Species delimitation in recent New Zealand species radiations

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1 Species delimitation in recent New Zealand species radiations
Heidi M. Meudt Museum of New Zealand Te Papa Tongarewa Wellington, New Zealand What are plant species radiations, and why are they important? Understanding how global plant biodiversity arose and is maintained requires an understanding of plant species radiation - a process of diversification that produces morphologically and ecologically distinct, but genetically similar species. Species radiations are a feature of many world floras including that of New Zealand. Developing our understanding of species radiation will help us to understand the nature, evolutionary potential and adaptability of our flora to environmental change. The well understood geological and climatic record for New Zealand, together with the complexity of our flora provides for a unique model system to investigate plant evolutionary and ecological processes. Making the most of opportunities to study and understand these plants requires interdisciplinary research in palynology, morphology, cytology, ecology, physiology and in studies of genetic variation. It requires the collaboration of biologists, mathematicians, computer scientists, climatologists and geologists. It is with this collaborative spirit in mind that we would like to introduce the New Zealand Plant Radiation Network (NZPRN). The NZPRN aims to bring together researchers interested in botanical research to promote collaboration and discussion of ideas, methods and projects around New Zealand plant radiation. The presentations we are giving were contributed by members of the New Zealand Plant Radiation Network, but of course only some of us can present them. I am Ilse Breitwieser, from the Allan Herbarium, Landcare Research, New Zealand. Together with my co-author, Josephine Ward from Canterbury University, I will give you an introduction to our symposium.

2 The importance of New Zealand for understanding the phenomenon of species radiation Ilse Breitwieser, Allan Herbarium, Landcare Research, New Zealand Josephine Ward, School of Biological Sciences, University of Canterbury, New Zealand

3 NZ is a small island system that became isolated from the supercontinent of Gondwana over 80 mya. The nearest landmass is Australia, 2000 km across the Tasman Sea. Although it is small, NZ has a rich and diverse flora.

4 Indigenous Species Numbers
Green algae: ~1306 Red algae: 488 Diatoms: (+ ? marine) Brown algae: 153 Cyanobacteria: (+ ? marine) Lichens: (388 endemic – 23%) Hepatics: (314 endemic – 52%) Mosses: (115 endemic – 24%) Lycophytes and ferns: (90 endemic – 46%) Seed plants: (1591 endemic – 82%) Members of the New Zealand plant radiation network study algae, lichens, hepatics, mosses, lycophytes, ferns as well as seed plants. In this symposium, we are focusing on plant radiation of flowering plants only – because more than 80% of New Zealand’s indigenous flowering plant species are endemic.

5 What are the origins of this diversity and high percentage of endemism?
A long-standing hypothesis has the origins of the flora in Gondwana before New Zealand separated, with diversity evolving slowly through more than 80 million years of isolation. This is sometimes referred to as the Moa’s Ark hypothesis. The opposing hypotheis is that much of the flora is the result of long distance dispersal. Molecular phylogenetic studies over the last 15 year have given new insights into the origin and evolution of NZ plants. Here ae some examples from 4 flowering plant families, starting with the Asteraceae.

6 Raoulia alliance Anaphalioides Leucogenes Rachelia Ewartia Raoulia
The Raoulia alliance includes part but not all of the New Zealand paper daisies (tribe Gnaphalieae). It comprises over 50 species in 6 genera, and rivals the famous silversword alliance of Hawaii in size and diversity. All species are New Zealand endemics except for 2 species of Anaphalioides in New Guinea. The range of forms includes whipcord shrubs, a divaricate shrub, heteroblastic shrubs and herbs, cushion shrubs, a liane, large and small-leaved subshrubs, mat-forming perennial subshrubs and herbs, a rhizomatous perennial herb with distant annual shoots, and a facultative annual herb. Raoulia Helichrysum

7 Raoulia alliance: ecological diversity
Habitats range from coastal beaches and cliffs to the tops of mountains, from bogs to semi-deserts, and from shady banks to exposed braided shingle river floodplains and alpine rock faces. Such morphological and ecological diversity is often assumed to be adaptive, but this has not been fully investigated for this or any other New Zealand species radiation.

8 Character expressions in undescribed species “M”
1 2 3 4 5 6 7 8 9 10 Undescribed species “M” Argyrotegium Raoulia subg. Raoulia Raoulia subg. Psychrophyton Helichrysum depressum group The disparate elements of the Raoulia alliance were initially hypothesized to be genetically close. They show a reticulate character distribution among the genera. This is a graphic example showing just a few characters in an undescribed species, linking it to three different genera. We also found a lot of hybridisation between the species. Florets mainly female Fruits papillose Distinct prostrate and uprights shoots Pappus bases not interlocking Pappus tip cells rounded 6. Leaves with black pigment 7. Involucral bracts acute 8. Pappus hairs numerous, in several series 9. Florets few 10. Leaves very small

9 Raoulia alliance: ITS phylogeny
Our molecular phylogenetic studies form 1999 confirmed that the Raoulia alliance is descended from a single New Zealand colonizer, with the 2 New Guinea species probably dispersed from New Zealand. Great amount of homoplasy reflects reticulate pattern of character-state distribution. The very little sequence divergence was found coupled with extensive morphological and ecological diversity indicates a recent rapid burst of speciation. Breitwieser et al., 1999

10 Craspedia Craspedia belongs to the same daisy tribe as the Raoulia alliance, but it is part of a primarily Australian lineage, with only Craspedia found in NZ. Craspedias are rosette herbs. They are characterised by dense double compound flowering heads, not just an aggregation of florets into capitula but also an aggregation of capitula. Although there are only 6 described species in NZ, these are highly variable and 45 distinct undescribed entities have been listed.

11 Craspedia Small sequence variation within the NZ lineage
Neighbour network from AFLP profiles of a wide sample of NZ Craspedia AUS 1 AUS 2 AUS 3 NZ ITS & ETS sequences (nuclear) Small sequence variation within the NZ lineage New Zealand Craspedia Our molecular phylogenetic studies indicate a single origin for New Zealand Craspedia by recent dispersal from Australia. In our combined ITS/ETS tree the New Zealand samples of Craspedia show little sequence variation compared with Australia - despite more morphological & ecological variation in New Zealand Craspedia. Our AFLP neighbour net graph of New Zealand Craspedia shows no tree-like structure --- which suggests rapid morphological and ecological diversification of the NZ lineage. Compared with Australian Craspedia, the New Zealand species show extensive morphological diversity but little sequence divergence, indicating recent rapid diversification in New Zealand.

12 Brachyglottis Brachyglottis repanda Brachyglottis saxifragoides
Brachyglottis is another daisy genus, this time in tribe Senecioneae. It has 31 species, 30 in New Zealand and one in Tasmania. It is morphologically diverse, ranging from rosette herbs to shrubs and small trees and one liane. Brachyglottis cassinioides Brachyglottis cassinioides

13 Brachyglottis alliance 5' trnK / matK ITS
Brachyglottis bellidioides Brachyglottis bellidioides 98 Brachyglottis haastii 62 Brachyglottis haastii 58 Brachyglottis southlandica Brachyglottis southlandica 85 Brachyglottis compacta Brachyglottis compacta 88 Brachyglottis greyi Brachyglottis greyi Bedfordia linearis 100 Bedfordia linearis 91 Bedfordia salicina Bedfordia salicina Brachyglottis brunonis Brachyglottis brunonis 96 Brachyglottis cassinioides Brachyglottis cassinioides Brachyglottis huntii Brachyglottis huntii Haastia recurva Haastia recurva 92 73 100 Haastia sinclairii Haastia sinclairii Brachyglottis adamsii Brachyglottis adamsii Brachyglottis arborescens Brachyglottis arborescens Brachyglottis elaeagnifolia Brachyglottis elaeagnifolia Brachyglottis kirkii Brachyglottis kirkii 100 Brachyglottis perdicioides Brachyglottis perdicioides Brachyglottis repanda Brachyglottis repanda Brachyglottis sciadophila Brachyglottis sciadophila Dolichoglottis scorzoneroides Dolichoglottis scorzoneroides 100 Haastia pulvinaris Haastia pulvinaris Traversia baccharoides Traversia baccharoides Senecio dunedinensis 94 Senecio dunedinensis 53 Senecio quadridentatus Senecio quadridentatus 65 Senecio glaucophyllus Senecio glaucophyllus Senecio rufiglandulosus 63 51 Senecio rufiglandulosus Senecio minimus Our molecular phylogenetic analysis indicate that Brachyglottis is paraphyletic, but that there is a single origin in New Zealand for a group comprising Brachyglottis, the 3 small New Zealand genera Dolichoglottis. Traversia and Haastia, and the ditypic Australian genus Bedfordia. 69 Senecio lautus 43 100 62 Senecio vulgaris Senecio vulgaris Senecio glomeratus 92 95 Senecio glomeratus 86 Senecio minimus Senecio lautus Senecio jabcobaea 85 Senecio jacobaea 59 Petasites fragrans Petasites fragrans Euchiton fordianus 46 Euchiton fordianus 81 29 Inula orientalis Inula orientalis Pachystegia insignis Pachystegia insignis Abrotanella muscosa Abrotanella muscosa 55 Cotula coronopifolia Cotula coronopifolia Calendula officinalis Calendula officinalis Dasyphyllum dicanthoides Dasyphyllum dicanthoides

14 Brachyglottis alliance:
Brachyglottis, Dolichoglottis, Traversia, Haastia, Bedfordia Traversia baccharoides Haastia pulvinaris Brachyglottis and the 3 small New Zealand genera Dolichoglottis, Traversia and Haastia show even more morphological diversity with the addition of mats, cushions and substantial tress. This extensive morphological diversity is again coupled with little sequence divergence, suggesting recent rapid diversification. Brachyglottis cassinioides Haastia sinclairii Dolichoglottis lyallii

15 Myosotis Our next example is from Boraginaceae.
Myosotis is a widely distributed genus of over 100 species. It has 2 centres of diversity, one in western Eurasia and one in NZ. NZ has over 40 species which show extensive morphological and ecological diversity.

16 Myosotis Winkworth et al. 2002 Mol.Phyl.Evol.
ITS, matK, psbA-trnA, ndhF New Zeland Eurasia A molecular phylogenetic study by Winkworth et al. indicates a Eurasian origin for the genus, with a single dispersal event to New Zealand. A low level of genetic diversity coupled with a high level of morphological diversity suggests recent rapid expansion. The few species in Australia, New Guinea and South America have originated from dispersal events from New Zealand.

17 Ourisia We move now to the family Plantaginaeae. Ourisias are herbs or subshrubs with fused, 5-lobed corollas in a variety of shapes and colours. They occupy a wide range of habitats but are often found in wet, rocky, sheltered alpine sites. Ourisia has 29 species almost evenly split between South America and New Zealand, with a single species in Tasmania.

18 Ourisia Meudt & Simpson. 2006. Biol. J. Linn. Soc.
Heidi M. Meudt, Biogeography lecture 3 Flora of New Zealand , Oct 2005 Ourisia Since our last IBC symposium 6 years ago, Heidi Meudt has published extensively on phylogeny, taxonomy, biogeography and species delimitation in Ourisia. The New Zealand and Tasmanian species are the result of a single dispersal event from South America, probably in the New Zealand South Island. The New Zealand ourisias are morphologically distinct, occupy different microhabitats, and represent a recent and rapid species radiation in New Zealand. Meudt & Simpson Biol. J. Linn. Soc.

19 Veronica Veronica evenosa Veronica stricta
Veronica sect. Hebe, also in the Plantaginaceae, has more than 120 species in new Zealand, mostly woody plants with opposite leaves and flowers wit fused corollas and 2 stamens. It was formerly known as the Hebe complex and contains the genera Hebe, Chionohebe, Parahebe, Heliohebe, Leonohebe and Hebejeebie. Veronica pulvinaris Veronica tetragona

20 Veronica lilliputiana Veronica hulkeana Veronica elliptica
Heidi M. Meudt, Biogeography lecture 3 Flora of New Zealand , Oct 2005 Veronica tubata Veronica lilliputiana Veronica hulkeana Veronica elliptica Veronica cupressoides Veronica hookeriana Veronica tetragona Veronica salicifolia It contains a vast array of forms from tiny herbs to subshrubs, mats, cushions, whipcord shrubs, other forms of shrubs and a few small trees. It is found from the coast to the alpine zone in a wide range of habitats. There are also a few species in South America, Australia, French Polynesia, and New Guinea. Veronica chionohebe Veronica raoulii Veronica venustula Veronica speciosa Slide courtesy of Phil Garnock-Jones

21 Albach & Meudt (2010); Evonne Low, thesis
hebe clade sun hebe clade speedwell hebe clade Veronica Molecular phylogentic studies have shown descent from a single New Zealand ancestor and once again the pattern of low sequence divergence coupled with extreme morphological and ecological diversity, suggesting rapid and recent diversification. The species radiation began about 9 million years ago and and had 2 major phases, first into 5 major clades , perhaps coinciding with the opening up of colder, unforested habitats, and then much later, beginning about 4 mya, diversification within the true hebe – clade, which now contains three quarters of the total species. Several small clades radiated into distinct habitats. In the most recent molecular phylogeny of Veronica these are treated by Dirk Albach and Heidi Meudt as informal groups: The true hebes sun hebes speedwell hebes snow hebes and semi-whipcord hebes snow hebe clade semiwhipcord hebe clade

22 Ranunculus Our next example is in the family Ranunculaceae. Ranunculus is a worldwide genus of about 500 species of herbaceous plants with typically yellow, unspecialized flowers. The informally named New Zealand Alpine Group has 17 species in New Zealand and 2 in Australia, all alpine except for one in the New Zealand subantarctic islands. This group is phenotypically and ecologically very diverse. R. sericophyllus R. pachyrrhizus

23 Phylogenetic affinities, species delimitation and adaptive
Carlos Lehnebach 2008: Phylogenetic affinities, species delimitation and adaptive radiation of New Zealand Ranunculus. (PhD thesis) Carlos Lehnebach confirmed in his PhD that the New Zealand Alpine Ranunculus Group originated from a single dispersal to New Zealand. His study showed low sequence divergence. Therefore adaptive species radiation was assumed. Carlos tested this in his PhD and will talk about his results in this symposium.

24 Species radiation Evolution from single found population into array of morphologically and ecologically diverse species As you see, molecular phylogenetic studies of species-rich genera or groups of genera in NZ have shown a similar pattern time after time: a pattern of evolution from a single founder population into an array of morphologically and ecologically diverse species. These diverse species are genetically similar, indicating rapid evolution. A species radiation is rapid evolution from a single founder population into an array of morphologically and ecologically diverse species. Such patterns are often called species radiations. It is becoming more and more apparent that New Zealand is a hotspot for these species radiations.

25 Why does NZ have such a wealth of species radiations?
Firstly, it’s a small area that has been isolated for a very long time. Unlike on a continent, it can’t be readily colonized by neighbouring species. And there is of course its geology – since the early Miocene, New Zealand has lain at the boundary of the Pacific and Australian plates. Tectonic activity in the late Miocene and accelerating through the Pliocene, 5 to 2 mya, led to the rapid uplift of the axial mountains, as well as volcanic activity and marine transgressions. Further massive changes in landform and climate came with the glacial-interglacial cycles from two and a half million to 14,000 years ago, as the advancing and retreating ice transformed the landscape and changed the climate from cold and dry to warm and moist and back again. Plant survival would often depend on the ability to cope with changing environments. Many would become extinct. But for those that could do so there were great opportunities for expansion and diversification into a myriad of new habitats. So in the last 5 million years, plants with the potential for evolutionary diversification have radiated into a range of forms and habitats, to produce much of the remarkable diversity of the present day flora. McGlone, M., Stevens, G. & McCulloch, B. Prehistoric New Zealand Heinemann Reed, Auckland.

26 New Zealand Plant Radiation Network
Species radiation: Significance of polyploidy Species delimitation Impact of hybridisation Adaptive radiations Drivers of plant diversification [Mention last symposium to introduce this one ] In this symposium we will examine recent progress in understanding some factors that may have contributed to these species radiations.

27 Polyploidy Polyploidy common in New Zealand flora, e.g., Raoulia alliance, Veronica Polyploidy common in New Zealand plant radiations Polyploidy is a significant factor in plant evolution. It is important as genome duplications within species, and it is particularly important following hybridization between species , as a means of facilitating meiotic pairing and thus hybrid fertility. Polyploids are common in NZ plant species radiations.

28 Three ploidy levels: L. grandiceps, L. leontopodium: diploid L
Three ploidy levels: L. grandiceps, L. leontopodium: diploid L. neglecta: tetraploid L. tarahaoa: octoploid Leucogenes L. leontopodium L. grandiceps For example, in the Raoulia alliance, there are three ploidy levels within Leucogenes, ascending from diploid L. grandiceps and L. leontopodium, through tetraploid L. neglecta, to octoploid L. tarahaoa. Brian Molloy suggested in the 1990ies that this could have arisen from two polyploid events: the first giving rise to tetraploid L. neglecta, and the second subsequently to octoploid L. tarahaoa. L. neglecta insert map here L. tarahaoa

29 Principal components analysis of AFLP data for Leucogenes
AFLP profiles group samples of each species. L. grandiceps L. leontopodium L. neglecta L. tarahaoa Diploid L. leontopodium & tetraploid L. neglecta cluster together. This is consistent with derivation of L. neglecta from L. leontopodium by autopolyploidy. Rob Smissen and I tested Brian’s hypothesis. We examined AFLP profiles, nuclear ITS sequences, and chloroplast sequences for representative samples of the four species to get more insight into the evolution and geographic variation of the species. AFLP profiles strongly group samples of each species. Also, samples of the diploid L. leontopodium and tetraploid L. neglecta cluster together. This is consistent with a derivation of L. neglecta from L. leontopodium by autopolyploidy. However, the octoploid L. tarahaoa does not cluster closely with either L. neglecta or L. leontopodium. This indicates that the species has independent origin. In our second talk, Brian Murray will discuss the evolutionary signficance of polyploidy in the New Zealand flora. Octoploid L. tarahoa does not cluster with either L. neglecta or L. leontopodium. This indicates that the species has independent origin.

30 Pachycladon Some New Zealand plant radiations, such as that in Pachycladon, have produced a relatively small number of species .

31 Myosotis Others, such as in Myosotis, are much more species-rich.
One factor influencing the perceived extent of a radiation is the number of species delimited.

32 New Zealand Ozothamnus
I will give again an example from the New Zealand paper daisies. The genus Ozothamnus in New Zealand has diversified into a range of shrub forms, but the boundaries between them are so obscured that the number of taxa has been reduced from 11 to one.

33 Raoulia : diversity of mat and cushion form
In comparison, the genus Raoulia has also diversified, in this case into a range of mat and cushion forms, but the boundaries between them are clear cut, and Raoulia remains New Zealand’s largest endemic genus in terms of species number - 30. In the third talk in this symposium Heidi Meudt will review how species have been delimited in New Zealand plant species radiations. She will focus on specific examples for which morphological, ecological and genetic data are being generated.

34 Hybrids Raoulia mammilaris X Leucogenes grandiceps
Hybridisation is widely recognized as a potent force in plant evolution. This is because of its potential for producing successful new combinations of features, and even entirely novel features. Hybridisation is remarkably common in the New Zealand flora, often between species of widely different morphology. From such combinations, it was hypothesized that genetic differentiation has not kept pace with that of the phenotype, and that species identity is being maintained by factors other than inability to cross. (This lack of genetic differentiation has now of course been substantiated in a number of molecular phylogenetic studies.) In the Raoulia alliance hybridisation occurs not only across species boundaries, but more surprisingly and controversially, across most generic boundaries. Intergeneric hybrids between diploid members of Leucogenes and other genera of New Zealand Gnaphalieae such as the cushion species of Raoulia are well documented. Here, Raoulia mammilaris on one side, Leucogenes grandiceps on the other and the hybrid in the middle.

35 In fact, every one of the about 50 New Zealand species of Anaphalioides, Ewartia, Helichrysum, Leucogenes and Raoulia is part of a single network of wild hybrid combinations. That are the genera that form the Raoulia alliance I mentioned earlier. From such combinations, it was hypothesized that genetic differentiation has not kept pace with that of the phenotype, and that species and genus identity is being maintained by factors other than inability to cross. (This lack of genetic differentiation has now of course been substantiated by molecular phylogenetic studies.) [Add something on demonstrated importance of ancient hybridization as a driver of species radiation ?] In our 4th talk, Rob Smissen will talk about the impact of hybridisation on reconstructing the evolutionary history of species radiations.

36 Adaptive radiation: Ranunculus lyallii
In the 5th talk in this symposium, Carlos Lehnebach will present evidence for adaptive radiation in two of New Zealand’s most outstanding alpine plant species radiations, those of Ranunculus and

37 Adaptive radiation: Myosotis
M. pulvinaris Adaptive radiation: Myosotis and Myosotis. He will emphasize phenotype-environment correlations and he will introduce studies aimed at understanding the physiological and adaptive advantages of different phenotypes. M. traversii M. colensoi

38 Ecology of plant radiations in New Zealand
Are our plant radiations adaptive and are there adaptive zones? Within radiations is the pattern generalist ancestors, specialised descendants? Do radiations interact so that colonisation chronology impacts on niche dominance and habitat use? The ongoing nature of geological and climatic change makes it all the more critical to understand the drivers of evolutionary change, and to use information such as that from species radiations in New Zealand to contribute to the understanding of large-scale patterns of diversity elsewhere in the world. In the last talk of our symposium Bill and Daphne Lee and collaborators will talk about the ecological context and processes for New Zealand Plant radiations. Since New Zealand is a small country with very few inhabitants, just about 4 Mill, we also have a small science community. However, our strength is cross-disciplinary research. Therefore research results from plant systematists could get used to answer questions such as: are plant radiations adaptive? Or do radiations interact?

39 Conclusion New Zealand ideal for study of plant evolution
Oceanic island Isolation Continental fragment Long fossil record Diverse flora with Gondwana elements and origin from long distance dispersal Dispersal followed by radiation and range expansion Conclusion In conclusion, NZ is an ideal model for the study of plant evolution. Studies on oceanic islands have contributed greatly to the understanding of evolution. New Zealand has many typical oceanic island features such as isolation from continental land masses and topographic and climatic diversity. However, NZ is not an oceanic island system. It is a continental fragment. This gives it added advantages for evolutionary studies, including a long fossil record and a diverse flora with ancient elements from Gondwana, as well as those originating from long distance dispersal. Both the fossil record and molecular phylogenetic studies show evidence of dispersal to New Zealand in the Tertiary, and especially the late Tertiary, from about 5 mya, followed by radiation and range expansion. This coincides with a period of tumultuous tectonic activity and then glacial-interglacial cycles, both of which transformed the landscape and the climate. Some habitats would have been destroyed but many new ones created. These could be colonized by biota with the necessary evolutionary potential.

40 Of course all this change is not just a thing of the past. We are constantly reminded, most recently by events in NZ, Japan and Chile, that landform and climate continue to change. Mountains continue to rise, ice to advance and retreat, sea levels and climate to change. Usually these changes are so slow that they are unnoticeable in a human lifetime. Occasionally changes speed up, as we have experienced at home in ChCh over the last 10 months. Here earth movement has sometimes been in metres both vertically and horizontally. Rock has crumbled and hillsides have fallen, as nature reminds us that change is ongoing, and that evolution is not only something we study but something we are all a part of.

41 Acknowledgements Allan Herbarium staff, Landcare Research
NZPRN members Photos: Phil Garnock-Jones, Peter Heenan, Carlos Lehnebach, Pete Lockhart, Heidi Meudt, John Lovis, and Rainer Vogt