Presence Of Reproductive Structures Research Articles

Introducing palaeolithobiology

ABSTRACT A growing literature of deep but also surficial fossilized remains of lithobiological life, often associated with igneous rocks, necessitates the unfolding of a sub-discipline within paleobiology. Here, we introduce the term paleolithobiology as the new auxiliary sub-discipline under which fossilized lithobiology should be handled. We present key criteria that distinguish the paleolithobiological archive from the traditional one and discuss sample strategies as well as scientific perspectives. A majority of paleolithobiological material consists of deep biosphere fossils, and in order to highlight the relevance of these, we present new data on fungal fossils from the Lockne impact crater. Fungal fossils in the Lockne drill cores have been described previously but here we provide new insights into the presence of reproductive structures that indicate the fungi to be indigenous. We also show that these fungi frequently dissolve and penetrate secondary calcite, delineating the role lithobionts plays in geobiological cycles. We hope that the formalization of the sub-discipline paleolithobiology will not only highlight an overlooked area of paleobiology as well as simplify future studies of endo- and epilithic fossil material, but also improve our understanding of the history of the deep biosphere.

Loglinear modeling of the “duster” condition in the African oil palm in Colombia

A new physiopathy in oil palms that has been called "duster" for which at present no causal agent is known, is gaining interest in agronomic research. In 2015 we carried out a count of reproductive structures to evaluate the severity in genetic materials of three different origins in a plantation in Colombia. The aim was to determine the possible relationships between disorder and the presence of reproductive structures . For the data analysis a cluster analysis was performed and then we assessed the relative risk between the state of the disorder, the origin and structures of the plant and we applied a log-linear model to study the dependence between variables classified in clusters: palms showing high fruiting and grouped with low fruiting. We observed that fruiting was not statistically related to the presence of physiopathy. We also observed that Brabanta origin were the least susceptible and showed the best fruiting.

Changes in plant collection practices from the 16th to 21st centuries: implications for the use of herbarium specimens in global change research.

Background and AimsHerbaria were recently advertised as reliable sources of information regarding historical changes in plant traits and biotic interactions. To justify the use of herbaria in global change research, we asked whether the characteristics of herbarium specimens have changed during the past centuries and whether these changes were due to shifts in plant collection practices.MethodsWe measured nine characteristics from 515 herbarium specimens of common European trees and large shrubs collected from 1558 to 2016. We asked botanists to rank these specimens by their scientific quality, and asked artists to rank these specimens by their beauty.Key ResultsEight of 11 assessed characteristics of herbarium specimens changed significantly during the study period. The average number of leaves in plant specimens increased 3-fold, whereas the quality of specimen preparation decreased. Leaf size negatively correlated with leaf number in specimens in both among-species and within-species analyses. The proportion of herbarium sheets containing plant reproductive structures peaked in the 1850s. The scientific value of herbarium specimens increased until the 1700s, but then did not change, whereas their aesthetic value showed no systematic trends.ConclusionsOur findings strongly support the hypothesis that many characteristics of herbarium specimens have changed systematically and substantially from the 16th to 21st centuries due to changes in plant collection and preservation practices. These changes may both create patterns which could be erroneously attributed to environmental changes and obscure historical trends in plant traits. The utmost care ought to be taken to guard against the possibility of misinterpretation of data obtained from herbarium specimens. We recommend that directional changes in characters of herbarium specimens which occurred during the past 150‒200 years, primarily in specimen size and in the presence of reproductive structures, are accounted for when searching for the effects of past environmental changes on plant traits.

Sex expression and genotypic sex ratio vary with region and environment in the wetland moss Drepanocladus lycopodioides

Abstract Sex ratio variation is common among organisms with separate sexes. In bryophytes, sex chromosome segregation at meiosis suggests a balanced progeny sex ratio. However, most bryophyte populations exhibit female-biased phenotypic sex ratios based on the presence of reproductive structures on gametophytes. Many bryophyte populations do not form sexual organs, and genotypic sex ratio variation in such populations is mostly unknown. We tested sex expression, and phenotypic and genotypic sex ratios against environmental parameters in natural populations of the unisexual wetland moss Drepanocladus lycopodiodes at 11 sites in each of three regions in southern Sweden. We identified sex in 660 individual ramets, based on sexual structures, when present, or with a specifically designed molecular marker, when absent. All regions exhibited a female bias in phenotypic and genotypic sex ratios. Sex ratio biases and sex expression differed between regions. Sex ratios were less female-biased in larger patches. Wetter patches exhibited a stronger female bias in genotypic sex ratio and lower sex expression. This is the first evidence of environmental effects on genotypic sex ratio in mosses. A higher frequency of females in wet patches could be due to higher female resource demands for sporophyte production or higher male sensitivity to wetness. A higher incidence of females than males in moister sites aligns with female flowering plants, but differs from reproductive bryophytes in drier environments. Taken together with previous results, our data indicate that sex ratio variation and its drivers differ among species, their life histories and environments.

Factors affecting morphological transformation and secondary attachment of apexes of Chondracanthus chamissoi (Rhodophyta, Gigartinales)

Fragments of Chondracanthus chamissoi have the capacity of secondary attachment. In the laboratory, apexes of upright branches of C. chamissoi placed 1–2 mm and parallel to horizontal substrata underwent morphological transformation prior to becoming attached, changing from thick and blunt to elongated and cylindrical and from straight to curved towards the substratum, where they eventually produced secondary attachment discs. When transformation occurred, signs could already be observed after 3 days of incubation. Several factors that could affect transformation and attachment were tested. The vertical or horizontal orientation of the fragments, the angle of incidence of light, and the phase of the life cycle had no effect on transformation, whereas the presence of reproductive structures had a negative effect compared to vegetative fragments. Low light intensity and low water flow favored the transformation response. Calcareous substrata (bivalve shells and coralline crusts) produced the highest frequency of transformation and other solid substrata (glass slides, rock, and sea-squirt tunic) followed in the ranking, but fleshy seaweeds (Ulva sp., Sarcothalia crispata, and C. chamissoi) failed to produce any response. Thus, the experimental upright branches developed features and reactivity similar to basal branches when the former were placed in conditions similar to those where the latter occur in the natural environment. Vegetative reproduction has been incorporated in cultivation techniques of C. chamissoi, but it could also be used in repopulation or restoration programs of this species.

Multiple factors influence population sex ratios in the Mojave Desert moss Syntrichia caninervis

Natural populations of many mosses appear highly female-biased based on the presence of reproductive structures. This bias could be caused by increased male mortality, lower male growth rate, or a higher threshold for achieving sexual maturity in males. Here we test these hypotheses using samples from two populations of the Mojave Desert moss Syntrichia caninervis. We used double-digest restriction-site associated DNA (RAD) sequencing to identify candidate sex-associated loci in a panel of sex-expressing plants. Next, we used putative sex-associated markers to identify the sex of individuals without sex structures. We found a 17:1 patch-level phenotypic female to male sex ratio in the higher elevation site (Wrightwood) and no sex expression at the low elevation site (Phelan). In contrast, on the basis of genetic data, we found a 2:1 female bias at the Wrightwood site and only females at the Phelan site. The relative area occupied by male and female genets was indistinguishable, but males were less genetically diverse. Our data suggest that both male-biased mortality and sexual dimorphism in thresholds for sex expression could explain genetic and phenotypic sex ratio biases and that phenotypic sex expression alone over-estimates the extent of actual sex ratio bias present in these two populations of S. caninervis.

Effectiveness of essential oils for postharvest control of Phyllosticta citricarpa (citrus black spot) on citrus fruit

The in vitro and in vivo control of Phyllosticta citricarpa (citrus black spot, CBS) on citrus fruits was evaluated using 14 essential oils (EOs) extracted from Uruguayan native plants. In vitro, volatile components of Chenopodium ambrosioides completely inhibited fungal growth. The dilution agar test showed that fungus reproduction was completely inhibited by Conyza bonaerensis essential oil (EO). The other 12 EOs tested showed high inhibition after 10–15d, presenting fungistatic effects. In vivo, assays were performed on fruit of lemon [Citrus limon (L.) Burm] and Valencia orange [Citrus sinensis (L.) Osbeck] in order to evaluate the effects of liquid and volatile EO phases on reproduction. Typical lesions of CBS without reproductive structures were exposed to Ch. ambrosioides and C. bonaerensis EOs for 20 d at 27°C and cycles of 16h light and 8h dark. The volatile components of Ch. ambrosioides were able to control 100% of P. citricarpa reproduction in orange and lemon fruit. The growth of other fungi such, as Colletotrichum gloeosporoides and Fusarium sp., was also inhibited. Nevertheless, the liquid phase was not effective to control the pathogen. In another test, carton boxes with 20 fruits, each presenting typical CBS symptoms, but without the presence of reproductive structures, were exposed to 0.01 and 0.05% of Ch. ambrosioides EO (w/v). The fruits were stored at 5°C for 20d and then kept for 7d at room temperature. A 40% reduction of reproduction was observed in citrus fruit exposed to 0.05% of EO. GC–MS analysis of EOs showed that Ch. ambrosioides EO was composed of 76% monoterpene compounds (49 and 27% of oxygenated and hydrocarbons, respectively), while C. bonaerensis EO presented 17% monoterpenes and 10% sequisterpenes.

Are free-floating planktonic hydroids (Cnidaria, Hydrozoa) common components of the pelagic fauna from the South Brazilian Bight?

We analysed 267 zooplankton samples collected in the South Brazilian Bight (SBB; 23–27°S) to determine whether hydroids, typically benthic, are common components of the pelagic SBB. Two species, Clytia arborescens, recorded for the first time in the Atlantic Ocean, and Clytia sp. were identified. While these planktonic hydroids were frequent or relatively so in shallow shelf waters (~23% of the samples <50 m isobaths, and 5% of the samples >100 m), abundances were low (up to 61 hydranths m−3) suggesting a low trophic impact. Such colonies are probably fragments of benthic colonies detached by storms and/or tides. Given the good condition of the coenosarc, existence of gastric content, and presence of reproductive structures, development of these species appears to be normal in the pelagic environment. Existence in the plankton may increase their capacity for dispersion.

Phenology, biomass and productivity of sub-Antarctic Ruppia filifolia

Seagrasses play important ecological roles in shallow coastal ecosystems from tropical to sub-polar seas. Ruppia filifolia (Phil.) Skottsberg is the seagrass with the world’s southernmost distribution but with virtually unknown biology and ecology. The goal of this study was to identify the ecological roles that R. filifolia might play in sub-Antarctic environments through the assessment of the development and primary productivity of this aquatic flowering plant. We monitored biomass and shoot density, rhizome growth and the presence of reproductive structures during 1 year in Skyring Sound, sub-Antarctic Chile. Ruppia filifolia forms perennial meadows with high biomass (124–293 g DW m−2) and shoot density (1800–5300 shoot m−2), a continuous presence of vertical stems and a rhizome plus root to shoot biomass ratio >1. Plant development shows a unimodal seasonal pattern with flowering in spring, and fruiting and maximum growth during summer. An average rhizome plastochrone of 37 days and median rhizome elongation of 27.5 cm plant−1 year−1 rank R. filifolia as a slow-growing seagrass. Primary productivity varied from 0.5 to 4.2 g DW m−2 day−1, resulting in an annual primary production of 700 g DW m−2. Ruppia filifolia in sub-Antarctic environments might play ecosystem roles (carbon sequestration, sediment stabilization, structural habitat, nutrition sources) as important as those played by seagrasses in tropical or temperate coastal environments.

Reproductive phenology and sharing of floral resource among hummingbirds (Trochilidae) in inflorescences of Dahlstedtia pinnata (Benth.) Malme. (Fabaceae) in the Atlantic forest.

The purpose of this study was to investigate the reproductive phenology and sharing of floral resource (nectar) of Dahlstedtia pinnata (Benth.) Malme. (Fabaceae), endemic of Atlantic forest, among hummingbirds. For the phenology, we looked at the presence of reproductive structures in the plants, and for floral resource sharing, the frequency of potential pollinators and foraging behaviors were examined. This study was conducted in Pedra Branca State Park, in state of Rio de Janeiro, in a dense ombrophilous forest, between August 2010 and August 2011. Flowering occurred between December 2010 and March 2011, and fruiting between April and June 2011. Hummingbirds' foraging schedules differed significantly, with legitimate visits to the flowers occurring in the morning and illegitimate visits occurring during late morning and the afternoon. Five species visited flowers, three of which were legitimate visitors: Phaethornis ruber, P. pretrei, and Ramphodon naevius. Amazilia fimbriata and Thalurania glaucopis females only visited illegitimately. Phaethornis ruber robbed nectar (78% of illegitimate visits, n=337). Ramphodon naevius, with a territorial foraging behavior and a body size bigger than that of other observed hummingbird species, dominated the floral visits, which suggests that D. pinnata is an important nourishing resource for this endemic bird of the Atlantic forest, currently globally categorized as Near Threatened.

An interactive key (Lucid) for the identifying of the genera of seed plants from the Ducke Reserve, Manaus, AM, Brazil

The identification of Amazonian plants is still difficult for many reasons, one being the lack of collections over large areas of the region. As a consequence of the poor knowledge on the Amazonian flora, many taxonomic publications (revisions and floristic treatments) become out of date within a few years. In this context, the on-line publication of taxonomic treatises has been suggested, since it allows constant data updates; and this type of publication should therefore be more valued by the scientific community. An excellent field guide for the Ducke Reserve (Manaus, central Amazonian Brazil) was published, based exclusively on vegetative characters. However, the presence of reproductive structures in the collected material does not facilitate identification with this type of field guide. Furthermore, as in any printed key, the text cannot be updated, except through a new edition. As an example of a way to facilitate the identification of Amazonian plants, an interactive, multiple-entry key to the seed plant genera that occur in the Ducke Reserve was created using the program Lucid 3.5. The key includes vegetative and reproductive characters and many illustrations, and is available on-line. We discuss here the peculiarities and advantages of this type of electronic publication.

Population dynamics of Sargassum lapazeanum (Fucales, Phaeophyta) from the Gulf of California, Mexico

M. Rivera and R. Scrosati. 2006. Population dynamics of Sargassum lapazeanum (Fucales, Phaeophyta) from the Gulf of California, Mexico. Phycologia 45: 178–189. DOI: 10.2216/05-47.1We studied the population dynamics of Sargassum lapazeanum from the southwestern Gulf of California, Mexico, between February 2000 and February 2001. We qua.gified the seasonal changes in frond density, stand biomass, frond size structure and inequality, presence of reproductive structures, and rates of recruitment, growth, and mortality. Fronds were present during the entire year, although with a marked seasonality: mean frond density, frond length, and stand biomass were highest in spring and lowest in winter. The strong increase in frond density between winter and spring resulted from the combination of high recruitment and low mortality rates. Growth rates were highest in spring; the highest absolute value (3.6 cm d−1) is among the highest found for brown seaweeds. The frond size structure became best developed in late spring. Reproductive structures peaked in abundance in late spring and became mostly lost by late summer. Senescence started in late spring and increased dramatically during the summer. The strong decrease in frond density between summer and autumn resulted from the combination of low recruitment and high mortality rates. In early autumn, primarily only small fronds remained in the population, including new recruits and remnants of previously large fronds. The seasonal pattern in the temporal abundance changes for S. lapazeanum agrees with a general model proposed for subtropical species of this genus.

Seasonal changes in abundance and shifts in dominance of life history stages of the carrageenophyte Sarcothalia crispata (Rhodophyta, Gigartinales) in south central Chile

The population dynamics of the carrageenophyte Sarcothalia crispatais described from subtidal beds at two localities in south-central Chile. Seasonal fluctuations in total density and biomass were not evident. Frondswere identified to phase by the presence of reproductive structures and theresorcinol reaction. The monthly changes in abundance of each kind offrond were determined. Permanent gametophytic or sporophyticdominance was not evident: the more exposed site showed a seasonal shiftfrom sporophytic dominance in summer to gametophytic dominance inwinter, whereas the more protected site showed an interannual shift fromgametophytic to sporophytic dominance. The differences between localitiesand years suggest a very local population dynamics with large contributionof self-seeding to the maintenance of the S. crispata beds.