Links between global taxonomic diversity,ecological diversity and the expansion of vertebrates on land

Tetrapod biodiversity today is great; over the past 400 Myr since vertebrates moved onto land, global tetrapod diversity has risen exponentially, punctuated by losses during major extinctions. There are links between the total global diversity of tetrapods and the diversity of their ecological roles, yet no one fully understands the interplay of these two aspects of biodiversity and a numerical analysis of this relationship has not so far been undertaken. Here we show that the global taxonomic and ecological diversity of tetrapods are closely linked. Throughout geological time, patterns of global diversity of tetrapod families show 97 per cent correlation with ecological modes. Global taxonomic and ecological diversity of this group correlates closely with the dominant classes of tetrapods (amphibians in the Palaeozoic, reptiles in the Mesozoic, birds and mammals in the Cenozoic). These groups have driven ecological diversity by expansion and contraction of occupied ecospace, rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.     

The sweet jelly of Combretum lanceolatum flowers (Combretaceae): a cornucopia resource for bird pollinators in the Pantanal, western Brazil

 The pollination biology of the neotropical scandent shrub Combretum lanceolatum was studied in the seasonally-flooded Pantanal region in western Brazil. This plant bears horizontally oriented inflorescences, whose yellowish green flowers begin to expand at dusk and are fully open at dawn. Instead of fluid nectar the flowers produce sweet gelatinous secretion in form of pellets. The glandular complex of the flower is composed of the inner wall of the receptacle and its tubular extension, being equivalent to the nectariferous disk of the nectar-producing species within the genus. The jelly is produced at night, contains mannan and is imbibed by free hexoses. It originates by swelling and disintegration of the inner wall, after contact with the nectar generated concomitantly in the mesophyll. Combretum lanceolatum is unique within the genus in its production of jelly pellets instead of liquid nectar. A new term, the jelly-flower, is proposed for flowers with this kind of reward. The pellet is not replaced once removed by a bird, and thus resembles a fruit in its availability to consumers, another unique feature that distinguishes this species within the genus. The jelly pellets offered by the many flowered branches attract a great diversity of bird visitors (28 species from eight families), which feed on this copious food resource and pollinate the flowers. The most effective pollinators probably are thrushes, tanagers, and orioles. Flocking parakeets and macaws sometimes feed on the petals, thus acting as flower plunderers. Combretum lanceolatum presents a high fruit set under natural conditions, which likely favours its spreading and becoming a weed species. Received July 11, 2000 Accepted November 18, 2000     

Cryptic species in Diacyclops bicuspidatus (Copepoda:Cyclopoida): evidence from crossbreeding studies

The problem of cryptic species in Diacyclops bicuspidatus was examined using interpopulation crosses of four populations collected from a: (1) permanent flood lake in Kiev, Ukraine, (2) temporary pool in Kiev, (3) permanent pond in St. Petersburg, Russia (1200 km to north from Kiev) and (4) lake in Crimea (1100 km south of Kiev). The only interpopulation crosses to exhibit fertility were those between the St. Petersburg population and each of the two Kiev populations. The crosses between the Kiev and Crimea populations, between the St. Petersburg and Crimea populations, and between the two Kiev populations were sterile, as evidenced by either nonviable eggs, empty egg membranes or incomplete copulations. The F₁ hybrids resulting from the St. Petersburg permanent pond X Kiev flood lake cross were fertile and produced mature F₂ offspring. Some data on development times of parental and hybrid lines are presented. The St. Petersburg parental line showed development times almost twice as long as those of the Kiev flood lake population when reared at 10 °C and 20 °C in the laboratory. The F₁ offspring of the cross between St. Petersburg females and Kiev floodlake males showed similar development times to females of the St. Petersburg parental lines at both temperatures. The F₂ hybrids also showed development times that approximated those of the St. Petersburg parental line. These crossbreeding studies suggest the presence of cryptic species in the D. bicuspidatus inhabiting ecologically different populations in many parts of its large holarctic range.     

Importance of fire in influencing the occurrence of snakes in an upland region of arid Australia

In arid Australia, changes to historic fire regimes may now produce more large‐scale wildfire events. The impacts of these fires on fauna communities are poorly known. We sought to test the impacts of fire on the occurrence of two arid‐zone snake species, the desert death adder (Acanthophis pyrrhus) and monk snake (Parasuta monachus), specialist inhabitants of hummock grassland and mulga shrubland, respectively. We also examined the influence of fire on the occurrence of a habitat generalist, the sympatric Stimson's python (Antaresia stimsoni). Under an Information‐Theoretic framework we modelled the occurrence of each species with a range of habitat variables, including fire history, using logistic regression. As predicted, the two habitat specialists were more likely to be encountered at locations that had a lower percentage of surrounding area burnt in the most recent wildfires (2002), while fire variables failed to predict the occurrence of the habitat generalist. Acanthophis pyrrhus, already predisposed to endangerment through a suite of life‐history characteristics, may be at increased risk through accidental and deliberate burning and fragmentation of old‐growth hummock grasslands. We stress the importance of prescribed burning and natural fire breaks in maintaining areas of old‐growth hummock grassland across the landscape.     

Intercompany Energy Integration

Reusing heat through process integration in heat exchanger networks has long been a key measure for increasing energy efficiency in energy‐intensive industries. Thermal pinch analysis is commonly used for a systematic matching of process streams and thus planning of optimal process integration in large chemical plants. The possible savings increase with the amount of heat and the number of integrated process streams. Therefore co‐ siting of several companies in a symbiotic network opens new opportunities for process integration even in small and medium‐size enterprises (SMEs), but also introduces new challenges. Thermal pinch analysis is extended here to account for piping distances and fluctuations and limited availability of energy flows by adding additional costs for the piping system and a backup utility system in the optimization function. Cooperative game theory is proposed to derive a sharing of savings between the partners of the industrial symbiosis that is optimal for each partner and should prevent partners from leaving the network because of higher benefits in a subgroup or alone. It is argued that knowledge about the optimality of a network for each partner creates trust between the partners that is a necessary base for the long‐term commitment needed in industrial symbioses. An exemplary symbiotic network combining the production of pulp and woody biomass energy carriers is used to illustrate the proposed approaches.     

New syntaxa for the prodrome of Italian vegetation

The aim of this study is to provide new syntaxa for the Italian vegetation checklist. For the class Rhamno–Prunetea which includes the class Paliuretea the new alliance Rhamno saxatilis–Paliurion spinae-christi is described, that is included in the order Paliuretalia spinae-christi with a central-western Mediterranean and sub-Mediterranean distribution. Otherwise, the more thermophilous Paliurus spina-christi vegetation is included in the new suballiance named as Oleo sylvestris–Paliurenion spinae-christi within the alliance Oleo–Ceratonion of the class Quercetea ilicis. For the class Trifolio–Geranietea medii, a new alliance named Hyperico calabricae–Asphodelion macrocarpi is proposed here.     

Olfactory versus visual cues in a floral mimicry system

 We used arrays of artificial flowers with and without fragrance to determine the importance of olfactory and visual cues in attracting insects to a floral mimic. The mimic is a fungus, Puccinia monoica Arth., which causes its crucifer hosts (here, Arabis drummondii Gray) to form pseudoflowers that mimic co-occurring flowers such as the buttercup, Ranunculus inamoenus Greene. Although pseudoflowers are visually similar to buttercups, their sweet fragrance is distinct. To determine whether visitors to pseudoflowers were responding to fragrance we performed an experiment in which we removed the visual cues, but allowed fragrance to still be perceived. In this experiment we found that pseudoflower fragrance can attract visitors by itself. In other experiments we found that the relative importance of olfactory and visual cues depended on the species of visitor. Halictid bees (Dialictus sp.) had a somewhat greater visual than olfactory response, whereas flies (muscids and anthomyiids) were more dependent on olfactory cues. We also used bioassays to determine which of the many compounds present in the natural fragrance were responsible for attraction. We found that halictid bees were equally attracted to pseudoflowers and to a blend containing phenylacetaldehyde, 2-phenylethanol, benzaldehyde and methylbenzoate in the same relative concentrations as in pseudoflowers. Flies, on the other hand, only responded to pseudoflower scent, indicating that we have not yet identified the compound(s) present in pseudoflowers that are attracting them. The ability of insects to differentiate pseudoflowers from true flowers by their fragrance may be important in the evolution of the mimicry system. Different fragrances may facilitate proper transfer of both fungal spermatia and pollen, and thus make it possible for the visual mimicry to evolve. Received: 3 January 1996 / Accepted: 13 August 1996     

Species richness and composition of amphibians and reptiles in a fragmented forest landscape in northeastern Bolivia

We quantified patterns of species richness and species composition of frogs and reptiles (lizards and snakes) among three habitats (continuous forest, forest islands, and a seasonally flooded savannah) and between forest island size and isolation classes in a floristic transition zone in northeastern Santa Cruz Department, Bolivia. Species richness was similar across macrohabitats, as was faunal composition of forested habitats, although savannah harbored a distinct herpetofauna. On forest islands, richness and composition of forest frogs was largely related to isolation, whereas reptiles were affected by both isolation and habitat. The observation that isolation rather than area was the primary driver of distribution patterns on forest islands stands in contrast to many studies, and may be a function of (1) the greater range in forest island isolation values compared to area or (2) the long history of isolation in this landscape.