DEMANDAS SOCIALES EN LA TERCERA GENERACIÓN DE DERECHOS HUMANOS

This section, of the thesis has outlined a possible transport mechanism and direction of orchid “dust seed” to New Zealand from dispersal from a North – West arc. With the paucity of molecular evidence available, relating to CA species, the centre of origin (CEO) is unable to be established. Based on generalised rules, (Ricklefs,1993), involving; genera and species density, site, and climate, it would appear that the CEO of the CA could be Papua New Guinea with Australian or South-West Pacific Island steps to New Zealand. Alternatively, or in combination with a far earlier introduction, orchids may have been present prior to the Gondwana-New Zealand separation, (McGlone, 1985) and adapted to their present morphology through time.

With the advent of molecular analysis, orchids have been accorded a far earlier history than at first thought, (Chase, 2005). The most recent common ancestor of extant orchids, occurred in the Late Cretaceous (76–84 Mya ago), (Ramirez, 2007). Based on the separation of New Zealand from Gondwana some 80mya, (McDowall, 2008; McGlone, 1985; Pole, 2001), it is possible that ancestral fungi and orchid species have been in residence earlier than New Zealand’s separation. However, more recent thought, based on authenticated orchid fossils and molecular evolutionary evidence, places the diversification of Orchidaceae and Epidendroideae into the Early Eocene Climatic Optimum rather than the earlier Late Cretaceous, (Gustafsson, 2010).

Moki Wind vectors and direction

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 plant 50 100 200 500 1000 2000

Distance from plant in mm

Wind force in m/s 26.6 42.00 6.3 22.6 4.1 7.8 12.1

The early Miocene era 21-16.5mya, (Rait, 1992), currently provides evidence of orchids in the New Zealand landscape with the first epiphytic orchid fossils dated from this time being found in NZ, (Conran, 2009). Epiphytic orchids such as the fossils found (Dendrobium and Earina) which belong to the Australian basal clades of the Vandeae / Cymbideae, Epidendreae (Earina) and the Australasian clade of Dendrobium (sensu lato) suggest that the NZ orchid genera have arisen from long distance wind dispersal from Australia and/or New Guinea.

The universal character of the Orchidaceae is the obligate mycoheterotrophic requirement of orchid seed prior to germination, (Burgeff, 1936; Curtis, 1939; Rasmussen, 1995). (see Section B Chapter 1). The Dikarya : Glomeromycotina, Ascomycotina and Basidiomycotina are ancestral to the various mycorrhizal taxons, (Selosse, 1998), and have been recorded as being present in the Australian section of Gondwana, (Lepp, 2005).

Diversification events, estimated to occur from 30mya, were obtained from nucleotide substitution rates in the fungal 18S rDNA gene, Moncalvo (2008). This phylogenetic construct from a worldwide sampling of ITS rDNA sequences revealed eight clades: that correlate with the geographic origin of the strains.

A. One Southern Hemisphere clade. B. One Southern Hemisphere, Eastern Asia clade. C. Two temperate, Northern Hemisphere clades. D. Three Asian clades. E. One neo-tropical clade,

Paleoclimatology provides evidence, based on phylogenetic reconstruction of a worldwide sampling of ITS rDNA sequences of Basidiomycota, that fluctuations of climate occurred regularly throughout the South Pacific-Asian-Australasian area, (Parrish, 1982). Shifts in the long-distance overall dispersion of the basidiomycete Ganoderma applanatum through the Asian- Australasian region by episodic events of dispersal within the Southern Hemisphere has been recorded, (Moncalvo, 2008).

Analysis of the Southern Hemisphere clade, indicated restricted gene flow with vicariance by distance and then island type strain development and speciation. This indicates that dispersal bias plays an important role in explaining the Southern Hemisphere distribution of many fungal taxa, (Moncalvo, 2008).

Fungal diversification and existence in New Zealand anteceded the orchid evidence. Indicating that potential mycorrhizal fungi could have been present to initiate germination of orchid seed embryos and implement the naturalization of vagrant long distance orchid species carried to New Zealand by long distance wind dispersal. The mycorrhizal requirement of seeds of the Orchidaceae have a broad spectrum of orchid mycorrhizal diversity compared to the adult plant , (Hadley, 1970; McCormick, 2004; Rasmussen, 1995). Fungal endophytes of N. iridescens are identified and discussed in Section B Winds over the southwestern Pacific, from the mid to late Campanian (Mid / Late Cretaceous) period 80-70 mya to the present time, shifted South and retracted Northwards in conjunction with the North hemisphere interstadial

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periods, (Denton, 2010), thus,.giving a greater latitudinal range of origins for wind carried long distance seed dispersal over a period of time. .

Dehiscence in N. iridescens occurs between the December to January- February period and appears to be related to climatic conditions. Vegetative propagation occurs through the formation of root tubers “droppers” (Fig. 3.2) on the plant over the wet cool winter / spring season. As the summer season becomes dryer the droppers commence aestivation and thus provide protection to the plant over the summer autumn drought periods. When the dry period ends the winter wet period, June July, initiates the droppers to activate and produce the current seasons shoots and roots. Floral production of N. iridescens then occurs over the period July—September and pod production starts , after fertilization, between September- November period.

Adaptation to local wind conditions and the escalator effect of these to high- level long distance trajectories can be observed and partially calibrated at the immediate plant site. Only a small sample set was measured since the windows of recording opportunities were limited (timing of pod dehiscence, very few pods and lack of suitable weather to initiate the pod dehiscence). The observations do however show that Nematoceras spp. pedicel elongation and dehiscence place the seed pod in a position of optimal wind strength able to support local distribution of Nematoceras “dust seeds” .

On the current evidence it would appear that the New Zealand endemic Orchidaceae have been derived from founder events arising from “dust seed” wind distribution from Australia and / or Papua New Guinea since 30 mya. The range of suitable fungal endophyte taxa was already established in NZ and able to initiate germination of the mycoheterotrophic orchid seed.