidence for genomic convergence and lineage-specific innovation, using comparative genomics to identify repeatable signatures associated with independent transitions to parasitism.
Helminths provide a tractable comparative system spanning major parasitic lineages (platyhelminths and nematodes) and have a wide range of life cycles. With genomes now available for more than 270 parasitic worm species, I will present a meta-analysis of sequenced platyhelminth and parasitic nematode genomes to identify genomic features repeatedly associated with helminth parasitism and to quantify the extent of independent recurrence of similar features across helminths. Comparative genomic analyses consistently indicate a mix of recurrent patterns and lineage-specific innovation: absence of canonical antigenic variation; persistence linked to expansions of surface/tegument gene families; rapid evolution of secreted repertoires (notably proteases); and reduced metabolic capacity, especially in endoparasitic flatworms, together with broad losses of auxiliary pathways, including cofactor and vitamin biosynthesis. Robust interpretation of these patterns requires a comparative framework spanning parasites and their free-living relatives across deep evolutionary timescales. Community resources and comparative genomics platforms are therefore essential for translating expanding genome catalogues into testable hypotheses about parasite evolution, host-immune evasion, and the identification of candidate targets for anthelmintic development.

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Pavlos Pavlidis

Associate Professor for Bioinformatics, Department of Biology, University of Crete
Institute of Computer Science in Foundation for Research and Technology – Hellas (FORTH-ICS)

Pavlos Pavlidis is an Associate Professor of Bioinformatics in the Department of Biology at the University of Crete and an affiliated faculty member at the Institute of Computer Science of the Foundation for Research and Technology - Hellas (FORTH), where he leads the Evolutionary Biology and Bioinformatics (EvoLAB) research group. His scientific work focuses on the interface of computational and theoretical population genetics with evolutionary biology. The central axis of his research is understanding the forces and mechanisms that shape the evolution of natural populations using a combination of mathematical modeling, algorithmic approaches, and the analysis of large-scale genomic data (DNA sequences, expression profiles, Hi-C data). His academic journey began with a degree in Agricultural Biotechnology from the Agricultural University of Athens and a Master’s degree in Molecular Biology and Plant Biotechnology from the University of Crete. He completed his doctoral studies in Evolutionary Biology in 2011 at the Ludwig-Maximilians University (LMU) in Munich with the distinction summa cum laude, under the supervision of Prof. Wolfgang Stephan. This was followed by postdoctoral research in Heidelberg (HITS), where he specialized in High-Performance Computing (HPC) for population biology, as well as at IMBB-FORTH as a Marie-Curie Fellow, focusing on the evolution of gene regulatory networks. From 2016 until his election at the University of Crete, he served as a Researcher at the Institute of Computer Science of FORTH.

Dr. Pavlidis has developed innovative computational tools for detecting natural selection (e.g., SweeD, RAiSD, OmegaPlus), which serve as reference points in international literature. His published work includes articles in top-tier scientific journals. He maintains active international collaborations with research centers in Germany, the USA, and Turkey. Furthermore, he is deeply involved in training the next generation of scientists through the Bioinformatics graduate program of the School of Medicine and undergraduate courses in the Departments of Biology and Computer Science at the University of Crete.

Abstract

Title : At the Crossroads of the Mediterranean: Population Structure and Admixture History of Cretans

The island of Crete occupies a pivotal geographic position in the Mediterranean, serving as a longstanding crossroads between Southern Europe, Anatolia, and the Levant throughout human history. Despite its strategic location and exceptionally rich archaeological record (and its long and well-documented past,), the fine-scale population genetic structure of modern Cretans and their genetic relationships to other Mediterranean/North African/Balkan populations remain “ insufficiently resolved . Island populations provide valuable frameworks for investigating how geographic isolation, founder effects, and historical gene flow shape genomic diversity. We analyzed genome-wide SNP data from multiple Cretan regional (sub)populations alongside central and eastern Mediterranean reference populations including samples from mainland Greece, Italy, the Balkans, Anatolia, and the Levant. We applied complementary approaches including projection PCA, sliding-window Fst analysis, and formal admixture tests using f-statistics to reconstruct population relationships and infer demographic history. We observe detectable population structure among regional Cretan groups despite the island's relatively small size. Mountain populations show elevated differentiation compared to coastal populations, consistent with reduced gene flow in rugged terrain and substantial genetic drift. However, low principal component variance suggests a recent common ancestry followed by rapid drift in isolated communities. Cretan populations/demes show strongest affinities to Aegean, Peloponnesian and Southern Italian, Spanish groups, as well as samples from Turkey, with evidence of historical connections to both Levantine and Anatolian populations. Window-based analyses reveal genomic heterogeneity. F-statistics confirm shared drift with other Aegean populations while detecting subtle differentiation among Cretan regions. Admixture graph modeling supports complex demographic scenarios.

Our integrative approach reveals a complex demographic history for Crete shaped by its central role within Mediterranean interaction networks. The population structure reflects strong drift in mountain, isolated demes, overlaid on a mosaic of Mediterranean ancestries. Cretan populations maintain genomic connections to diverse Mediterranean groups,including Aegean, Italian, Levantine, and Anatolian populations, with patterns varying across the genome and among regions. This work demonstrates how geography and history interact to create fine-scale population structure even within island contexts, and provides insights into the broader demographic processes that shaped genetic diversity across the Mediterranean basin.