Population dynamics and reproduction strategies of planktonic foraminifera in the open ocean

It has long been assumed that the population dynamics of planktonic foraminifera is characterised by synchronous reproduction associated with ontogenetic vertical migration. However, due to contradictory observations, this concept became controversial, and subsequent studies provided evidence both in favour and against these phenomena. Here we present new observations from replicated vertically resolved profiles of abundance and shell size variation in four species of planktonic foraminifera from the tropical Atlantic to test for the presence, pattern, and extent of synchronised reproduction and ontogenetic vertical migration in this oceanic region. Specimens of Globigerinita glutinata, Globigerinoides ruber ruber, Globorotalia menardii and Orbulina universa were collected over the first 700 m resolved at nine depth intervals at nine stations over a period of 14 d. Dead specimens were systematically observed irrespective of the depth interval, sampling day and size. Conversely, specimens in the smaller size fractions dominated the sampled populations at all times and were recorded at all depths, indicating that reproduction might have occurred continuously and throughout the occupied part of the water column. However, a closer look at the vertical and temporal size distribution of specimens within each species revealed an overrepresentation of large specimens in depths at the beginning of the sampling (shortly after the full moon) and an overrepresentation of small individuals at the surface and subsurface by the end of the sampling (around new moon). These observations imply that a disproportionately large portion of the population followed for each species a canonical reproductive trajectory, which involved synchronised reproduction and ontogenetic vertical migration with the descent of progressively maturing individuals. This concept is consistent with the initial observations from the Red Sea, on which the reproductive dynamics of planktonic foraminifera has been modelled. Our data extend this model to non-spinose and microperforate symbiont-bearing species, but contrary to the extension of the initial observations on other species of foraminifera, we cannot provide evidence for ontogenetic vertical migration with ascent during maturation. We also show that more than half of the population does not follow the canonical trajectory, which helps to reconcile the existing contrasting observations. Our results imply that the flux of empty shells of planktonic foraminifera in the open ocean should be pulsed, with disproportionately large amounts of disproportionately large specimens being delivered in pulses caused by synchronised reproduction. The presence of a large population reproducing outside of the canonical trajectory implies that individual foraminifera in a fossil sample will record in the calcite of their shells a range of habitat trajectories, with the canonical trajectory emerging statistically from a substantial background range.

Population dynamics and reproduction strategies of planktonic foraminifera in the open ocean

It has long been assumed that the population dynamics of planktonic foraminifera is characterised by synchronous reproduction associated with ontogenetic vertical migration. However, due to contradictory observations, this concept became controversial and subsequent studies provided evidence both in favor and against these phenomena. Here we present new observations from replicated vertically resolved profiles of abundance and shell size variation in four species of planktonic foraminifera from the tropical Atlantic to test for the presence, pattern and extent of synchronised reproduction and ontogenetic vertical migration in this oceanic region. Specimens of Globigerinita glutinata, Globigerinoides ruber ruber, Globorotalia menardii and Orbulina universa were collected over the first 700 m resolved at nine depth intervals at nine stations over a period of 14 days. Dead specimens were systematically observed irrespective of the depth interval, sampling day and size. Conversely, specimens in the smaller size fractions dominated the sampled populations at all times and were recorded at all depths indicating that reproduction might have occurred continuously and throughout the occupied part of the water column. However, a closer look at the vertical and temporal size distribution of specimens within each species revealed an overrepresentation of large specimens in depths at the beginning of the sampling (shortly after the full moon) and an overrepresentation of small individuals in surface and subsurface by the end of the sampling (around new moon). These observations imply that a disproportionately large portion of the population followed for each species a canonical reproductive trajectory, which involved synchronised reproduction and ontogenetic vertical migration with the descent of progressively maturing individuals. This concept is consistent with the initial observations from the Red Sea, on which the reproductive dynamics of planktonic foraminifera has been modelled. Our data extend this model to non-spinose and microperforate symbiont-bearing species, but contrary to the extension of the initial observations on other species of foraminifera, we cannot provide evidence for ontogenetic vertical migration with ascent during maturation. We also show that more than half of the population does not follow the canonical trajectory, which helps to reconcile the existing contrasting observations. Our results imply that the flux of empty shells of planktonic foraminifera in the open ocean should be pulsed, with disproportionately large amounts of disproportionately large specimens being delivered in pulses caused by synchronised reproduction. The presence of a large population reproducing outside of the canonical trajectory implies that individual foraminifera in a fossil sample will record in the calcite of their shells a range of habitat trajectories, with the canonical trajectory emerging statistically from a substantial background range.

Reproduction strategies of the silver birch (Betula pendula Roth) at post-industrial sites

The study aimed to evaluate the parameters of reproductive traits, specimens’ fertility and reproductive efficiency observed in Betula pendula populations growing at different types of sites (zinc-lead heaps, coal mine heaps and unpolluted site). The leaf biomass and the biometric characteristics of inflorescences and fructifications were identified. Moreover, the biometric parameters of B. pendula seedlings were evaluated for examined sites. Seed-originated trees mostly of age 40 were randomly selected and from each tree, a branches from 1.70 m height and orientation N–S, W–E to the cardinal points of the stem were chosen. In the laboratory, selected soil parameters, the viability of pollen and the seeding value of seeds were analysed. According to the multidimensional statistical analysis the populations of B. pendula growing on post-industrial wastelands represent different morphotypes with lower values of almost all the reproductive traits, compared to the unpolluted birch population. Such traits as the male:female catkin number ratio and the non-embryo seed number were positively correlated with the heavy metal content at the zinc-lead heaps; at the same time these traits were negatively correlated with soil fertility. The fully developed seed number and the mature female catkin number were strongly correlated with the available potassium and phosphorus soil content but also with the leaf number on the generative shoots. The specimens of birch growing in these three habitats did not develop a universal reproductive strategy. Some differences in fecundity, the condition of seeds and the patterns of seed germination were found. The resulting seedling survival is determined by the plasticity of biometric traits, sheltered places for germination, etc. Seedlings that originated from heaps (local gene resources) are more suitable for use in the reclamation of large amounts of waste.

Gametophytic phase of the Indonesian ferns Amblovenatum immersum (Blume) Mazumdar and Christella subpubescens (Blume) Holttum (Thelypteridaceae)

The gametophytic generation of Amblovenatum immersum and Christella subpubescens (Thelypteridaceae), including spore germination, morphological development of the gametophytes, major vegetative features and reproduction strategies, was studied. For both species, the spore germination was of the Vittaria type and the developmental pattern was of the Drynaria type. Adult gametophytes were cordate and hairy, with unicellular and secretory hairs located in the margins and both the ventral and dorsal surfaces of the prothalli. C. subpubescens has another type of acicular hairs only in the margin of the prothallus. Gametangia were of the normal type described for leptosporangiate ferns. In A. immersum all the gametophytes were female. In C. subpubescens the gametophytes produced at first instance female gametangia and then became bisexual with time. Antheridiogen activity was observed in both species, suggested by the presence of small young ameristic gametophytes with antheridia surrounding well-developed female ones.

Productive reconfiguration, reproduction strategies and social capital in rural spaces: an exploratory analysis in the northwest of the State of Mexicoico

Este artículo explora la relación que mantienen las estrategias de reproducción social con las características socioeconómicas, actividades agrícolas y no agrícolas, así como el capital social de las unidades domésticas campesinas. Mediante un estudio de caso fundamentado en una encuesta aplicada en la comunidad de Mavoro, localizada al noroeste del Estado de México, se identificó la complementariedad entre las actividades agrícolas y no agrícolas, como la principal estrategia de reproducción. Sin embargo, la complementariedad productiva, cumple funciones diferenciadas entre los hogares rurales, resultado de factores como: tamaño de la parcela, escolaridad, edad, capital social de vinculación y capital social de puente.

Reproduction strategies in a marine protist: A digital experiment

<p>Understanding the biology of reproduction is important for retracing key evolutionary processes (e.g. speciation and adaptation) in any group of organisms, yet gaining detailed insights often poses a major challenge. Planktonic Foraminifera are a group of globally distributed marine microbial eukaryotes that are important contributors to the global carbon cycle and, due to their fossil record, are widely used as model organisms to investigate the responses of plankton to past environmental changes. The extant biodiversity of planktonic Foraminifera shows restricted distribution patterns and local adaptations of some species, whereas others are cosmopolitan in the world ocean. Hypotheses on their diversification and population dynamics so far entirely rely on the assumption of a nearly exclusively sexual reproduction.</p><p>So far, reproduction in culture has not been successful under laboratory conditions, and thus details on their life cycle and its influence on the evolution of the group remain unknown. Only the production of flagellated gametes has been observed and is taken as an indication for sexual reproduction. Yet, sexual reproduction by spawning of gametes in the open ocean relies on sufficient gamete encounters to maintain viable populations. This represents a problem especially for unflagellated protists like planktonic Foraminifera, which lack the means of active propulsion and are characterized by low population densities in large areas of the world ocean.</p><p>To increase the sparse knowledge on the reproductive biology of planktonic Foraminifera, we applied a dynamic, individual-based modelling approach with parameters based on laboratory and field observations. We tested if random gamete encounters under commonly observed population densities are sufficient for maintaining viable populations or if alternative strategies, such as asexual reproduction or synchronization in depth and time, are indispensable to achieve reproduction success. Our results show that a strict synchronization of gamete release in time and/or space seems inevitable for a successful maintenance of populations. We further argue that planktonic Foraminifera optimized their individual reproductive success at the expense of community-wide gene flow, which may explain their high degree of diversity as well as hampered evolvability. Our modelling approach helps to illuminate the ecology and evolution of this important marine calcifier and to predict the existence of necessary reproduction strategies, which may be detectable in future field and laboratory experiments.</p>

Hamming neural network application with FPGA device

The Hamming neural network is a kind of counterfeit neural system that substance of two kinds of layers (feed forward layers and repetitive layer). In this study, two pattern entries are utilization in the binary number. In the first layer, two nerves were utilization as the pure line work. In the subsequent layer, three nerves and a positive line work were utilization. The Hamming Neural system calculation was also implemented in three reproduction strategies (logical gate technique, programming program encryption strategy and momentary square chart technique). In this study in programming of VHDL and FPGA machine was utilization.

Morphological and Chemical Traits of Cladonia Respond to Multiple Environmental Factors in Acidic Dry Grasslands

Terricolous lichen communities in lowlands occur especially in open dry habitats. Such communities are often dominated by species of the genus Cladonia, which are very variable in morphology, reproduction strategies, and secondary metabolites. In this work, we investigated traits-environment relationships considering vegetation dynamics, substrate pH, disturbance, and climate. A total of 122 plots were surveyed in 41 acidic dry grasslands in the western Po Plain (Northern Italy). Relationships between Cladonia traits and environmental variables were investigated by means of a model-based Fourth Corner Analysis. Thallus morphology and metabolites responded to vegetation dynamics, substrate pH, disturbance, and climate, whereas reproduction strategies responded only to vegetation dynamics. Traits’ correlations with vegetation dynamics elucidate their colonization patterns in open dry habitats or suggest biotic interactions with bryophytes and vascular plants. In addition, correlations between metabolites and environmental factors support interpretations of their ecological roles. Our results also stress the importance of studying traits’ relationships with climatic factors as an alert towards lichen reactions to climate change.