Konstantinos Sotiropoulos

Understanding how environmental conditions shape the functional composition of ecological communities is a central goal in community ecology. In this study, we apply this framework to the reptile and amphibian assemblages within Greece’s Mount Chelmos protected area. Based on comprehensive field surveys (2018–2021) across 168 sampling stations, we compiled species trait databases and quantified functional diversity using a corrected Rao’s Q index. We modeled the response of functional diversity to climate, land cover, topography (altitude, slope, aspect), geographic location, and taxonomic diversity, using Generalized Additive Models (GAMs). Additionally, we examined traitspace structure via PCA and evaluated environmental drivers of trait composition with multivariate GAMs. For reptiles, functional diversity was significantly affected by altitude, climate, and aspect, with higher values predicted in water-associated marginal zones surrounding the mountain massif. Traitspace analysis revealed clear ecological structuring along axes related to locomotion, body size, reproductive mode, foraging strategy, and substrate use, shaped by distinct combinations of environmental filters. In amphibians, environmental effects on functional diversity were not statistically significant; however, traitspace showed discernible responses to land cover, climate, and aspect, suggesting weaker—though detectable—filtering processes. Collectively, our findings indicate that Mount Chelmos functions as a system that modulates diversity, with environmental filters operating at fine-to-medium spatial scales to shape the functional composition and diversity of its herpetofauna.

Facultative paedomorphosis, the retention of larval traits in sexually mature individuals, plays a crucial role in species ecology and evolution and is influenced by complex interactions between environmental factors. Here, we compile all known cases of paedomorphosis in all newt species in Greece and report 20 new localities, mainly in Northern Pindos National Park. Our results indicate that paedomorphosis tends to occur more frequently in stable aquatic environments in combination with unfavourable external conditions (lack of precipitation and higher temperatures). Furthermore, species-specific patterns related to the occurrence of paedomorphosis were also unveiled: Mesotriton alpestris prefers high-elevation and permanent ponds; Lissotriton graecus occurs predominantly in artificial, lowland ponds; and Triturus macedonicus is associated with a stable hydroperiod and fish absence. Overall, conservation strategies should explicitly account for paedomorphic populations, emphasizing the value of artificial ponds, which are able to support this life-history strategy. Lastly, the Northern Pindos Mountain Range emerges as a major European intra-specific diversity hotspot.

Accurately predicting species’ responses to anthropogenic climate change is hampered by limited knowledge of their spatiotemporal ecological and evolutionary dynamics. We combine landscape genomics, demographic reconstructions, and species distribution models to assess the eco-evolutionary responses to past climate fluctuations and to future climate of an Afro-Palaearctic migratory raptor, the lesser kestrel (Falco naumanni). We uncover two evolutionarily and ecologically distinct lineages (European and Asian), whose demographic history, evolutionary divergence, and historical distribution range were profoundly shaped by past climatic fluctuations. Using future climate projections, we find that the Asian lineage is at higher risk of range contraction, increased migration distance, climate maladaptation, and consequently greater extinction risk than the European lineage. Our results emphasise the importance of providing historical context as a baseline for understanding species’ responses to contemporary climate change, and illustrate how incorporating intraspecific genetic variation improves the ecological realism of climate change vulnerability assessments.

The primary objective of this study was to investigate patterns of abundance and diversity among reptiles and amphibians within the protected area of Mount Chelmos, located in Peloponnese, Greece. Our aim was to examine the drivers influencing abundance (for lizards, snakes, chelonians, anurans, urodels) and diversity (for reptiles and amphibians) within the finely-scaled study area and identify biodiversity hotspots. Land cover significantly impacted the abundance and diversity of all studied groups. Elevation had a significant impact on the abundance of snakes, chelonians, and anurans, as well as on reptile and amphibian diversity. Climate influenced all groups except chelonians. Slope significantly impacted anuran abundance and amphibian diversity. Aspect primarily influenced the abundance of lizards, anurans, and urodels, as well as reptile diversity. We have also identified abundance and diversity hotspots, emphasizing the importance of conservation and management efforts. In reptiles, abundance hotspots were predicted in the west, east, and south of the mountainous massif, whereas amphibian abundance hotspots were mapped to the west and east-southeast of the massif. Regarding diversity, the patterns were similar for both reptiles and amphibians, with hotspots emerging in the west, south, and southeast boundaries of the study area, and a few spots north of the mountainous region. Notably, many of these hotspots coincided with areas susceptible to human exploitation and vehicular transit.

The genetic structure and dispersal dynamics of reptile populations are profoundly influenced by natural processes and human activities. While natural dispersal is shaped by species’ characteristics and paleogeographical features, human-mediated translocations have become increasingly prevalent, posing ecological challenges. Mitochondrial genetic markers have been pivotal in untangling invasion pathways for various species. Our study focuses on the Dalmatian Algyroides, Algyroides nigropunctatus (Duméril & Bibron, 1839), a lizard species endemic to the Balkan Peninsula, where recent observations in the Apulian region of Italy suggest an introduced population. Genetic analyses employing two mtDNA markers (16S and ND4 genes) elucidate the phylogenetic relationships of the Dalmatian Algyroides and trace the geographic origin of the introduced population. Our findings reveal areas in western Greece and southwestern Albania as the most probable areas of the source population, while we identify two previously undetected geographical lineages in the native range, highlighting the complex evolutionary history of the species in the region. Additionally, indications of potential glacial refugia and post-glacial dispersal patterns shed more light on the species’ demographic dynamics.

Body size variation is central in the evolution of life‐history traits in amphibians, but the underlying genetic architecture of this complex trait is still largely unknown. Herein, we studied the genetic basis of body size and fecundity of the alternative morphotypes in a wild population of the Greek smooth newt (Lissotriton graecus). By combining a genome‐wide association approach with linkage disequilibrium network analysis, we were able to identify clusters of highly correlated loci thus maximizing sequence data for downstream analysis. The putatively associated variants explained 12.8% to 44.5% of the total phenotypic variation in body size and were mapped to genes with functional roles in the regulation of gene expression and cell cycle processes. Our study is the first to provide insights into the genetic basis of complex traits in newts and provides a useful tool to identify loci potentially involved in fitness‐related traits in small data sets from natural populations in non‐model species.

Migrating birds are often exposed to variable environments and face a multitude of stress exposures along their long-distance flights. During stopover refueling, migratory birds must balance the need to accumulate energy reserves to continue their migration with the need to respond to environmental and physiological stressors. We examined the gene expression patterns of different Heat Shock Proteins (HSPs) in migrating birds during stopover at different body condition states (lean vs. fat), to provide some first insights on the role of HSPs in bird migration and explore the concept of a trade-off between refueling and stress response. Our results showed upregulation of HSP expression at release that could be associated with muscle growth and increased cholesterol and lipid synthesis needed for birds to fuel their upcoming migration. On the other hand, during capture, upregulation of HSP5 could be attributed to physiological recovery from the non-stop endurance flight when crossing the Sahara Desert-Mediterranean Sea ecological barrier. All birds significantly increased their fuel loads up to 48% of lean body mass and we provide evidence for muscle rebuilding during stopover as flight muscle mass increased by 10%, highlighting the fact that stopover sites can play a major role in the physiological recovery of migrants.

Invertebrate populations are amongst the most widespread species, inhabiting a variety of habitats, however there is limited conservation effort due to the scarce knowledge on their population genetics. Here, we assess levels of genetic diversity and population structure of the Epirus dancing grasshopper (Chorthippus lacustris), a steno-endemic species, located in Northwest Greece, exhibiting a fragmented distribution. By utilizing two mitochondrial genes and amplified fragment length polymorphisms (AFLPs), we detected moderate to high levels of genetic diversity of the focal populations. Haplotype network analysis revealed the existence of private haplotypes with low genetic differentiation suggesting a sudden expansion of the species in the study area with subsequent isolations on suitable habitats. Despite the low genetic differentiation between the studied populations, our data further suggest a subtle subdivision of the populations and the existence of three genetic clusters. Implications for insect conservation: Our study is the first to provide insights into the population genetics of the steno-endemic grasshopper C. lacustris, highlighting the importance of preserving focal populations. The species inhabits areas subject to high changes in land use and fragmentation. We argue that the preservation and management of suitable habitats is essential for the viability of the grasshopper populations.

Many herpetofauna species have been introduced outside of their native range. MtDNA barcoding is regularly used to determine the provenance of such populations. The alpine newt has been introduced across the Netherlands, the United Kingdom and Ireland. However, geographical mtDNA structure across the natural range of the alpine newt is still incompletely understood and certain regions are severely undersampled. We collect mtDNA sequence data of over seven hundred individuals, from both the native and the introduced range. The main new insights from our extended mtDNA phylogeography are that 1) haplotypes from Spain do not form a reciprocally monophyletic clade, but are nested inside the mtDNA clade that covers western and eastern Europe; and 2) haplotypes from the northwest Balkans form a monophyletic clade together with those from the Southern Carpathians and Apuseni Mountains. We also home in on the regions where the distinct mtDNA clades meet in nature. We show that four out of the seven distinct mtDNA clades that comprise the alpine newt are implicated in the introductions in the Netherlands, United Kingdom and Ireland. In several introduced localities, two distinct mtDNA clades co-occur. As these mtDNA clades presumably represent cryptic species, we urge that the extent of genetic admixture between them is assessed from genome-wide nuclear DNA markers. We mobilized a large number of citizen scientists in this project to support the collection of DNA samples by skin swabbing and underscore the effectiveness of this sampling technique for mtDNA barcoding.