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.

Modes of climate variability bridge proximate and evolutionary mechanisms of masting

There is evidence that variable and synchronous reproduction in seed plants (masting) correlates to modes of climate variability, e.g. El Niño Southern Oscillation and North Atlantic Oscillation. In this perspective, we explore the breadth of knowledge on how climate modes control reproduction in major masting species throughout Earth's biomes. We posit that intrinsic properties of climate modes (periodicity, persistence and trends) drive interannual and decadal variability of plant reproduction, as well as the spatial extent of its synchrony, aligning multiple proximate causes of masting through space and time. Moreover, climate modes force lagged but in-phase ecological processes that interact synergistically with multiple stages of plant reproductive cycles. This sets up adaptive benefits by increasing offspring fitness through either economies of scale or environmental prediction. Community-wide links between climate modes and masting across plant taxa suggest an evolutionary role of climate variability. We argue that climate modes may ‘bridge’ proximate and ultimate causes of masting selecting for variable and synchronous reproduction. The future of such interaction is uncertain: processes that improve reproductive fitness may remain coupled with climate modes even under changing climates, but chances are that abrupt global warming will affect Earth's climate modes so rapidly as to alter ecological and evolutionary links. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants’.

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.

Method for Recording and Reproducing an Experimental Research into the Field Emitter Properties Based on Carbon Nanotubes

A method for recording and emulating a complex experiment in field emission was developed. The method includes processing of three types of data streams: data on the electrical characteristics of the field cathode (voltage and current pulses), data on the field emission projector (glow patterns) and time-of-flight mass spectrometer data (mass spectra of volatile products in the measuring chamber). The LabView software environment implements an algorithm for synchronous reproduction of multichannel experiment data with the possibility of processing it in real time. The program has a built-in set of software tools that implement the functionality and repeat the experiment many times, pause at specified points in time, as well as change the time flow rate in the emulation. The capabilities of the method are demonstrated by the example of studying field emission from a nanocomposite field cathode based on carbon nanotubes.