Comparison of direct and indirect measures of predation in different populations of primates

Plenilstvo velja za pomemben dejavnik v evoluciji morfologije, fiziologije in vedenja primatov. Vendar ga je težko opazovati in natančno meriti, zato se nekateri raziskovalci poslužujejo posrednih merilcev plenjenja, ko v analizah poskušajo ovrednotiti pomen plenilstva. V diplomskem delu sem raziskovala primerjavo med neposrednim merilcem plenjenja – ocenjeno pogostostjo uplenitve (OPU) in dvema nadomestnima, posrednima merilcema plenjenja: telesna masa in uporaba habitata (talni/drevesni način življenja). S pomočjo obstoječe primatološke literature sem zbrala potrebne podatke za 80 populacij in 56 vrst primatov iz vseh področij, kjer primati živijo. V tem vzorcu je OPU segala od 0 do 25 %, pri čemer je bila večina podatkov (60 %) med 0 in 5 %. S splošnim linearnim modelom sem preverila, kolikšen delež variance OPU lahko razložimo s telesno maso plena in uporabo habitata. Rezultati kažejo, da so primati z večjo telesno maso plenjeni redkeje kot majhni primati, medtem ko uporaba habitata ne vpliva na pogostost plenjenja in ni primerna kot nadomestni merilec za oceno pritiska plenilcev. Kljub temu, da sem našla statistično pomembno povezavo med OPU in telesno maso primatov, pa je napovedna zmogljivost modela šibka, saj so odstopanja od tega splošnega trenda precejšnja. Kaže, da velika telesna masa sicer lahko do neke mere deluje kot zaščita pred plenilci, vendar pa je potrebna izjemna previdnost, kadar raziskovalci telesno maso uporabijo kot nadomestni merilec za oceno pritiska plenilcev.Predation is thought to play a major role in the evolution of morfology, fisiology and behavior of primates. However, it is hard to observe and measure, which lead some resarchers to use indirect measures of predation when trying to evaluate predation presaure. In my diploma thesis I investigated the relationship between a direct measure of predation – estimated predation rates (EPR) – and two proxy measures, body mass and terrestriality (terrestrial/arboreal way of living). From the existing primate literature I was able to compile the required data for 80 populations, covering 56 species from all major primate radiations. In this sample EPR that ranged from 0 to 25 %, where most (60 %) of the data ranged between 0 and 5 %. I used general lineral model to determine the proportion of the EPR variance that can be explained by body mass and terrestriality. The results show that body mass was significantly related with EPR, while terrestriality was not and it does not appear to be suitable as a proxy measure of predation. Despite a statistically significant result, the association between EPR and body mass appears to be weak. It appears that large body mass may protect primates from predator attacks to a certain extent but researchers should use it as a proxy measure for predation only with great caution