Preface: New challenges in anostracan research,a tribute to Graziella Mura

Although conjugating algae are considered to have a cosmopolitan freshwater distribution, numerous ecological and taxonomic investigations revealed that many desmid taxa (at the level of genus, species and variety) are capable of occupying specific geographic zones, characterized by particular climatic attributes. Earlier studies have dealt with influences of temperature and irradiation (photosynthetically active radiation and ultraviolet radiation) on the physiology and ultrastructure of desmids. Yet, recent investigations demonstrated a clear relationship between these climatic factors and the distributional potential of conjugating algae, taking into account their photosynthetic, physiological and ultrastructural adaptations which had been revealed during and after certain temperature and irradiation treatments. Despite the fact that desmids can be considered as high-light-adapted algae, various species- and strain-specific characteristics and adaptations appeared in accordance with the light intensities predominating at their source localities, as estimated by their photosynthetic performance (obtained from PAM fluorometry and oxygen evolution measurements), pigment composition and morpho-anatomical characteristics. Interestingly, the high-light adaptation of photosynthesis as well as the relatively high growth temperature optima for majority of the desmid species investigated may provide some support for Coesel’s hypothesis on the origin of desmids in the tropical zone.     

Contrasts in the large herbivore faunas of the southern continents in the late Pleistocene and the ecological implications for human origins

Aim

Africa is renowned for the current abundance and diversity of its large mammals. The aim of this study was to assess distinctions evident in the functional composition of continental large herbivore faunas during the late Pleistocene before extinctions depleted the megafauna outside Africa.

Location

The African large herbivore fauna was compared with that formerly inhabiting South America, Australia, North America, Eurasia and tropical Asia during the late Pleistocene.

Methods

Pleistocene faunas were reconstructed from the literature in terms of their relative body size composition, grazer/browser contributions and taxonomic representations, omitting forest and island species.

Results

Although the three southern continents were closely similar in the overall species richness of large herbivores that they supported during the late Pleistocene, South America had a predominance of very large herbivores, while most of Australia's mammalian herbivores were relatively small and those of Africa were intermediate. Africa had many more grazers, especially in the size range 100–1000 kg, than other continents. The South American pattern resembled that in North America and Eurasia, while Africa and Australia diverged in different ways.

Main conclusions

Neither the total extent of savannas in each continent nor the morphological features enabling bovid radiation seemed adequate on their own to explain the greater richness of macrograzers in Africa. Africa is characterized by the widespread occurrence of arid/eutrophic savannas, which are unrepresented in other continents. The prevalence of savanna is partly attributable to the high elevation of interior eastern and southern Africa, associated with relatively low rainfall, and to the comparatively high soil fertility, related to volcanic influences. This promoted an abundance and diversity of medium‐sized grazing ruminants unrivalled elsewhere. Indigenous grasses in South America and Australia are less well adapted to withstand severe grazing than the African grasses introduced to support livestock. The locally high abundance of African ungulates presented conditions that facilitated the adaptive transition by early hominins from plant‐gatherers to meat‐scavengers.     

Taxonomic and biogeographical notes on Malagassy desmids (Chlorophyta, Desmidiaceae)

At least 40 % of the desmid taxa encountered during a short stay in Madagascar appeared to be characterized by a non-cosmopolitan distribution. The majority of those taxa have only been reported from Africa or from both Africa and tropical Asia, suggesting dispersal biogeography as underlying model of present day composition of the Malagassy desmid flora. A number of species are taxonomically and biogeographically discussed. Two species are described as new to science: Cosmarium madagascariense sp. nov., and Micrasterias madagascariensis sp. nov.     

Algal community patterns in Slovenian bogs along environmental gradients

In 2005 and 2006, epiphyton samples were collected from seven lowland and montane peat bogs in Slovenia. Water temperature, pH, conductivity, dissolved oxygen and saturation were measured at the same time. Diatoms, desmids and Cyanobacteria were the most abundand groups in species number. Canonical Correspondence Analysis (CCA) was carried out on Cyanobacteria, diatom and desmid flora composition. This analysis showed that shading was the most important parameter in Cyanobacteria distribution and bedrock the most important one in that of diatoms and desmids. Cluster analyses were carried out based on the Cyanobacteria, diatom and desmid data. The Cyanobacteria and diatom data separated sites, whereas the desmid data revealed a temporal aspect.     

Circum-Antarctic continental distribution patterns in pteridophyte species

Four major austral continental distribution patterns are evident in pteridophytes. Twenty-two species are completely circum-Antarctic. Another 39 species are partially circum-Antarctic, occurring in Australasia (Australia and New Zealand) and Africa (including Madagascar) but not South America, while 29 are in Africa and South America but not Australasia, and 13 are in South America and Australasia but not Africa. Two hypotheses are considered as explanations for the patterns: continental drift following the breakup of Gondwana and long-distance dispersal. Fossil evidence indicates that the majority of pteridophyte families involved appeared after the southern continents had drifted apart, so long-distance dispersal is likely to explain the distribution of species in these families on now widely separated continents. For those families extant before the break-up, there is no indication in the fossil record that the species involved were present in Gondwana. Aspects of the ecology of the species that are partly or completely circum-Antarctic indicate that long-distance dispersal, rather than continental drift, is a likely explanation for the patterns.     

Low genetic differentiation between two geographically separated populations of demersal gadiform fishes in the Southern Hemisphere

The distribution patterns of many fishes between the three continents (Africa, Australia, and South America) in the Southern Hemisphere have been uncovered to be influenced by mostly vicariance or historical dispersal. Although some demersal fishes with intercontinental distribution are suggested to be more influenced by current/recent dispersal, few genetic studies have been made for demersal fishes so far. To provide more information for such fishes, genetic divergence was analyzed for two pairs of gadiform species and subspecies distributed around Australasia and South America: the blue grenadier, Macruronus novaezelandiae (from New Zealand) and the Patagonian grenadier, M. magellanicus (from South America) as well as two subspecies of the southern blue whiting, Micromesistius australis pallidus (from New Zealand) and M. a. australis (from South America). The sequence analyses of two mitochondrial DNA regions showed no divergence between Australasian and South American populations of the grenadiers and the southern blue whiting. The microsatellite DNA analysis also indicated significant but very minimal genetic differentiation between the two geographic populations of each pair. These results imply rather recent separation of the two geographic populations. Current/recent dispersal may be an important common factor for determining the distribution of demersal fishes in the Southern Hemisphere. Nonetheless, low but significant genetic differentiation observed requires treating the two populations of the economically important grenadiers and southern blue whiting, respectively, as different stocks for proper resource management.     

DISTRIBUTION OF THE XANTHOPHYLL LOROXANTHIN IN DESMIDS (CHAROPHYCEAE,CHLOROPHYTA)1

Forty-seven species of desmids, representing all four families, were examined for the presence of the xanthophyll loroxanthin by reverse-phase high-performance liquid chromatography. In the Desmidiaceae 28 of the 35 species examined possessed loroxanthin, and in the Mesotaeniaceae two of the six examined had loroxanthin present. All six species of the families Peniaceae and Closteriaceae examined possessed loroxanthin. Although the distribution of loroxanthin appears to be disjunct in the desmids and does not have strict taxonomic significance, it does follow a coherent pattern consistent with current ideas on desmid phylogeny. This pattern suggests that loroxanthin synthesis probably evolved once in the desmid lineage, with one or more subsequent reversals.     

The Southern African orchid flora: composition, sources and endemism

Aim The Southern African orchid flora is taxonomically well known, but the biogeographical and diversity patterns have not yet been analysed. In particular, we want to establish whether (a) it is, like the Southern African flora in general, more diverse than would be expected from its latitude and area; (b) it is an African flora, or whether it contains palaeoendemic relicts of a Gondwanan orchid flora; (c) the diversity and endemism in the orchid flora is concentrated in particular biomes and habitat types; and (d) the patterns of endemism in the flora can be accounted for by current environmental parameters, or whether we need to invoke historical explanations. Location Southern Africa. Methods We used the recent floristic account of the Southern African orchids, in conjunction with a data base of over 14,642 herbarium records, to assign the species and subspecies of Southern African orchids to biomes, habitats, and clades. We explored the relationship between the number and endemism of entities (species, subspecies and varieties) and the biomes and habitats. We compared the richness of this flora with that of 31 other regions from all continents and latitudes, to establish whether the Southern African orchid flora is richer or poorer than expected. We assigned the Southern African orchid species to 16 monophyletic clades and mapped the global distribution of these clades to establish the continental affinities of the flora. Main conclusions The Southern African orchid flora is not any more diverse than could be expected from its latitude or area, while the two tropical African floras included were less diverse than expected. Latitude is an excellent predictor of regional orchid species richness; this might indicate that available habitat is more important for orchid diversity than gross area available, since latitude is probably correlated with the extent of suitable habitat. The Southern African orchid flora is clearly an African flora, since all clades are also found in tropical Africa, while many of them are absent from the Americas or Asia. Conversely, while most African orchid clades are also found in Southern Africa, both the Americas and Asia contain many clades absent from Africa. The distribution of orchid entities among the biomes in Southern Africa is very uneven, with two of the seven biomes totally devoid of orchids. Habitats and biomes that have no equivalent in tropical Africa are high in endemism, and habitats and biomes which are also well developed in tropical Africa are low in endemism. Endemism appears largely explained in terms of modern habitats. However, two patterns (the high endemism in the Succulent Karoo and the lack of endemism in the southern Cape among epiphytic orchids) may also be explained in terms of Quaternary climatic changes.     

THE SEASONAL DISTRIBUTION,ABUNDANCE AND DIVERSITY OF DESMIDS (CHLOROPHYTA) IN A SOFTWATER,NORTH TEMPERATE STREAM1

Suspended and benthic algal communities from a mildly acidic, third-order Rhode Island stream were examined to determine the seasonal distribution, abundance and diversity of the lotic desmids. Within a one-year sampling period, 148 species and 202 subspecific taxa of desmids were identified, representing 23 genera. Species of Cosmarium and Closterium accounted for approximately 70% of the desmids present, and were the most diverse and abundant taxa during all seasons except spring, when Hyalotheca dissiliens was the dominant desmid species. Average abundance and species richness generally were greatest during summer for both suspended and benthic desmids. Most desmids occurred in benthic habitats, and were randomly distributed among substrata. Average seasonal abundance was 7.4 × 10⁴ cells·g^?1 dry wt substratum, among 13 types of substrata. Highest desmid abundance was measured among substrata with intricate morphologies, such as Fontinalis spp., which was associated with 1.2 × 10⁶ desmid cells·g^?1 dry wt substratum, or 1.7 × 10³ cells·cm^?2 substratum. Cell division was observed for 70 desmid taxa, and average seasonal reproduction (based on cell numbers) among all substrata ranged from 4% in winter to 20% during summer. In addition, sexually produced zygospores were found occasionally for H. dissiliens. Desmids were distributed among most substrata examined in this stream, with abundance comparable to reported estimates from softwater lakes and acid bogs. In contrast to established dogma, lotic desmids are not incidental drift organisms, but rather comprise a viable and persistent component of the stream periphyton.     

Phylogeny of the sundews, Drosera (Droseraceae), based on chloroplast rbcL and nuclear 18S ribosomal DNA Sequences

The sundew genus Drosera consists of carnivorous plants with active flypaper traps and includes nearly 150 species distributed mainly in Australia, Africa, and South America, with some Northern Hemisphere species. In addition to confused intrageneric classification of Drosera, the intergeneric relationships among the Drosera and two other genera in the Droseraceae with snap traps, Dionaea and Aldrovanda, are problematic. We conducted phylogenetic analyses of DNA sequences of the chloroplast rbcL gene for 59 species of Drosera, covering all sections except one. These analyses revealed that five of 11 sections, including three monotypic sections, are polyphyletic. Combined rbcL and 18S rDNA sequence data were used to infer phylogenetic relationships among Drosera, Dionaea, and Aldrovanda. This analysis revealed that all Drosera species form a clade sister to a clade including Dionaea and Aldrovanda, suggesting that the snap traps of Aldrovanda and Dionaea are homologous despite their morphological differences. MacClade reconstructions indicated that multiple episodes of aneuploidy occurred in a clade that includes mainly Australian species, while the chromosome numbers in the other clades are not as variable. Drosera regia, which is native to South Africa, and most species native to Australia, were clustered basally, suggesting that Drosera originated in Africa or Australia. The rbcL tree indicates that Australian species expanded their distribution to South America and then to Africa. Expansion of distribution to the Northern Hemisphere from the Southern Hemispere occurred in a few different lineages.     

On the Distribution and Origin of Salix in the World

1. The distribution of Salix species among the continents. There are about 526 species of Salix in the world, most of which are distributed in the Northern Hemisphere with only a few species in the Southern Hemisphere. In Asia, there are about 375 species, making up 71.29 percent of the total in the world, including 328 endemics; in Europe, about 114 species, 21.67 percent with 73 endemics; in North America, about 91 species, 17.3 percent with 71 endemics; in Africa, about 8 species, 1.5 percent, with 6 endemics. Only one species occurs in South America. Asia, Europe and North America have 8 species in common (excluding 4 cultivated species). There are 34 common species between Asia and Europe, 14 both between Europe and North America and between Asia and North America, 2 between Asia and Africa. Acording to the Continental Drift Theory, the natural circumstances which promoted speciation and protected newly originated and old species were created by the orogenic movement of the Himalayas in the middle and late Tertiary. Besides, the air temperature was a little higher in Asia than in Europe and North America (except its west part) and the dominant glaciers were mountainous in Asia during the glacial epoch in the Quaternary Period. Then willows of Europe moved southwards to Asia. During the interglacial period they moved in opposite direction. Such a to-and-fro willow migration between Asia and Europe and between and North America occurred so often that it resulted in the diversity of willow species in Asia. Those species of willows common among the continents belong to the Arctic flora. 2. The multistaminal willows are of the primitive group in Salix. Asia has 28 species of multistaminal willows, but Europe has only one which is also found in Asia. These 28 species are divided into two groups, “northern type” and “southern type”, according to morphology of the ovary. The boundary between the two forms in distribution is at 40°N. The multistaminal willows from south Asia, Africa and South America are very similar to each other and may have mutually communicated between these continents in the Middle or Late Cretaceous Period. The southern type willows in south Asia are similar to the North American multistaminal willows but a few species. The Asian southern type willows spreaded all over the continents of Europe, Asia and North America through the communication between them before the Quaternany Period. Nevertheless, it is possible that the willows growing in North America immigranted through the middle America from South America. The Asian northern type multistaminal willows may have originated during the ice period. The multistaminal willows are more closed to populars in features of sexual organs. They are more primitive than the willows with 1-3 stamens and the most primitive ones in the genus. 3. The center of origin and development of willows Based on the above discussion it is reasonable to say that the region between 20°-40°N in East Asia is the center of the origin and differentiation of multistaminal willows. It covers Southern and Southwestern China and northern Indo-China Pennisula.     

Desmids from the Auvergne (France)

An investigation has been made into the present occurrence and distribution of desmids in the French Auvergne. 27 samples from different habitats revealed the presence of 280 taxa belonging to 251 species, of which 120 had not previously been recorded from this region.The number of taxa per sample varied from 2 to 118; especially the samples from mesotrophic lakes were very rich in desmid species. An annotated list with corresponding figures of the recognized taxa is presented, and previous reports relating to desmids from the study-area are discussed.     

Phytoplankton periodicity in Ogelube Lake,Anambra State,Nigeria during 1979–1980

Ogelube is a tropical oligotrophic lake having a desmid dominated phytoplankton with maximum density during the warmest season. During the rainy season, the lake cools, phytoplankton declines and dominance shifts to algae other than desmids. The lake cools further as harmattan advances, while phytoplankton reaches its minimum, suggesting water temperature to be more important than other environmental conditions. Decrease in phytoplankton density with falling water temperature was probably due to slower reproduction, rather than to increased death rate.     

DNA bar-coding reveals source and patterns of <Emphasis Type="Italic">Thaumastocoris peregrinus</Emphasis> invasions in South Africa and South America

Thaumastocoris peregrinus is a recently introduced invertebrate pest of non-native Eucalyptus plantations in the Southern Hemisphere. It was first reported from South Africa in 2003 and in Argentina in 2005. Since then, populations have grown explosively and it has attained an almost ubiquitous distribution over several regions in South Africa on 26 Eucalyptus species. Here we address three key questions regarding this invasion, namely whether only one species has been introduced, whether there were single or multiple introductions into South Africa and South America and what the source of the introduction might have been. To answer these questions, bar-coding using mitochondrial DNA (COI) sequence diversity was used to characterise the populations of this insect from Australia, Argentina, Brazil, South Africa and Uruguay. Analyses revealed three cryptic species in Australia, of which only T. peregrinus is represented in South Africa and South America. Thaumastocoris peregrinus populations contained eight haplotypes, with a pairwise nucleotide distance of 0.2–0.9% from seventeen locations in Australia. Three of these haplotypes are shared with populations in South America and South Africa, but the latter regions do not share haplotypes. These data, together with the current distribution of the haplotypes and the known direction of original spread in these regions, suggest that at least three distinct introductions of the insect occurred in South Africa and South America before 2005. The two most common haplotypes in Sydney, one of which was also found in Brisbane, are shared with the non-native regions. Sydney populations of T. peregrinus, which have regularly reached outbreak levels in recent years, might thus have served as source of these three distinct introductions into other regions of the Southern Hemisphere.     

The taxonomy and biogeography of the Cladocera

For a variety of reasons, including the analysis of a number of taxa having the same names on different continents, we have concluded overwhelmingly that the chydorid Cladocera are not cosmopolitan in distribution but instead are restricted to smaller regions by their specific ecological requirements for habitat type and also by long-term events in earth history. Recent study ofChydorus faviformis and species resembling it indicates there has been no effective exchange of genetic material between North America and South America, nor between Australia and Asia, nor even between China, Malaysia, and India in southern Asia. Moreover, the patterns of distribution are even narrower than this, as in North America, for example, taxa having the same names in the southern states as in the northern states are differentiated at the species level in some instances, possibly in most. Southern species push northward along the Atlantic Coast for varying distances, one species having reached Nova Scotia and Newfoundland probably during the warm interval in mid-Postglacial time. Thus, when species are studied closely to define their morphological limits, cosmopolitanism disappears, and patterns of distribution emerge that are very similar to those of other animals and plants. The ‘species’ that have been claimed to be cosmopolitan are being shown to be groups or complexes of morphologically similar species instead, each member species of which has a much more restricted distribution than the group or complex as a whole. To explain how the different continents can have such similar lists of ‘species’ without intercontinental dispersal of resting eggs occurring almost continuously, we are suggesting plate tectonics and the drifting of continents, either apart or together.     

A phylogeny of Anisophylleaceae based on six nuclear and plastid loci: ancient disjunctions and recent dispersal between South America, Africa, and Asia

The Anisophylleaceae comprise 29-34 species of shrubs and trees occurring in lowland forests and swamps in tropical Africa, Asia, and South America. These species are placed in four genera with disjunct geographic distributions; Anisophyllea has 25-30 species in South America, Africa, and Malesia; Combretocarpus has one species in Sumatra and Borneo; Poga one species in equatorial Africa; and Polygonanthus two in the Amazon Basin. Here we use a phylogeny based on six nuclear and plastid loci sequenced for 15 species representing the four genera to infer their relationships and the relative and absolute ages of the range disjunctions. Combretocarpus is sister to the other three genera, and Polygonanthus then sister to Poga and Anisophyllea. Ansiophyllea, represented by 12 species from all three continents, is monophyletic. A relaxed Bayesian clock calibrated with the oldest fossils from a relevant outgroup, Tetramelaceae, suggests that the disjunctions between Combretocarpus, Poga, and Polygonanthus date back to the Cretaceous, Mid-, and Upper Eocene, whereas the intercontinental disjunctions within Anisophyllea appear to date back only some 22-23 million years and thus probably result from long-distance dispersal.     

Southern hemisphere biogeography inferred by event-based models: plant versus animal patterns

The Southern Hemisphere has traditionally been considered as having a fundamentally vicariant history. The common trans-Pacific disjunctions are usually explained by the sequential breakup of the supercontinent Gondwana during the last 165 million years, causing successive division of an ancestral biota. However, recent biogeographic studies, based on molecular estimates and more accurate paleogeographic reconstructions, indicate that dispersal may have been more important than traditionally assumed. We examined the relative roles played by vicariance and dispersal in shaping Southern Hemisphere biotas by analyzing a large data set of 54 animal and 19 plant phylogenies, including marsupials, ratites, and southern beeches (1,393 terminals). Parsimony-based tree fitting in conjunction with permutation tests was used to examine to what extent Southern Hemisphere biogeographic patterns fit the breakup sequence of Gondwana and to identify concordant dispersal patterns. Consistent with other studies, the animal data are congruent with the geological sequence of Gondwana breakup: (Africa(New Zealand(southern South America, Australia))). Trans-Antarctic dispersal (Australia <--> southern South America) is also significantly more frequent than any other dispersal event in animals, which may be explained by the long period of geological contact between Australia and South America via Antarctica. In contrast, the dominant pattern in plants, (southern South America(Australia, New Zealand)), is better explained by dispersal, particularly the prevalence of trans-Tasman dispersal between New Zealand and Australia. Our results also confirm the hybrid origin of the South American biota: there has been surprisingly little biotic exchange between the northern tropical and the southern temperate regions of South America, especially for animals.     

Some new and interesting ecological observations on desmids from the Province of Vojvodina (Northern Serbia)

A detailed qualitative investigation of the desmid community in the territory of the Province of Vojvodina (Northern Serbia, part of the Pannonian Plain) revealed a surprisingly high number of desmid taxa. Although most of the desmids were marked as rare, according to the results of physico-chemical analyses of water samples, several taxa were frequently recorded in habitats that are generally deemed unsuitable for desmids. The ecological characteristics of 18 desmid taxa, some of which known as acidophilic and/or oligotrophic, are briefly discussed. The unexpected presence of many desmid taxa is explained by assuming that their tolerance threshold to various physico-chemical parameters has changed considerably. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

A transcontinental comparison of the diversity and composition of tropical forest understory herb assemblages

Although tropical forests are renowned for their high plant diversity, to date there has been no global quantitative evaluation of the local species richness of terrestrial forest herbs in tropical forests. In this paper, richness and composition of terrestrial herb assemblages is compared in tropical forests of America, Africa and South East Asia. We established 86 non-continuous transects of 445 m each. Herb species richness was analysed and compared to six environmental parameters using minimal adequate regression models and simultaneous autoregressive models. At the global scale, we found a close relationship between herb species richness and temperature parameters, with no differences between continents. The subdivision into three main taxonomic groups (ferns, monocots, dicots) showed that each group has distinct relations to environmental factors and differences in richness between continents. Most of the 72 families found have pantropical distributions but 12, 11, and 16 families were significantly over-represented in America, Africa, and Asia, respectively. Although total species richness was closely related to climatic factors, ferns, monocots and dicots were represented by distinct sets of families with varying species richness on each continent. Which species are found at a given site may thus reflect group-specific evolutionary and historical factors.     

藜科植物的起源、分化和地理分布

全球藜科植物共约130属1500余种,广泛分布于欧亚大陆、南北美洲、非洲和大洋洲的半干旱及盐碱地区。它基本上是一个温带科,对亚热带和寒温带也有一定的适应性。本文分析了该科包含的1l族的系统位置和分布式样,以及各个属的分布区,提出中亚区是现存藜科植物的分布中心,原始的藜科植物在古地中海的东岸即华夏陆台(或中国的西南部)发生,然后向干旱的古地中海沿岸迁移、分化,产生了环胚亚科主要族的原始类群;起源的时间可能在白垩纪初,冈瓦纳古陆和劳亚古陆进一步解体的时期。文章对其迁移途径及现代分布式样形成的原因进行了讨论。