Pupation-temperature range in 12Drosophila species from different ecological backgrounds

Summary A comparison of pupation-temperature range was made in the laboratory on a temperature gradient (3–38°C) using 12 species ofDrosophila representing four species groups and four different ecological backgrounds (temperate-montane forest:virilis group; desert;repleta group; cosmopolitan:melanogaster group; tropical forest:willistoni group). Within groups, differences are found which usually reflect species' distributions. Comparisons of species' mating-, oviposition- and pupation-temperature ranges reveal that pupation most-often occurs at temperatures beyond those for mating and oviposition. Each species reflects a different combination of temperature effects. Individual species have different temperature-limits for mating, oviposition and pupation. Temperatures permissive for one response are not predictive of limits on other responses. Among species, temperature can affect a particular response differently. Within groups, species differences can be at high and/or low temperatures for any response, and temperature effects among closely related species can manifest themselves in one, or any combination of responses. One cannot predict which responses will be most and least limited, or at which end of the temperature scale a response will be most limited. Among groups,common, but notabsolute temperature ranges generally correspond to the geographic distributions and ecological backgrounds of the species triads. The evaluation of temperature effects on species, based on a single activity, may not be adequate for predicting adaptive strategies.     

Heat shock proteins in three relatedDrosophila species belonging to theobscura group

The effect of heat shock on protein synthesis in three relatedDrosophila species belonging to theobscura group was analyzed on SDS-acrylamide gels. Four major heat shock proteins (hsps) were found in these species, in which synthesis reaches a maximum at 34°C. Although the higher molecular weight proteins are conserved, differences in size were found for the small hsps in these species. By means of in situ hybridization usingD. melanogaster probes for the small hsp genes, it was inferred that the small hsp genes of theobscura group species are clustered at the 27A locus in all three species.     

Green leaf volatiles interrupt aggregation pheromone response in bark beetles infesting southern pines

Summary Green leaf volatiles were shown to interrupt responses to aggregation pheromones of three species of bark beetles (Coleoptera: Scolytidae) which infest pines in the southern United States [the southern pine beetle,Dendroctonus frontalis Zimm.; the four-spined engraver,Ips avulsus (Eichhoff); and the five-spined engraver,Ips grandicollis (Eichhoff)]. The order of effectiveness of the compounds tested for each species was hexanal>hexanal+hexan-1-ol>hexan-1-ol. Neither hexanal, hexan-1-ol nor hexanal+hexan-1-ol was as effective in interrupting pheromone responses ofD. frontalis as verbenone, a known inhibitor of this species. Other than interspecific chemical signals, this is the first report of an interruptant forIps species, and the only report of a pheromone interruptant active for bothIps andDendroctonus species.     

Egg-species recognition in cannibalistic hatchlings of the land snailsArianta arbustorum andHelix pomatia

Summary Laboratory experiments were conducted to determine whether cannibalistic hatchling of the land snailsArianta arbustorum andHelix pomatia discriminate between eggs of the two species. Hatchlings from both species showed a significant choice for conspecific eggs and consumed on average 1 egg in 4 days. Eggs from the other species were only occasionally eaten.     

Germ cell chromosomes in two species of terrestrial isopods from India

Summary In 2 species of terrestrial isopods, namelyPorcellio assamensis andP. laevis, the diploid and haploid numbers of chromosomes have been established to be 48 and 24 respectively for the former species and 50 and 25 respectively for the latter species. Female heterogamety of the ZW type has been found to exist inP. laevis.The authors express their sincere thanks to Prof. G.P. Sharma, and to Prof. S. Khera, Department of Zoology, Panjab University, Chandigarh, for the necessary laboratory facilities.     

Multiple prismatic calcium phosphate layers in the jaws of present-day sharks (Chondrichthyes; Selachii)

Summary Jaws of large individuals, over 2 m in total length, of the shark speciesCarcharodon carcharias (great white shark) andIsurus oxyrinchus (mako shark) of the family Lamnidae, andGaleocerdo cuvieri (tiger shark) andCarcharhinus leucas (bull shark) of the family Carcharhinidae were found to have multiple, up to five, layers of prismatic calcium phosphate surrounding the cartilages. Smaller individuals of these species and other known species of living chondrichthyans have only one layer of prismatic calcium phosphate surrounding the cartilages, as also do most species of fossil chondrichthyans. Two exceptions are the fossil shark generaXenacanthus andTamiobatis. Where it is found in living forms, this multiple layered calcification does not appear to be phylogenetic, as it appears to be lacking in other lamnid and carcharhinid genera and species. Rather it appears to be functional, only appearing in larger individuals and species of these two groups, and hence may be necessary to strengthen the jaw cartilages of such individuals for biting.     

Ribosomal gene numbers in Microseridinae (Compositae: Cichorieae)

Summary 8 species of the subtribe Microseridinae contain between 1100 and 3400 genes for 25 and 18 S ribosomal RNA. The gene numbers seem to evolve by discrete steps. Their trend follows a general reduction in genome size during the evolution of the annual species ofMicroseris, but numbers remain high in one of them and inAgoseris grandiflora. 2 species ofPyrrhopappus differ by a duplication of the ribosomal gene numbers; 5 S ribosomal RNA genes in 4 species are repeated roughly 10,000 times.We thank Miss S. Werner, Miss A. Roth and Miss U. Krehan for help with some of the experiments. This paper is part of a project supported by grant Ba 536/1-5 from the Deutsche Forschungsgemeinschaft.     

Evolutionary and ecological implications of cardenolide sequestration in the monarch butterfly

Summary Monarch butterflies sequester cardenolides from their larval host plants in the milkweed genusAsclepias for use in defense against predation. Of 108Asclepias species in North America, monarchs are known to feed as larvae on 27. Research on 11 of these has shown that monarchs sequester cardenolides most effectively, to an asymptote of approximately 350 g/0.1 g dry butterfly, from plants with intermediate cardenolide contents rather than from those with very high or very low cardenolide contents. SinceAsclepias host plant species are distributed widely in space and time across the continent, monarchs exploit them by migration between breeding and overwintering areas. After overwintering in central Mexico, spring migrants east of the Rocky Mountains exploit three predominantAsclepias species in the southern USA that have moderately high cardenolide contents. Monarchs sequester cardenolides very effectively from these species. First generation butterflies are thus well protected against predators and continue the migration north. Across the northern USA and southern Canada most summer breeding occurs on a fourthAsclepias species and in autumn most of these monarchs migrate back to Mexican overwintering sites. The ecological implications of this cycle of cardenolide sequestration for the evolution of monarch migration are discussed.     

Evolution and ecological correlates of uniparental reproduction in freshwater snails

We review the spatial and temporal correlates of uniparental reproduction in freshwater snails as they pertain to the ecological hypotheses for the maintenance of biparental sex. The biogeographic evidence from two species (Potamopyrgus antipodarum andBulinus truncatus) presently supports the Red Queen hypothesis that biparental reproduction is selected as a way to reduce the risk to progeny of parasite attack. Uniparental reproduction in these species is associated with low levels of infection by parasites (castrating digenetic trematodes), suggesting that parthenogenesis or self-fertilization can replace cross-fertilization when the risk of infection is low. In addition, inB. truncatus, the opportunity for cross-fertilization coincides with the season in which parasite attack is highest. In a third species (Campeloma decisum), parthenogenetic reproduction is correlated with latitude and the presence of a non-castrating trematode that may prevent cross-fertilization; these patterns suggest that parthenogenesis has been selected as a mechanism to assure reproduction. Finally, we discuss the spotty taxonomic distribution of parthenogenetic species.     

Albumin concentration in plasma of two related species ofCeratophrys (Anura Leptodactylidae) from two different environments

Summary Albumin concentration in plasma of two related species ofCeratophrys, C. cranwelli andC. ornata was analyzed and shown to be higher in the former species, which is the adaptive form found in dry areas.     

Dynamics of increase in muscle fibers in fishes in relation to size and growth

Summary Dynamics of increase of white myotomal muscle fibers of four species of freshwater teleosts (Salmo gairdneri, Pimephales notatus, Esox masquinongy andE. americanus vermiculatus) from three families (Salmonidae, Cyprinidae, Esocidae) representing a variety of maximum attainable sizes and growth rates, have been investigated. There are at least three major differences in these dynamics, and there appears to be an association between the ability of a fish species to attain large size (and grow fast) and its ability to recruit new fibers into this predominant tissue of the myotomal mass.     

Cytotaxonomy of the myobatrachid frogs of the genusLimnodynastes

Summary 4 of the 5 species ofLimnodynastes of theperoni group show 2n=24. Onlysalmini has 2n=22, thus resembling the species ofPlatyplectron (thedorsalis andornatus complexes) which all show 22 chromosomes. This 2nd group also includes species (ornatus) with very low DNA amounts. From a karyological point of view, the species of thePlatyplectron (plus eventuallysalmini) group appear more differentiated than the species of theperoni group, from which they have probably arisen.Research partly supported by a contribution from C.N.R., Rome.     

Notable diversity in hemoglobin expression patterns among species of the deep-sea clam, <Emphasis Type="Italic">Calyptogena</Emphasis>

The deep-sea clams Calyptogena nautilei and C. tsubasa, which live in the cold-seep area at a depth of 3570 m in the Nankai Trough, Japan, have abundant hemoglobins (Hbs) in erythrocytes, similar to other Calyptogena species. We determined the cDNA-derived amino acid sequences of Hbs from two Calyptogena species. C. tsubasa was found to contain two dimeric Hbs, Hb I consisting of 145 amino acid residues and Hb II with 137 residues, similar to known Hbs from C. soyoae and C. kaikoi. Sequence identity was over 90% among the orthologous chains of Calyptogena Hbs. On the other hand, surprisingly, C. nautilei contained two monomeric Hbs, Hb III containing 141 residues and Hb IV with 134 residues. In addition, Hbs III and IV showed only 33–42% sequence identity with Hbs I and II from other Calyptogena species. The distal (E7) histidine, one of the functionally important residues of the heme protein, is replaced by glutamine in all Hb chains of Calyptogena species. A phylogenetic analysis indicated that C. nautilei Hb III is closer to Hb I from other Calyptogena species. We suppose that a Hb gene was duplicated at least three times in an immediate ancestor of Calyptogena and, presumably depending on physiological conditions different Hb sets are being expressed: dimeric Hbs I and II in C. soyoae, C. kaikoi and C. tsubasa, and monomeric Hbs III and IV in C. nautilei. Received 13 May 2003; received after revision 5 June 2003; accepted 12 June 2003     

Panorpa communis L. undPanorpa vulgaris Imhoff und Labram,zwei Arten

Summary P. communis andP. vulgaris are biological species, reproductively isolated by pre- and post-mating isolation mechanisms. Both species build their own specific ecological niches, but morphologically they differ only very little-perhaps they are sibling species.     

The origin of the brown frogs with 2n=24 chromosomes

Late replication and C-banding analyses of somatic metaphase chromosomes were attempted on three species of brown frogs with 2n=26 chromosomes (Rana japonica, R. tsushimensis andR. temporaria), and three with 2n=24 chromosomes (R. ornativentris, R. dybowskii andR. chensinensis), which are distributed in the Palearctic region. The late replication banding patterns were highly conserved in these species. Four chromosome inversions were demonstrated inR. ornativentris, two inR. dybowskii and two inR. tsushimensis. From a detailed comparison of late replication and C-banding patterns between the 2n=26 and the 2n=24 species, it was found that an end-to-end fusion of two small chromosomes (nos 11 and 13) in an ancestral 2n=26 species may have produced the medium-sized no. 6 chromosome of the 2n=24 species.     

Karyological pattern of two Chilean lizards species of the genusLiolaemus (sauria; iguanidae)

Summary The karyotypes of Chilean lizardsLiolaemus pictusandLiolaemus cyanogaster is described for the first time. Both species possess 34 chromosomes; 6 pairs of macrochromosomes and 11 pairs of microchromosomes. Karyologically it is possible to differenciate this species because the pair No. 2 is metacentric (m) inL. pictusand submetacentric (sm) inL. cyanogaster. It is shortly discussed the signification of formule 2n=34 for the species ofLiolaemus analized karyologically and its possible mechanism of acquisition.     

Biochemical genetic differentiation among seed chalcid species of genusMegastigmus (Hymenoptera: Torymidae)

The degree of genetic variability and the taxonomic status of adults of 14 seed chalcid species of the genusMegastigmus was analyzed using electrophoresis on horizontal starch gel. Variability of chalcid populations with host tree was observed in 21 host species. A total of 13 enzyme loci were considered. Seven of the loci were found to be polymorphic. The electrophoretic data strongly supported the adaptation of each chalcid species to a limited number of congeneric hosts, and confirmed the morphologically-based taxonomy of the genus. The resulting dendrogram separated the chalcid species into three distinct groups, infesting 1) Pinaceae spp., 2) Cupressaceae spp., and 3) Angiosperm spp., respectively. The highest level of overall genetic similarity was observed among the chalcid populations infesting conifers of the generaPseudotsuga andAbies. The genetic identity values observed among populations infesting 5 differentAbies species tended to reflect the occurrence of conspecific populations rather than that of distinct chalcid species. Genetic identity was similarly important among the chalcid species infesting seeds of Cupressaceae. By contrast, a large genetic distance was observed between two seed chalcids attacking a same host,Rosa montana.     

Chromosomal evolution and zoogeographic origin of southeast Asian shrews (genusCrocidura)

To the origins and evolution of Indomalayan shrews, we investigated the chromosomal variations of 14 species ofCrocidura from SE Asia. Intraspecific polymorphism was mainly due to variation in the number of short chromosomal arms butC. lepidura andC. hutanis showed a polymorphism due to a centric fusion. The undifferentially stained karyotypes were similar in 9 species, all possessing 2n=38 and FN=54–56 (68);C. fuliginosa had 2n=40 and FN=54–58. These karyotypes are close to the presumed ancestral state for the genusCrocidura. Four species from Sulawesi had a reduced diploid number (2n=30–34), a trend not observed among other SE Asian species but present in few Palaearctic taxa. Compared to the apparent stasis of karyotypic evolution observed among other SE Asian species, the high degree of interspecific differences reported among Sulawesian shrews is unusual and needs further investigation.Stasis and reduction in diploid number found in both Indomalayan and Palaearctic species suggest that these two groups share a common ancestry. This is in sharp contrast to most Afrotropical species which evolved towards higher diploid and fundamental numbers. The zoogeographical implications of these results are discussed.     

Two related butterfly species avoid oviposition near each other's eggs

Summary Some butterfly species avoid egg-laying on plants which already bear conspecific eggs, and thus reduce food competition between their offspring. In twoPieris species the females produce in their accessory glands an oviposition-deterring pheromone (ODP), which is combined with the egg during oviposition. The ODP collected from eggs or accessory glands ofP. brassicae inhibits oviposition byP. rapae and vice versa. The ODP of either species stimulates tarsal receptors in both species. The antennae of the two pierids respond to the volatiles of their own and each other's eggs. Thus the ODPs of the two species may reduce not only intraspecific, but also interspecific food competition between their larvae.     

Démonstration du caractère géographique de la parthénogénèse deSaga pedo Pallas et de sa polyploïdie,par comparaison avec les espèces bisexuéesS. ephippigera Fisch. etS. gracilipes Uvar

Summary The males of two species of Palestine,Saga ephippigera Fisch. andS. gracilipes Uvar have respectively 33 and 31 chromosomes in the diploid state.S. pedo Pallas, a parthenogenetic thelytoc species largely distributed in Europe, has 68 chromosomes and probably represents a tetraploid. The cells of the three species have identical dimensions and the polyploidS. pedo is even the smallest in size.