Chromosomal fission accounts for small‐scale radiations in Zamia (Zamiaceae; Cycadales)

Zamia is unique among Cycadales in its diversity of morphology, ecology and chromosome numbers. The chromosome numbers in Zamia range from 16 to 28, excluding 20, manifest as both interspecific and intraspecific series. It has long been recognized that Robertsonian transformations (chromosomal fission or fusion) probably dominate karyotype evolution in Zamiaceae, although it has been debated whether chromosome numbers are increasing or decreasing. We re‐analyse published karyotypes of Zamia spp., relating both chromosome forms and sizes to recent phylogenetic data. We show that karyotype evolution is most probably moving towards increased asymmetry, with higher numbers of smaller chromosomes, thus supporting chromosomal fission. We also address additional hypotheses for increasing chromosome numbers, namely pericentric inversions and unequal translocations. Finally, we discuss the role of these chromosomal changes in evolutionary radiations. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 168–185.     

Production of 3-methylbutanal from L-leucine by tomato extract

Crude extracts from fresh tomatoes (Lycopersicon esculentumMILL.),V. R. Moscow variety, grown in a greenhouse were capable ofproducing 3-methylbutanal and 3-methyl-l-butanol in the presenceof L-leucine, as evidenced by gas chromatography. The productionof 3-methylbutanal was also demonstrated by thin-layer chromatographyusing the 2,4-dinitrophenylhydrazone of the aldehyde producedfrom ¹⁴C-L-leucine used as substrate. (Received April 13, 1968; )     

Permo--Carboniferous Paleoecology and Morphotypic Series

The genera of primitive and synapsid reptiles which form theusual morphotypic series leading to cynodonts are not membersof a phyletic series. Ecological analyses show three developingevolutionary lines during the Permo-Carboniferous—onelowland, living on deltas and in swamps; a second somewhat moreupland; and a third distinctly upland. The members of thesethree lines are the source of the morphotypic genera, but mostof them come from deposits formed in lowlands where they cameby successive invasions from moreupland habitats. Evidence ofthe upland lines comes from these lowland sites, from invadinganimals, and from those introduced by mechanical transport fromtheir upland habitats. The brain cases and masticatory structures ofthe members ofthe morphotypic series—Hylonomus, Haptodus, Varanosaurus,Ophiacodon, Dimetrodon, Eotitanosuchus, Scymnognathus, Lycosuchus,Thrinaxodon—are examined in light of the ecological interpretations.Deformed coordinates applied to the lateral aspects of the skullsof the genera show clearly that the morphotypes do not providea coherent evolutionary series. The "trends" of evolutionarychange from Hylonomus to Thrinaxodon can best be seen if thesetwo and Haptodus are used as an evolutionary series, the stagesthat are missing interpolated, and the roles ofthe other generaevaluated on the basis of this more or less idealized, conceptualseries.     

Behavioural and chemical mechanisms of plant‐mediated deterrence and attraction among frugivorous insects

1. Herbivory often induces systemic plant responses that affect the host choice of subsequent herbivores, either deterring or attracting them, with implications for the performance of both herbivore and host plant. Combining measures of herbivore movement and consumption can efficiently provide insights into the induced plant responses that are most important for determining choice behaviour. 2. The preferences of two frugivorous stink bug species, Nezara viridula and Euschistus servus between cotton plants left undamaged or damaged by Helicoverpa zea and Heliothis virescens larvae were investigated. A novel consumer movement model was used to investigate if attraction rates or leaving rates determined preferences. Stink bug consumption rates were measured using salivary sheath flanges. Finally, the systemic induction of selected phenolic‐based and terpenoid secondary metabolites were measured from heliothine herbivory on developing cotton bolls, to investigate if they explained stink bug feeding responses. 3. Heliothine herbivory did not affect the N. viridula feeding preference. However, we found opposing effects of H. zea and H. virescens herbivory on the behaviour of E. servus. Avoidance of H. zea‐damaged plants is not obviously related to phenolic or terpenoid induction in cotton bolls; whereas a preference for H. virescens‐damaged plants may be related to reductions in chlorogenic acid in boll carpel walls. 4. The present results highlight the inferential power of measuring both consumer movement and consumption in preference experiments and combining behavioural responses with phytochemical responses. Furthermore, while plant‐mediated interactions among herbivorous insects are well studied, interactions among frugivorous species specifically have been poorly documented.