Effects of potassium and gibberellic acid on stem growth of whole sunflower plants

Abstract The effects of gibberellic acid (GA₃) on whole sunflower (Helianthus annuus L.) plants grown at three potassium (K) levels (0.0, 0.5 and 5.0 mM) were studied. A tenfold increase in the length of the first internode was observed when plants grown without K were treated with GA₃. The uneven K distribution along the plant (higher K content in the higher internodes) was enhanced by GA₃ treatment. Gibberellic acid increased the content of reducing sugars, especially in K-deficient plants. An increase in the K level in the nutrient solution resulted in a decrease of the osmotic potential of stem segments. Osmotic potential differences within the elongating first internode were increased by GA₃ treatment.     

Electrophoretic characterization of Amaranthus L. seed proteins and its systematic implications

The seed protein profiles of 11 Amaranthus taxa (Amaranthaceae) from Spain were studied. These profiles were evaluated as a chemical character to clarify the taxonomic complexity in the genus. Tricine-sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles of the Amaranthus seed proteins studied showed a range of peptides varying from 64 to 12 kDa, with a larger number of protein bands observed between 25.1 and 12 kDa. For the taxonomic study, 14 bands, some of them subdivided into several isoforms, were considered. The similarity analysis based on the SDS-PAGE profile is a useful character for the discrimination of species in Amaranthus , except for A. cruentus and A. hypochondriacus , for which a hybrid population was found. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 57–63.     

Concordance between ecotypes and macroinvertebrate assemblages in Mediterranean streams

1. According to the guidelines of the European Water Framework Directive, assessment of the ecological quality of streams and rivers should be based on ecotype-specific reference conditions. Here, we assess two approaches for establishing a typology for Mediterranean streams: a top-down approach using environmental variables and bottom-up approach using macroinvertebrate assemblages.
2. Classification of 162 sites using environmental variables resulted in five ecotypes: (i) temporary streams; (ii) evaporite calcareous streams at medium altitude; (iii) siliceous headwater streams at high altitude; (iv) calcareous headwater streams at medium to high altitude and (v) large watercourses.
3. Macroinvertebrate communities of minimally disturbed sites ( n  = 105), grouped using UPGMA (unweighted pair-group method using arithmetic averages) on Bray–Curtis similarities, were used to validate four of the five ecotypes obtained using environmental variables; ecotype 5, large watercourses, was not included as this group had no reference sites.
4. Analysis of similarities ( anosim ) showed that macroinvertebrate assemblage composition differed among three of the four ecotypes, resulting in differences between the bottom-up and top-down classification approaches. Siliceous streams were clearly different from the other three ecotypes, evaporite and calcareous ecotypes did not show large differences in macroinvertebrate assemblages and temporary streams formed a very heterogeneous group because of large variability in salinity and hydrology.
5. This study showed that stream classification schemes based on environmental variables need to be validated using biological variables. Furthermore, our findings indicate that special attention should be given to the classification of temporary streams.     

Relationships between the close congeners Anthoxanthum odoratum and A. alpinum (Poaceae, Pooideae) assessed by morphological and molecular methods

Anthoxanthum alpinum Löve & Löve has been described as a diploid perennial distributed in northern Eurasia and the high mountains of central and eastern Europe. Difficulties in finding reliable morphological differences between this taxon and the widespread tetraploid Anthoxanthum odoratum L. have resulted in taxonomists treating them as conspecific, despite the cytological differentiation. The purpose of this study was to use different approaches to assess the relationships between close congeners, such as the pair A. odoratum / A. alpinum . Macromorphological, micromorphological, and molecular data were gathered and analysed for 14 populations representing both taxa from Scandinavia and the Iberian Peninsula. Different cluster analyses were performed to study the relatedness between individuals and populations. Subsequently, a principal components analysis was computed on the basis of macromorphological quantitative traits, and principal coordinates analysis was used to analyse qualitative, micromorphological, and random amplification of polymorphic DNA (RAPD) data. An analysis of molecular variance was applied to the molecular data, and the genetic differentiation between samples was measured using the F _ST estimator. The results showed that the geographical origin was more important than the ploidy level in explaining the relatedness between specimens and populations. Moreover, a strong correlation was found between the micromorphological traits and environmental parameters. The results of the analyses do not support the assignment of a specific taxonomic rank to A. alpinum .  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 237–252.     

Phylogeny of the pollinating yucca moths, with revision of Mexican species (Tegeticula and Parategeticula; Lepidoptera, Prodoxidae)

The yucca moths ( Tegeticula and Parategeticula ; Lepidoptera, Prodoxidae) are well known for their obligate relationship as exclusive pollinators of yuccas. Revisionary work in recent years has revealed far higher species diversity than historically recognized, increasing the number of described species from four to 20. Based on field surveys in Mexico and examination of collections, we describe five additional species: T. californica Pellmyr sp. nov. , T. tehuacana Pellmyr & Balcázar-Lara sp. nov. , T. tambasi Pellmyr & Balcázar-Lara sp. nov., T. baja Pellmyr & Balcázar-Lara sp. nov. and P. ecdysiastica Pellmyr & Balcázar-Lara sp. nov . Tegeticula treculeanella Pellmyr is identified as a junior synonym of T. mexicana Bastida. A diagnostic key to the adults of all species of the T. yuccasella complex is provided. A phylogeny based on a 2104-bp segment of mitochondrial DNA (mtDNA) in the cytochrome oxidase I and II region supported monophyly of the two pollinator genera, and strongly supported monophyly of the 17 recognized species of the T. yuccasella complex. Most relationships are well supported, but some relationships within a recent and rapidly diversified group of 11 taxa are less robust, and in one case conflicts with a whole-genome data set (amplified fragment length polymorphism, AFLP). The current mtDNA-based analyses, together with previously published AFLP data, provide a robust phylogenetic foundation for future studies of life-history evolution and host interactions in one of the classical models of coevolution and obligate mutualism.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 297–314.     

Hatching and viability of rotifer diapausing eggs collected from pond sediments

1. Planktonic rotifers inhabiting variable environments produce diapausing eggs that accumulate in the sediment of lakes and ponds, forming egg banks that may withstand adverse periods. A common assumption in zooplankton diapausing egg bank studies is to count as viable all eggs in the sediment that look healthy. This assumption should be challenged by asking how effectively ‘healthy‐looking’ eggs represent viable eggs. 2. In this study, viability of more than 1100 ‘healthy‐looking’ diapausing eggs belonging to the Brachionus plicatilis species complex was assessed in a laboratory hatching experiment. Eggs were collected at different depths from sediment cores obtained from 15 ponds located in coastal and inland areas of Eastern Spain. 3. Only approximately one half of the ‘healthy‐looking’ diapausing eggs hatched after incubation in experimental conditions. Almost all the hatchlings (99.4%) survived to maturity. The proportion of ‘healthy‐looking’ diapausing eggs that hatched varied among areas and among ponds within area, and substantially declined with sediment depth. Most of the hatchlings (88%) were obtained from the uppermost 2 cm of sediment. ‘Healthy‐looking’ eggs from upper sediment layers hatched after significantly shorter incubation times than eggs recovered from deeper layers. 4. Both decreased hatching success and increased incubation time for hatching with sediment depth suggest that older ‘healthy‐looking’ eggs are less responsive to hatching stimuli and could become unviable. However, the strong correlation found between the number of ‘healthy‐looking’ eggs and the number of hatchlings indicates that the abundance of ‘healthy‐looking’ eggs is a good index of egg bank viability.     

Exotic riparian vegetation lowers fungal diversity but not leaf decomposition in Portuguese streams

1. We characterised the fungal communities of eight streams in Portugal, four bordered by native deciduous forest and four bordered by pure stands of Eucalyptus globulus .
2. Aquatic hyphomycete species richness and evenness, but not numbers of water-borne conidia, of aquatic hyphomycetes were significantly lower in eucalypt bordered streams.
3. Multivariate analyses subdivided the fungal communities into two distinct groups corresponding to riparian vegetation.
4. Despite these differences in the dominant decomposer community, decay rates of eucalypt leaves (accounting for ≥98% of naturally occurring leaves in eucalypt bordered streams, absent in native forest) and chestnut leaves (occurring naturally in native forests) did not differ between the two groups of streams.     

Are predatory birds effective secondary seed dispersers?

We have studied the unusual phenomenon of secondary seed dispersal of Lycium intricatum seeds on a small oceanic Atlantic island (Alegranza, Canarian Archipelago) in which a small frugivorous lizard ( Gallotia atlantica ) and two different predatory birds participate, a shrike ( Lanius excubitor ) and a kestrel ( Falco tinnunculus ). Endemic lizards that are common prey of both bird species consume Lycium fruits. Lizard remains were significantly matched with the presence of Lycium fruits in the regurgitation pellets of the two predatory birds. Seeds were found in 7.3% of the lizard droppings, 31.0% of kestrel pellets and 55.7% of shrike regurgitations. The mean number of seeds per dropping or pellet was 4.8 ±4 in lizard, 20.2 ±34.5 in shrike and 6.7 ±8.1 in kestrel. The percentage of viable seeds showed significant differences among all four treatments, decreasing in the following direction: seeds collected directly from plants (98.0%), shrikes (88.0%), lizards (72.3%), and kestrels (31.7%). Seeds from Lycium fresh fruits and shrike pellets showed significantly higher germination rates than those from lizard droppings and kestrel pellets. While lizards and shrikes are effective seed dispersers, kestrel gut treatment decreases seed viability. Seed viability is always higher than seed germination in each of the four treatments. In this island environment, Lycium seeds are under an important random influence during the seed dispersal process. Secondary seed dispersal seems to acquire a relevant dimension in small and remote insular environments or isolated continental systems where interactions among the different elements involved are intense, all of them are abundant native residents, and they have been coexisting for a long time. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 345–352.     

Implications of the mastoid anatomy of larger extant felids for the evolution and predatory behaviour of sabretoothed cats (Mammalia, Carnivora, Felidae)

Muscle attachments in the mastoid region of the skull of extant felids are studied through dissection of two adult tigers Panthera tigris (Linnaeus, 1758) Pocock, 1930, a lion Panthera leo (Linnaeus, 1758) Pocock, 1930 and a puma Puma concolor (Linnaeus, 1771) Jardine, 1834, providing for the first time an adequate reference for the study of the evolution of that region in sabretoothed felids. Our study supports the inference by W. Akersten that the main muscles inserting in the mastoid process in sabretooths were those originating in the atlas, rather than those from the posterior neck, sternum and forelimb. Those inferences were based on the anatomy of the giant panda, Ailuropoda melanoleuca (David, 1869) Milne-Edwards, 1870, raising uncertainties about homology, which were founded, as revealed by our results. The mastoid muscle insertions in extant felids differ in important details from those described for Ailuropoda , but agree with those described for domestic cats, hyenas and dogs. The large, antero-ventrally projected mastoid process of pantherines allows a moderate implication of the m. obliquus capitis anterior in head-flexion. This contradicts the widespread notion that the function of this muscle in carnivores is to extend the atlanto-cranial joint and to flex it laterally, but supports previous inferences about the head-flexing function of atlanto-mastoid muscles in machairodontines. Sabretooth mastoid morphology implies larger and longer-fibred atlanto-mastoid muscles than in pantherines, and that most of their fibres ran inferior to the axis of rotation of the atlanto-occipital joint, emphasizing head-flexing action.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 207–221.