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PREDATION PRESSURE ON ARTIFICIAL CATERPILLARS INDICATES ENEMY-REDUCED TIME AND SPACE
SEIFERT, Carlo Lutz
This thesis explores patterns of predation on artificial caterpillars in two neotropical lowland rainforest ecosystems. The specific aim was to test if enemy-reduced time and space does exist for physical undefended caterpillars. Our results indicated that larval Lepidoptera are capable to lower predation risk by nocturnal foraging and by avoiding habitats of high light irradiance. Thus, habitat-specific host plant choice by adult females and a timely scheduled foraging behaviour of the caterpillars could remarkably increase the survival rate of immature stages.
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Ecology of ants along elevational rainforest gradients in the tropics
MOSES, Jimmy
The thesis investigates the community ecology and species diversity of tropical ants on tropical mountains. The primary focus is on the changes in the ground-dwelling ant communities along elevational rainforest gradients, and how their elevational patterns are influenced by various biotic and abiotic factors. First, we investigated how elevation, leaf litter depth and their interaction affect the abundance, species richness and composition of ground-dwelling ants on Mt. Wilhelm (Papua New Guinea). Next, we investigated how ant communities change with forest succession in time along an extensive tropical elevational gradient in Southern Papua New Guinea. The aim was to assess both spatial and temporal trends in the ant communities and whether these changes could serve as indicators towards ecological recovery after human-induced forest disturbance. Finally, we assessed the relationships of ant species richness and activity, and their relative use of six nutrients, with elevation and season in three different tropical mountain regions (New Guinea,Tanzania and Ecuador).
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The effect of tropical land use change on soil-dwelling ants and termites, their interaction and on ecosystem processes they affect
TŮMA, Jiří
In this thesis I explore the role of tropical soil-dwelling ants and termites in driving ecosystem processes, their mutual interaction and their responses to tropical land use change. To do this I use a combination of methods, including a full review of the ant-termite interaction literature, field sampling for ants and termites, DNA barcoding-based inference of ant predation on termites, and creation and implementation of a new protocol for measuring terrestrial bioturbation. I found that the literature mainly documents anecdotal observations of interactions between ants and termites, the vast majority of which are predatory. Many of these appear to be opportunistic predation of termites by non-specific ants, although some ant species have developed sophisticated methods that enable them to specialise on termite predation. My field sampling demonstrated that soil ants and termites are susceptible to habitat degradation, with logging having minimal impacts, but conversion to oil palm affecting both groups to a greater extent. The predation rate of ants on termites differs between ant taxa, but seems to be stable across habitats. Finally, termites are important for soil bioturbation in all habitat types, but overall, this ecosystem function relies only on few species in oil palm plantations, raising concerns about susceptibility of this function to future extinctions. My work emphasizes the importance of maintaining the diversity of these two trophically linked groups for the ecosystem functions they provide.
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Ant succession in post mining sites
Hovorková, Marie ; Frouz, Jan (advisor) ; Mudrák, Ondřej (referee)
Succession is often studied by using a chronosequence. When using a chronosequence we study a set of sites with different ages at the same time and by comparing them we conclude what kind of changes occurred during time (space for time substitution). Only a few studies however compare how results obtained by using a chronosequence differ from those obtained by long-term studies. In my theses I repeated a study that investigated succession of ant communities on brown coal mining spoil dumps in Sokolov district after 19 years. There are chronosequences of two types of sites (spontaneous succession and recultivation) in Sokolov coal mining district. By repeating the original study I could compare changes that occurred du- ring time with changes along a chronosequnce. Relationship between occurrence of ant groups with different ecological requirements and age of site was also investigated. RDA model and variation partitioning were used to find out statistical significance between sites and their age. An increase in number of species was recorded on the spoil dumps. 22 ant species were found in the year 2020, from which 5 species were new on the dumps. All the new species are specialists, two of them are dendrophilous. A statistically significant increase in abundance of forest species with site age was...
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Mechanisms structuring arboreal ant communities along ecological gradients in New Guinea rainforests
PLOWMAN, Nichola Sarah
The thesis explores the community ecology and diversity of tropical ants, with a strong focus on the arboreal ants of Papua New Guinea rainforests. The aim was to investigate the drivers of community structure in these diverse communities, and how these change along the ecological gradients of elevation and forest succession. Using unique datasets from censuses of whole forest plots at low, mid and high elevation forests, the effects of vegetation structure and nest microhabitat use on ant community structure and diversity are compared across elevations. Furthermore, a community study of an understorey ant-plant mutualism was undertaken to explore elevational changes in interaction networks and the costs and benefits of mutualistic interaction. For lowland primary and secondary forest, taxonomic, functional and phylogenetic diversity of arboreal ant communities were quantified. In addition, aspects of the methodology of community functional diversity studies are examined, and suggested improvements to data handling in cases where full datasets are not available are discussed.
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