Transactions of the Botanical Society of Edinburgh

Summary

Evidence is adduced that the ‘hypogynous bodies’ found in two unrelated sections of Hypericum are, at the same time, ‘new’ organs in Hypericum and yet homologous with sterile stamen facicles in other genera of the Guttiferae. Their reappearance is related to the development of specialised insect pollination.     

Weak phylogenetic signal for specialisation in antagonistic liana–tree networks

Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialised and have a strong phylogenetic signal for specialisation. As lianas and trees interact antagonistically, we expect to find phylogenetic signal for specialisation.

Aims: We aimed to answer the following questions: (1) Is the liana–tree network specialised? (2) Is the specialisation of liana–tree network related to the abundance of both the life forms? (3) Is liana and tree specialisation related to species phylogeny? (4) Do phylogenetically related liana species occupy phylogenetically related tree species, and vice versa?

Methods: For three areas in southern Brazil, we calculated the specialisation value of each liana and tree species (d') and of the entire network (H₂′). Binomial regression and null models were used to test the role of abundance on d' and H₂′, respectively. We searched for the presence of phylogenetic signal with phylogenetic independent contrasts for d'. We also compared the similarity of species sets and their interaction with phylogenetic distance between them using Mantel test.

Results: All three networks had significant values of H₂′, but the values of d' did not have significant phylogenetic signals. Closely related lianas did not share similar host-tree assemblages and vice versa. Rare species were more specialised than abundant species, and abundance did not influence H₂′.

Conclusions: Our study indicates that the significant H₂′ may be due to co-evolution in some lineages of lianas and trees. Nevertheless, the abundance of species may also play an important role in species interaction, mainly rare species.     

Evolution of arboreal tunnelling by larvae of Aenetus (Lepidoptera: Hepialidae)

Abstract

Aspects of larval feeding and tunnelling were described for seven species of the wood-boring genus Aenetus. The species were studied in Australia, New Caledonia, and New Zealand. A sequential pattern of larval feeding involving transfer from a fungal based diet to callus tissue in live trees, previously known for A. virescens, was confirmed for A. cohici and inferred for A. dulcis and A. paradiseus. A specialised “transfer” morph linking the two feeding stages in A. virescens was also confirmed for A. cohici and two unidentified species. The wood-boring habit involved entry into the host above ground level and the construction of a tunnel which extends into and then down the stem. Tunnels were often located on the lower surface of leaning branches or stems. Tunnel entrances were open to the host surface, but overlain by a silk- /frass web. Bark and underlying tissue were removed from around the tunnel entrance and a callus growth resulted, which the larva consumed. The evolutionary history of arboreal tunnelling in the Hepialidae was investigated using biogeographic analysis of generic distribution. It is argued that evolution and variation in arboreal tunnelling resulted from specialised recombinations of generalised ancestral characters. It is suggested that the study of arboreal tunnelling can provide a source of useful characters for systematic analysis of phylogenetic relationships within Aenetus. The potential systematic value of tunnel characters is illustrated for A. virescens.     

A new Indian species of Riccia L. with connections to northern Australia

Introduction. During a recent explorative field trip to the Western Ghats a new species of Riccia was discovered with possible links to the northern Australian species, Riccia caroliniana Na-Thalang.

Key Results. Morphological similarities between the new species, R. sahyadrica and R. caroliniana include the ventral positioning of the photosynthetic tissue in the ventral section of the thallus in specialised structures known as ventral lamellae. These form a v-shaped patterning along the ventral surface of the thallus and are unique to these two species. Both species also bear similar spores with differences in the micro-ornamentation. Differences between the two species also extend to sexual condition, whereby R. caroliniana is dioicous and R. sahyadrica is monoicous.

Conclusions. A new species, Riccia sahyadrica Manju & Cargill is described and illustrated and compared to the only other morphologically similar species, R. caroliniana endemic to northern Australia. Both species possess the unique characteristic of bearing ventral photosynthetic tissue in contrast to the dorsal position typically seen in all other Riccia species.     

Apoptosis-like DNA fragmentation in leaves and floral organs precedes their developmental senescence

ABSTRACT

We investigated the senescence of flag leaves of durum wheat (Triticum durum) during grain-filling, and of petal-like ray flowers of Jerusalem artichoke (Helianthus tuberosus) at anthesis. In both systems, we observe cleavage of DNA to high molecular weight fragments, followed by further degradation to nucleosomal fragments (laddering), a classical hallmark of apoptosis. We show that DNA fragmentation in such specialised leaves is triggered early in organ development, before the appearance of visual symptoms of senescence. Our observations support the hypothesis that senescence and cell death are part of the plant developmental program, activated by developmental cues.     

Sperm Penetration and in vitro Fertilization of the Egg of the House Cricket Acheta domesticus

Summary

A study of sperm penetration of the egg of the house cricket, Acheta domesticus, using a fluorescent microscope technique, showed that sperm penetration of the chorion, prior to fertilization, is not restricted to a specialised area of the egg surface, such as the micropyle. An acrosomal filament is seen on penetrating sperm. Polyspermy (multiple sperm attachment) is seen under normal conditions.

Eggs fertilized in vitro developed to the 4 day (pre-katatrepsis) stage, but did not undergo katatrepsis. Development was confirmed by cytogenetic studies. The percentage of eggs showing cleavage nuclei (i.e. initial development) was 59% after in vitro fertilization and 5% in ovarian eggs incubated in a hypotonic medium.     

Revision of the Acanthoclinidae (Pisces: Perciformes), with descriptions of a new genus and five new species

Abstract

The family Acanthoclinidae includes 10 species: Acanthoclinus fuscus Jenyns, 1842; Taumakoides littoreus ((Forster) Bloch & Schneider, 1801); T. rua n. sp.; T. marilynae n. sp.; T. matti n. sp.; Belonepterygion fasciolatum (Ogilby, 1889); Beliops xanthokrossos n. gen. et sp.; Acanthoplesiops indicus (Day, 1888); A. hiatti Schultz, 1953; and A. psilogaster n. sp. Acanthoclinus quadridactylus (Bloch & Schneider, 1801) and A. trilineatus Griffin, 1933, are reduced to synonymy under Taumakoides littoreus ((Forster) Bloch & Schneider, 1801).

Osteological and morpological character states, between and within genera, suggest that Acanthoclinus and Taumakoides are close to the stock from which the family is derived. There is also compelling evidence that T. matti is the least specialised species of Taumakoides. Progressive specialisation is evident in the remaining genera, with Acanthoplesiops being the most highly specialised.

The family occurs primarily in shallow waters of the Indian and western Pacific oceans; most of the species are found about New Zealand. The centre of origin of the Acanthoclinidae was probably on the Indian-Australian Plate (which includes the New Zealand continental shelf). Acanthoplesiops hiatti and A. indicus are considered to be endemics of the Pacific and African plates, respectively.

A key to species is included.     

Colony orientation and successful defence behaviour in the conifer aphid, Schizolachnus pineti

We studied colony structure and body orientation behaviour of Schizolachnus pineti, a specialised aphid feeding on needles of Scots pine. Aphids feeding at the margin of a colony always face towards the centre of the colony, bounding the colony with their legs. This behaviour increased the defence success aginst the specialised parasitoid (Pauesia unilachni) and the specialised predator (Scymnus nigrinus). Both enemies had less success when attacking S. pineti from the abdominal site when compared to the front. We assume that the defence orientation displayed by marginally feeding aphids has an adaptive nature and is particularly effective when feeding in a row on linear plant structures such as needles.     

Seed and microsite limitation in Rheum nobile,a rare and endemic plant from the subnival zone of Sino-Himalaya

Background: Species persistence, particularly in monocarpic species, depends on the successful recruitment of individuals. An understanding of the factors that limit the recruitment of rare monocarpic plant species is therefore vital for their conservation.

Aims: To identify the factors limiting the recruitment of Rheum nobile, a rare and highly specialised monocarpic giant herb endemic to the high eastern Himalayas.

Methods: Seed sowing (seeds added or not added) and seedling transplanting experiments were conducted in disturbed (vegetation removed) and undisturbed plots in the vicinity of established populations of R. nobile to explore the mechanisms of recruitment limitation. Four levels of photosynthetically active radiation (0, 15, 30 and 50 μmol m^?2 s^?1) and two sowing positions (beneath and above grass litter or moss layer) were manipulated in the laboratory to determine how ground cover limited seedling emergence.

Results: Seed addition increased seedling recruitment. Disturbance significantly increased seedling emergence and establishment. Seed germination significantly decreased with the reduction of light availability, but 31.7% of all seeds germinated in complete darkness. Seedling emergence was close to zero when seeds were sown on top of a layer of grass litter or moss, but rose to 34.5% when the seeds were sown beneath such layers.

Conclusions: Our results indicate that the recruitment of R. nobile is limited by a combination of seed and microsite availability. Therefore, in order to conserve this species, we suggest adding seeds to suitable sites and implementing soil disturbances in existing populations to create suitable microsites.     

Molecular phylogenetic support for a broader delimitation of Uvaria (Annonaceae), inclusive of Anomianthus,Cyathostemma, Ellipeia,Ellipeiopsis and Rauwenhoffia

Abstract

Uvaria (Annonaceae), a large palaeotropical genus of woody climbers, closely resembles several other smaller genera, including Anomianthus, Cyathostemma, Ellipeia, Ellipeiopsis and Rauwenhoffia. A molecular phylogenetic analysis of this group was undertaken using maximum parsimony, maximum likelihood and Bayesian methods based on four chloroplast DNA regions (matK, psbA‐trnH spacer, rbcL and trnL‐F). The resultant trees were moderately well resolved with significant statistical support for most nodes. Uvaria is shown unequivocally to be paraphyletic, with all representatives of the other five genera nested within it. The distinguishing morphological characteristics of the related genera are re‐evaluated, and interpreted as no more than specialised adaptations of the basic Uvaria structure. The generic names Anomianthus, Cyathostemma, Ellipeia, Ellipeiopsis and Rauwenhoffia are accordingly reduced to synonymy with Uvaria, necessitating 11 new nomenclatural combinations and four replacement names.     

Breeding site specificity in the domestic species of Drosophila

Summary The emergences of domestic Drosophila species from fruits and vegetables in a market are analysed by partitioning the species diversity. Confidence limits are determined for the components of diversity.Despite some coexistence of different species within the same breeding site, ecological differences between them are revealed. Partitioning of the breeding sites is more important than partitioning of the season. D. melanogaster, D. simulans, and D. subobscura are specialised on fruits and D. busckii on vegetables. D. immigrans and D. hydei are less specialised. The coexistence is explained by reference to ecological theory.     

Mature trees as keystone structures in Holarctic ecosystems – a quantitative species comparison in a northern English park

Background: Mature trees often provide ecological niches of value to specialised flora and fauna, signalled by such attributes as epiphytes, trunk rot and dead branches. In Britain, they are often found in parklands and wood pastures, which are rare habitats in Europe.

Aims: As species differences in veteran attributes of such trees have not been studied, we surveyed eight Holarctic tree species in Chillingham Park, in north-east England, where the stems are of broadly similar age (200–250 years).

Methods: The following variables were scored for 779 trees: presence or absence of veteran attributes, community status (alone, in a group, or in a linear feature), stem diameter, altitude at which growing, and the ground vegetation.

Results: Trees were generally of only moderate mean diameter. Alder (Alnus glutinosa) and ash (Fraxinus excelsior) had the most veteran attributes (4.30 and 4.16, respectively), followed by oak (Quercus sp.) (3.65), then by birch (Betula agg.) (3.49), beech (Fagus sylvatica) (3.12), sycamore (Acer pseudoplatanus) (2.77), larch (Larix sp.) (2.47) and Scots pine (Pinus sylvestris) (1.92). Trees growing at middle altitudes and alone, or in linear features (rather than in groups), had most veteran attributes; 32% of trees exhibited three or more.

Conclusions: To capture the veteran tree interest of a site, a survey protocol must consider the history of a site as well as the numbers of veteran attributes exhibited by individual trees, which may differ among species. Finally, alder has not attracted particular attention in these habitats, and we suggest that its fast-growing and rot-prone nature may make it of particular interest for conservation of saproxylic biodiversity.     

A specialised transducing phage of P22 for which the ability to form plagues is associated with transduction of the proAB region

Summary The multisite mutantproAB47 has been used to isolate specialised transducing phages of P22 for theproA andproB genes. Several of the preparations contain phages that form small plaques, and many of the properties of these suggest that the small plaques are formed by the transducing phages. Preliminary studies on the transduction of theproAB region by one such phage suggest that it forms fairly stable heterogenotes, both from apro point mutant and fromproAB47. The fact that the latter mutant is missing the phage attachment site results in a delay in integration of the specialised transducing phage.     

Life Cycle of Botryodiplodia theobromae, a Soft Rot Pathogen of Yam

Botryodiplodia theobromae Pat. forms chlamydospores and specialised hyphae in diseased yam tissues in which condition it tides over unfavourable periods. With favourable conditions the chlamydospores germinate and the specialised hyphae formed serve as sources of infection to new hosts and infect through wounds. Germination tubes infect by means of terminal appressoria, and nutrition within the host is effected by production of haustoria.     

The Trochidae and Turbinidae of the Kermadec Ridge (Mollusca: Gastropoda)

Abstract

Taieria erebus (Gnaphosidae) was found to be a versatile predator: it captured insects both cursorially (away from webs) and kleptopar-asitically (on alien webs); it captured spiders in both the presence and absence of webs; and it also ate the eggs of host spiders (oophagy). When T. erebus invaded webs, it was as an aggressive mimic — it performed a repertoire of vibratory behaviours to lure the host spider. Although T. erebus pursued and captured spiders on diverse web-types, it was more effective as a predator when invading densely (rather than sparsely) woven cribellate and non-sticky webs, and was especially effective on non-cribellate sticky webs. Gnaphosids are traditionally referred to as hunting spiders, but T. erebus built a small prey-capture web. T. erebus also preyed on segestriid spiders, then used their webs to catch more prey, this being an unusual example of a spider using, as a tool for predation, the spinning-work of another species from an unrelated family. T. erebus used specialised behaviours to prey on nesting cursorial spiders. Prey was either grasped or stabbed; the venom of T. erebus was highly potent against spiders. Experiments indicated that vision was of little or no importance in the predatory behaviour of T. erebus. The behaviour of T. erebus is compared to that of Portia, a web-building salticid spider which is very versatile in its predatory behaviour and has acute vision. T. erebus is discussed in relation to hypotheses concerning gnaphosid and salticid evolution.     

Generalised pollination systems for three invasive milkweeds in Australia

Because most plants require pollinator visits for seed production, the ability of an introduced plant species to establish pollinator relationships in a new ecosystem may have a central role in determining its success or failure as an invader. We investigated the pollination ecology of three milkweed species – Asclepias curassavica, Gomphocarpus fruticosus and G. physocarpus – in their invaded range in southeast Queensland, Australia. The complex floral morphology of milkweeds has often been interpreted as a general trend towards specialised pollination requirements. Based on this interpretation, invasion by milkweeds contradicts the expectation than plant species with specialised pollination systems are less likely to become invasive that those with more generalised pollination requirements. However, observations of flower visitors in natural populations of the three study species revealed that their pollination systems are essentially specialised at the taxonomic level of the order, but generalised at the species level. Specifically, pollinators of the two Gomphocarpus species included various species of Hymenoptera (particularly vespid wasps), while pollinators of A. curassavica were primarily Lepidoptera (particularly nymphalid butterflies). Pollinators of all three species are rewarded with copious amounts of highly concentrated nectar. It is likely that successful invasion by these three milkweed species is attributable, at least in part, to their generalised pollinator requirements. The results of this study are discussed in terms of how data from the native range may be useful in predicting pollination success of species in a new environment.     

Do native and invasive herbivores have an effect on Brassica rapa pollination?

• Mutualistic (e.g. pollination) and antagonistic (e.g. herbivory) plant–insect interactions shape levels of plant fitness and can have interactive effects.
• By using experimental plots of Brassica rapa plants infested with generalist (Mamestra brassicae) and specialised (Pieris brassicae) native herbivores and with a generalist invasive (Spodoptera littoralis) herbivore, we estimated both pollen movement among treatments and the visiting behaviour of honeybees versus other wild pollinators.
• Overall, we found that herbivory has weak effects on plant pollen export, either in terms of inter‐treatment movements or of dispersion distance. Plants infested with the native specialised herbivore tend to export less pollen to other plants with the same treatment. Other wild pollinators preferentially visit non‐infested plants that differ from those of honeybees, which showed no preferences. Honeybees and other wild pollinators also showed different behaviours on plants infested with different herbivores, with the former tending to avoid revisiting the same treatment and the latter showing no avoidance behaviour. When taking into account the whole pollinator community, i.e. the interactive effects of honeybees and other wild pollinators, we found an increased avoidance of plants infested by the native specialised herbivore and a decreased avoidance of plants infested by the invasive herbivore.
• Taken together, our results suggest that herbivory may have an effect on B. rapa pollination, but this effect depends on the relative abundance of honeybees and other wild pollinators.

     

Inter- and intra-specific diversity of Cuban Pinguicula (Lentibulariaceae) based on morphometric analyses and its relation with geographical distribution

Background: Phenotypic variations have been observed in populations of west Cuban Pinguicula species. Such populations occur in patches under different ecological conditions associated with specialised habitats and separated by geographical and ecological barriers, which can lead to morphological differentiation.

Aims: To analyse morphological diversity among species and populations of Cuban Pinguicula; and to test if morphological variability is associated with geographical distribution and distance between populations.

Methods: We sampled a total of eight populations of P. albida, P. cubensis and P. filifolia and tested for morphometric differences among them by Principal Component Analysis (PCA) and analysis of variance (ANOVA) based on 31 quantitative traits. We also assessed the geographical isolation with respect to morphological distance.

Results: The studied species showed high morphological variability at both species and population level. Reproductive characteristics appeared to be more promissory than vegetative ones in distinguishing geographical groups since they clearly defined populations; nevertheless a strong component of individual variation was observed. According to the distance analysis, such morphological variations were correlated with fragmented populations and isolation and allowed the differentiation of two morphotypes of P. albida and two of P. filifolia.

Conclusions: We conclude that high phenotypic variation of the analysed species is related to geographical and ecological isolation which have led to the differentiation of morphotypes within species.     

Pollination system of the Pilosocereus leucocephalus columnar cactus (tribe Cereeae) in eastern Mexico

It has been suggested that there is a geographic dichotomy in the pollination systems of chiropterophilous columnar cacti: in intra‐tropical areas they are pollinated almost exclusively by bats, whereas in extratropical areas they are pollinated by bats, birds and bees. However, currently the studies are clumped both taxonomically (mainly Pachycereeae species) and geographically (mainly in the Tehuacan Valley and the Sonoran Desert). This clumping limits the possibility of generalising the pattern to other regions or cactus tribes. Only four of the 36 chiropterophilous cacti in Pilosocereus have been studied. Despite the tropical distribution of two Pilosocereus species, bees account for 40–100% of their fruit set. We examined how specialised is the pollination system of P. leucocephalus in eastern Mexico. As we studied tropical populations, we expected a bat‐specialised pollination system. However, previous studies of Pilosocereus suggest that a generalised pollination system is also possible. We found that this cactus is mainly bat‐pollinated (bats account for 33–65% of fruit set); although to a lesser degree, diurnal visitors also caused some fruit set (7–15%). Diurnal visitors were more effective in populations containing honeybee hives. P. leucocephalus is partially self‐compatible (14–18% of fructification) but unable to set fruit without visitors. Despite the variation in pollination system, P. leucocephalus shows more affinity with other columnar cacti from tropical regions than with those from extratropical regions. Although we report here that a new species of tropical Pilosocereus is relatively bat‐specialised, this Cereeae genus is more flexible in its pollination system than the Pachycereeae genera.     

RECENT BIOACOUSTIC PUBLICATIONS (mainly 1993)

ABSTRACT

Some acoustic signals produced by small insects are very low in amplitude and attenuate rapidly with distance. To achieve high quality recordings with such signals, the use of specialised microphones or of sound insulation chambers is necessary. This paper presents a simple and efficient method for the recording of acoustic signals emitted by small sources. Its principle is based upon the use of two simultaneous digital recordings from two microphones: one records the ambient noise while the other records the ambient noise plus the signal to analyse. Both these recordings are converted into digital files and then a simple subtraction between the two isolates the signal with a good signal-to-noise ratio. With this method of background noise removal, the recording of low amplitude sounds in an uninsulated room with common microphones becomes possible. We have applied this method to the study of 12 complete courtships of Drosophila melanogaster and particularly to the analysis of pulse sounds produced by the male in presence of a female. The study focuses mainly on the rhythm of production of pulse trains over the course of the courtship.