Yorgos Mertzanis

Dr. Yorgos Mertzanis


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 April 2020 in bioRxiv
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VGVincenzo Gervasi
Vincenzo Gervasi
JLJohn Linnell
John Linnell
TBTomaž Berce
Tomaž Berce
LBLuigi Boitani
Luigi Boitani
RCRok Cerne
Rok Cerne
OGOlivier Gimenez
Olivier Gimenez
SUMMARY: Sharing space with large carnivores on a human-dominated continent like Europe results in multiple conflictful interactions with human interests, of which depredation on livestock is the most widespread. Wildlife management agencies maintain compensation programs for the damage caused by large carnivores, but the long-term effectiveness of such programs is often contested. Therefore, understanding the mechanisms driving large carnivore impact on human activities is necessary to identify key management actions to reduce it. We conducted an analysis of the impact by all four European large carnivores on sheep husbandry in 10 European countries, during the period 2010-2015. We ran a hierarchical Simultaneous Autoregressive model, to assess the influence of ecological and anthropogenic factors on the spatial and temporal patterns in the reported depredation levels across the continent. On average, about 35,000 sheep were compensated in the ten countries as killed by large carnivores annually, representing about 0.5% of the total sheep stock. Of them, 45% were recognized as killed by wolves, 24% by wolverines, 19% by lynx and 12% by bears. At the continental level, we found a positive relationship between wolf distribution and the number of compensated sheep, but not for the other three species. Impact levels were lower in the areas where large carnivore presence has been continuous compared to areas where they disappeared and recently returned. The model explained 62% of the variation in the number of compensated sheep per year in each administrative unit. Only 13% of the variation was related to the ecological components of the process. Synthesis and Applications: Large carnivore distribution and local abundance alone are poor predictors of large carnivore impact on livestock at the continental level. A few individuals can produce high damage, when the contribution of environmental, social and economic systems predisposes for it, whereas large populations can produce a limited impact when the same components of the system reduce the probability that depredations occur. Time seems to play in favour of a progressive reduction in the costs associated with coexistence, provided that the responsible agencies focus their attention both on compensation and co-adaptation.

26 September 2025 in Animals
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DMDespina Migli
Despina Migli
CAChristos Astaras
Christos Astaras
NKNikolaos Kiamos
Nikolaos Kiamos
SKStefanos Kyriakidis
Stefanos Kyriakidis
YMYorgos Mertzanis
Yorgos Mertzanis
Dionisios YoulatosDionisios Youlatos
Dionisios Youlatos
The European wildcat exhibits considerable plasticity in its habitat requirements across its distribution, with differences increasing along a continental-scale latitudinal gradient. While wildcats often favor deciduous and mixed forests with dense cover and prey, studies show these preferences vary across their expansion. Range-wide conservation efforts will benefit from incorporating knowledge generated by robust regional ecological models. We used data from a large camera trap grid (n = 292 stations), spanning across eight wildcat-associated habitats, within its range in northern Greece, to understand the regional ecological parameters affecting the species’ habitat selection. We analyzed the data using single-season density-induced detection heterogeneity occupancy models (Royle–Nichols), considering 12 environmental and anthropogenic parameters. The global model’s GoF was high (p = 0.9). Elevation and percent forest cover were both significantly negatively related to wildcat occupancy (as derived from the modeled “relative abundance index” N). Likewise, there was a negative, but moderate, relation between distance to freshwater bodies and human settlements with wildcat occupancy. We used the model-average coefficients to generate a predictive map of wildcat relative abundance across northern Greece, which identified 47,930 km2 of potential wildcat habitat. Assuming a range of densities between 0.05 and 0.3 ind/km2 in areas with predicted low, medium, and high relative abundance, we speculate the putative wildcat population in northern Greece to be between 3535 and 7070 individuals. The findings, which vary from ecological models of the species in northern Europe, show the need for regional models and the importance of Greece, and the Balkan peninsula, for the species.

6 December 2024 in Animals
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TTTzoulia-Maria Tsalazidou-Founta
Tzoulia-Maria Tsalazidou-Founta
NKNikoletta Karaiskou
Nikoletta Karaiskou
YMYorgos Mertzanis
Yorgos Mertzanis
ISIoannis Sofos
Ioannis Sofos
SPSpyros Psaroudas
Spyros Psaroudas
MSMaria Satra
Maria Satra
Habitat fragmentation poses a significant threat to the existence and reproduction of large carnivores, such as brown bears, as it affects the genetic connectivity of populations and, consequently, their long-term viability. Understanding the genetic makeup and dispersal patterns in areas where brown bears live is crucial for developing effective conservation plans and promoting human-brown bear coexistence. In this study, 214 hair samples were collected non-invasively from brown bears and were genetically analyzed using fifteen specific microsatellite loci to shed light on the genetic status and demography of a sub-population residing in Central Greece (Trikala-Meteora area). The broader Central and South Pindos regions have not been studied for over a decade; however, high levels of genetic diversity, a lack of heterozygosity deficiency, and no signs of inbreeding, along with an estimated effective population size (Ne = 99), confirm the good conservation status of this sub-population. Moreover, the existence of a natural and apparently functional corridor in Central Pindos was demonstrated by bear movements between the western and eastern parts of the project area, enhancing the sustainability of the population. These findings will contribute to future efforts to conserve natural corridors that enable functional connectivity among large areas of brown bear territories in Greece.

4 August 2022 in Genes
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TTTzoulia-Maria Tsalazidou-Founta
Tzoulia-Maria Tsalazidou-Founta
ESEvangelia A. Stasi
Evangelia A. Stasi
MSMARIA SAMARA
MARIA SAMARA
YMYorgos Mertzanis
Yorgos Mertzanis
MPMaria Papathanassiou
Maria Papathanassiou
APArcprom Project
Arcprom Project
In order to optimize the appropriate conservation actions for the brown bear (Ursus arctos L.) population in Greece, we estimated the census (Nc) and effective (Ne) population size as well as the genetic status of brown bear sub-populations in three National Parks (NP): Prespa (MBPNP), Pindos (PINDNP), and Rhodopi (RMNP). The Prespa and Pindos sub-populations are located in western Greece and the Rhodopi population is located in eastern Greece. We extracted DNA from 472 hair samples and amplified through PCR 10 microsatellite loci. In total, 257 of 472 samples (54.5%) were genotyped for 6–10 microsatellite loci. Genetic analysis revealed that the Ne was 35, 118, and 61 individuals in MBPNP, PINDNP, and RMNP, respectively, while high levels of inbreeding were found in Prespa and Rhodopi but not in Pindos. Moreover, analysis of genetic structure showed that the Pindos population is genetically distinct, whereas Prespa and Rhodopi show mutual overlaps. Finally, we found a notable gene flow from Prespa to Rhodopi (10.19%) and from Rhodopi to Prespa (14.96%). Therefore, targeted actions for the conservation of the bears that live in the abovementioned areas must be undertaken, in order to ensure the species’ viability and to preserve the corridors that allow connectivity between the bear sub-populations in Greece.

15 August 2024 in bioRxiv
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AHAnne G. Hertel
Anne G. Hertel
APAida Parres
Aida Parres
SFShane Frank
Shane Frank
JRJulien Renaud
Julien Renaud
NSNuria Selva
Nuria Selva
MBMarta De Barba
Marta De Barba
Three-quarters of the planet’s land surface has been altered by humans, with consequences for animal ecology, movements and related ecosystem functioning. Species often occupy wide geographical ranges with contrasting human disturbance and environmental conditions, yet, limited data availability across species’ ranges has constrained our understanding of how human impact and resource availability jointly shape intraspecific variation of animal space use. Leveraging a unique dataset of 752 annual GPS movement trajectories from 370 brown bears ( Ursus arctos ) across the species’ range in Europe, we investigated the effects of human impact (i.e., human footprint index), resource availability, forest cover and disturbance, and area-based conservation measures on brown bear space use. We quantified space use at different spatio-temporal scales during the growing season (May - September): home range size; representing general space requirements, 10-day long-distance displacement distances, and routine 1-day displacement distances. We found large intraspecific variation in brown bear space use across all scales, which was profoundly affected by human footprint index, vegetation productivity, and recent forest disturbances creating opportunity for resource pulses. Bears occupied smaller home ranges and moved less in more anthropized landscapes and in areas of higher resource availability. Forest disturbances reduced space use while contiguous forest cover promoted longer daily movements. The amount of strictly protected and roadless areas within bear home ranges were too small to affect space use. Anthropized landscapes may hinder the expansion of small and isolated populations, such as the Apennine and Pyrenean, and obstruct population connectivity, for example between the Alpine or Carpathian with the Dinaric Pindos populations. Our findings call for actions to maintain bear movements across landscapes with high human footprint, for example by maintaining forest integrity, to support viable bear populations and their ecosystem functions.