The Effects of Modifying Sucrose Concentration on the Development of Maize Kernels Grown in vitro

Intact Zea mays L. kernels attached to cob tissue develop tomaturity when grown in vitro. This experiment was designed todetermine if it is possible to prolong kernel growth by refreshingthe culture medium. Blocks of maize kernels were grown in vitroon media containing several concentrations of sucrose. Kernels,at all concentrations of sucrose, developed to maturity at 30–35d post-pollination, indicating that it is not possible to extendthe kernel growth phase by supplying a carbohydrate source.Kernels grown on media containing 80 g 1^–1 or higher sucroseconcentration had a significantly greater percentage of kernelsthat developed to maturity, and had greater weight and starchcontent per seed. Zea mays, kernel culture, seed development, starch     

Do geographic distribution,niche property and life form explain plants' vulnerability to global change?

We modelled the future distribution in 2050 of 975 endemic plant species in southern Africa distributed among seven life forms, including new methodological insights improving the accuracy and ecological realism of predictions of global changes studies by: (i) using only endemic species as a way to capture the full realized niche of species, (ii) considering the direct impact of human pressure on landscape and biodiversity jointly with climate, and (iii) taking species' migration into account. Our analysis shows important promises for predicting the impacts of climate change in conjunction with land transformation. We have shown that the endemic flora of Southern Africa on average decreases with 41% in species richness among habitats and with 39% on species distribution range for the most optimistic scenario. We also compared the patterns of species' sensitivity with global change across life forms, using ecological and geographic characteristics of species. We demonstrate here that species and life form vulnerability to global changes can be partly explained according to species' (i) geographical distribution along climatic and biogeographic gradients, like climate anomalies, (ii) niche breadth or (iii) proximity to barrier preventing migration. Our results confirm that the sensitivity of a given species to global environmental changes depends upon its geographical distribution and ecological proprieties, and makes it possible to estimate a priori its potential sensitivity to these changes.     

Floral ecostratigraphy in practice

Fossil plant associations are best named by traditional phytosociological methods from genera or species prominent in a reference collection. The named association then has some stability during later palaeoecological interpretation and threedimensional mapping in sedimentary basins. Biostrati-graphic zones are best established from successions of events in similar associations within a specified area. Such events may not have occurred in other types of association, nor have been contemporaneous in separate areas. These events are most effectively correlated when the likely environment and ecology of the associations are also considered.     

The pay-off from superparasitism in the egg parasitoid Trissolcus basalis, in relation to patch defence

1. In species such as quasi-gregarious egg parasitoids, which exploit defendable patches, the fitness pay-off from superparasitism is an important factor in considering the evolution of patch defence and optimal patch defence strategies.
2. When oviposition in a previously parasitized host has a non-zero fitness pay-off, competing parasitoids are not only able to diminish the future value of a patch to other females by depleting unparasitized hosts, but also devalue the previous investment of other females in the patch by superparasitizing.
3. In Trissolcus basalis , an egg parasitoid of pentatomid bugs, the fitness pay-off from superparasitism is higher than 0.5 when the time interval between ovipositions is less than 3 h, suggesting that defending a previous investment will be an important component of patch defence behaviour.
4. The data suggest a mechanism for the high early pay-off, which involves the superparasitizing female adjusting the sex ratio of its offspring in favour of males. Males develop more quickly than females and thus may have a competitive advantage.     

Vulnerability of African mammals to anthropogenic climate change under conservative land transformation assumptions

Recent observations show that human‐induced climate change (CC) and land transformation (LT) are threatening wildlife globally. Thus, there is a need to assess the sensitivity of wildlife on large spatial scales and evaluate whether national parks (NPs), a key conservation tools used to protect species, will meet their mandate under future CC and LT conditions. Here, we assess the sensitivity of 277 mammals at African scale to CC at 10′ resolution, using static LT assumptions in a ‘first‐cut’ estimate, in the absence of credible future LT trends. We examine the relationship between species' current distribution and macroclimatic variables using generalized additive models, and include LT indirectly as a filter. Future projections are derived using two CC scenarios (for 2050 and 2080) to estimate the spatial patterns of loss and gain in species richness that might ultimately result. We then apply the IUCN Red List criteria A3(c) of potential range loss to evaluate species sensitivity. We finally estimate the sensitivity of 141 NPs in terms of both species richness and turnover. Assuming no spread of species, 10–15% of the species are projected to fall within the critically endangered or extinct categories by 2050 and between 25% and 40% by 2080. Assuming unlimited species spread, less extreme results show proportions dropping to approximately 10–20% by 2080. Spatial patterns of richness loss and gain show contrasting latitudinal patterns with a westward range shift of species around the species‐rich equatorial zone in central Africa, and an eastward shift in southern Africa, mainly because of latitudinal aridity gradients across these ecological transition zones. Xeric shrubland NPs may face significant richness losses not compensated by species influxes. Other NPs might expect substantial losses and influxes of species. On balance, the NPs might ultimately realize a substantial shift in the mammalian species composition of a magnitude unprecedented in recent geological time. To conclude, the effects of global CC and LT on wildlife communities may be most noticeable not as a loss of species from their current ranges, but instead as a fundamental change in community composition.     

Ultrastructure of spermiogenesis and spermatozoa of four Oriopsis species (Sabellinae, Sabellidae, Polychaeta)

The ultrastructure of sperm from four species of Oriopsis is described. Males of Oriopsis bicoloris produce sperm with an elongate nucleus divided into four rods, connected proximally, and four long mitochondria lying along the nucleus. The axoneme runs in the middle of the nuclear and mitochondria1 rods. Oriopsis brevicollaris males have sperm with an elongate nucleus and long midpiece comprised of four mitochondria wrapped around the axoneme. Males of O. mobilis have sperm with an elongate nucleus and long midpiece similar to that of O. brevicollaris , although the midpiece is much longer. Oriopsis dentata males havc sperm with a flattened head, similar to those of mammals, though the midpiece is simple and the axoneme free. The variability of reproductive mechanisms within the Polychaeta is discussed with reference to the elucidation of the function of various sperm morphologies. The implications for the taxonomy and systematics of Oriopsis , and the Sabellidae as a whole, are also discussed. It is concluded that Oriopsis is not monophyletic and examination of reproductive structures in other small sabellids is required. Study on reproduction in the type species, O. armandi , is needed to establish the reproductive method of Oriopsis and so allow revision of this genus.     

New Fabriciola species (Polychaeta, Sabellidae, Fabriciinae) from the eastern Atlantic, with a description of sperm and spermathecal ultrastructure

New species in the genus Fabriciola Friedrich are described. Fabriciola is defined by a single synapomorphy, the presence of non-vascularized, ventral filamentous appendages. Otherwise the genus is variable, with differences among species in chaetae, eyes, and peristomial organization. The new species, Fabriciola flammula, F. liguronis and F. parvus , reflect this heterogeneity. Fabriciola liguronis has spermathecae in the radiolar crown of females, the first record of these structures in Fabriciola , but F. flammula and F. parvus lack spermathecae. Sperm ultrastructure in all three species share apomorphies with other fabriciins, but vary in other respects. Fabriciola may be paraphyletic, but material of the type species F. spongicola (Southern, 1921) has been unobtainable so far, and detailed study of this species is required to define the genus Fabriciola adequately.     

Survival and Breeding Transitions for a Reintroduced Bison Population: a Multistate Approach

Abstract: The iconic plains bison (Bison bison) have been reintroduced to many places in their former range, but there are few scientific data evaluating the success of these reintroductions or guiding the continued management of these populations. Relying on mark-recapture data, we used a multistate model to estimate bison survival and breeding transition probabilities while controlling for the recapture process. We tested hypotheses in these demographic parameters associated with age, sex, reproductive state, and environmental variables. We also estimated biological process variation in survival and breeding transition probabilities by factoring out sampling variation. The recapture rate of females and calves was high (0.78 ± 0.15 [SE]) and much lower for males (0.41 ± 0.23), especially older males (0.17 ± 0.15). We found that overall bison survival was high (>0.8) and that males (0.80 ± 0.13) survived at lower rates than females (0.94 ± 0.04), but as females aged survival declined (0.89 ± 0.05 for F ≥15 yr old). Lactating and non-lactating females survived at similar rates. We found that females can conceive early (approx. 1.5 yr of age) and had a high probability (approx. 0.8) of breeding in consecutive years, until age 13.5 years, when females that were non-lactating tended to stay in that state. Our results suggest senescence in reproduction and survival for females. We found little support for the effect of climatic covariates on demographic rates, perhaps because the park's current population management goals were predicated from drought-year conditions. This reintroduction has been successful, but continued culling actions will need to be employed and an adaptive management approach is warranted. Our demographic approach can be applied to other heavily managed large-ungulate systems with few or no natural predators.     

Cladistics and polychaetes

A series of cladistic analyses assesses the status and membership of the taxon Polychaeta. The available literature, and a review by Fauchald & Rouse (1997), on the 80 accepted families of the Polychaeta are used to develop characters and data matrices. As well as the polychaete families, non-polychaete taxa, such as the Echiura, Euarthropoda, Onychophora, Pogonophora (as Frenulata and Vestimentifera), Clitellata, Aeolosomatidae and Potamodrilidae, are included in the analyses. All trees are rooted using the Sipuncula as outgroup. Characters are based on features (where present) such as the prostomium, peristomium, antennae, palps, nuchal organs, parapodia, stomodaeum, segmental organ structure and distribution, circulation and chaetae. A number of analyses are performed, involving different ways of coding and weighting the characters, as well as the number of taxa included. Transformation series are provided for several of these analyses. One of the analyses is chosen to provide a new classification. The Annelida is found to be monophyletic, though weakly supported, and comprises the Clitellata and Polychaeta. The Polychaeta is monophyletic only if taxa such as the Pogonophora, Aeolosomatidae and Potamodrilidae are included and is also weakly supported. The Pogonophora is reduced to the rank of family within the Polychaeta and reverts to the name Siboglinidae Caullery, 1914. The new classification does not use Linnaean categories, and the Polychaeta comprises two clades, the Scolecida and Palpata. The Palpata has the clades Aciculata and Canalipalpata. The Aciculata contains the Phyllodocida and Eunicida. The Canalipalpata has three clades; the Sabellida (including the Siboglinidae) Spionida and Terebellida. The position of a number of families requires further investigation.     

A cladistic analysis of Siboglinidae Caullery, 1914 (Polychaeta, Annelida): formerly the phyla Pogonophora and Vestimentifera

It has been proposed in recent years that the phyla Pogonophora and Vestimentifera are a derived clade of polychaete annelids. It has also been proposed that if this clade belongs among polychaetes, then the taxon name Pogonophora is misleading and should revert to a name first formulated for the group, Siboglinidae Caullery, 1914. This recommendation is adopted in this paper, and a cladistic study using terminals of 'generic' rank in the former Pogonophora (including Vestimentifera) is undertaken. The purpose of this is to assess which taxon names should now be used for clades within Siboglinidae, and to provide a revised taxonomy, based on phylogenetic principles. Another major aim is to assess the position of the vestimentiferan clade within Siboglinidae. The results show that Vestimentifera is the sister group to Sclerolinum, and this clade is then sister group to Frenulata, i.e. the remaining Siboglinidae. The results suggest that all taxa within Siboglinidae that are not genera or species are redundant, except for the following: Siboglinidae is defined as the first polychaete, and all its descendants, to have an gut occluded by expanded endoderm filled with chemoautotrophic bacteria, as seen in the holotype of Riftia pachyptila Jones, 1981. Monilifera can be defined based on apomorphy-based system such that it is the first siboglinid, and all its descendants, to have rings of chaetae (uncini) in the opisthosoma, as seen in the holotype of Sclerolinum magdalenae Southward, 1972. Vestimentifera can be denned as the first siboglinid and all its descendants to have a vestimentum as seen in the holotype of Riftia pachyptia. Frenulata is defined as the siboglinid, and all its descendants, to have a mid-trunk girdle, as seen in the holotype of Siboglinum weberi Caullery, 1914. The taxa of generic rank are not defined here since their monophyly was not investigated.