Ulf Swenson

Allozyme diversity in endemic flowering plant species of the Juan Fernandez Archipelago, Chile: Ecological and historical factors with implications for conservation

The level and apportionment of allozyme diversity were determined for 29 endemic (and 1 native) species from the Juan Fernández Islands, Chile. Mean diversities at the species level (H(es) = 0.065) are low but comparable to those measured for other insular endemics in the Pacific. A high mean proportion (0.338) of species-level diversity resides among populations. Diversity statistics were compared for species in different ecological-life history trait categories and abundance classes. Species occurring in large populations and those present in scattered small populations have higher diversities than species occurring in one or two populations. Although not significant with the conservative statistical test employed, lower diversity was found in highly selfing species as compared to animal- or wind-pollinated species. The apportionment of genetic diversity within and among populations (G(ST) values) is not significantly different for any of the species categories. Of particular interest is the lack of difference between animal- and wind-pollinated species because previous analyses of large data sets showed higher differentiation between populations of animal- than wind-pollinated species. Historical factors, both ecological and phylogenetic in nature, can influence the level and apportionment of diversity within insular endemics, and thus ecological correlates of diversity seen in many continental species may not apply to endemics. The results have several conservation implications. The preservation of large populations or several small populations is important for conserving diversity within species because when species are reduced to one or two populations, allozyme diversity is sharply reduced. High mean G(ST) values for the species examined illustrate the need for conserving as many populations as possible, either in the wild or in the garden, to preserve maximal diversity within species. Effective conservation strategies require empirical knowledge of each species.

Phylogeny, character evolution, and classification of Sapotaceae (Ericales)

We present the first cladistic study of the largely tropical family Sapotaceae based on both morphological and molecular data. The data were analyzed with standard parsimony and parsimony jackknife algorithms using equally and successive weighted characters. Sapotaceae are confirmed to constitute two main evolutionary lineages corresponding to the tribes Isonandreae‐Mimusopeae‐Sideroxyleae and Chrysophylleae‐Omphalocarpeae. The Sideroxyleae are monophyletic, Isonandreae are polyphyletic as presently circumscribed, and as suggested by the analyses, the subtribe Mimusopeae‐Mimusopinae has evolved within the Mimusopeae‐Manilkarinae, which hence is also paraphyletic. Generic limits must be altered within Sideroxyleae with the current members Argania, Nesoluma and Sideroxylon. Argania cannot be maintained at a generic level unless a narrower generic concept is adopted for Sideroxylon. Nesoluma cannot be upheld in a narrow or broad generic concept of Sideroxylon. The large tribe Chrysophylleae circumscribes genera such as Chrysophyllum, Pouteria, Synsepalum, and Xantolis, but the tribe is monophyletic only if the taxa from Omphalocarpeae are also included. Neither Chrysophyllum nor Pouteria are monophyletic in their current definitions. The results indicate that the African taxa of Pouteria are monophyletic and distinguishable from the South American taxa. Resurrection of Planchonella, corresponding to Pouteria section Oligotheca, is proposed. The African genera Synsepalum and Englerophytum form a monophyletic group, but their generic limits are uncertain. Classification of the Asian genus Xantolis is particularly interesting. Morphology alone is indecisive regarding Xantolis relationships, the combined unweighted data of molecules and morphology indicates a sister position to Isonandreae‐Mimusopeae‐Sideroxyleae, whereas molecular data alone, as well as successive weighted combined data point to a sister position to Chrysophylleae‐Omphalocarpeae. An amended subfamily classification is proposed corresponding to the monophyletic groups: Sarcospermatoideae (Sarcosperma), Sapotoideae (Isonandreae‐Mimusopeae‐Sideroxyleae) and Chrysophylloideae (Chrysophylleae‐Omphalocarpeae), where Sapotoideae circumscribes the tribes Sapoteae and Sideroxyleae as well as two or three as yet unnamed lineages. Morphological characters are often highly homoplasious and unambiguous synapomorphies cannot be identified for subfamilies or tribes, which we believe are the reason for the variations seen between different classifications of Sapotaceae.

Phylogenetic relationships among New Caledonian Sapotaceae (Ericales): molecular evidence for generic polyphyly and repeated dispersal

The phylogeny of a representative group of genera and species from the Sapotaceae tribe Chrysophylleae, mainly from Australia and New Caledonia, was studied by jackknife analyses of sequences of nuclear ribosomal DNA. The phylogeny conflicts with current opinions on generic delimitation in Sapotaceae. Pouteria and Niemeyera, as presently circumscribed, are both shown to be nonmonophyletic. In contrast, all species currently assigned to these and other segregate genera confined to Australia, New Caledonia, or neighboring islands, form a supported clade. Earlier classifications in which more genera are recognized may better reflect relationships among New Caledonian taxa. Hence, there is need for a revision of generic boundaries in Chrysophylleae, and particularly within the Pouteria complex, including Leptostylis, Niemeyera, Pichonia, Pouteria pro parte (the main part of section Oligotheca), and Pycnandra. Section Oligotheca have been recognized as the separate genus Planchonella, a monophyletic group that needs to be resurrected. Three clades with strong support in our jackknife analysis have one Australian species that is sister to a relatively large group of New Caledonian endemics, suggesting multiple dispersal events between this small and isolated tropical island and Australia. The phylogeny also suggests an interesting case of a relatively recent and rapid radiation of several lineages of Sapotaceae within New Caledonia.

Biogeography of Nothofagus supports the sequence of Gondwana break-up

The Austral biota reveals many links between Australasia and South America that have challenged biogeographers for many years. Nothofagus, the Southern Beech, is probably the classical example. With the general acceptanceof continental drift, the break-up of Gondwana is regarded as primarily responsible for many disjunct patterns expressed in the Southern Hemisphere biota. Vicariance biogeography is the principal tool used to investigate biogeographic patterns of extant plant groups, resulting in areagrams or general area cladograms. These are often at odds with current geological knowledge, and on this basis, alternative hypotheses of area relationships and geological history have, therefore, been suggested. One such areagram was recently advocated by Linder & Crisp (1995) in a biogeographic analysis of Nothofagus. Three explanations, often in combination, account for incongruence: long-distance dispersals, extinctions, and erroneous geological models. All of these parameters ought to be considered in the analysis. Here we report the result of a historical biogeographic analysis of Nothofagus where we compare the reconciled trees between a well-supported Nothofagus phylogeny and two geological hypotheses: (1) the current view of Gondwana break-up, and (2) the areagram by Linder & Crisp. Our analysis makes use of extant and extinct taxa, as well as the assumption of long-distance dispersals as defined by maximized vicariance. Our results show that Nothofagus existed prior to the break-up of Gondwana and, most importantly, its present distribution supports, and is dependent upon, the traditional break-up sequence of East Gondwana, compatible with three vicariance events. The areagram, conceived as an alternative geological hypothesis, presents a more parsimonious solution, but fails to explain numerous past distributions in areas such as Antarctica, South America, and Tasmania. We therefore recommend a conservative approach to use (general) areagrams in historical biogeography.

Phylogeny of Hippophae (Elaeagnaceae) Inferred from Parsimony Analysis of Chloroplast DNA and Morphology

Abstract We here report the results from two parsimony analyses of all 15 recognized taxa in Hippophae (Elaeagnaceae), one based on chloroplast DNA (cpDNA), and one based on a combined data set of morphological characters and cpDNA. The genera Elaeagnus and Shepherdia were used as outgroup taxa. In general, the results are congruent with a previous RAPD study, and partly with some of the previous proposed classifications. Monophyly of Hippophae is strongly supported. The most widespread species, H. rhamnoides, is, in spite of low support, most likely monophyletic and distinguished by a single molecular synapomorphy. Due to weak internal support, we refrain from recognizing any sections within the genus. Three taxa, first published as nomina nuda but used by several authors, are here validated and/or described. These are Hippophae neurocarpa subsp. stellatopilosa, H. goniocarpa, and H. litangensis. The latter two were originally suggested to form one species with two subspecies, but they are clearly not monophyletic, a single lineage of evolution, but rather are sister to two different species in the analyses. Together with earlier information from isozymes (unpubl. data) and RAPDs, we believe they are results of two independent hybridisations and we describe them as species. In conjunction, a maternal mode of cpDNA inheritance is suggested. Communicating Editor: Alan T. Whittemore

A phylogenetic analysis of 100+ genera and 50+ families of euasterids based on morphological and molecular data with notes on possible higher level morphological synapomorphies

Abstract. A data matrix of 143 morphological and chemical characters for 142 genera of euasterids according to the APG system was compiled and complemented with rbcL and ndhF sequences for most of the genera. The data were subjected to parsimony analysis and support was assessed by bootstrapping. Strict consensus trees from analyses of morphology alone and morphology + rbcL + ndhF are presented. The morphological data recover several groups supported by molecular data but at the level of orders and above relationships are only superficially in agreement with molecular studies. The analyses provide support for monophyly of Gentianales, Aquifoliales, Apiales, Asterales, and Dipsacales. All data indicate that Adoxaceae are closely related to Dipsacales and hence they should be included in that order. The trees were used to assess some possible morphological synapomorphies for euasterids I and II and for the orders of the APG system. Euasterids I are generally characterised by opposite leaves, entire leaf margins, hypogynous flowers, “early sympetaly” with a ring-shaped corolla primordium, fusion of stamen filaments with the corolla tube, and capsular fruits. Euasterids II often have alternate leaves, serrate-dentate leaf margins, epigynous flowers, “late sympetaly” with distinct petal primordia, free stamen filaments, and indehiscent fruits. It is unclear which of these characters represent synapomorphies and symplesiomorphies for the two groups, respectively, and there are numerous expections to be interpreted as reversals and parallelisms.

Pacific Biogeography of the Asteraceae Genus Abrotanella (Senecioneae, Blennospermatinae)

Historical biogeography of the trans-Pacific Asteraceae genus Abrotanella (Senecioneae, Blen- nospermatinae) was analyzed with cladistic methods. The genus comprises 19 alpine species and is restricted to six areas of endemism, South America, Australia-New Guinea, Tasmania, New Zealand, Stewart Island, and the sub-Antarctic Campbell and Auckland Islands. Two area cladograms were constructed, one conform- ing to the sequence of Gondwanaland break-up, the other considering also the physical barrier of a glaciated Antarctica. Four fully resolved cladograms of Abrotanella were mapped on the area cladograms using the computer software COMPONENT to assess conformity between distribution patterns in Abrotanella and geological area relationships. The analysis revealed a convoluted pattern, suggesting several cases of dispersal. The distribution of the species apparently reflects migration, possibly via stepping stones along former archipelagos, and long-distance dispersals. A possible ancestral area was estimated by the use of ancestral area analysis, reversible parsimony, and Fitch optimization. All methods indicate South America as part of the area where Abrotanella originated. The distribution of at least two species are most parsimoniously explained by dispersals from South America to Stewart Island and from New Zealand to Australia and New Guinea, respectively. Removal of these two allegedly dispersed species from the component analyses reveals an underlying pattem in agreement with geology if South America is considered as the sister area to the West Pacific.

EVOLUTIONARY LINEAGES IN SAPOTACEAE (ERICALES): A CLADISTIC ANALYSIS BASED ON ndhF SEQUENCE DATA

The phylogeny of the Sapotaceae was investigated by DNA sequence analysis of the chloroplast gene ndhF. Three or possibly four main evolutionary lineages were identified. Sarcosperma is the sister group of all other Sapotaceae, which together form two strongly supported monophyletic groups. One large clade with strong support is comprised of the tribes Isonandreae, Mimusopeae, and Sideroxyleae, and also includes the genus Capurodendron of tribe Chrysophylleae. The second large clade with strong support is formed by the tribes Chrysophylleae and Omphalocarpeae, as well as Diploon of tribe Sideroxyleae. Weak support was found for a position of the genus Xantolis as sister to the Chrysophylleae‐Omphalocarpeae, but this genus could equally well constitute a separate evolutionary lineage. The relationships between many of the genera within each of the larger clades are still unclear, but based on the results, a discussion of diagnostic characters in the Sapotaceae from a cladistic perspective is presented.

Multi-gene phylogeny of the pantropical subfamily Chrysophylloideae (Sapotaceae): evidence of generic polyphyly and extensive morphological homoplasy

We present a molecular phylogeny of 26 out of the 28 currently accepted genera in the subfamily Chrysophylloideae (Sapotaceae) using parsimony, parsimony jackknifing, and Bayesian inference. A data matrix of 8984 characters was obtained from DNA sequences of seven chloroplast loci, two nuclear loci, indels coded as binary characters, and morphology. Our phylogenetic reconstruction suggests that Chrysophyllum, Pouteria, and Pradosia, as well as some sections within Chrysophyllum and Pouteria, are all polyphyletic. These taxa were previously described largely on the basis of unique combinations of states for a set of morphological characters. Mapping some of these characters onto one of the most parsimonious trees indicates that the symplesiomorphic flower in the subfamily was probably 5‐merous, had stamens inserted in the tube orifice, staminodes, seeds with foliaceous cotyledons, exserted radicle, and endosperm. These characters have subsequently been lost multiple times and cannot be used as synapomorphies to support broad generic concepts. Despite the high degree of homoplasy some well‐defined clades can be described on the basis of alternative character state combinations. Also, many of these well‐supported clades appear to be restricted to particular geographical areas (e.g. all taxa in Australasia form a monophyletic group). Hence, we suggest that the segregate genera Aningeria, Malacantha, and Martiusella may ultimately be resurrected, and probably also Donella and Gambeya, but their circumscriptions are still unclear. One species, Chrysophyllum cuneifolium, may have originated from a hybridization event between continents where the maternal genome (cpDNA) comes from South America and the nuclear genome comes from Africa.

Phylogeny, diagnostic characters and generic limitation of Australasian Chrysophylloideae (Sapotaceae, Ericales): evidence from ITS sequence data and morphology

Current generic limits in Chrysophylloideae (Sapotaceae) from Australia, New Caledonia and the Pacific islands have been shown not to correspond to monophyletic groups. In particular, revisions of generic boundaries are necessary for Pouteria and Niemeyera. We present the first cladistic study of a large representative sample from these areas based on (i) nuclear ribosomal DNA (nrDNA) sequence data, and (ii) combined data of nrDNA and morphology. The data were analyzed with parsimony jackknifing using equal weights and gaps coded as binary characters. Our results from the two data sets are highly congruent and morphological data often increase support as well as tree resolution. A basal polytomy prevents hypotheses of intergeneric relationships, but several groups receive strong support, and hence, four segregates of Pouteria (Beccariella, Planchonella, Sersalisia and Van‐royena) are resurrected. Four others, Albertisiella, Bureavella, Iteiluma and Pyriluma are rejected. Niemeyera is redefined as a small genus confined to Australia. Generic limits within the sister group to Niemeyera are still unclear, a group that includes Leptostylis and Pycnandra. Furthermore, Van‐royena may have originated from an intergeneric hybridization event. Traditionally used and newly identified morphological characters are scrutinized for their diagnostic value. For instance, the position of stamen insertion within the corolla tube is a strong indication of generic relationship. Unique synapomorphies are rare and genera must be distinguished on character state combinations. Following the results, several taxonomic combinations are necessary (Beccariella brownlessiana, B. macrocarpa, B. singuliflora, B. vieillardii, Pichonia daenikeri, Planchonella asterocarpon, P. dothioense, P. myrsinifolia, P. myrsinodendron and P. xylocarpa).