RESEARCH

• YASUNI DARWIN INITIATIVE PROJECT LAUNCHED
• EVOLUTIONARY PATTERNS IN PLEUROCARPOUS MOSSES
• AN ENDEMIC DATE PALM OF THE CAPE VERDE ISLANDS?
• AREA CLADISTICS

• PHENOTYPIC PLASTICITY IN ALGAE: A TAXONOMIC DILEMMA

YASUNÍ DARWIN INITIATIVE PROJECT LAUNCHED

Nancy C. Garwood

Yasuní National Park and the adjacent Huaorani Ethnic Reserve form the largest protected area in Ecuador's hyperdiverse Amazonian rainforest. 'Biodiversity basics strengthening sustainability of the Yasuní Amazonian rainforest, Ecuador' is a collaborative project with Pontificia Universidad Católica del Ecuador (PUCE), funded by the UK's Darwin Initiative. Our aim is to enhance conservation and sustainable use of this extraordinary forest by working closely with local Huaorani communities in developing identification guides and educational material that improves communication between all groups concerned with management of the region.

The project was launched in September 2001, when Darwin Fellow Gorky Villa and project co-leader Dr. Renato Valencia visited the NHM (see Fig. 1). In January this year, I travelled to Ecuador. First call was to meet Dr. Hugo Navarrete (a fern taxonomist), who is Director of the Herbarium at PUCE and co-leader of the project (while Renato is on a leave of absence). As the official project title is a bit of a mouthful, and doesn't translate easily into Spanish, the project is locally known as "Intercambio de conocimiento para conservar la biodiversidad en Yasuní". And 'intercambio' - exchange - it was! The focus of my visit was to establish formal agreements with two Huaorani communities, Guiyero and Dicaro, the closest communities to the field station which will be our base - Estación Cientifica Yasuní (ECY). Warm relationships have already been developed between ECY and the people of Guiyero and Dicaro. In both communities, a 'town meeting' was attended by a large and diverse segment of the community - men, women, old, young, children and babies. Gorky first described the objectives of the project, stopping frequently so a member of the community could translate this into Huao for those who did not speak Spanish. Then he read out the agreement, again waiting for it to be translated.

Fig. 1. Renato Valencia and Darwin Fellow Gorky Villa (left) examine specimens in the General Herbarium during their visit to the NHM.

One of our main objectives, based upon earlier discussions between ECY and the communities, is to produce a natural history and identification guide to the 250 most common trees of Yasuní. This will include information from both the Huao and scientific communities and be published in Spanish, Huao, and eventually English. The guide will be a much-needed link between the Huaorani and others involved in conservation, management and ecotourism of the Yasuní forest, but also a vital link between older and younger generations of Huaorani. We had brought along examples of the kinds of books and educational materials we hope to produce during the project with help from the communities - for the communities. "Flora da Reserva Ducke", filled with plant photos, and several Field Studies Council foldout guides, chock-full of colourful diagrams, were particularly helpful. That these were in Portuguese and English was not a stumbling block, as the images of plants spoke a universal language - particularly to the older and more knowledgeable elders who did not speak (let alone read) Spanish.

As the books, guides and copies of the agreement were passed around those assembled and intensively studied, the discussion in Huao about the agreement began - often loud and excited. We "cowori" (non-Huao) found it impossible to follow the direction of the discussions, as one after another individual got up and shouted or whispered. Questions were translated and fired at us. In the middle of discussions at both communities, we feared that all was lost! The biggest concern in Guiyero was that we only wanted ONE name for each tree - that we didn't understand that trees had many names! We assured them that we were interested in learning all the names they used, and why, and would include them in the tree book. But, one by one, each point was discussed and resolved until everyone was satisfied that the agreement was beneficial to the Huaorani as well as the "cowori". Amid broad smiles, the agreements were signed (see Fig. 2)!

Fig. 2. Members of the Huao community of Guiyero with NHM and PUCE staff after the signing of the agreement for cooperation.

Fig. 3. Boyo, Apa and Coeri, from the Huao community of Dicaro, discuss one of the important palms of Yasuni.

Contact: Nancy Garwood

EVOLUTIONARY PATTERNS IN PLEUROCARPOUS MOSSES

Angela Newton

Temperate woodland with abundant pleurocarpous mosses. (Photo: Angela Newton).

Almost half of all extant species of mosses, in about 60 families, are pleurocarpous, that is, with lateral sporophytes and (usually) a creeping growth-form. They can frequently form extensive mats covering the ground, rocks, rotten logs, tree trunks and branches, and are very abundant in temperate woodlands and tropical forests, and in boreal regions. The traditional arrangement into three Orders (Hookeriales, Hypnales and Leucodontales) was based on morphological characters but was rather unsatisfactory, with the position and circumscription of certain species, genera and families changing frequently. Recent work using molecular data has indicated that at least the Hypnales and Leucodontales are paraphyletic and cannot be maintained. Current work at the NHM is focused on resolving the relationships of the pleurocarpous mosses, to provide a stable phylogeny that can be used to study the evolution of the plants and their characters.

Although traditional morphological characters seem to have led to inaccurate conclusions being reached about the relationships of the orders of pleurocarpous mosses, there is still invaluable information to be obtained from this source. Even though the plants are quite small, the morphology is complex, with multiple routes by which very similar features can be derived. Careful examination has revealed differences where none were apparent before, allowing noticeable similiarities to be disentangled and the information to be used, in combination with molecular sequence data, to address questions at several different levels within the pleurocarpous mosses.

A pendulous moss, Zelometeorium patulum, in tropical forest. (Photo: Angela Newton).

One unresolved question has been whether the pleurocarpous mosses form a monophyletic group, or whether there are two groups independently derived from the acrocarpous mosses. The Rhizogoniaceae is a small group of mosses from the southern hemisphere, some of which are acrocarpous and some pleurocarpous, and appear to form a grade from which two major groups of pleurocarpous mosses are derived. Resolution of the relationships of the Rhizogoniaceae is critical to unravelling the evolution of the pleurocarpous mosses, and this is the subject of PhD research by Neil Bell.

Thuidium, a genus of pleurocarpous mosses with a very regular branching pattern. (Photo: Angela Newton).

Within the principal group of pleurocarps, consisting of most members of the superorder Hypnanae, molecular data alone have until recently not provided any useful resolution of the relationships, while inclusion of morphological data has improved resolution, but there has been little support for the groups found. In our current project, molecular sequence data from the chloroplast genes rbcL, rps4 and trnL-F has been extracted in the Botany molecular lab by Cymon Cox and Neil Bell (NHM), for 106 exemplars of mosses from most families of pleurocarps. Together with morphological data, this has been used in phylogenetic analyses using maximum parsimony and maximum likelihood to provide a more resolved topology. Several small groups of pleurocarpous mosses are basal to a larger group that appears to have evolved very rapidly, resulting in a large number of families that are discrete but with very short branch lengths between the groups. In further research it is intended to explore the timing and possible causes of this rapid radiation.

Neckeropsis disticha showing lateral sporophytes. (Photo: Angela Newton).

Contact: Angela Newton

AN ENDEMIC DATE PALM OF THE CAPE VERDE ISLANDS?

Sally Henderson

Praia da Lagoa, Maio. (Photo: S.Henderson).

The African Republic of Cape Verde consists of nine inhabited and several uninhabited volcanic islands set out in the Atlantic Ocean, about 500 km off the most westerly point of the African mainland and 1500 km south of the Canary Islands. Most are rugged and mountainous; three (Sal, Maio, and Boa Vista) are flat, desert islands with sandy beaches. Precipitation is meagre and very erratic - indeed Cape Verde can be seen as an island extension of the Sahel zone. The islands were discovered and colonised by the Portuguese in the 15th century; they subsequently became a trading centre for African slaves and most Cape Verdeans descend from both groups. The islands and their people thus have affinities with both sub-Saharan Africa and Portugal, but are also unique in terms of history, identity, culture and biodiversity.

Phoenix atlantica is a date palm of the Cape Verde Islands that is apparently found nowhere else in the world. Perhaps because the Cape Verdes are a particularly isolated and under-resourced set of islands, or perhaps because palms are notoriously awkward to collect, little is known about the taxonomy, origins and natural history of this magnificent palm. It is currently the focus of a collaborative project between Sally Henderson (NHM), Isildo Gomes (Instituto Nacional de Investigaçao e Desenvolvimento Agrário, INIDA) and Samuel Gomes (INIDA) .

P. atlantica at one of Chevalier's syntype sites, Santigago. (Photo: W.Baker).

Whether or not P. atlantica is in fact a distinct species is unclear. It may be that it merely represents a feral form of the date palm (P. dactylifera), a species which is widely cultivated and whose natural distribution is unknown. The problem is exacerbated by a lack of knowledge on the full extent of morphological variation in P. dactylifera. Fortunately the range of molecular variation has been more fully investigated, providing a basis for making comparisons with the Cape Verdean Phoenix.

Like its taxonomic status, the conservation status of this palm is equally uncertain, a situation epitomised by the exclusion of Phoenix atlantica from the recent Cape Verde Red List because of a lack of data. Information available on the natural distribution of P. atlantica is scant and often inaccurate; in many cases only literature records, often with inexact localities, are available. The problem is further aggravated by the taxonomic uncertainties and because the species is believed to have been planted in some places. Threats to the survival of the species also require investigation, especially the impact of heavy grazing by goats. These are the most common farm stock on the islands and are recognised as presenting the greatest threat to all vegetation; however, no studies have been made of their effects on seedling mortality and the resulting health of P. atlantica populations.

Phoenix, Boavista. (Photo: W. Baker).

In May 2002, fieldwork on Phoenix atlantica was carried out on the four most easterly islands (Sal, Boa Vista, Maio and Santiago). Photographic records, herbarium and DNA collections were made of the palm, and its current distribution and abundance was documented. Subsequent molecular and morphological analysis is yet to be conducted but promises exciting results that will help elucidate the relationship between the Cape Verde Phoenix and P. dactylifera. Historical aspects of the palm (is it native or introduced, if the latter, when and by whom?) are more difficult to answer but molecular work may go some way towards answering such fascinating questions.

The importance of clarifying the taxonomy and conservation status of Phoenix atlantica is clear. Potentially it is one of only two endemic tree species in the Cape Verde Islands and one of only four palm species native to Europe and Macaronesia. However, whether or not Phoenix of the Cape Verdes proves to be distinct from the date palm P. dactylifera, it is clear that it is of prime importance to the locals in terms of shade, food for livestock and materials for building shelters. It also provides welcome relief for the eyes in an otherwise desolate and seemingly endlessly barren landscape.

Phoenix, Boavista. (Photo: W.Baker).

Contact: Sally Henderson

AREA CLADISTICS

Chris Humphries

Because there has been a huge proliferation of methods and sharply contrasting opinions as to what historical biogeography is all about, cladistic (vicariance) biogeography is currently enjoying one of its periodic bouts of navel gazing. Despite the fact that panbiogeography and cladistic biogeography gave great promise for achieving a classification of the areas of endemism for the whole world, the results of nearly forty years of endeavour remain inconclusive for many areas around the Pacific and Indian Oceans and the land masses of the Northern Hemisphere. There are huge questions, for example, about the patterns of change of continents through time and indeed the relationships of areas of endemism of modern biotas. New work is being pursued with an Australian colleague, Malte Ebach, to argue the case that Area Cladistics is the way forward to discover geographic congruence and to demonstrate that many of the other described methods are generative, ad hoc procedures that can be placed on the discard pile.

The general problem is about what causes ambiguity in biogeographic data. Close agreement of several taxon-area cladograms rarely yields a perfect result, even amongst the best examples. For a whole variety of reasons different areas of endemism may be hard to diagnose, because they appear to overlap in terms of their taxonomic components, taxa may not be evenly distributed, or they do not occur in areas that one might expect to find them. In cladistic parlance, ambiguity in distribution data is incongruence and the question we ask is how can the hidden congruent patterns best be resolved.

In devising a method it has been necessary to re-examine the subtle interplay between resolution and information content for both taxa and areas in which the taxa occur, to see whether congruent signals revealing interrelationships of areas can be extracted from noisy, apparently incongruent data. Without going into details, Area Cladistics is a pattern method devised to discover areas of endemism, the relationships between them and the relative positions of continents (or parts of them) through time (see Fig. 1).

Our main finding to date is that geographical incongruence, paralogy, is due to sympatry, extinction and multiple speciation within areas of endemism. Geographical congruence on the other hand is the result of allopatric (geographic) speciation. Vicariance, dispersal and combinations of both, are recognized causes for allopatric speciation. Area cladistics highlights the concept that all these events occur in response to geological changes (e.g. continental drift) either directly, by the formation of geographical boundaries, or indirectly, at the level of ocean currents. Finding one common biogeographic pattern from several unrelated groups is a qualitative approach to interpret the positions of continental margins through time. We believe that producing areagrams (the consensus of two or more taxon-area cladograms) by using area cladistics will add to the body of knowledge that yields more precise interpretations of the Earth's past, and realise the promise of the early pioneers of cladistic biogeography.

Malte Ebach is planning to come to the NHM later this year as a post-doctoral fellow where it is hoped he will undertake some new empirical studies involving a variety of groups of taxa from diatoms to trilobites and undertake theoretical studies with David Williams and me.

Fig. 1. Area Cladistics. (a) Taxic cladogram; (b) Taxic/area cladogram. Note that areas A-C are paralogous (i.e. occur more than once on the cladogram; (c-e) sub-trees removing paralogy; (f) Areagram showing the interrelationships of the areas; (g) Hypothetical distribution map showing the areagram.

Contact: Chris Humphries

PHENOTYPIC PLASTICITY IN ALGAE: A TAXONOMIC DILEMMA

Elliot Shubert

Introduction

Phenotypic plasticity (also morphological variability or polymorphism) refers to the genetically mediated response to external and/or internal environmental changes producing the phenotype, the visible expression of the genotype. Phenotypic plasticity is a general phenomenon, which occurs when the morphology of an organism changes in response to a change in the environment. Phenotypic plasticity is found in many plant taxa, particularly microalgae, but was not readily apparent until investigators started culturing algae in the laboratory.

Phenotypic Plasticity in Desmodesmus The range of phenotypic plasticity in the green alga, Desmodesmus (formerly the spiny form of Scenedesmus) is dramatic. When Desmodesmus is cultured in dilute medium, a four-celled colony with spines is formed (Fig. 1). The position of spines varies according to "species", i.e. on terminal cells only, or on terminal and medial cells, allowing spine number and position to be used as taxonomic characters for species.

Fig. 1. SEM of D. subspicatus UTEX 2532, a 4-celled colony, 10,000x (Shubert & Massalski unpubl.).

Fig. 2. Cyclomorphosis in a clonal culture of Desmodesmus, which exhibits extensive phenotypic plasticity. Individual morphs are more conspicuous during a particular growth stage (after Trainor 1998).

Because phenotypic plasticity is well understood in Desmodesmus, it offered the opportunity of further study. Does phenotypic plasticity occur at the ultrastructural level? Can ultrastructural characters be used to define taxa? What developmental changes occur when colonies are transformed to unicells and vice versa? What is the chemical nature of the highly structured outer wall? Is there a molecular similarity/difference between strains/species? Which genes are controlling phenotypic plasticity? How wide ranging is phenotypic plasticity in taxa from different ecosystems?

Fig. 3. SEM of D. subspicatus UTEX 2532, unicell, 20,000x (Shubert & Massalski unpubl.).

Current Research Programme

In brief, using the SEM Prof Massalski and I discovered that D. subspicatus shows variability at the ultrastructural level. Two strains of D. subspicatus, UTEX 1358 and 2532, were examined in detail for selected wall ultrastructural characters and quantified, such as warts (density), spines (length), openings (diameter), and bristles (presence or absence). Cell and colony dimensions were also measured. A preliminary analysis of morphometric measurements (mean values) of the two strains showed that there was variation between morphs within and between strains. Notably, the wart density of spineless colonies of UTEX 1358 was reduced by 2/3 and cell dimensions were smaller compared to spiny colonies. The spiny unicells of UTEX 2532 are larger with more and longer spines than UTEX 1358. By culturing D. subspicatus in various media, we have demonstrated that unicells are larger than individual cells in colonies and have more spines per cell. Spine length varied between the different morphs. When iron was removed from the medium there were fewer "warts" per sq µm. Thus, care must be exercised when using ultrastructural characters to define species. Our research raises numerous taxonomic questions, including: How do we describe a plastic species whose characters are environmentally controlled, when environments change with time? How do we identify morphological stages of the same organism from field collections?

A project with Dr Wilk-Wozniak demonstrated that many "species" of Desmodesmus inhabit reservoirs in Poland. Again, phenotypic plasticity was not apparent when field samples were examined, but, when Desmodesmus was isolated into culture the full morphological range was observed. We are using the SEM to document their ultrastructural features and compare them to closely related taxa, e.g. Pediastrum. The interesting thing about Desmodesmus is that you do not know where the research will lead you.

A project on the nature of the outer sculptured wall, initiated with Jake Alexander (Imperial College), has proved challenging and interesting. We knew that the wall (described as algaenan) was resistant to degradation (Desmodesmus wall fragments have been found in fossil material). We have tried to destroy the outer wall with various acid treatments (conc. acetic acid, hydrochloric acid, nitric acid and sulphuric acid) and acetolysis, but SEM observations have shown no change in the wall. We are planning to treat the cells with several enzyme treatments, as well as trying additional oxidation techniques. Using a French Pressure Cell (30,000 psi) colonies were broken up into single cells and cell wall fragments. Using the analytical SEM Probe we have found measurable levels of Carbon, Phosphorous, Sulphur, Calcium, Magnesium, Potassium, and Sodium. We are planning to treat the cells with several different enzymes and we are trying different staining protocols.

Dr Paul Hayes (Department of Biological Sciences, University of Bristol) and I are initiating a project to identify the genes controlling development. Desmodesmus is an ideal model organism for investigating the origins of multicellularity and gene control in the production of spines and outer wall ultrastructure. Over the next few years, I foresee that this research programme will produce new and exciting concepts about the evolution and development of Desmodesmus.

Contact: Elliot Shubert