The role of preadaptation, propagule pressure and competition in the colonization of new habitats

To successfully colonize new habitats, organisms not only need to gain access to it, they also need to cope with the selective pressures imposed by the local biotic and abiotic conditions. The number of immigrants, the preadaptation to the local habitat and the presence of competitors are important factors determining the success of colonization. Here, using two experimental set-ups, we studied the effect of interspecific competition in combination with propagule pressure and preadaptation on the colonization success of new habitats. Our model system consisted of tomato plants (the novel habitat), the two-spotted spider mite Tetranychus urticae as our focal species and the red spider mite Tetranychus evansi as a competitor. Our results show that propagule pressure and preadaptation positively affect colonization success. More successful populations reach larger final population sizes either by having higher per capita growth rates (due to preadaptation effects) or by starting a population with a larger number of individuals. Although populations are more successful colonizing non-competitive environments than competitive ones, propagule pressure and preadaptation counteract the negative effects of competition, promoting colonization success. Our study shows the importance of propagule pressure and preadaptation for successful colonization of new habitats by providing the ability to cope with both the exigencies of new environments and the community context

To adapt or go extinct? The fate of megafaunal palm fruits under past global change

Past global change may have forced animal-dispersed plants with megafaunal fruits to adapt or go extinct, but these processes have remained unexplored at broad spatio-temporal scales. Here, we combine phylogenetic, distributional and fruit size data for more than 2500 palm (Arecaceae) species in a time-slice diversification analysis to quantify how extinction and adaptation have changed over deep time. Our results indicate that extinction rates of palms with megafaunal fruits have increased in the New World since the onset of the Quaternary (2.6 million years ago). In contrast, Old World palms show a Quaternary increase in transition rates towards evolving small fruits from megafaunal fruits. We suggest that Quaternary climate oscillations and concurrent habitat fragmentation and defaunation of megafaunal frugivores in the New World have reduced seed dispersal distances and geographical ranges of palms with megafaunal fruits, resulting in their extinction. The increasing adaptation to smaller fruits in the Old World could reflect selection for seed dispersal by ocean-crossing frugivores (e.g. medium-sized birds and bats) to colonize Indo-Pacific islands against a background of Quaternary sea-level fluctuations. Our macro-evolutionary results suggest that megafaunal fruits are increasingly being lost from tropical ecosystems, either due to extinctions or by adapting to smaller fruit sizes.</p

Diversification in evolutionary arenas : Assessment and synthesis

Understanding how and why rates of evolutionary diversification vary is a central issue in evolutionary biology and ecology. The concept of adaptive radiation has attracted much interest, but is metaphorical and verbal in nature, making it difficult to quantitatively compare different evolutionary lineages or geographic regions. In addition, the causes of evolutionary stasis are relatively neglected. Here we review the central concepts in the evolutionary diversification literature and bring these together by proposing a general framework for estimating rates of diversification and quantifying their underlying dynamics, which can be applied across clades and regions and across spatial and temporal scales. Our framework describes the diversification rate (d) as a function of the abiotic environment (a), the biotic environment (b) and clade-specific phenotypes or traits (c); thus d~a,b,c. We refer to the four components (a-d) and their interactions collectively as the &#039;Evolutionary Arena&#039;. We outline analytical approaches to this conceptual model that open up new avenues for research, and present a case study on conifers, for which we parameterise the general model. We also discuss three conceptual examples based on existing literature: the Lupinus radiation in the Andes in the context of emerging ecological opportunity and fluctuating fragmentation due to climatic oscillation; oceanic island radiations in the context of archipelago isolation and island formation and erosion; and biotically driven radiations of the Mediterranean orchid genus Ophrys. The results of the conifer case study are consistent with the long-standing scenario that large niches, lack of competition, and high-rates of niche evolution differentially promote diversification, but these results go further by quantifying the statistical interactions between variables representing these three drivers. The conceptual examples illustrate how using the synthetic Evolutionary Arena framework results in highlighting gaps in current knowledge, and thus help to identify future directions for research on evolutionary radiations. In this way, the Evolutionary Arena framework promotes a more general understanding of variation in evolutionary rates by making quantitative results comparable between case studies, thereby allowing new syntheses of evolutionary and ecological processes to emerge

Quantitative estimates of glacial refugia for chimpanzees (Pan troglodytes) since the Last Interglacial (120,000 BP)

Paleoclimate reconstructions have enhanced our understanding of how past climates have shaped present-day biodiversity. We hypothesize that the geographic extent of Pleistocene forest refugia and suitable habitat fluctuated significantly in time during the late Quaternary for chimpanzees (Pan troglodytes). Using bioclimatic variables representing monthly temperature and precipitation estimates, past human population density data, and an extensive database of georeferenced presence points, we built a model of changing habitat suitability for chimpanzees at fine spatio-temporal scales dating back to the Last Interglacial (120,000 BP). Our models cover a spatial resolution of 0.0467° (approximately 5.19 km2 grid cells) and a temporal resolution of between 1000 and 4000 years. Using our model, we mapped habitat stability over time using three approaches, comparing our modeled stability estimates to existing knowledge of Afrotropical refugia, as well as contemporary patterns of major keystone tropical food resources used by chimpanzees, figs (Moraceae), and palms (Arecacae). Results show habitat stability congruent with known glacial refugia across Africa, suggesting their extents may have been underestimated for chimpanzees, with potentially up to approximately 60,000 km2 of previously unrecognized glacial refugia. The refugia we highlight coincide with higher species richness for figs and palms. Our results provide spatio-temporally explicit insights into the role of refugia across the chimpanzee range, forming the empirical foundation for developing and testing hypotheses about behavioral, ecological, and genetic diversity with additional data. This methodology can be applied to other species and geographic areas when sufficient data are available.Additional co-authors: Alfred K. Assumang, Emma Bailey, Mattia Bessone, Bartelijntje Buys, Joana S. Carvalho, Rebecca Chancellor, Heather Cohen, Emmanuel Danquah, Tobias Deschner, Zacharie N. Dongmo, Osiris A. Doumbé, Jef Dupain, Chris S. Duvall, Manasseh Eno-Nku, Gilles Etoga, Anh Galat-Luong, Rosa Garriga, Sylvain Gatti, Andrea Ghiurghi, Annemarie Goedmakers, Anne-Céline Granjon, Dismas Hakizimana, Josephine Head, Daniela Hedwig, Ilka Herbinger, Veerle Hermans, Sorrel Jones, Jessica Junker, Parag Kadam, Mohamed Kambi, Ivonne Kienast, Célestin Y. Kouakou, Kouamé P. N′Goran, Kevin E. Langergraber, Juan Lapuente, Anne Laudisoit, Kevin C. Lee, Nadia Mirghani, Deborah Moore, David Morgan, Emily Neil, Sonia Nicholl, Louis Nkembi, Anne Ntongho, Christopher Orbell, Lucy Jayne Ormsby, Liliana Pacheco, Alex K. Piel, Lilian Pintea, Andrew J. Plumptre, Aaron Rundus, Crickette Sanz, Volker Sommer, Tenekwetche Sop, Fiona A. Stewart, Jacqueline Sunderland-Groves, Nikki Tagg, Angelique Todd, Els Ton, Joost van Schijndel, Hilde VanLeeuwe, Elleni Vendras, Adam Welsh, José F. C. Wenceslau, Erin G. Wessling, Jacob Willie, Roman M. Wittig, Nakashima Yoshihiro, Yisa Ginath Yuh, Kyle Yurkiw, Christophe Boesch, Mimi Arandjelovic, Hjalmar Küh

Madagascar’s extraordinary biodiversity: Threats and opportunities

Madagascar's unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar's terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as themost prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar

Madagascar’s extraordinary biodiversity: Evolution, distribution, and use

Madagascar's biota is hyperdiverse and includes exceptional levels of endemicity. We review the current state of knowledge on Madagascar's past and current terrestrial and freshwater biodiversity by compiling and presenting comprehensive data on species diversity, endemism, and rates of species description and human uses, in addition to presenting an updated and simplified map of vegetation types. We report a substantial increase of records and species new to science in recent years; however, the diversity and evolution of many groups remain practically unknown (e.g., fungi and most invertebrates). Digitization efforts are increasing the resolution of species richness patterns and we highlight the crucial role of field- and collections-based research for advancing biodiversity knowledge and identifying gaps in our understanding, particularly as species richness corresponds closely to collection effort. Phylogenetic diversity patterns mirror that of species richness and endemism in most of the analyzed groups. We highlight humid forests as centers of diversity and endemism because of their role as refugia and centers of recent and rapid radiations. However, the distinct endemism of other areas, such as the grassland-woodland mosaic of the Central Highlands and the spiny forest of the southwest, is also biologically important despite lower species richness. The documented uses of Malagasy biodiversity are manifold, with much potential for the uncovering of new useful traits for food, medicine, and climate mitigation. The data presented here showcase Madagascar as a unique living laboratory for our understanding of evolution and the complex interactions between people and nature. The gathering and analysis of biodiversity data must continue and accelerate if we are to fully understand and safeguard this unique subset of Earth's biodiversity

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Quantitative estimates of glacial refugia for chimpanzees (Pan troglodytes) since the Last Interglacial (120,000 BP).

Paleoclimate reconstructions have enhanced our understanding of how past climates have shaped present-day biodiversity. We hypothesize that the geographic extent of Pleistocene forest refugia and suitable habitat fluctuated significantly in time during the late Quaternary for chimpanzees (Pan troglodytes). Using bioclimatic variables representing monthly temperature and precipitation estimates, past human population density data, and an extensive database of georeferenced presence points, we built a model of changing habitat suitability for chimpanzees at fine spatio-temporal scales dating back to the Last Interglacial (120,000 BP). Our models cover a spatial resolution of 0.0467° (approximately 5.19 km2 grid cells) and a temporal resolution of between 1000 and 4000 years. Using our model, we mapped habitat stability over time using three approaches, comparing our modeled stability estimates to existing knowledge of Afrotropical refugia, as well as contemporary patterns of major keystone tropical food resources used by chimpanzees, figs (Moraceae), and palms (Arecacae). Results show habitat stability congruent with known glacial refugia across Africa, suggesting their extents may have been underestimated for chimpanzees, with potentially up to approximately 60,000 km2 of previously unrecognized glacial refugia. The refugia we highlight coincide with higher species richness for figs and palms. Our results provide spatio-temporally explicit insights into the role of refugia across the chimpanzee range, forming the empirical foundation for developing and testing hypotheses about behavioral, ecological, and genetic diversity with additional data. This methodology can be applied to other species and geographic areas when sufficient data are available

The role of plant functional traits in cenozoic angiosperm radiations

Es ist ein zentrales Ziel der Evolutionsbiologie, zu verstehen warum sich gewisse Organismengruppen in viele Arten diversifizieren, während die Diversifikation in anderen Gruppen, Zeiten und Orten viel langsamer vonstatten geht. Angiospermen, mit einer Diversität von ca. 250'000 Arten, sind ein exzellentes Taxon um dieses Phänomen zu untersuchen, da ihre Diversität sowohl räumlich als auch phylogenetisch ungleich verteilt ist. Diese Diversitätsunterschiede könnten von evolutionären Radiationen – der Vervielfältigung von Arten – herrühren, doch die Ursachen oder 'Auslöser' dieser Radiationen in Angiospermen sind noch unzureichend verstanden. Angiospermen verfügen über eine spektakuläre Vielfalt an morphologischen Formen und 'functional traits' (funktionelle Merkmale, z.B. Wuchsform, Blattgrösse, Blattform) und evolvierten infolgedessen eine breite Spanne von ökologischen Strategien, assoziiert mit verschiedenen Habitaten, Biomen und Vegetationstypen. Das wiederholte 'erfinden' von 'intrinsic traits' (innerer Merkmale) wurde daher als möglicher Antrieb der Angiospermen-Diversifikation vorgeschlagen. In dieser Dissertation stelle ich die Hypothese auf, dass das Zusammenspiel von vegetativen 'functional traits' und Umwelt (z.B. Klima und Habitat) einige der spektakulären evolutionären Radiationen in Angiospermen während des Känozoikums (von vor ca. 66 Mio. Jahren bis jetzt) erklären könnte. Radiationen sind oft markant in den mediterranen Ökosystemen (MTEs, Mediterranean-type ecosystems) der Welt: der südafrikanischen Kap Region, Westaustralien, Kalifornien, Chile und dem Mittelmeerraum. Diese 'hotspots' enthalten etwa 20% der bekannten Gefässpflanzen, fast 50'000 Arten, in einem Gebiet das weniger als 5% der Erdoberfläche bedeckt. Obwohl sie sich geografisch getrennt auf verschiedenen Kontinenten befinden, teilen die fünf MTEs ein ähnliches Klima mit trockenen, heissen Sommern und kühlen, nassen Wintern. Diese Bedingungen könnten die Selektion für Arten mit kleinen, immergrünen Hartlaub-Blättern (sklerophyll), mit tiefem spezifischem Blattgewicht (SLA, specific leaf area) und einer Strauch- Wuchsform gefördert haben, was in analogen Vegetationstypen in den MTEs resultierte. Diese Merkmale können 'adaptiv' oder 'exaptiv' sein. Merkmale sind 'Adaptationen' wenn sie von der Umwelt natürlich selektioniert wurden und 'Exaptationen' wenn sie zuvor für eine bestimmte Funktion evolvierten (eine Adaptation), aber dann für einen neuen Zweck verwendet werden. Hier nutze ich Methoden aus den Bereichen der 'functional trait' Ökologie und molekularen Phylogenetik und wende vergleichende phylogenetische Methoden an, um zu einem besseren Verständnis der 'functional traits'-Evolution zu gelangen. Ich benutze hierfür mediterrane Ökosysteme und mehrere Angiospermen-Clades als Studiensystem. Diese umfassen Penaceae, Phyliceae und Diosmeae (Kapitel II), Rhamnaceae (Kapitel III und IV), Proteaceae (Kapitel V) und Ericaceae, Fagales und Poales (Kapitel VI). Die räumliche Verbreitung der Arten in diesen Clades in verschiedenen Vegetationstypen und Biomen und deren intrinsische Variation in vegetativen 'functional traits' und ökologischen Strategien, macht sie ideal um diese Hypothese zu testen. In Kapitel II untersuchte ich ob Veränderungen in Diversifikationsraten, 'functional traits' und Habitaten gemeinsam in den Phylogenien auftreten. Ich erstellte datierte Phylogenien für drei Kap-Clades (Penaceae, Phyliceae und Diosmeae) und zeigte in allen drei Clades parallel, dass Habitatswechsel von afromontanen Wäldern zu Fynbos mit Verringerung in Blattfläche und SLA assoziiert waren und entweder mit Erhöhungen der Diversifikationsrate zusammenfielen oder diesen vorausgingen. Des Weiteren sind Penaceae, Phyliceae und Diosmeae Arten typische Vertreter ihrer Vegetationstypen in Bezug auf ihre Merkmale. Ich argumentierte, dass die Expansion des Fynbos auf Kosten der Wälder im Miozän, angetrieben von Veränderungen im Feuerregime und der Aridifikation des Kaps, eine ökologische Gelegenheit zur Diversifikation der Fynbos-Stammeslinien dargestellt haben könnte. In Kapitel III testete ich die Hypothese, dass Kontinent-abhängige Artbildungs- und Aussterberaten zu Ungleichheiten in der Diversität der fünf MTEs dieser Welt geführt haben. Zu diesem Zweck erstellte und datierte ich Phylogenien für 280 Rhamnaceae Arten (27% der Gesamtartenzahl der Familie) und zeigte, dass Rhamnaceae-Stammeslinien in MTEs generell höhere Diversifikationsraten hatten als andernorts, dass aber Artbildungs- und Aussterbedynamiken ein Kontinent-abhängiges Muster aufwiesen. Hohe Artbildungs- und Aussterberaten wurden in kalifornischen Rhamnaceae Linien gefunden, sowie signifikant tiefe Aussterberaten in Rhamnaceae in MTEs des Kaps und Australiens. Diese Resultate deuteten auf unabhängige evolutionäre Geschichten von Rhamnaceae in MTEs hin, möglicherweise verbunden mit der Intensität von Klima-Oszillationen und der geologischen Geschichten der Regionen. In Kapitel IV vertiefte ich die Resultate von Kapitel III und testete, ob die Kontinent- abhängigen Muster von Artbildung und Aussterben in MTEs mit der Evolution von sklerophyllen (hartlaubigen) und nicht-sklerophyllen Merkmalssyndromen in diesen Regionen verbunden sein könnten. Diese Merkmalssyndrome beinhalteten artspezifische Daten über SLA, Blattgrösse, Spineszenz, Blattphänologie, Wuchsform und Blattrand-Typ. Resultate legen nahe, dass die Evolution von Sklerophyllie (Hartlaubigkeit) zu erhöhten Diversifikationsraten in Rhamnaceae-Linien in den MTEs des Kaps und Australiens beigetragen hat, indem die Reduktion der Aussterberaten evolutionäre Beständigkeit vereinfachte. Die historisch relativ stabilen Bedingungen am Kap und in Australien sind konsistent mit dieser Beständigkeits-Hypothese. Des weiteren wurde die morphologische Konvergenz in MTEs lange als Adaptation an die klimatischen Ähnlichkeiten dieser Regionen interpretiert; allerdings zeigte ich, dass diese Merkmalssyndrome wahrscheinlich vor dem sommerdürrem Klima in den MTEs evolvierten, womit sie nicht für dieses Selektionsregime adaptiv sein können. Nichtsdestotrotz, Hartlaubigkeit evolvierte zeitgleich mit dem Habitatswechsel ans Kap und in die australischen MTEs und könnte somit potentiell eine Adaptation an die für diese Region typischen Bodenbedingungen sein. In Kapitel V testete ich die Voraussage, dass die Evolutionsraten von 'functional traits' und klimatischen Nischen während einer Radiation gekoppelt sind. Hierfür erstellte ich eine datierte Phylogenie für 337 Proteaceae-Arten (21% der Gesamtartenzahl der Familie) und sammelte Daten für 'functional traits' von Blättern (Blattfläche, Hartlaubigkeit, Blattform) und die klimatischen Nischen von 261 bzw. 1645 Arten. Die Resultate wiesen darauf hin, dass stabilisierende Selektion der Auslöser gewesen sein könnte, dass Stammeslinien die in offenen Vegetationstypen evolvierten sich auf Merkmals- und klimatische Nischen-Optima diversifiziert haben, welche sich von denen in geschlossenen Vegetationstypen unterscheiden. Ausserdem waren die Evolutionsraten von Merkmalen und klimatischen Nischen stark korreliert, und diese Raten waren besonders hoch in Clades die in offener Vegetation vorkommen. Ich argumentierte, dass die Einwirkung variabler Mikroklimate in offenen Landschaften wie denen in MTEs, die ansonsten durch geschlossene Bewaldung gedämpft werden, höhere innerartliche Variabilität der Merkmale begünstigen könnte, was Radiationen in diesen Systemen vereinfacht hätte. In Kapitel VI entwickelte ich ein konzeptuelles Gerüst um intrinsische und extrinsische Variablen welche in einer Radiation involviert sind zu klassifizieren. In den Testgruppen Ericaceae, Fagales und Poales fand ich dreizehn Veränderungen in Diversifikationsregimes (d.h. Radiationen) und stellte fest, ob die assoziierten Variablen vor der relevanten Radiation (Hintergrundvariablen), gleichzeitig mit der Radiation (Auslöser) oder später (Modulator) evolvierten. Die Resultate legten nahe, dass Radiationen sowohl extrinsische Voraussetzungen als auch intrinsische Merkmale benötigen, aber dass die Abfolge derselben nicht wichtig ist. Diversifikations-Treiber zeichnen sich dadurch aus, dass sie innerhalb der Radiation variabler sind als konservierte Merkmale die lediglich die Belegung eines neuen Habitats ermöglichen. Dieses konzeptuelle Gerüst vereinfacht die Untersuchung von kausativen Faktoren von evolutionären Radiationen. Die Forschungsarbeit in dieser Dissertation betont das komplexe Zusammenspiel zwischen biologischer Diversität, morphologischer Form und der globalen Umwelt. Das Aufdecken der Innovation und Evolution von 'functional traits' und deren Rolle in Angiospermen-Diversifikation kann viel zu einem erhöhten Verständnis der gegenwärtigen Vielfalt und Verbreitung von Arten beitragen, genauso auch zum Aufzeigen der Konsequenzen der ökologischen Dominanz gewisser funktioneller Typen, und damit funktioneller Diversität in bestehenden Ökosystemen. SYNOPSIS It is a central goal in evolutionary biology to understand why some groups of organisms diversify into many species, while diversification is much slower in other groups, times and places. Flowering plants (angiosperms), with a standing diversity of ca. 250.000 species, is an excellent taxon to investigate this phenomenon, as their diversity is unevenly distributed, both spatially and phylogenetically. These diversity discrepancies may have resulted from evolutionary ‘radiation’ – the multiplication of species – but the causes or ‘triggers’ of radiations in angiosperms remain poorly understood. Angiosperms display a spectacular variety of morphological forms and ‘functional traits’ (e.g. growth forms, leaf sizes, leaf shapes) and have consequently evolved a wide range of ecological strategies associated with different environments, biomes and vegetation types. The repeated ‘innovation’ of intrinsic traits has therefore been proposed as a possible driver of diversification in angiosperms. In this thesis, I hypothesize that the interaction between vegetative functional traits and environments (e.g. climate and habitat) may explain some of the spectacular evolutionary radiations in angiosperms during the Cenozoic (ca. 66 Ma till present). Radiations are often prominent in the Mediterranean-type ecosystems (MTEs) of the world: the Cape, Western Australia, California, Chile and the Mediterranean Basin. These ‘hotspots’ contain about 20% of the known vascular plant species, almost 50’000, in an area which covers less than 5% of the Earth’s surface. Although they are geographically separated on different continents, the five MTEs share a similar climate of dry, hot summers and cool, wet winters. These conditions may have selected for species with small, evergreen, sclerophyllous leaves, with a low specific leaf area (SLA) and a shrubby growth form, resulting in analogous vegetation types among MTEs. These traits may be ‘adaptive’ or ‘exaptive’. Traits are ‘adaptations’ if they are naturally selected for by the environment and ‘exaptation’ if they have previously evolved for a particular function (an adaptation), but are coopted for a new use. Here, I used methodologies from the fields of functional trait ecology and molecular phylogenetics and I applied phylogenetic comparative methods to contribute to a better understanding of functional trait evolution and the role of traits in evolutionary radiation, by using Mediterranean- type ecosystems and several angiosperm clades as study systems. These include Penaeaceae, Phyliceae and Diosmeae (chapter II), Rhamnaceae (chapters III and IV), Proteaceae (chapter V) and Ericaceae, Fagales and Poales (chapter VI). The spatial distribution of the species in these clades in different vegetation types and biomes, and their intrinsic variation in vegetative functional traits and ecological strategies, makes them ideal to test the hypotheses. In chapter II I investigated the co-occurrence of shifts in diversification rates, functional traits and habitats on phylogenetic trees. I built dated phylogenetic trees for three Cape clades (Penaeaceae, Phyliceae and Diosmeae) and showed that afromontane forest to fynbos shifts were associated with decreases in leaf area and SLA and preceded or coincided with increases in diversification rates in a parallel fashion. Furthermore, Penaeaceae, Phyliceae and Diosmeae species are typical members of their vegetation types in terms of their traits. I argued that expansion of the fynbos at the cost of forest in the Miocene, driven by changes in fire regime and aridification in the Cape, may have provided an ecological opportunity for the diversification of fynbos lineages. In chapter III I tested the hypothesis that continent-dependent speciation and extinction rates have led to disparity in diversity between the five MTEs of the world. To this end I built and dated phylogenetic trees for 280 Rhamnaceae species (27% of total number of species in the family) and demonstrated that Rhamnaceae lineages in MTEs generally showed higher diversification rates than elsewhere, but speciation and extinction dynamics showed a pattern of continent-dependence. High speciation and extinction rates were detected in Californian Rhamnaceae lineages and significantly low extinction rates in Rhamnaceae occurring in Cape and Australian MTEs. These results indicated independent evolutionary histories of Rhamnaceae in MTEs, possibly related to the intensity of climate oscillations and the geological history of the regions. In chapter IV I elaborated the results from chapter III, and tested if the continent-dependent pattern of speciation and extinction in MTEs may be associated with the evolution of sclerophyllous and non-sclerophyllous trait syndromes in these regions. These trait syndromes included species-specific data on specific leaf area, leaf size, spinescence, leaf phenology, growth form and leaf margin type. Results suggested that the evolution of sclerophylly has contributed to increased diversification rates of Cape and Australian Rhamnaceae lineages, by reducing extinction rates, and thereby facilitating evolutionary persistence. The historical relatively stable conditions in the Cape and Australia are consistent with this persistence hypothesis. Furthermore, the morphological convergence in MTEs has long been interpreted as adaptation to climatic similarities among these regions; however, I demonstrated that these trait syndromes have likely evolved prior to summer-drought climates in MTEs, thereby failing to be adaptive to this selective regime. Nevertheless, sclerophylly evolved contemporaneously with the transitions to Cape and Australian MTEs, and may therefore potentially be an adaptation to edaphic conditions typical of these regions. In chapter V I tested the prediction that rates of functional trait evolution and climatic niche evolution are coupled during radiation. To this end, I built a dated phylogenetic tree for 337 Proteaceae species (21% of total number of species in the family) and collected leaf functional trait data (blade area, sclerophylly, leaf shape) and climatic niche data for 261 and 1645 species respectively. Results indicated that stabilizing selection may have triggered lineages which evolved in open vegetation types to diversify towards trait and climatic niche optima distinct from those which evolved in closed vegetation types. Furthermore, the rates of trait and climatic niche evolution were strongly correlated, and these rates were particularly high in clades occurring in open vegetation. I argued that the exposure to variable micro-climates in open landscapes such as those in MTEs, which are otherwise buffered by closed forest covers, may favour higher interspecific trait variability, which may have facilitated the radiations in these systems. In chapter VI I developed a conceptual framework to classify intrinsic and extrinsic variables involved in radiation. Using Ericaceae, Fagales and Poales as test cases, thirteen shifts in diversification regimes (i.e. radiations) were detected and I determined whether the associated variables originated before the relevant radiations (backgrounds), simultaneously with the radiations (triggers), or evolved later (modulators). These results suggested that radiations require both extrinsic conditions and intrinsic traits, but the sequence of these is not important. Diversification drivers can be identified as being more variable within a radiation than conserved traits that only allow occupation of a new habitat. This framework may facilitate exploration of the causative factors of evolutionary radiations. The research in this thesis emphasizes the intricate interplay between biological diversity, morphological form, and the global environment. Revealing the roles of innovation and evolution of functional traits in angiosperm diversification can contribute much to an increased understanding of current species diversity and distribution, as well as reveal the consequences for ecological dominance of certain functional types, and thus functional diversity, in extant ecosystems

Beyond climate: convergence in fast evolving sclerophylls in Cape and Australian Rhamnaceae predates the mediterranean climate

Morphological convergence in mediterranean-type ecosystems (MTEs) has long been interpreted as adaptation to climatic similarities among the five MTEs of the world. Here, we challenge this model using the globally distributed Rhamnaceae. We collected functional trait data (specific leaf area, leaf area, spinescence, leaf phenology, growth form and leaf margin type) and biome data to test for trait convergence in MTEs, for models of trait evolution and ancestral state reconstruction and for the effect of traits on speciation and extinction rates, using a phylogenetic framework. We show that leaf functional traits evolve to three optima, which correspond to (a) the edaphically specialized Australian and Cape MTEs (AC), (b) the mediterranean-type climates, but edaphically normal Chile, California and Mediterranean Basin (CCM), and (c) the non-mediterranean habitats. We find that Rhamnaceae in CCM are predominantly characterized by non-sclerophylly, the ancestral state in Rhamnaceae, and Rhamnaceae in AC by sclerophylly. These leaf character syndromes have evolved prior to mediterranean climates in MTEs, thereby failing to be adaptive to this selective regime. However, sclerophylly evolved contemporaneously with the transitions to AC, and may therefore be an adaptation to nutrient-poor soils. The evolution of sclerophylly has contributed to increased diversification rates of Pomaderreae in Australia and Phyliceae in the Cape, by reducing extinction rates and thereby facilitating evolutionary persistence. The historical relatively stable conditions in AC are consistent with this persistence hypothesis. Synthesis. In this study we integrate the fields of macroevolution and ecology and show that low extinction rates may not only account for the ecological, but also for the floristic dominance of sclerophylly in the hyperdiverse Australian and Cape mediterranean-type ecosystems