Ecologically relevant cryptic species in the highly polymorphic Amazonian butterfly Mechanitis mazaeus s.l. (Lepidoptera: Nymphalidae; Ithomiini)

The understanding of mimicry has relied on a strong biosystematic framework ever since early naturalists first recognized this textbook example of natural selection. We follow in this tradition, applying new biosystematics information to resolve problems in an especially difficult genus of tropical butterflies. Mechanitis species are important components of Neotropical mimetic communities. However, their colour pattern variability has presented challenges for systematists, and has made it difficult to study the very mimicry they so nicely illustrate. The South American Mechanitis mazaeus and relatives have remained particularly intractable. Recent systematists have recognized one highly polytypic species, whereas earlier work recognized the melanic Andean foothill races as a distinct species: Mechanitis messenoides. Recent molecular evidence suggests M. mazaeus and M. messenoides are genetically well differentiated, but evidence of morphological and ecological differences indicative of separate species was still lacking. Thus, it remains to be conclusively demonstrated whether this is an extreme case of a polymorphic mimetic species, or whether distinct co‐mimetic lineages are involved. Here we provide evidence that M. mazaeus and M. messenoides are ecologically distinct and identify consistent morphological differences in both adult and immature stages. These ecological and morphological differences are correlated with mitochondrial sequence data. In spite of some overlap in almost all traits, wing shape, adult colour pattern, and larval colour pattern differ between the two species, in addition to clutch size and larval host use in local sympatry. Although three well‐differentiated mitochondrial DNA (mtDNA) haplogroups were identified within these two species, one for M. mazaeus and two within M. messenoides, no morphological or ecological differences were found between two mtDNA haplogroups, both of which appear to belong to M. messenoides. We conclude that M. mazaeus and M. messenoides are distinct although highly polymorphic species, each with multiple sympatric co‐mimetic forms, and suggest that further work is needed to clarify the identity of other phenotypes and subspecies of Mechanitis. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 540–560.     

Locust Ion Transport Peptide (ITP): A Putative Hormone Controlling Water and Ionic Balance in Terrestrial Insects

SYNOPSIS. The anterior (ileum) and posterior (rectum) segmentsof the locust hindgut constitute the reabsorptive regions ofthe excretory system, which conserves or eliminates body waterand solutes as required for osmotic homeostasis. Hindgut transportmechanisms in the desert locust have previously been well describedbut the neuropeptide hormones that may naturally control theseprocesses are only now being identified. Ion Transport Peptide(ITP) has been isolated from locust corpus cardiacum (CC) andits full sequence of 72 amino acids deduced from its cDNA. NativeITP has the same actions as crude CC extracts in stimulatingCl^– , Na⁺, K⁺, and fluid absorption and inhibiting H⁺secretion (i.e., influencing pH regulation). The deduced aminoacid sequence of ITP was confirmed by showing biological activityof expressed and synthetic forms of this peptide. ITP has highsequence homology with a large family of crustacean hormonesthat include hyperglycaemic (CHH) and moult-inhibiting hormones(MIH) and is the first member reported outside crustaceans.     

Polydomy in ants: what we know, what we think we know, and what remains to be done

The correct identification of colony boundaries is an essential prerequisite for empirical studies of ant behaviour and evolution. Ant colonies function at various organizational levels, and these boundaries may be difficult to assess. Moreover, new complexity can be generated through the presence of spatially discrete subgroups within a more or less genetically homogeneous colony, a situation called polydomy. A colony is polydomous only if individuals (workers and brood) of its constituent nests function as a social and cooperative unit and are regularly interchanged among nests. This condition was previously called polycalic, and the term polydomy was used in a broader sense for a group of daughter nests of the same mother colony (implying limited female dispersal), without regard to whether these different nests continued to exchange individuals. We think that this distinction between ‘polycaly’ and ‘polydomy’ concerns two disparate concepts. We thus prefer the narrower definition of polydomy, which groups individuals that interact socially. Does this new level of organization affect the way in which natural selection acts on social traits? Here, after examining the history of terms, we review all ant species that have been described as expressing polydomous structures. We show that there is no particular syndrome of traits predictably associated with polydomy. We detail the existing theoretical predictions and empirical results on the ecology of polydomy, and the impact of polydomy on social evolution and investment strategies, while carefully distinguishing monogynous from polygynous species. Finally, we propose a methodology for future studies and offer ideas about what remains to be done. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 319–348.     

Cluster root development in Grevillea robusta (Proteaceae). II. The development of the endodermis in a determinate root and in an indeterminate, lateral root

Light, fluorescence and electron microscopy were employed to follow the development of the endodermis in cluster roots and lateral roots of Grevillea robusta A. Cunn. ex R. Br. Endodermal cells had three different origins: rootlet endodermis arose from the rootlet meristem; endodermis covering the primordium shortly after initiation came from division of parental endodermis; cells at the junction between parent and rootlet endodermis developed from re-differentiated rootlet cortical cells. In the cluster root, the Casparian band formed in three ways, and was not initially present opposite the two sets of single xylem elements in the rootlet stele. A new clearing technique was developed that allowed visualization of xylem, suberized endodermis, Casparian band formation and phenolic compounds. In lateral roots, endodermal differentiation was asynchronous, but was related to position relative to protoxylem poles. However, the observed delay began before these poles had differentiated. At the tip of mature rootlets, which are determinate, the endodermis terminates in a 'dome' of cells, with the initial cell differentiating as an endodermal cell. Results are discussed in terms of determinate development in roots and the spatial and temporal contexts within which this development takes place.     

An Electron Microscopical Study of the Interaction of Monoclonal Antibodies with Gametes of the Malarial Parasite Plasmodium gallinaceum1

Anti-malarial gamete antibodies prevent the fertilization of gametes in the mosquito midgut and prevent transmission of malaria. Recently, hybridoma cell lines secreting monoclonal antibodies (10G3 and 11C7) against gametes of the malarial parasite have been developed. These antibodies act synergistically to mediate 80–90% suppression of the infectivity of gametocytes, although neither monoclonal antibody alone has a significant effect on gametocyte infectivity. We performed immuno-electron microscopy to characterize the interactions of these monoclonal antibodies with gametes of Plasmodium gallinaceum. Male gametes exposed to either 10G3 or 11C7 agglutinated into loose clusters, while those exposed to a mixture of 10G3 and 11C7 agglutinated into long, rope-like bundles. This difference appears to be related to the distribution of the antibodies on the surface of the gametes. When 10G3 or 11C7 labeled with a ferritin-conjugated anti-mouse Ig were used singly, the ferritin particles were distributed in focal areas over the surface of the parasites. By contrast, when the male gametes were exposed to a mixture of 10G3 and 11C7, the ferritin particles were distributed over their entire surface. Female gametes reacted similarly to these antibodies. These observations indicate that combinations of antibody specificities that reduce fertilization efficiency coat the entire surface of the gametes. On the other hand, focal interactions resulting from a single antibody are unable to block fertilization.     

Staining of Viable and Nonviable Myotubes and of Myofibrils by the Fluorescent Dye Merocyanine 540

Merocyanine 540 (MC 540) has been reported to interact specifically with excitable plasma membranes in live cells [3]. Here we show that the MC 540 fluorescence staining pattern previously believed to be characteristic of viable myotubes [3] is observed in formaldehyde-fixed cells. In contrast, viable myotubes show an MC 540 fluorescence staining pattern that is characteristic of cell surface staining (no internal structures fluoresce). The specific I-band and H-zone fluorescence of isolated myofibrils is also consistent with the interpretation that the fluorescence patterns previously reported for viable myotubes are in fact characteristic of cells with disrupted plasma membranes. Time-course observations of MC 540 and trypan blue staining of myotubes suggest that when plasma membrane integrity is lost, MC 540 fluorescence can be visualized inside the cell 5–10 min before trypan blue absorbance. Thus the trypan blue viability assay can be misleading when applied to myotubes.     

Cell Surface Carbohydrates in Tritrichomonas foetus1

The cell surface of Tritrichomonas foetus was characterized by using 18 highly purified lectins with specificities for N-acetyl glucosamine, N-acetyl galactosamine, galactose, mannose, and sialic acid. The specificity of the lectin-induced cell agglutination was verified by inhibition of the agglutination with the specific sugars. By using cytochemical techniques associated with electron microscopy, carbohydrates were detected on the cell surface of T. foetus. The following techniques were used: periodic acid-thiosemicarbazide-silver proteinate, concanavalin A-horseradish peroxidase, and ruthenium red. Anionic sites were detected on the cell surface of the protozoan at pH's 1.8 and 7.2 with the use of colloidal iron hydroxide and cationized ferritin particles, respectively. The binding of colloidal iron particles, as well as the agglutination induced by the lectin from Limulus polyphemus, indicated the presence of sialic acid on the cell surface of T. foetus.     

A COMPARISON OF THE GROWTHS OF WILD AND OF CULTIVATED OATS IN MANGANESE-DEFICIENT SOILS

Two species of wild oats, Avena fatua and A. ludoviciana , and two varieties of cultivated oats for comparison, were grown to maturity in pots of manganese-deficient soil with and without added manganese.
A. ludoviciana showed different leaf symptoms of manganese deficiency from A. fatua and the cultivated varieties. In other respects wild and cultivated oats were similar in their responses to the level of manganese supply, though differences were observed in the severity of the effects. These are summarized in Table 6. The relative susceptibility to manganese deficiency of the wild and cultivated oats differed according to the effect considered. The total dry weight at harvest is an integration of all the preceding effects on growth and is therefore presumably the best single criterion for determining susceptibility to manganese deficiency. On the basis of per cent loss of total dry weight at harvest due to lack of manganese, A. fatua is judged less susceptible and A. ludoviciana more susceptible than the two cultivated varieties and no distinction can be made between the latter.
The most interesting differences between wild and cultivated oats in response to the level of manganese supply occurred in seed production. Manganese-deficient wild oats showed a smaller reduction in the number of seeds formed but a greater reduction in the size and manganese content of individual seeds than the cultivated varieties.
Manganese deficiency lowered the percentage of viable seeds and the percentage of dormant seeds produced by both A. fatua and A. ludoviciana.