Brückner, Adrian (2018)
Resources and oribatid mites:
Effects on life history, chemical ecology, biochemistry and food selection.
Technische Universität Darmstadt
Ph.D. Thesis, Primary publication
Abstract
Nutrition affects nearly all traits and physiological process of an organism and especially hetereotrophs are regulated by nutrient quality. Numerous studies have demonstrated the influence of nourishment on herbivorous insects, but also on “classical” model organisms (e.g. the fruit fly or mice). The relationship of nutrients, trait expression and food selection, in detritivores, however, remains uncertain. For this thesis I hence focused on the influence of resources on multiple traits of oribatid mites (life history, chemical ecology and biochemistry). Oribatids are a speciose group of soil-dwelling micro-invertebrates which are globally present in virtually all terrestrial habitats, fostering soil structure and fertility by contribution to elemental cycles. I was specifically interested in how defensive as well as life-history traits and the flow/incorporation of biomolecules from resources into animals, are affected by diets and which mechanisms underlie resource selection. To elucidate these relationships, I used the parthenogenetic oribatid mite Archegozetes longiestosus, which has been used as a model organisms for more than 25 years. This mite possesses many, easily measurable life-history and morphological traits. Furthermore, it has large opisthonotal glands, which synthesize chemical defensive secretions used as strong repellent agents against predators, thus influencing the structure and stability of soil food webs. In general, I could demonstrate that life history parameters of A. longisetosus were affected by resource and that the foods’ elemental stoichiometry could partly explain these patterns. Furthermore, nutritional quality did not only influence the mean expression of traits, but also their variation. Consequently, I found a stoichiometric optimum for trait variation – i.e. Bertrand’s and threshold-elemental-ratio rule like relationships. Focusing on chemical ecology, age (ontogeny) as well as nutritional supplementation influenced the relative composition and amount of the mites’ defensive secretions. I used this data to parametrize a functional response model for chemical defense that revealed a strong nutritional correlation of long-term chemical defense and nutrients (especially sugars and fats). Regarding the translocation of specific biomolecules, I demonstrated a direct trophic transfer of neutral lipid fatty acids from the food to mites, rendering fatty acids as reliable biomarkers for food web ecology. In contrast, amino acids were only selectively utilized, leading to a homeostasis of amino acid composition in mites. My results also indicated that all, but especially the highly bioactive aromatic compounds from the opisthonotal glands are synthesized de novo from carbohydrate/fat derived precursors, once again highlighting the importance of sugars and fats for the maintenance of an effective chemical defense. Olfactory preference tests with semi-natural resources (bacteria, fungi, lichen and litter powder) – emitting different volatile organic compounds and differing in their resource composition – revealed an innate olfactory preference for oribatid mites. Archegozetes longiestosus especially favored food which was rich in fatty acids, suggesting a potentially adaptive connection of resource selection and chemical anti-predator defense – thus spanning two trophic levels – in oribatid mites.
Keywords: nutritional ecology, evolutionary ecophysiology, soil food web, mites, biochemical ecology
Item Type: | Ph.D. Thesis | ||||
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Erschienen: | 2018 | ||||
Creators: | Brückner, Adrian | ||||
Type of entry: | Primary publication | ||||
Title: | Resources and oribatid mites: Effects on life history, chemical ecology, biochemistry and food selection | ||||
Language: | English | ||||
Referees: | Heethoff, PD Dr. Michael ; Jürgens, Prof. Dr. Andreas | ||||
Date: | 2018 | ||||
Place of Publication: | Darmstadt | ||||
Refereed: | 17 May 2018 | ||||
URL / URN: | http://tuprints.ulb.tu-darmstadt.de/7427 | ||||
Abstract: | Nutrition affects nearly all traits and physiological process of an organism and especially hetereotrophs are regulated by nutrient quality. Numerous studies have demonstrated the influence of nourishment on herbivorous insects, but also on “classical” model organisms (e.g. the fruit fly or mice). The relationship of nutrients, trait expression and food selection, in detritivores, however, remains uncertain. For this thesis I hence focused on the influence of resources on multiple traits of oribatid mites (life history, chemical ecology and biochemistry). Oribatids are a speciose group of soil-dwelling micro-invertebrates which are globally present in virtually all terrestrial habitats, fostering soil structure and fertility by contribution to elemental cycles. I was specifically interested in how defensive as well as life-history traits and the flow/incorporation of biomolecules from resources into animals, are affected by diets and which mechanisms underlie resource selection. To elucidate these relationships, I used the parthenogenetic oribatid mite Archegozetes longiestosus, which has been used as a model organisms for more than 25 years. This mite possesses many, easily measurable life-history and morphological traits. Furthermore, it has large opisthonotal glands, which synthesize chemical defensive secretions used as strong repellent agents against predators, thus influencing the structure and stability of soil food webs. In general, I could demonstrate that life history parameters of A. longisetosus were affected by resource and that the foods’ elemental stoichiometry could partly explain these patterns. Furthermore, nutritional quality did not only influence the mean expression of traits, but also their variation. Consequently, I found a stoichiometric optimum for trait variation – i.e. Bertrand’s and threshold-elemental-ratio rule like relationships. Focusing on chemical ecology, age (ontogeny) as well as nutritional supplementation influenced the relative composition and amount of the mites’ defensive secretions. I used this data to parametrize a functional response model for chemical defense that revealed a strong nutritional correlation of long-term chemical defense and nutrients (especially sugars and fats). Regarding the translocation of specific biomolecules, I demonstrated a direct trophic transfer of neutral lipid fatty acids from the food to mites, rendering fatty acids as reliable biomarkers for food web ecology. In contrast, amino acids were only selectively utilized, leading to a homeostasis of amino acid composition in mites. My results also indicated that all, but especially the highly bioactive aromatic compounds from the opisthonotal glands are synthesized de novo from carbohydrate/fat derived precursors, once again highlighting the importance of sugars and fats for the maintenance of an effective chemical defense. Olfactory preference tests with semi-natural resources (bacteria, fungi, lichen and litter powder) – emitting different volatile organic compounds and differing in their resource composition – revealed an innate olfactory preference for oribatid mites. Archegozetes longiestosus especially favored food which was rich in fatty acids, suggesting a potentially adaptive connection of resource selection and chemical anti-predator defense – thus spanning two trophic levels – in oribatid mites. Keywords: nutritional ecology, evolutionary ecophysiology, soil food web, mites, biochemical ecology |
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URN: | urn:nbn:de:tuda-tuprints-74276 | ||||
Classification DDC: | 500 Science and mathematics > 500 Science 500 Science and mathematics > 590 Animals (zoology) |
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Divisions: | 10 Department of Biology 10 Department of Biology > Ecological Networks 10 Department of Biology > Synthetic Ecological Networks |
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Date Deposited: | 27 May 2018 19:55 | ||||
Last Modified: | 27 May 2018 19:55 | ||||
PPN: | |||||
Referees: | Heethoff, PD Dr. Michael ; Jürgens, Prof. Dr. Andreas | ||||
Refereed / Verteidigung / mdl. Prüfung: | 17 May 2018 | ||||
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