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Future of Molecular Systematics Adaptive Radiations . . . Systematics meets Ecology . . . Emergence of Life Forms • emergence of 3 domains of life with 6+ kingdoms 1. Biogeography 2. Ecology Ecology Biogeography 3. Genomics Morphology Ecology and phylogenetics intertwined when looking at the emergence of life forms on earth and their subsequent diversification Genetics Phylogeny Development Taxonomy Cytology Emergence of Life Forms • rise of major lineages of eukaryota - many of which we do not yet know how related Emergence of Life Forms Emergence of Life Forms • movement of plants onto land and their subsequent diversification • and finally the rise and domination of flowering plants Ordovician-Devonian Emergence of Life Forms Adaptive Radiations Emergence of flowering plants has two important facets: 1. Radiation - large number of species resulted 2. Adaptive - exploited incredible array of ecological strategies or niches • in 130 my angiosperms dominate biomes from tropical forests to arctic tundra . . . Adaptive Radiations • . . . rainfall gradients from the wettest to the most arid habitats on earth . . . Adaptive Radiations • . . . and exploited reproductive biology in elaborate outcrossing and seed dispersal methods to forgoing sex altogether via apomixis and parthenogenesis Adaptive Radiations • . . . life forms from giant emergent tropical trees to the tiniest aquatic duckweeds . . . Adaptive Radiations • Angiosperms show all necessary characteristics of an adapative radiation • Key innovation spurring this adaptive radiation? flowers? triaperturate pollen? vessels? Variation in Lineage Diversity Variation in Lineage Diversity Variation in lineage diversity relates to the appearance of unequal numbers of species in sister lineages Variation in lineage diversity relates to the appearance of unequal numbers of species in sister lineages Besides some unique exceptions, the expectation is that sister lineages should show roughly equal numbers of species - as they are equal in age 1. Differential extinction One lineage (clade (clade 1) 1) is more diverse simply because the other was maladapted perhaps to a changing environment What are the exceptions? Variation in Lineage Diversity Differential extinction is well known in the fossil record: 6 great extinction events Pleistocene megafauna Variation in Lineage Diversity Differential extinction is well known in the fossil record: Diverse lycopods & horsetails in Carboniferous Variation in Lineage Diversity Variation in lineage diversity relates to the appearance of unequal numbers of species in sister lineages Variation in Lineage Diversity Flowering plants show remarkable ability to co-evolve with other organisms: Pollination 2. Coevolution One lineage (clade (clade 2) 2) is more diverse because of the ability to co-evolve with other organisms Variation in Lineage Diversity Flowering plants show remarkable ability to co-evolve with other organisms: Chemical arm’ arm’s race Scutellaria Variation in Lineage Diversity Variation in lineage diversity relates to the appearance of unequal numbers of species in sister lineages 3. Adaptive radiation One lineage (clade (clade 2) 2) is more diverse due to combination of species radiation and adaptation into many ecological zones perhaps due to the origin of a novel feature Phyllobrotica Adaptive Radiations Adaptive Radiations “. . . species occasionally arriving after long intervals in a new and isolated district, and having to compete with new associates, will be eminently liable to modification, modification, and will often produce groups of modified descendants” [Darwin, 1853] descendants” “. . . an isolated region, if large and sufficiently varied in its topography, soil, climate and vegetation, will give rise to a diversified fauna according to the law of adaptive radiation from primitive and central types. Branches B ranches will spring off in all directions to take advantage of every possible opportunity of food.” 1900] securing food. [Osborn, 1902] food.” First use of term adaptive radiation Adaptive Radiations “. . . adaptive radiation strictly speaking refers to more or less simultaneous divergence of numerous lines all from much the same ancestral adaptive type into different, also diverging adaptive zones. [Simpson, 1953] zones.” Issues in Adaptive Radiations • It is clear that few of the classic cases of adaptive radiation have been studied rigorously from a combined systematic and ecological point of view Two main issues: Issues in Adaptive Radiations Issues in Adaptive Radiations 1. The very characters whose diversification is being examined (e.g. beak size, shape, function in Darwin’ Darwin’s finches), can also be used to determine relationships and classify the organisms possessing them - potentially circular! circular! 2. Extreme convergence and divergence is likely in groups that are undergoing adaptive radiations Divergence: Divergence: changes in homologous structures among related species; changes permit each species to specialize in different environments Convergence: Convergence: changes in analogous structures among unrelated species; changes permit each species to specialize in the same environment Issues in Adaptive Radiations These two issues in studying adaptive radiations are best addressed by using an independent source of information molecular phylogenetic characters Ecology Biogeography Morphology Genetics Phylogeny Development Taxonomy Cytology Adaptive Radiations Illustration of these problems with 3 examples of adaptive radiation Rift Valley Cichlids Rift Valley Cichlids Cichlids possess a double jaw system, the pharyngeal jaw is thought to be a key innovation for species proliferation and divergence in feeding strategies Cichlids possess a double jaw system, the pharyngeal jaw is thought to be a key innovation for species proliferation and divergence in feeding strategies mtDNA tree • species with similar feeding strategies between lakes related? • species showing different feeding strategies within a lake related? • divergence within each lake! lake! • convergence between lakes! Lake Tanganyika Lake Malawi Salvia Staminal Lever The giant genus Salvia (Lamiaceae) possesses two stamens with elongated connective tissue Lake Tanganyika Lake Malawi Salvia Staminal Lever Posterior thecae abort, fuse, and can form a lever device a p 4 stamens 2 stamens connectives Salvia Salvia Staminal Lever The resulting staminal lever has been regarded as a key innovation for the species diversification in Salvia via pollination shifts What does molecular phylogenetics indicate? Jay Walker _ UW Grad Salvia Staminal Lever lever mechanism 250 spp. 500 spp. 90 spp. Hawaiian Island Radiations Isolated, oceanic islands provide some of the most classic examples of adaptive radiation • isolation - once you get there, you can’ can’t go back NE trade winds 2 volcanic ridges • great ecological diversity - many niches to exploit • low diversity many niches open • low competition, predation, herbivory - you can be different • Salvia is polyphyletic with 3 separate lineages of “Salvia” each sister to other genera without elongated connective • lever mechanism evolved convergently 3 times • lever mechanism correlated with significant species diversification each time it evolved relative to sister lineages - key innovation! Hawaiian Island Radiations Isolated, oceanic islands provide some of the most classic examples of adaptive radiation • archipelago is a series of geologically dated islands • fixed volcanic hotspot but Pacific plate conveyor belt Hawaiian Island Radiations Isolated, oceanic islands provide some of the most classic examples of adaptive radiation Hawaiian Island Radiations Best studied group is the Hawaiian silversword complex Phylogenetics, cytology, biogeography, ecology, physiology, hybridization, evolution • older to younger islands allow for dispersal biogeographical analysis Silverswords Hawaiian Island Radiations Kauai-11 endemic Silversword Cladogram (simplified) Oahu-2 endemic Wilkesia gymnoxiphium Dubautia paleata Maui Nui-7 endemic Hawaii-3 endemic Argyroxiphium sandwicense N 5.2 mya estimate oldest youngest island Plus 5 indigenous species Tarweed (California USA) OG Dubautia paleata Kauai Dubautia waialealae Kauai Dubautia laxa indigenous Wilkesia gymnoxiphium Kauai Wilkesia hobdyi Kauai Argyroxiphium caliginis Maui Argyroxiphium grayanum Maui Argyroxiphium virescens Maui Argyroxiphium sanwicense M&H H Argyroxiphium kauense Hawaii Hawaiian Lobeliads Why the Hawaiian lobeliads? Hawaiian Lobeliads Why the Hawaiian lobeliads? • largest group: 6 genera, 115 species) • 1/9th of native flora • considered derived from 3-5 separate colonizations • phenomenal variation in habitat, life form, flowers, and fruits Hawaiian Lobeliads Why the Hawaiian lobeliads? • appear to have coevolved with the endemic Hawaiian honeycreepers Hawaiian Lobeliads What are the Hawaiian lobeliads? • appear to have coevolved with the endemic Hawaiian honeycreepers • honeycreepers represent a separate adaptive radiation Lobelia gloria-montis Lobelia telekii - Mt. Kenya Hawaiian Lobeliads What are the Hawaiian lobeliads? Hawaiian Lobeliads What are the Hawaiian lobeliads? Brighamii Delissia Hawaiian Lobeliads What are the Hawaiian lobeliads? Hawaiian Lobeliads What are the Hawaiian lobeliads? Clermontia Trematolobelia Hawaiian Lobeliads What are the Hawaiian lobeliads? Hawaiian Lobeliads The Hawaiian lobeliads represent a single (not 5) lineage/colonization! Cyanea Givnish et al. 2009 Hawaiian Lobeliads The Hawaiian lobeliads are an even more spectacular adaptive radiation Hawaiian Lobeliads Remarkable divergent and convergent character evolution - but fruit color is perfectly consistent with relationships Hawaiian Lobeliads Hawaiian Lobeliads Two clock calibrations - using Asterid fossils or using Hawaiian Island ages - place the differentiation of Hawaiian lobeliads at 12-13 mya Two clock calibrations - using Asterid fossils or using Hawaiian Island ages - place the differentiation of Hawaiian lobeliads at 12-13 mya Original colonist arrived in Gardner Pinnacles - large volcanic islands 12-13 mya Hawaiian Lobeliads Hawaiian Lobeliads Lobeliads are one of the oldest radiations of extant Hawaiian biota – but their honeycreeper pollinators would not arrive for another 7-9 my (oh-oh!) But . . . a recent paper shows that the 5 recently extinct Hawaiian Honeyeaters – and thought to be recently derived from AustralAsian Honeyeaters – are in fact 14-17 my old and derived from an American clade waxwings, silky flycatchers, and palm chats Hawaiian lobeliads 13-14 mya Hawaiian Honeycreepers 7 mya Fleischer et al. 2008 Hawaiian Lobeliads Adaptive Radiations . . . Systematics meets Ecology . . . • Early lobeliads had initial radiation with Hawaiian honeyeaters • later radiation of two large genera (Cyanea and Clermontia) pimarily with Hawaiian honeycreepers