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

Abstract. 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.

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

10.5194/bg-2021-141 ◽

2021 ◽

Author(s):

Julie Meilland ◽

Michael Siccha ◽

Maike Kaffenberger ◽

Jelle Bijma ◽

Michal Kucera

Keyword(s):

Population Dynamics ◽

Vertical Migration ◽

Planktonic Foraminifera ◽

Large Population ◽

Size Variation ◽

Open Ocean ◽

Depth Interval ◽

Shell Size ◽

Reproduction Strategies ◽

Synchronous Reproduction

Abstract. 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.

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Intraspecific size variation in planktonic foraminifera cannot be consistently predicted by the environment

10.1101/468165 ◽

2018 ◽

Author(s):

Marina C. Rillo ◽

C. Giles Miller ◽

Michal Kucera ◽

Thomas H. G. Ezard

Keyword(s):

Relative Abundance ◽

Net Primary Productivity ◽

Size Structure ◽

Planktonic Foraminifera ◽

Size Variation ◽

Population Level ◽

Museum Collection ◽

Shell Size ◽

Neogloboquadrina Dutertrei ◽

Subtropical Oceans

AbstractThe size structure of plankton communities is an important determinant of their functions in marine ecosystems. However, few studies have quantified how organism size varies within species across space. Using a recently-digitised museum collection, we investigate at high intraspecific resolution how planktonic foraminifera, an important microfossil group, vary in size across the tropical and subtropical oceans of the world. We measured 3799 individuals of nine species in 53 seafloor sediments and analysed potential size biases in the museum collection. For each site, we obtained corresponding local values of mean annual sea-surface temperature (SST), net primary productivity (NPP), and relative abundance of each species. Given former studies, we expected species to reach largest shell sizes under optimal environmental conditions. At species level, we find the expected pattern; however, at population level, species greatly differ in how much size variation is explained by SST, NPP and/or relative abundance. While some species show a high predictability of size variation given one single variable (Trilobatus sacculifer, Globigerinella siphonifera, Pulleniatina obliquiloculata, Globorotalia truncatulinoides), other species showed either weak or no relationships between size and the studied covariates (Globigerinoides ruber, G. conglobatus, Neogloboquadrina dutertrei, G. menardii, Globoconella inflata). By incorporating intraspecific variation and sampling broader geographical ranges compared to previous studies, we conclude that shell size variation in planktonic foraminifera species cannot be consistently predicted by the environment. Our results caution against the general use of size as a proxy for planktonic foraminifera environmental optima, and emphasise the need for more studies analysing their within-species size variation. More generally, our findings show that contrasting results can be obtained when analysing patterns at different organisational levels, and highlights the utility of natural history collections.

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Reproduction of a marine planktonic protist: Individual success versus population survival

10.1101/2020.11.04.368100 ◽

2020 ◽

Author(s):

Manuel F. G. Weinkauf ◽

Michael Siccha ◽

Agnes K. M. Weiner

Keyword(s):

Sexual Reproduction ◽

Field Experiments ◽

Planktonic Foraminifera ◽

World Ocean ◽

Distribution Patterns ◽

Open Ocean ◽

Population Densities ◽

Reproduction Strategies ◽

Individual Success ◽

Modelling Approach

AbstractUnderstanding the biology of reproduction is important for retracing key evolutionary processes in organisms, yet gaining detailed insights often poses major challenges. Planktonic Foraminifera are globally distributed marine microbial eukaryotes and important contributors to the global carbon cycle. Their extant biodiversity shows restricted distribution patterns of some species, whereas others are cosmopolitan in the world ocean. Planktonic Foraminifera cannot be bred under laboratory conditions, and thus details of their life cycle remain incomplete. Solely the production of flagellated gametes has been observed and taken as an indication for an exclusively sexual reproduction. Yet, sexual reproduction by spawning of gametes in the open ocean relies on sufficient gamete encounters to maintain viable populations, which represents a problem for organisms that lack the means of active propulsion and are marked by low population densities. To increase knowledge on the reproductive biology of planktonic Foraminifera, we applied a dynamic, individual-based modelling approach with parameters based on laboratory and field observations to test if random gamete encounters under commonly observed population densities are sufficient for maintaining viable populations. We show that temporal synchronization and potentially spatial concentration of gamete release seems inevitable for maintenance of the population. We 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. Our modelling approach helps to illuminate foraminiferal population dynamics and to predict the existence of necessary reproduction strategies, which may be detected in future field experiments. This study therefore contributes to our understanding of plankton ecology and evolution and their reproductive strategies in the open ocean.

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A biophysical model of the interaction between vertical migration of crustacean zooplankton and circulation in the Lower St. Lawrence Estuary

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-095 ◽

1999 ◽

Vol 56 (12) ◽

pp. 2420-2432 ◽

Cited By ~ 15

Author(s):

Bruno A Zakardjian ◽

Jeffrey A Runge ◽

Stephane Plourde ◽

Yves Gratton

Keyword(s):

Population Dynamics ◽

Vertical Migration ◽

Horizontal Distribution ◽

Calanus Finmarchicus ◽

Biophysical Model ◽

Crustacean Zooplankton ◽

Simple Formulation ◽

Lawrence Estuary ◽

Circulation Patterns ◽

St Lawrence Estuary

As an essential step in modeling the influence of circulation on the population dynamics of marine planktonic copepods, we define a simple formulation of swimming behavior that can be used in both Eulerian and Lagrangian models. This formulation forces aggregation of the population toward a preferential depth and can be stage specific and time varying, thus allowing description of either diurnal or seasonal vertical migration. We use the formulation to examine the interaction between the circulation and vertical distribution in controlling horizontal distribution of the common planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary, Canada. We first introduce diel migration into a simple one-dimensional model and then into a model of residual two-dimensional circulation patterns representative of conditions encountered in the Lower St. Lawrence Estuary. Results from the latter indicate that interactions between circulation and stage-specific swimming behaviors are the main mechanisms for aggregation of planktonic crustaceans at the head of the Laurentian Channel and highlight the implications of flushing of the surface-dwelling young stages for the population dynamics of C. finmarchicus in the Lower St. Lawrence Estuary.

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POPULATION DYNAMICS OF SEX-DETERMINING ALLELES IN HONEY BEES AND SELF-INCOMPATIBILITY ALLELES IN PLANTS

Genetics ◽

10.1093/genetics/91.3.609 ◽

1979 ◽

Vol 91 (3) ◽

pp. 609-626 ◽

Cited By ~ 1

Author(s):

Shozo Yokoyama ◽

Masatoshi Nei

Keyword(s):

Population Dynamics ◽

Population Size ◽

Honey Bee ◽

Honey Bees ◽

Finite Population ◽

Large Population ◽

Allele Frequencies ◽

Self Incompatibility ◽

Overdominant Selection ◽

Incompatibility Alleles

ABSTRACT Mathematical theories of the population dynamics of sex-determining alleles in honey bees are developed. It is shown that in an infinitely large population the equilibrium frequency of a sex allele is l/n, where n is the number of alleles in the population, and the asymptotic rate of approach to this equilibrium is 2/(3n) per generation. Formulae for the distribution of allele frequencies and the effective and actual numbers of alleles that can be maintained in a finite population are derived by taking into account the population size and mutation rate. It is shown that the allele frequencies in a finite population may deviate considerably from l/n. Using these results, available data on the number of sex alleles in honey bee populations are discussed. It is also shown that the number of self-incompatibility alleles in plants can be studied in a much simpler way by the method used in this paper. A brief discussion about general overdominant selection is presented.

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Late Pleistocene glacial–interglacial shell-size–isotope variability in planktonic foraminifera as a function of local hydrography

Biogeosciences ◽

10.5194/bg-12-4781-2015 ◽

2015 ◽

Vol 12 (15) ◽

pp. 4781-4807 ◽

Cited By ~ 12

Author(s):

B. Metcalfe ◽

W. Feldmeijer ◽

M. de Vringer-Picon ◽

G.-J. A. Brummer ◽

F. J. C. Peeters ◽

...

Keyword(s):

Size Range ◽

North Atlantic Ocean ◽

Life Stage ◽

Planktonic Foraminifera ◽

Isotope Analysis ◽

Past Research ◽

Individual Species ◽

Shell Size ◽

Size Fractions ◽

Water Column Stratification

Abstract. So-called "vital effects" are a collective term for a suite of physiologically and metabolically induced variability in oxygen (δ18O) and carbon (δ13C) isotope ratios of planktonic foraminifer shells that hamper precise quantitative reconstruction of past ocean parameters. Correction for potential isotopic offsets from equilibrium or the expected value is paramount, as too is the ability to define a comparable life stage for each species that allows for direct comparison. Past research has focused upon finding a specific size range for individual species in lieu of other identifiable features, thus allowing ocean parameters from a particular constant (i.e. a specific depth or season) to be reconstructed. Single-shell isotope analysis of fossil shells from a mid-latitude North Atlantic Ocean piston core covering Termination III (200 to 250 ka) highlight the advantage of using a dynamic size range, i.e. utilising measurements from multiple narrow sieve size fractions spanning a large range of total body sizes, in studies of palaeoclimate. Using this methodology, we show that isotopic offsets between specimens in successive size fractions of Globorotalia inflata and Globorotalia truncatulinoides are not constant over time, contrary to previous findings. For δ18O in smaller-sized globorotalids (212–250 μm) it is suggested that the offset from other size fractions may reflect a shallower habitat in an early ontogenetic stage. A reduction in the difference between small and large specimens of G. inflata between insolation minima and maxima is interpreted to relate to a prolonged period of reduced water column stratification. For the shallow-dwelling species Globigerina bulloides, no size–isotope difference between size fractions is observed, and the variability in the oxygen isotopic values is shown to correlate well with the seasonal insolation patterns. As such, patterns in oxygen isotope variability of fossil populations may be used to reconstruct past seasonality changes.

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Highly replicated sampling reveals no diurnal vertical migration but stable species-specific vertical habitats in planktonic foraminifera

Journal of Plankton Research ◽

10.1093/plankt/fbz002 ◽

2019 ◽

Vol 41 (2) ◽

pp. 127-141 ◽

Cited By ~ 11

Author(s):

Julie Meilland ◽

Michael Siccha ◽

Manuel F G Weinkauf ◽

Lukas Jonkers ◽

Raphael Morard ◽

...

Keyword(s):

Vertical Migration ◽

Planktonic Foraminifera ◽

Diurnal Vertical Migration ◽

Stable Species ◽

Species Specific

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How small and constrained is the genome size of angiosperm woody species

Silvae Genetica ◽

10.1515/sg-2015-0002 ◽

2015 ◽

Vol 64 (1-6) ◽

pp. 20-32 ◽

Cited By ~ 1

Author(s):

Deepak Ohri

Keyword(s):

Genome Size ◽

Cell Size ◽

Large Population ◽

Size Variation ◽

Woody Species ◽

Herbaceous Species ◽

Wood Fibers ◽

Genome Size Variation ◽

Woody Habit ◽

Taxonomic Groups

AbstractAngiosperm hardwood species are generally considered to show an average smaller genome size with a narrow range of variation than their herbaceous counterparts. Various explanations pertaining to limitations of cell size exerted by wood fibers, the requirement of smaller stomata, longer generation time, large population size, etc., have been put forward to account for their small and constrained genome size. Yet studies done in the past several years show that genomically as well as evolutionarily, hardwoods are as diverse and active as their herbaceous counterparts. This is entirely supported by the presence of well developed inter and intraspecific polyploid series and natural triploidy in many genera. Polyploidy, in some instances has been shown to confer adaptability to arid and salt stress conditions and in colonization of new areas. Moreover, hardwoods also show reasonable amenability to the induced polyploidy which abruptly changes the balance between nuclear and cell size. Polyploidy has been induced in many hardwoods to restore fertility in interspecific hybrids and for the production of triploids.Furthermore, some cases studied show that genome size variation in hardwoods can be as variable as that of herbaceous species. Genome size has been shown to vary remarkably both at homoploid level as well as by polyploidy in certain genera. In the same way, the genome size is not correlated with the habit in certain groups having both herbaceous and woody taxa. This point is further proved by the presence of secondary and insular woody habit in certain cases where either the transition to woodiness is not followed by any diminution in the genome size, or the genome size of insular woody species may be even more than that of the congeneric herbaceous species. This shows that woody habit does not by itself put any constraints on the genome size either at homoploid or at polyploidy levels. The genome size in fact, not only varies significantly in many congeneric woody species but also may not show any correlation with the habit when woody and herbaceous species are compared in some narrow taxonomic groups studied.

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