The evolution of the chelicerate life cycle

A comparative study is made of the life-cyle in Chelicerata, and its evolution. Various types of forms or instars, and various evolutionary phenomena are distinguished. They are arranged in a chronological diagram constituting a general model of the evolution of the chelicerate life-cycle. A glossary is added in which terminology is defined.In the present paper, Chelicerata are classified according to van der Hammen (1977); the classification of Mites is based on van der Hammen (1972b).     

Morphometrics and adaptatives aspects in africanized honeybees (Apis mellifera)

The introduction of the African bees (Apis mellifera scutelata) in Brazil and their expansion in the American Continent created the opportunity to study the process of species adaptation in a new environment. In that process, within intra-specific variability, normalising selection can favour individuals that present a better adaptative morphology and they will constitute the most frequent type found in the population. To test that hypothesis morphometric analyses in samples of colonies of africanized bees and in samples of the populations were performed. The development of the colonies was also evaluated in terms of the amount of their brood, honey and pollen. Analysis of the data indicates that more developed colonies are formed by individuals closer to the population average with concerning morphological traits.     

Pollen morphology in <Emphasis Type="Italic">Lysipomia</Emphasis> (Campanulaceae: Lobelioideae) and interpretation of shape artifacts

The pollen of 32 species of Lysipomia was examined by light, scanning, and transmission electron microscopy. Two pollen types occur in the genus: 3-colporate and 6-colporate. The 3-colporate condition occurs in only two species, L. laciniata and L. pumila. The remaining 30 species are 6-colporate, a condition known from only one other genus in the Campanulaceae. Surface sculpturing among the species is uniformly striate. Pollen shape was highly variable within a single individual in comparisons of pollen gathered from herbarium specimens, FAA preserved material collected in the field, and fresh pollen from cultivated individuals grown from seed. Shape may change from oblate spheroidal to subprolate as a result of drying time and temperature, and should not be used as a morphological character in systematic studies if infraspecific variation is seen. When fresh or preserved pollen is not available, rehydrated pollen should be compared to reduce the possibility of inadvertent artifact production confounding the analysis of morphological data.     

Floral morphology,micromorphology and palinology of selected Sedum s.l. species (Crassulaceae)

Sedum L. (Crassulaceae) is a large and taxonomically difficult genus whose delimitation and classification are under debate. Due to the controversial results of previous cytological, morphological, and molecular studies, further investigations are needed in order to gain a shared taxonomy of the current recognized species clades. In the present paper, morphological and micromorphological features of 23 selected Mediterranean species of Sedum s.l. – collected from exsiccata or fresh specimens throughout Italy – were investigated, in order to provide additional data toward their classification above species level. In particular, the study focused on flower structure and morphology, floral epidermal surfaces and pollen morphology. The distribution pattern of the examined microcharacters across the species revealed a wide range of variation and different combinations of the single characters. NMDS analysis allowed individuating discrete groups that showed a general consistency with the current systematic delimitation of species groups. Our study also evidenced for the first time the wide morphological variability of nectaries and of the glandular indumentum, not previously investigated in detail. In addition, we proposed the combined use of floral diagrams and floral formulae as valuable tools in studying the variability of flower structure at genus level.     

Morphologic variation of two key biostratigraphical proteaceous-like pollen taxa across the Cretaceous–Paleogene boundary in northern South America

Echitriporites trianguliformis and E. suescae comb. nov. are two species of proteaceous-like triaperturate pollen that have been widely reported in several sedimentary sequences from northern South America, especially in Colombia and Venezuela. Despite their biostratigraphic significance and because of their morphological similarity, distinction between the two species has been difficult, leading to a biased understanding of their chronostratigraphic ranges. In this study, we compare 75 pollen grains spanning the Maastrichtian–Danian time interval through traditional and geometric morphometrics, and a newly proposed Procrustes-based method (index of pollen curvature). Traditional assessments show subtle variation between specimens; however, geometric morphometrics and the curvature index allow quantifying morphological differences in the degree of concavity-convexity through time. Therefore, geometric morphometrics and curvature index results enable us to constrain the stratigraphic ranges of both taxa. We suggest a coetaneous range for E. trianguliformis and E. suescae comb. nov. during the Late Cretaceous, but the presence of only E. trianguliformis after the Cretaceous–Paleogene boundary event. In addition, we propose a threshold value of 1.5 µm for the curvature index as a tool for distinguishing between these two taxa. We conclude that the combination of geometric morphometrics and the curvature index provides a powerful tool to distinguish between morphological closely-related pollen taxa that are difficult to distinguish through both light microscope visual comparisons and statistical analysis of morphometric measurements.     

Geometric craniometric analysis of sexual dimorphism and ontogenetic variation: A case study based on two geographically disparate species, Aethomys ineptus from southern Africa and Arvicanthis niloticus from Sudan (Rodentia: Muridae)

Non-geographic morphometric variation, particularly at the level of sexual dimorphism and ontogenetic (age-related) variation, has been documented in rodents, and useful for establishing whether to analyse sexes separately or together, and for selecting adult specimens for subsequent data recording and analysis. However, such studies have largely been based on traditional morphometric analyses of linear measurements that mainly focus on overall size, rather than shape-related morphometric variation. Unit-free, landmark/outline-based geometric morphometric analyses are considered to offer a more appropriate tool for assessing shape-related morphometric variation. In this study, we used geometric cranial morphometric analysis to assess the nature and extent of sexual dimorphism and age variation within the Tete veld rat, Aethomys ineptus (Thomas and Wroughton, 1908) from southern Africa and the African Nile rat, Arvicanthis niloticus (Desmarest, 1822) from Sudan. The results obtained were in turn compared with previously published results based on independent geometric and traditional cranial morphometric data from the same sampled populations examined in the present study. While our geometric morphometric results detected statistically significant sexual dimorphism in cranial shape within Ar. niloticus only, previously published results based on traditional morphometric data failed to detect significant sexual dimorphism within this species. However, similar to previously published traditional morphometric data, our geometric morphometric results detected statistically significant age-related variation in cranial shape and size within both Ae. ineptus and Ar. niloticus, with individuals of age classes 5 and 6 being considered to represent adult specimens. Our results highlight the importance of carefully evaluating both size- and shape-related non-geographic morphometric variation prior to the analysis of geographic variation and the delineation of species. Erroneous conclusions of non-geographic variation may have implications in the interpretation of geographic and evolutionary processes that may be responsible for morphological differences at both the inter- and intra-specific levels.     

PATTERNS OF QUANTITATIVE VARIATION IN LEPIDOPTERAN WING MORPHOLOGY: THE CONVERGENT GROUPS HELICONIINAE AND ITHOMIINAE (PAPILIONOIDEA: NYMPHALIDAE)

Wing morphology has historically been a major focus in taxonomic and evolutionary studies of lepidopterans. However, general patterns of quantitative variation and diversification in wing sizes and shapes and the factors underlying them have been unexplored. A morphometric study of wing variation in the convergent heliconine and ithomine butterflies reveals remarkable similarities, both in their morphologies at a given size and in their patterns of allometry and variability. The groups differ primarily in the relative lengths of inner and outer forewing margins, with larger species being more similar across groups than smaller ones. Allometric size-scaling variation accounts for more than 90% of the total morphological variation in the two groups and thus seems to be the major determinant of wing shape. Forewings and hind wings are isometric in size (area) with respect to one another; however, wing shape within and among groups is significantly allometric, resulting in considerable shape differences between small and large species. A strong trend of increasing variability from anterior to posterior along the wings is consistent with hypotheses of aerodynamic constraint. Wings and bodies represent classical morphological “character suites” in that size and shape variation are more tightly correlated within suites than among them. Such complexes argue against the overriding importance of aerodynamic factors, such as wing load and muscle development, in constraining gross morphology.     

Patterns of morphological and genetic variability in UK populations of the shore crab, Carcinus maenas Linnaeus, 1758 (Crustacea: Decapoda: Brachyura)

Previous research has identified extensive inter-population variability in the morphology of the shore crab (Carcinus maenas L.). To determine the source of this variation (genetic or environmental), morphological and genetic data were analysed from crabs collected from eight sites around the coast of the UK. Ten morphometric traits were measured from over 800 crabs and the degree of morphological similarity among sites was calculated using multivariate techniques. Allozyme electrophoresis was used to investigate patterns of genetic similarity. Extensive morphological variability was detected: eight out of the ten morphometric traits analysed were useful when discriminating between crabs from each site. Discriminant function analysis revealed that over 35% of individuals could be classified to their site of origin on the basis of their morphology. In contrast, the allozyme analysis revealed low levels of genetic variability, both within the meta-population and among the crab population at each site. Pairwise comparisons revealed a moderate correlation between the degree of morphological and genetic similarity of crabs at each site, which suggests that the observed phenotypic variability has a genetic component. However, only around 20% of the phenotypic variability detected was associated with the patterns of genetic similarity. This means that patterns of morphological variability in this species are largely determined by the local environmental conditions: local factors could have a within-generation selective influence on mean trait values or C. maenas may exhibit phenotypic plasticity.     

Morphological and Molecular-Genetic Polymorphism of <Emphasis Type="Italic">Canthocamptus staphylinus</Emphasis> Jurine (Harpacticoida,Copepoda, Crustacea)

External morphological and genetic structures of 94 individuals of Canthocamptus staphylinus Jurine (Harpacticoida, Copepoda, Crustacea) from ten European water bodies differing in type, including species type locality, have been analyzed. Significant distinctions of populations on six morphological features and morphometric indexes are established. The variability of both morphological and genetic markers is noted. As a result, two main species morph forms are allocated, typical and small. According to nucleotide, the variety of mitochondrial DNA harpacticoid specimens falls into ten haplotypes and three clades on the phylogenetic tree. One of them corresponds with the group isolated on morphological features (harpacticoids from the Sysola River basin, Komi Republic). The same-sex population from Lake Pääjärvi (Finland), which is morphologically indistinguishable from the population from a type locality, is considerably divergent by nucleotide sequences of mtDNA. The role of geographical isolation and ecological factors in C. staphylinus microevolution is shown.     

Sur un occipital néandertalien des Pradelles (Marillac-le-Franc, Charente) : étude morphométrique préliminaire

In 2001 and 2003, several occipital fragments of a single mature skull were unearthed on the site of les Pradelles (Marillac-le-Franc, Charente). The archaeological context of the deposit allowed us to provisionally assign the remains to the Neandertal taxon. A morphometric study of this piece was conducted in order to confirm its placement in this lineage. Some features observed on this specimen and commonly described among Neandertals (e.g. the presence of a suprainiac fossa) as well as dimensional data locate the les Pradelles occipital within the morphological variability of Neandertals.     

A morphometric analysis of extant and early miocene fossil hominoid maxillo-dental specimens

It is demonstrated in this paper that before we can hope to formulate phylogenetic relationships between and amongst fossil hominoid material it is first necessary to sex the material accurately. In order to determine whether the morphological and morphometrical variability seen in fossil specimens is due to sexual or inter species dimorphism, it is necessary to calibrate fossil specimens against extant hominoid species' morphologies. Only after fossil specimens have been sexed is it possible to differentiate between morphologies that are related to sex and those that are species specific. This will help reduce fossil misallocation. A morphometric analysis of extant and fossilProconsul hominoid material is presented. Each fossil specimen has been sexed according to symplesiomorphic sex morphologies as defined in this paper. After the fossil specimens have been sexed they are analyzed using multivariate statistics. The identification of differing sex patterns within the specimens examined here suggests that a new species ofProconsul may have to be considered.     

Amino acids and sugars in nectar,and their putative evolutionary significance

Individual amino acids and sugars from flower nectar of 32 plant species with different pollination systems were quantified and compared. Data show that there is no correlation between sugar and amino acid concentration. Furthermore there is no correlation between composition and concentration of amino acids and evolutionary advancement, nor any direct relation with pollination systems. However, higher sugar concentrations are often linked with more advanced morphological characters. Nectars from pierced or damaged flowers or nectars contaminated with pollen exhibit modifications and increases in amino acid composition. The presence of proline probably indicates such pollen contamination. Most pollinating animals depend on flower nectar in their energetic requirements, yet innumerable alternative amino acid and protein sources exist. Future research has to consider the relationship between nutritional requirements of pollinating animals and dependence on flower nectars.Dedicated to Prof. Dr.L. van der Pijl, Den Haag, in honour of his 80th birthday.     

Historical ecology meets conservation and evolutionary genetics: a secondary contact zone between Carabus violaceus (Coleoptera, Carabidae) populations inhabiting ancient and recent woodlands in north-western Germany

Only very few cases have documented that an increase in connectivity after a period of fragmentation in ecological time has had an effect on the distribution, genetic structure and morphology of stenotopic species. In this study we present an example of clinal variability in a woodland ground beetle as a result of changes in the connectivity of a landscape during the last two centuries. The study area hosts both the nominate form Carabus violaceus s. str. and the subspecies Carabus violaceus purpurascens, which is ranked as a distinct species by some authors. We studied 12 Carabus violaceus populations from a 30 km transect of ancient and recent forests in north-western Germany. We analyzed three polymorphic enzyme loci, classified the elytron sculpture and measured the shape of the aedeagus tip of the specimens. Carabus violaceus showed secondary gradients both in allozyme markers and morphometric characters in our study area. A genetic differentiation of 16% between the populations is high but lies within the range of intraspecific variability in habitat specialists of the genus Carabus. Populations had no significant deficit of heterozygotes. We found many hybrid populations in terms of morphological properties. This study highlights the conservation value of ancient woodland and the consequences of landscape connectivity and defragmentation on the genetic setting of a ground beetle. Moreover, it shows that differences in the external shape of male genitalia do not prevent gene flow within the genus Carabus. Thus, the establishment of species status should not exclusively be based on this property.     

EXPERIMENTAL STUDIES IN PONDEROSA PINE. I. RELATIONSHIP BETWEEN VARIATION IN PROTEINS AND MORPHOLOGY

Ponderosa pine from California (Pinus ponderosa var. ponderosa) were crossed to one another and also to individuals from the Rocky Mountains (P. p. var. scopulorum). All crosses involved a single mother and a single pollen donor. Patterns of inheritance of electrophoretically-detectable loci followed Mendelian expectations with one exception. Shikimate dehydrogenase showed unpredictable banding patterns in intervarietal crosses. Variability at these biochemical loci was compared to variability at 14 morphometric characters. The relationship between these two levels of variation is complex and permits only one generalization: variability at one level is not a good predictor of variability at the other level.     

Numerical taxonomic study of some tribes of Brassicaceae from Egypt

 A systematic study of 45 taxa belonging to 23 genera of tribes Arabideae, Euclidieae, Hesperideae, Lunarieae, Matthioleae and Sisymbrieae of Brassicaceae from Egypt was conducted by means of numerical analysis based on sixty two morphological characters, including vegetative parts, pollen grains and seeds. On the basis of UPGMA clustering and PCO analysis, four main groups are recognised: Lunarieae, Euclidieae, Matthioleae and a mixed group. Representatives of these groups are clustered together based on characters with high factor loading in the PCO analysis. The tribe Euclidieae is the most homogeneous group, and the tribe Arabideae is the most heterogeneous one. Received November 9, 2001; accepted February 21, 2002 Published online: October 14, 2002 Addresses of the authors: K. Abdel Khalik, (e-mail: kadry.elsayedabdelkhalik@wur.nl), L. J. G. van der Maesen (e-mail: jos.vandermaesen@ wur.nl), W. J. M. Koopman, R. G. van der Berg, Group of Biosystematics, Gen. Foulkesweg 37, NL-6703 BL Wageningen, The Netherlands.     

Oligocene palynoflora in the northern part of South China sea

In the northern part of South China Sea, including Tonkin Gulf, Hainan Island, Leizhou Peninsula and some basins of Guangdong Province, Oligocene deposits are composed of motley, mainly grey, greyish green and dark red clay and sandstone, containing very rich pollen and spores. Most of them are of the components which exsisted in Tertiary, particularly in Oligocene deposits of Northern America and Eurasia, such as Gothanipollis paichanensis Ke & Shi, Ulmus granopollenites Rouse, Symplocos scabropollinia Traverse, Engelhardtia spackmaniana Traverse, etc. At the same time some important Oligocene and Early Miocene pollen types of Borneo are found there, such as Crassoretitriletes vanraadshooveni Germeraad & al., Florschuetzia semilobata Germeraad & al., F. trilobata Germeraad & al., Magnastriatites howardi Germeraad & al., Jandufouria seamrogiformis Germeraad & al., Verrucatosporites usmansis (Hammen) Germeraad & al., Margocolporites vanwijhci Germeraad & al., Psilatricolporites operculatus Hammen & Wymstra, Monoporites annulatus Hammen and Zonocostites sp., etc. On the other hand in Oligocene palynoflora of Borneo there appear pollen types assigned to temperate plants or mountain plants of northern hemispherae (Pinus, Picea, Tsuga, Ephedra and Alnus), which are found in abundence in Oligocene palynoflara of the investigated area particularly in Late Oligocene. All of this indicats that the palynoflora of the Northern part of South China Sea was closely related with that of Borneo in Oligocene. This similarity of palynofloras in the two localities may be due to the geographycal proximity of Borneo to the main land of Asia. In paleoecological aspect, we have found there is plenty of pollen and spores of land and fresh water plants, while those reflecting marine and coastal enviroments (Rhizophora and Sonneratia) are rather scanty. This shows that in Oligocene period the investigated area was a land. Tonkin Gulf along with Hainan Island and Leizhou Peninsula formed an inland depression at that time. Abundant pollen of mountain plants and temperate plants indicats, that there weremountains in or around the area of interest.