Future of Molecular Systematics
1. Biogeography Ecology
Adaptive Radiations Genetics 2. Ecology Biogeography
3. Genomics Phylogeny . . . Systematics meets Ecology . . . Morphology Taxonomy Ecology and phylogenetics intertwined when looking at Development Cytology the emergence of life forms on earth and their subsequent diversification
Emergence of Life Forms Emergence of Life Forms
• emergence of 3 domains of • rise of major lineages of life with 6+ kingdoms 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 • in 130 my angiosperms dominate ecological strategies or niches biomes from tropical forests to arctic tundra . . . Adaptive Radiations Adaptive Radiations
• . . . rainfall • . . . life forms from giant emergent gradients from the tropical trees to the tiniest aquatic wettest to the most duckweeds . . . arid habitats on earth . . .
Adaptive Radiations Adaptive Radiations
• . . . and exploited reproductive biology in elaborate outcrossing • Angiosperms show all necessary and seed dispersal methods to forgoing sex altogether via apomixis characteristics of an adapative and parthenogenesis 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 Variation in lineage diversity relates to the appearance of unequal numbers of species in sister lineages numbers of species in sister lineages
Besides some unique 1. Differential extinction exceptions, the expectation is that sister lineages One lineage (clade 1) is should show roughly equal more diverse simply numbers of species - as because the other was they are equal in age maladapted perhaps to a changing environment What are the exceptions?
Variation in Lineage Diversity Variation in Lineage Diversity
Differential extinction is well known in Differential extinction is well known in the fossil record: the fossil record: Pleistocene 6 great extinction events megafauna
Diverse lycopods & horsetails in Carboniferous Variation in Lineage Diversity Variation in Lineage Diversity
Variation in lineage diversity relates to the appearance of unequal Flowering plants show remarkable ability numbers of species in sister lineages to co-evolve with other organisms: Pollination
2. Coevolution
One lineage (clade 2) is more diverse because of the ability to co-evolve with other organisms
Variation in Lineage Diversity Variation in Lineage Diversity
Flowering plants show remarkable ability Variation in lineage diversity relates to the appearance of unequal Scutellaria to co-evolve with other organisms: numbers of species in sister lineages Chemical arm’s race
3. Adaptive radiation
One lineage (clade 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 “. . . an issololatteded region, if large and ssufufffiiccieiennttllyy vaaririeedd in its isolated district, and having to compete with new associates, will topography, soil, climate and vegetation, will give rise to a be eminently liable to modification, and will often produce groups diversifsifieied ffaunaauna acaccorcording to thethe law of adaptive radiation from of modified descendants” [Darwin, 1853] primitive and central types. BBrranches will spring off in all directions to takkee advantage of everery possibible opportunitity of securing foodood..” [Osborn, 190200]
First use of term adaptive radiation
Adaptive Radiations Issues in Adaptive Radiations
“. . . adaptive radiation strictly speaking refers to more or less • It is clear that few of the classic cases of adaptive radiation simultaneous divergence of numerous lines all from much the have been studied rigorously from a combined systematic and same ancestral adaptive type into different, also diverging ecological point of view adaptive zones.” [Simpson, 1953] Two main issues: Issues in Adaptive Radiations Issues in Adaptive Radiations
1. The very characters whose diversification is being examined 2. Extreme convergence and divergence is likely in groups that (e.g. beak size, shape, function in Darwin’s finches), can also be are undergoing adaptive radiations used to determine relationships and classify the organisms possessing them - potentially circular! Divergence: changes in homologous structures among related species; changes permit each species to specialize in different environments
Convergence: changes in analogous structures among unrelated species; changes permit each species to specialize in the same environment
Issues in Adaptive Radiations Adaptive Radiations
These two issues in studying adaptive radiations are best Illustration of these problems with 3 examples of adaptive addressed by using an independent source of information - radiation molecular phylogenetic characters
Ecology
Biogeography Genetics
Phylogeny Morphology Taxonomy
Development Cytology Rift Valley Cichlids Rift Valley Cichlids Cichlids possess a double jaw system, the pharyngeal jaw is Cichlids possess a double jaw system, the pharyngeal jaw is thought to be a key innovation for species proliferation and thought to be a key innovation for species proliferation and divergence in feeding strategies divergence in feeding strategies
mtDNA tree
• species with similar feeding • divergence within each lake! strategies between lakes related? • convergence between lakes! • species showing different feeding Lake Tanganyika Lake Malawi Lake Tanganyika Lake Malawi strategies within a lake related?
Salvia Staminal Lever Salvia Staminal Lever The giant genus Salvia (Lamiaceae) possesses two stamens with Posterior thecae abort, fuse, and can form a lever device elongated connective tissue a
p
4 stamens 2 stamens connectives Salvia Salvia Staminal Lever Salvia Staminal Lever lever mechanism The resulting staminal lever has been regarded as a key lever mechanism • Salvia is polyphyletic with 3 innovation for the species diversification in Salvia via 250 spp. separate lineages of “Salvia” pollination shifts each sister to other genera What does molecular phylogenetics indicate? without elongated connective 500 spp. Jay Walker _ UW Grad • lever mechanism evolved convergently 3 times
• lever mechanism correlated with significant species diversification each time it evolved relative to sister lineages - key innovation! 90 spp.
Hawaiian Island Radiations Hawaiian Island Radiations Isolated, oceanic islands provide some of the most classic examples Isolated, oceanic islands provide some of the most classic examples of adaptive radiation of adaptive radiation • isolation - once you • archipelago is a get there, you can’t series of geologically go back dated islands • fixed volcanic NE trade winds fixed volcanic • great ecological hotspot but Pacific diversity - many plate conveyor belt 2 volcanic niches to exploit ridges • low diversity - many niches open
• low competition, predation, herbivory - you can be different Hawaiian Island Radiations Hawaiian Island Radiations Isolated, oceanic islands provide some of the most classic examples Best studied group is the Hawaiian silversword complex of adaptive radiation Phylogenetics, cytology, • older to younger biogeography, ecology, islands allow for physiology, hybridization, evolution dispersal biogeographical analysis
Silverswords Hawaiian Island Radiations Kauai-11 endemic Silversword Cladogram (simplified) Tarweed (California USA) OG Oahu-2 endemic Dubautia paleata Kauai Dubautia waialealae Kauai Dubautia laxa indigenous Wilkesia gymnoxiphium Wilkesia gymnoxiphium Kauai Argyroxiphium Dubautia paleata Maui Nui-7 endemic 5.2 mya Wilkesia hobdyi Kauai sandwicense estimate Argyroxiphium caliginis Maui Argyroxiphium grayanum Maui Argyroxiphium virescens Maui Hawaii-3 endemic N oldest Argyroxiphium sanwicense M&H Argyroxiphium kauense Hawaii youngest island
Plus 5 indigenous species Hawaiian Lobeliads Hawaiian Lobeliads Why the Hawaiian lobeliads? Why the Hawaiian lobeliads?
• largest group: 6 • appear to have co- genera, 115 species) evolved with the • 1/9th of native endemic Hawaiian flora honeycreepers • considered derived from 3-5 separate colonizations • phenomenal variation in habitat, life form, flowers, and fruits
Hawaiian Lobeliads Hawaiian Lobeliads Why the Hawaiian lobeliads? What are the Hawaiian lobeliads?
• appear to have co- evolved with the endemic Hawaiian honeycreepers • honeycreepers represent a separate adaptive radiation
Lobelia gloria-montis
Lobelia telekii - Mt. Kenya Hawaiian Lobeliads Hawaiian Lobeliads What are the Hawaiian lobeliads? What are the Hawaiian lobeliads? Brighamii
Delissia
Hawaiian Lobeliads Hawaiian Lobeliads What are the Hawaiian lobeliads? What are the Hawaiian lobeliads?
Clermontia
Trematolobelia Hawaiian Lobeliads Hawaiian Lobeliads What are the Hawaiian lobeliads? The Hawaiian lobeliads represent a single (not 5) lineage/colonization!
Cyanea
Givnish et al. 2009
Hawaiian Lobeliads Hawaiian Lobeliads
The Hawaiian lobeliads are an even more spectacular adaptive radiation Remarkable divergent and convergent character evolution - but fruit color is perfectly consistent with relationships Hawaiian Lobeliads Hawaiian Lobeliads
Two clock calibrations - using Two clock calibrations - using Asterid fossils or using Asterid fossils or using Hawaiian Island ages - place the Hawaiian Island ages - place the differentiation of Hawaiian differentiation of Hawaiian lobeliads at 12-13 mya 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 But . . . a recent paper shows that the 5 their honeycreeper pollinators would not arrive for another 7-9 my (oh-oh!) 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 . . .
• later radiation of two • Early lobeliads had large genera (Cyanea and initial radiation with Clermontia) pimarily with Hawaiian honeyeaters Hawaiian honeycreepers