VU Research Portal Parasitism and the Evolutionary Loss of Lipogenesis Visser, B. 2012 document version Publisher's PDF, also known as Version of record Link to publication in VU Research Portal citation for published version (APA) Visser, B. (2012). Parasitism and the Evolutionary Loss of Lipogenesis. Ipskamp B.V. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. E-mail address: [email protected] Download date: 06. Oct. 2021 Parasitism and the Evolutionary Loss of Lipogenesis Cover: Symbiose mensuur tussen natuur en cultuur. Cover design: Leendert Verboom Lay-out: Bertanne Visser Printing: Ipskamp Drukkers B.V., Enschede Thesis 2012-1 of the Department of Ecological Science VU University Amsterdam, the Netherlands This research was supported by the Netherlands Organisation for Scientific Research (NWO, Nederlandse organisatie voor Wetenschappelijk Onderzoek), grant nr. 816-03-013. isbn xxx VRIJE UNIVERSITEIT Parasitism and the Evolutionary Loss of Lipogenesis ACADEMISCH PROEFSCHRIFT ter verkrijging van de graad Doctor aan de Vrije Universiteit Amsterdam, op gezag van de rector magnificus prof.dr. L.M. Bouter, in het openbaar te verdedigen ten overstaan van de promotiecommissie van de faculteit der Aard- en Levenswetenschappen op woensdag 25 januari 2012 om 13.45 uur in de aula van de universiteit, De Boelelaan 1105 door Bertanne Visser geboren te Delft promotor: prof.dr. J. Ellers Voor Adriana Visser-Verboom en Hugo Kok Contents Contents 1 1 General introduction 3 2 Lack of lipogenesis in parasitoids: A review of physiological mech- anisms and evolutionary implications 15 3 Loss of lipid synthesis as an evolutionary consequence of a parasitic lifestyle 29 4 Can host manipulation drive the evolutionary loss of traits in par- asitoids? 49 5 Host exploitation efficiency in a gall wasp community 61 6 Lack of transcription of the key gene in lipid synthesis, fatty acid synthase, reflects loss of lipogenesis in adult parasitic wasps 75 7 Discriminating between energetic content and dietary composition as an explanation for dietary restriction effects 101 8 Effects of a lipid-rich diet on adult parasitoid income resources and survival 115 9 Synthesis 125 Bibliography 141 Summary 179 Samenvatting 183 Acknowledgements 189 Curriculum vitae 195 Publications 197 Affilliation of committee members 199 Affiliation of co-authors 201 1 Chapter 1 General introduction A brief history of evolutionary theory Nowadays some scientists might say that the continued reference to the original theories of evolution has become a cliché and that many theoretical concepts pertaining to evolution have undergone far-reaching conceptual revisions. I agree that science in general should progress toward novel or extended theories and researchers in evolutionary biology should be critical to concepts in evolutionary theory to elucidate the natural world. However, in essence, science can only progress through building on the foundation of knowledge acquired throughout the history of science. Evolutionary biology still relies heavily on the fundamental theories incepted by Alfred Russell Wallace in his seminal paper ‘On the tendency of varieties to depart in- definitely from the original type’ (1858) and Charles Darwin’s book ‘On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life’ (1859). While highly controversial at that time and contradicting contemporary views on inheritance and ob- served variation between organisms, their pivotal work explains the process of descent with modification and natural selection acting on existing herita- ble variation within populations as the main driving force behind adaptive evolution. With the foundation of evolutionary theory in place, another major con- tribution to evolutionary theory was fuelled by the rediscovery of Mendel’s laws of genetics in 1900. Up to that point in time the mechanisms of inheri- tance had remained elusive and its eventual discovery was initially regarded contradictory to theory on the process of natural selection. Rediscovery of Mendel’s laws paved the way for numerous scientists, such as Ronald Fisher (1930), John Haldane (1932) and Sewall Wright (1932), to develop the field of population genetics, concerned with studying changes in allele propor- tions within populations through the processes of natural selection, genetic drift, mutation and gene flow. Within the following decades several other prominent scientists significantly contributed to the development of evo- lutionary theory, in which their considerations reached beyond the realm of genetics to include fields such as ecology, paleontology and botany, as 3 Chapter 1 well as the concept of speciation (Dobzhansky, 1937; Mayr, 1942; Rench, 1959; Simpson, 1944; Stebbins, 1950). These advances in evolutionary biol- ogy were collectively termed the Modern Synthesis (MS) by Julian Huxley (1942). Amongst others, multidisciplinarity of the MS led to a concep- tual framework addressing i) the key importance of genetic diversity within populations; ii) the phenotype as a means for natural selection to act upon within variable environments; and iii) the relationship between micro- and macro-evolutionary changes. Over the last couple of years further extensions of the MS have been propagated (Pigliucci, 2007; Pigliucci & Müller, 2010). Based on a theory originally proposed by Popper (Platnick & Rosen, 1987), these authors and others have argued that evolutionary theory began as a theory of form that through the inception of the MS led to a theory of genes, but that there is a current need to update the initial theory of form (Pigliucci, 2007). This expansion of the MS is referred to as the Extended Evolutionary Synthesis (EES). The EES conceptualizes evolutionary theory through the addition of numerous fields in biology. As summarized by Pigliucci (2007), exten- sions of the MS should embrace developmental biology, a field of research that was completely left out of the original MS, even though developmental biology was already an established field of research at the time the MS was formulated. Another major advancement revolves around incorporation of ecological theory. Despite the inclusion of ecology into the MS, the ecolog- ical settings that bring about evolutionary changes have remained largely unexplored (Maynard Smith & Szathmáry, 1995). Through technological advances during the last few decades, biology has witnessed the rise of other important fields, namely that of genomics, proteomics and metabolomics. These fields provide us with ever-increasing insights to move away from the black box principle that has been a frequent necessity in the concep- tion and extensions of evolutionary theory. Moreover, several important concepts employed in current research in evolutionary biology were not in- corporated in the MS, such as phenotypic plasticity (a norm of reaction or a variable phenotype of a single genotype across environments) and epi- genetic inheritance (changes in gene expression without alterations in the underlying DNA sequences that can be passed on to the next generation). Evolutionary theory has seen major advancements and will certainly un- dergo further extensions in the future. A major advancement formulated in the MS pertains to the importance of genetic variation and its translation into the phenotype for natural selection to act upon. Undeniably, these aspects are of key importance to fuel evolutionary changes. It is becoming 4 General introduction increasingly clear, however, that variables other than standing genetic vari- ation significantly contribute to evolutionary change. In this regard, one important concept is the evolution of novel traits, which is tackled by the EES. Yet the reciprocal process of trait loss continues to be regarded as an inevitable consequence of evolution and with it the notion that it only has a minor contribution to evolutionary change. It has been an area of research that, therefore, received considerably less attention. This thesis focuses on the loss of traits and why and how trait loss occurs during the course of evolution. I will first describe the importance of trait acquisition, how trait acquisition is linked to trait loss and current concepts and theories regarding the loss of traits. I will then outline the importance of ecological conditions and in particular nutrition to trait dynamics and fitness (average contribution of a genotype to the next generation), and last I will introduce the model system employed in the work described in this thesis. Trait acquisition, loss and evolutionary mechanisms Over the last few decades a key objective in evolutionary biology has been to unravel why novel traits arise, which mechanisms underlie trait acquisi- tion and the ways in which novel traits contribute to