Mechanistic understanding of ecological niche overlap in two sympatric lizard species

Dajčman, Urban (author), Žagar, Anamarija (mentor), Urzelai, Urtzi Enriquez (comentor)

Abiotic and biotic elements of the ecological niche are key to understanding species coexistence. This dissertation explores which factors enable the coexistence of two closely related lizard species – Horvath’s Rock Lizard (Iberolacerta horvathi) and the Common Wall Lizard (Podarcis muralis). Based on ecological niche theory, the study investigates how microclimate, physiology, parasitism, and interspecific competition shape their coexistence along an elevational gradient. The research integrates fieldwork, parasitological and ecophysiological laboratory analyses, and mechanistic modelling. Parasite identification and prevalence analyses revealed higher infection rates of I. horvathi with Karyolysus parasites, particularly at sites where the two species coexist. Physiological data shows adaptations of both species to different altitudinal conditions, with hemoglobin concentration in P. muralis increasing with elevation. Mechanistic models combining microclimatic data, biophysical models, and dynamic energy budget theory show that mid-elevations are most favorable for both species due to environmental heterogeneity. Under different competition scenarios, the subordinate species I. horvathi exhibited lower body temperatures and delayed reproduction. Climate change may affect the outcomes of competition in unpredictable ways; simulations suggest that thermal competition may weaken under higher environmental temperatures. The dissertation presents an innovative approach to mechanistic modelling of interspecific competition and provides an integrated framework for understanding the coexistence of similar species and their responses to climate change.

• Language: English
• Keywords: ecological niche, mechanistic modeling, abiotic niche, biotic niche, coexistence, syntopy, Podarcis muralis, Iberolacerta horvathi, parasites, Karyolysus
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Publisher: [U. Dajčman]
• Year: 2025
• PID: 20.500.12556/RUL-178188
• UDC: 598.161.212:576.89(043.3)
• COBISS.SI-ID: 265489411
• Publication date in RUL: 21.01.2026

Secondary language

• Language: Slovenian
• Title: Mehanistično razumevanje prekrivanja ekoloških niš dveh simpatričnih vrst kuščaric

Abstract

Abiotski in biotski elementi ekološke niše so ključni za razumevanje soobstoja vrst. V svoji disertaciji sem raziskoval, kateri dejavniki omogočajo sobivanje dveh sorodnih vrst kuščarjev, Horvatove kuščarice (Iberolacerta horvathi) in pozidne kuščarice (Podarcis muralis). Izhajajoč iz teorije ekološke niše, raziskave vključene v disertacijo preučujejo kako mikroklima, fiziologija, parazitizem in medvrstno tekmovanje oblikujejo sobivanje obeh vrst vzdolž višinskega gradienta. Delo združuje terenske raziskave, parazitološko in ekofiziološko laboratorijsko delo in mehanistično modeliranje. Analiza parazitov je pokazala večjo stopnjo okuženosti vrste I. horvathi s paraziti rodu Karyolysus, še posebej na lokacijah kjer vrsti sobivata. Fiziološki podatki so pokazali prilagoditve obeh vrst na različne višinske razmere, pri čemer se je pri vrsti P. muralis koncentracija hemoglobina povečevala z nadmorsko višino. Mehanistični modeli, ki združujejo mikroklimatske podatke, biofizikalne modele in modele teorije dinamične energetske bilance, so pokazali, da so srednje nadmorske višine najbolj ugodne za obe vrsti zaradi okoljske heterogenosti. Pod različnimi scenariji tekmovanja smo pri podrejeni vrsti, I. horvathi opazili nižje telesne temperature in zakasnjeno razmnoževanje. Klimatske spremembe lahko na rezultate tekmovanja vplivajo nepredvidljivo, simulacije so pokazale, da v primeru tekmovanja za toploto oziroma mesta za sončenje lahko le to zbledi ob povišanju okolijskih temperatur. Disertacija predstavlja inovativen pristop mehanističnega modeliranja tekmovanja med dvema vrstama in nudi celosten okvir za razumevanje sobivanja vrst istega ekološkega ceha in njihovih odzivov na podnebne spremembe.

• Keywords: ekološka niša, mehanistično modeliranje, abiotska niša, biotska niša, soobstoj, sintopija, Podarcis muralis, Iberolacerta horvathi, paraziti, Karyolysus