Vicariance and convergence in Magellanic and New Zealand long‐looped brachiopod clades (Pan‐Brachiopoda: Terebratelloidea)

Phylogenetic reconstructions using parsimony, maximum likelihood (ML), and Bayesian relaxed molecular clock analyses of ～2850 nucleotides of nuclear‐encoded small and large subunit ribosomal DNAs (SSU and LSU rDNAs) from 14 long‐looped (terebratelloid) ingroup and four short‐looped (terebratulidine) outgroup brachiopod taxa, together with ML analyses of ～663 nucleotides of mitochondrial cytochrome oxidase subunit 1 (cox1) from 12 terebratelloid taxa, show that deep divergence separates taxa endemic to waters in the vicinity of New Zealand from those with a Magellanic distribution around South America and Antarctica. This deep divergence also separates Magellanic Terebratella dorsata from New Zealand Terebratella sanguinea, showing that they are not congeneric. Instead, they belong to separate ‘Magellanic’ (MAG) and ‘New Zealand’ (NZ) clades that first diverged about 82 Mya (95% highest posterior density, 48–120 Mya), correlating with separation between the NZ and Antarctic tectonic plates. Sequence analyses also reveal (1) that the Antarctic endemic taxa Magellania fragilis and Magellania joubini are not congeneric with Magellania venosa, suggesting that their previous placement in Aerothyris should be restored, and (2) that divergence between Antarctic and NZ species of the terebratulide Liothyrella occurred much later than plate separation, perhaps because of continuing gene flow caused by long‐lived larvae. The topology of the rDNA and cox1 gene trees implies that radial ornament of the shell (‘ribbing’) has been gained (and/or lost) independently within the MAG and NZ clades. Radial ribs are widespread in articulate brachiopods throughout the Phanerozoic, but no comparisons of brachiopod rib morphology and morphogenesis have been published. Our comparisons of transverse shell mid‐sections in the scanning electron microscope reveal no obvious evidence of differences in morphology between independently gained ribs. We also consider several ways in which ribs may affect fitness, including effects on hydrodynamics. Only scanty and inconclusive evidence is available, but we suggest that effects (if any) are likely to be of small magnitude; adaptive value of brachiopod shell ribs remains to be demonstrated. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 631–645.     

Primary growth and morphological markers of interannual growth limits in Cupressaceae from Patagonia

The present study shows experimentally that primary growth of the native Patagonian Cupressaceae Austrocedrus chilensis (D. Don) Pic.-Serm et Bizz., Fitzroya cupressoides (Molina) I. M. Johnst. and Pilgerodendron uviferum (D. Don) Florin is potentially continuous. External morphological markers of interannual growth limits have been identified for the main axes of these species after several years of observation. Such limits correspond with axis portions in which internodes are relatively short and leaves have a small distal free end forming an acute angle with the axis. The causality of these results and their utility for studying the productivity, adaptation to different environments, population management and conservation of these threatened species are discussed.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 146 , 285–293.     

Plasticity to simulated shade is associated with altitude in structured populations of Arabidopsis thaliana

Plants compete for photosynthesis light and induce a shade avoidance syndrome (SAS) that confers an important advantage in asymmetric competition for light at high canopy densities. Shade plasticity was studied in a greenhouse experiment cultivating Arabidopsis thaliana plants from 15 populations spread across an altitudinal gradient in the northeast area of Spain that contain a high genetic variation into a reduced geographical range. Plants were exposed to sunlight or simulated shade to identify the range of shade plasticity. Fourteen vegetative, flowering and reproductive traits were measured throughout the life cycle. Shade plasticity in flowering time and dry mass was significantly associated with the altitude of population origin. Plants from coastal populations showed higher shade plasticity indexes than those from mountains. The altitudinal variation in flowering leaf plasticity adjusted negatively with average and minimum temperatures, whereas dry mass plasticity was better explained by negative regressions with the average, maximum and minimum temperatures, and by a positive regression with average precipitation of the population origin. The lack of an altitudinal gradient for the widest number of traits suggests that shade light could be a driver explaining the distribution pattern of individuals in smaller geographical scales than those explored here.     

Development and variation of the anuran webbed feet (Amphibia, Anura)

Webbed feet evolved convergently in most groups of aquatic tetrapods. However, extensive webbing is not always limited to an aquatic life style. In Anurans, hind limbs display great variation, including absence, of interdigital membranes, which is explained by differential growth rates of digital and interdigital tissues during early limb development. In order to explore web diversification in anurans, this paper presents analyses of: (1) hind limb early development and its relationship to the expression of interdigital membranes; (2) intraordinal variation of interdigital membranes in adult feet; and (3) intraordinal variation of metatarsal and digit lengths, including comments on metatarsal development. Study of limb development is carried out in larval series of 12 anuran species. Analysis of intraordinal variation comprises a sample of adults of 111 species. We recognize two configurations in the autopodium bud: (1) paddle-like shape with digits differentiated within the confines of interdigital tissues, and (2) pointed autopodium with digits differentiated beyond interdigital tissues. These early differences are conserved in adult morphology, in which allometry and isometry of digit IV (and metatarsal IV) with respect to other digits (and metatarsals) result in asymmetrical and paddle-like autopodium, respectively. The paddle-like autopodium is restricted to fossil and extant pipids and the hylids Pseudis and Lysapsus , whereas the asymmetrical one is present in most anurans. Both configurations seem to represent an early divergence of the autopodium shape. The paddle-like configuration observed in hylids appears as a reversion to an ancient condition that results from a conserved program of limb development.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 39–58.     

Fatty acids of leaf wax esters in Coincya Rouy (Brassicaceae)

A total of 46 populations belonging to the genus Coincya Ruoy (Brassicaceae) from the Iberian Peninsula was examined for their wax ester fatty acids composition. Size of ester fatty acids in the genus Coincya varies between 14 and 28 carbon atoms. This series is dominated by acids with an even number of carbon atoms. The most abundant acids are Ojg, C^y, C^^o and C₂₆ among evens and C₁₇ and C₂₁ among odds. A positive correlation was observed between chemical composition and environmental adaptation, and also with certain morphological characters. Changes relate to low temperatures or to high relative humidity, and there is a positive correlation between chemical composition and leaf glaucousness.     

Effect of harvester ants of the genus Pogonomyrmex on the soil seed bank around their nests in the central Monte desert,Argentina

1. The abundance and composition of soil seed banks is a key determinant of plant community structure. Harvester ants can remove huge quantities of preferred seeds close to the nest affecting composition and spatial distribution of plants. 2. In the central Monte desert (Argentina) ants of the genus Pogonomyrmex have high seed removal rates, especially of the five main grasses. The aim of this study was to establish if their foraging activity affects spatial patterns of the soil seed bank around their nests. Our hypotheses were: (1) removal by ants decreases seed abundance of preferred species in the soil; and (2) the effect varies in time. 3. Soil seed abundance was assessed at different distances from Pogonomyrmex nests in the litter and in bare soil at the beginning, the middle, and the end of the season (late spring‐early autumn). 4. A lower seed abundance of preferred species was observed close to the nest in the litter at the end of the season. Non‐preferred species showed no distance gradient. 5. The lower foraging activity and seed consumption at the beginning of the season could explain the temporal variation of the spatial effect. This was only observed in the litter, probably because of the higher removal frequency in this substrate. 6. Colonies of Pogonomyrmex spp. could enhance the heterogeneity of soil seed banks in the central Monte desert from the summer to the beginning of the autumn. Implications for vegetation dynamics depend on the degree to which seed density limits perennial grasses recruitment after ant activity season.     

Sex ratio, reproductive mode and genetic diversity in Triops cancriformis

1. Aquatic invertebrates display a wide array of alternative reproductive modes from apomixis to hermaphroditism and cyclical parthenogenesis. These have important effects on genetic diversity and population structure. Populations of the 'living fossil' Triops cancriformis display a range of sex ratios, and various reproductive modes are thought to underlie this variation. Using sex ratio information and histological analyses European populations have been inferred to be gonochoric (with separate males and females), selfing hermaphroditic and androdioecious, a rare reproductive mode in which selfing hermaphrodites coexist with variable proportions of males. In addition, some populations have been described as meiotic parthenogens.
2. Here we use population genetic analysis using microsatellite loci in populations with a range of sex ratios including a gonochoric population, and marker segregation patterns in heterozygote individuals reared in isolation, to clarify the reproductive mode in this species.
3. Our data show that populations in general have very low levels of genetic diversity. Non-gonochoric populations show lower genetic diversity, more heterozygote deficiencies, higher inbreeding coefficients and stronger linkage disequilibria than the gonochoric population. The maintenance of some heterozygosity in populations is consistent with some male influence in T. cancriformis populations, as would be expected from an androdioecious reproductive system. Results of marker segregation in eggs produced in isolation from non-gonochoric populations indicate that meiosis occurs and are consistent with two reproductive modes: selfing hermaphroditism and a type of ameiotic parthenogenesis.
4. Overall, our data indicate that androdioecy and selfing hermaphroditism are the most likely reproductive modes of non-gonochoric European Triops populations. Triops populations are strongly structured, suggesting high genetic drift and low levels of gene flow.     

Phylogeny of western Mediterranean Leptodirini, with an emphasis on genital characters (Coleoptera: Leiodidae: Cholevinae)

Abstract The tribe Leptodirini (Leiodidae: Cholevinae) is one of the largest radiations of Coleoptera in the subterranean environment. Although subjected to systematic and evolutionary studies, the phylogeny remains poorly understood. We assessed the phylogeny of the western Mediterranean lineages (Iberian Peninsula, Pyrenees and Sardinia) based on a cladistic analysis of fourteen characters of external morphology and twenty characters of the male and female genitalia, studied in 182 species belonging to thirty‐nine genera. We tested the monophyly of the traditional two main divisions of the group (infraflagellates and supraflagellates), as well as that of some ‘phyletic series’. The final matrix contained fifty‐eight terminal taxa, twenty‐four of which had different character state combinations. The strict consensus of the sixty most parsimonious trees recovered a monophyletic Leptodirini, but not their separation into infraflagellates and supraflagellates. The supraflagellates formed a paraphyletic group with respect to the infraflagellates (corresponding to our sampled ‘Speonomus’ series), with Notidocharis sister to all other included Leptodirini, and Speonomidius sister to Leptodirini excluding Notidocharis. The series ‘Spelaeochlamys’, including the Sardinian genera but excluding Pseudochlamys, was recovered as monophyletic with weak support. The ‘Quaestus’ series formed a polytomy with Pseudochlamys plus the ‘Speonomus’ series (including Bathysciola), which was recovered as monophyletic with strong support. Speonomus, Bathysciola, Quaestus and Troglophyes were para‐ or polyphyletic. Our results suggested the respective monophyletic origin of the Leptodirini from the Pyrenees (Pseudochlamys plus the ‘Speonomus’ series) and the Mediterranean coast plus Sardinia (series ‘Spelaeochlamys’). On the contrary, the Leptodirini of the Atlantic north coast of the Iberian Peninsula (series ‘Quaestus’ and ‘Speonomidius’) were not monophyletic.     

Size,structure and nitrogen content of seeds of Fabaceae in relation to nodulation

Looking for clues to explain the low rate and unpredictability of the pollination of allogamous, epiphytic orchids in the context of the success of the orchid family in general, we compared the pollination of two miniature twig epiphytes in Mexico: Notylia barkeri, a ‘weedy’, rewarding species, and Erycina crista‐galli, a rare, deceptive species. We measured the effects of the spatial organization of the flowers and various parameters of visibility and height above the ground in relation to the spatial organization of the seed capsules (which retrospectively measures the activity of the pollinators). The spatial presentation of the flowers of E. crista‐galli explained only 5% of the distribution of the seed capsules. For N. barkeri, with compound flowers, the spatial presentation, considering individual flowers or inflorescences, explained 12% and 45% of the distribution of the seed capsules, respectively, and all other interactions between the variables were insignificant. Both the deceptive and reward strategies resulted in the production of large numbers of seeds despite a low pollination percentage (1–5%). Notylia barkeri produced 11.8 (2005–6) and 53.7 (2007–8) times more seeds in total than E. crista‐galli. Furthermore, unlike E. crista‐galli, N. barkeri responded to loss of individuals after high winds with an increased production of flowers per plant. We suggest that orchids have evolved to specialize in chance, and instead of maximizing pollinator attraction, they maximize the seed production resulting from every casual encounter. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 251–266.