scholarly journals Density-dependent foraging and colony growth in a pelagic seabird species under varying environmental conditions

2013 ◽  
Vol 485 ◽  
pp. 287-294 ◽  
Author(s):  
RD Davies ◽  
S Wanless ◽  
S Lewis ◽  
KC Hamer
Keyword(s):  
Environmental Conditions ◽  
Colony Growth ◽  
Seabird Species ◽  
Density Dependent ◽  
Pelagic Seabird

scholarly journals Widespread gene flow between oceans in a pelagic seabird species complex

2017 ◽  
Vol 26 (20) ◽  
pp. 5716-5728 ◽  
Author(s):  
Katherine A. Booth Jones ◽  
Malcolm A. C. Nicoll ◽  
Claire Raisin ◽  
Deborah A. Dawson ◽  
Helen Hipperson ◽  
...  
Keyword(s):  
Gene Flow ◽  
Species Complex ◽  
Seabird Species ◽  
Pelagic Seabird

Quasi-cycles in crappie populations are forced by interactions among population characteristics and environment

2001 ◽  
Vol 58 (3) ◽  
pp. 594-601 ◽  
Author(s):  
Micheal S Allen ◽  
Leandro E Miranda
Keyword(s):  
Time Series ◽  
Environmental Conditions ◽  
Empirical Data ◽  
Population Model ◽  
Population Characteristics ◽  
Environmental Fluctuation ◽  
Density Dependent ◽  
Stock Recruitment ◽  
Variable Recruitment ◽  
Random Fluctuations

Crappie (Pomoxis spp.) populations have been characterized as cyclic, with strong year-classes recurring at 2- to 4-year intervals. We evaluated the potential for cyclic trends in crappie populations using a population model that included a density-dependent stock recruitment function and random environmental variation. Slow, medium, and fast growth were simulated over 100 years. The model predicted highly variable recruitment that was strongly influenced by environmental fluctuation at low and intermediate stock densities. At high stock density, recruitment was low, even if environmental conditions were favorable. Significant quasi-cycles occurred, but they were not sustained throughout the time series due to random environmental fluctuation. Quasi-cycles occurred because intermediate stock density and favorable environmental conditions occasionally combined to produce a very strong year-class that greatly increased stock density in the following 1–3 years and produced low recruitment, even if environmental conditions were favorable. Empirical data from 32 years of sampling age-0 crappies at Ross Barnett Reservoir showed trends similar to the simulated fluctuations. We conclude that crappie populations likely do not exhibit true cycles but may show quasi-cycles as a result of the interaction between random fluctuations in environment and density-dependent mechanisms. The frequency of such quasi-cycles may be enhanced by rapid growth and high exploitation.

scholarly journals Eco-evolutionary dynamics and collective dispersal: implications for salmon metapopulation robustness

2017 ◽  
Author(s):  
Justin D. Yeakel ◽  
Jean P. Gibert ◽  
Peter A. H. Westley ◽  
Jonathan W. Moore
Keyword(s):  
Local Adaptation ◽  
Environmental Conditions ◽  
Evolutionary Dynamics ◽  
Alternative Stable States ◽  
Evolutionary Model ◽  
Stable States ◽  
Geographic Mosaic ◽  
Density Dependent ◽  
Evolutionary Forces ◽  
Local Selection

The spatial dispersal of individuals is known to play an important role in the dynamics of populations, and is central to metapopulation theory. At the same time, local adaptation to environmental conditions creates a geographic mosaic of evolutionary forces, where the combined drivers of selection and gene flow interact. Although the dispersal of individuals from donor to recipient populations provides connections within the metapopulation, promoting demographic and evolutionary rescue, it may also introduce maladapted individuals into habitats host to different environmental conditions, potentially lowering the fitness of the recipient population. Thus, dispersal plays a dual role in both promoting and inhibiting local adaptation. Here we explore a model of the eco-evolutionary dynamics between two populations connected by dispersal, where the productivity of each is defined by a trait complex that is subject to local selection. Although general in nature, our model is inspired by salmon metapopulations, where dispersal between populations is defined in terms of the straying rate, which has been shown to be density-dependent, and recently proposed to be shaped by social interactions consistent with collective movement. The results of our model reveal that increased straying between evolving populations leads to alternative stable states, which has large and nonlinear effects on two measures of metapopulation robustness: the portfolio effect and the time to recovery following an induced disturbance. We show that intermediate levels of straying result in large gains in robustness, and that increased habitat heterogeneity promotes robustness when straying rates are low, and erodes robustness when straying rates are high. Finally, we show that density-dependent straying promotes robustness, particularly when the aggregate biomass is low and straying is correspondingly high, which has important ramifications for the conservation of salmon metapopulations facing both natural and anthropogenic disturbances.Media SummaryMany migratory species, such as salmon, are remarkable in finding their way home. This homing has allowed fine-scale adaptations to the environments in which they evolve. But some individuals do not find their way home and instead stray to other locations, especially when there are fewer individuals to help with collective decision-making. With an eco-evolutionary model, we discovered that an intermediate and density-dependent straying rate allows linked populations to be robust to disturbance but maintain local adaptations.

Sympatric population divergence within a highly pelagic seabird species complex (Hydrobatesspp.)

2018 ◽  
Vol 49 (1) ◽  
Author(s):  
Rebecca S. Taylor ◽  
Anna Bailie ◽  
Previn Gulavita ◽  
Tim Birt ◽  
Tomas Aarvak ◽  
...  
Keyword(s):  
Species Complex ◽  
Population Divergence ◽  
Sympatric Population ◽  
Seabird Species ◽  
Pelagic Seabird

scholarly journals Foraging plasticity in a pelagic seabird species along a marine productivity gradient

2010 ◽  
Vol 398 ◽  
pp. 259-274 ◽  
Author(s):  
VH Paiva ◽  
P Geraldes ◽  
I Ramírez ◽  
A Meirinho ◽  
S Garthe ◽  
...  
Keyword(s):  
Seabird Species ◽  
Productivity Gradient ◽  
Marine Productivity ◽  
Pelagic Seabird

scholarly journals State of the California Current 2019–2020: Back to the Future With Marine Heatwaves?

2021 ◽  
Vol 8 ◽  
Author(s):  
Edward D. Weber ◽  
Toby D. Auth ◽  
Simone Baumann-Pickering ◽  
Timothy R. Baumgartner ◽  
Eric P. Bjorkstedt ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Community Dynamics ◽  
Coastal Upwelling ◽  
Juvenile Fish ◽  
California Current ◽  
Trophic Levels ◽  
Warm Water ◽  
Seabird Species ◽  
Cool Water ◽  
The North

The California Current System (CCS) has experienced large fluctuations in environmental conditions in recent years that have dramatically affected the biological community. Here we synthesize remotely sensed, hydrographic, and biological survey data from throughout the CCS in 2019–2020 to evaluate how recent changes in environmental conditions have affected community dynamics at multiple trophic levels. A marine heatwave formed in the north Pacific in 2019 and reached the second greatest area ever recorded by the end of summer 2020. However, high atmospheric pressure in early 2020 drove relatively strong Ekman-driven coastal upwelling in the northern portion of the CCS and warm temperature anomalies remained far offshore. Upwelling and cooler temperatures in the northern CCS created relatively productive conditions in which the biomass of lipid-rich copepod species increased, adult krill size increased, and several seabird species experienced positive reproductive success. Despite these conditions, the composition of the fish community in the northern CCS remained a mixture of both warm- and cool-water-associated species. In the southern CCS, ocean temperatures remained above average for the seventh consecutive year. Abundances of juvenile fish species associated with productive conditions were relatively low, and the ichthyoplankton community was dominated by a mixture of oceanic warm-water and cosmopolitan species. Seabird species associated with warm water also occurred at greater densities than cool-water species in the southern CCS. The population of northern anchovy, which has been resurgent since 2017, continued to provide an important forage base for piscivorous fishes, offshore colonies of seabirds, and marine mammals throughout the CCS. Coastal upwelling in the north, and a longer-term trend in warming in the south, appeared to be controlling the community to a much greater extent than the marine heatwave itself.

scholarly journals dMSCC: A microfluidic platform for microbial single-cell cultivation under dynamic environmental medium conditions

2020 ◽  
Author(s):  
Sarah Täuber ◽  
Corinna Golze ◽  
Phuong Ho ◽  
Eric von Lieres ◽  
Alexander Grünberger
Keyword(s):  
Growth Rate ◽  
Single Cell ◽  
Environmental Conditions ◽  
Cellular Response ◽  
Large Scale ◽  
Single Cells ◽  
Model Organism ◽  
Colony Growth ◽  
Cell Cultivation ◽  
Natural Habitats

AbstractIn nature and in technical systems, microbial cells are often exposed to rapidly fluctuating environmental conditions. These conditions can vary in quality, e.g., existence of a starvation zone, and quantity, e.g., average residence time in this zone. For strain development and process design, cellular response to such fluctuations needs to be systematically analysed. However, the existing methods for physically emulating rapidly changing environmental conditions are limited in spatio-temporal resolution. Hence, we present a novel microfluidic system for cultivation of single cells and small cell clusters under dynamic environmental conditions (dynamic microfluidic single-cell cultivation (dMSCC)). This system enables to control nutrient availability and composition between two media with second to minute resolution. We validate our technology using the industrially relevant model organism Corynebacterium glutamicum. The organism was exposed to different oscillation frequencies between nutrient excess (feasts) and scarcity (famine). Resulting changes in cellular physiology, such as the colony growth rate and cell morphology were analysed and revealed significant differences with growth rate and cell length between the different conditions. dMSCC also allows to apply defined but randomly changing nutrient conditions, which is important for reproducing more complex conditions from natural habitats and large-scale bioreactors. The presented system lays the foundation for the cultivation of cells under complex changing environmental conditions.

Reevaluating evidence of density-dependent growth in northern fur seals (Callorhinus ursinus) based on measurements of archived skeletal specimens

2004 ◽  
Vol 61 (9) ◽  
pp. 1616-1626 ◽  
Author(s):  
Michael A Etnier
Keyword(s):  
Growth Rates ◽  
Environmental Conditions ◽  
Somatic Growth ◽  
Callorhinus Ursinus ◽  
Density Dependent ◽  
Fur Seals ◽  
Time Period ◽  
Northern Fur Seals ◽  
Time Periods ◽  
Dependent Growth

Analysis of length-at-age measurements of archived skeletal material shows that somatic growth rates of male northern fur seals (Callorhinus ursinus) vary inversely with population density. Von Bertalanffy growth curves were estimated for two series of known-age mandibles collected 1911–1920 (n = 156) and 1940–1953 (n = 151), time periods representing the historic population minimum and maximum, respectively. Mandibles from the former time period are larger than mandibles from the latter time period, suggesting a density-dependent response in somatic growth. Although density-dependent growth in northern fur seals has been suggested before, previous studies have been hampered by the potentially confounding factors of fisheries interactions, variable environmental conditions, and harvest of adult female northern fur seals. The material analyzed here pre-dates the substantial development of the Bering Sea groundfish fishery and the period of heaviest culling of females. Likewise, the two time periods examined are characterized by broadly similar climatic and environmental conditions. Therefore, the results support the hypothesis that measurements of somatic growth rates provide an index of population levels relative to carrying capacity. Growth rate studies could therefore be used to evaluate the current population status of northern fur seals.

Patterns of mouflon (Ovis gmelini) survival under moderate environmental conditions: effects of sex, age, and epizootics

1997 ◽  
Vol 75 (11) ◽  
pp. 1867-1875 ◽  
Author(s):  
N. Cransac ◽  
A. J. M. Hewison ◽  
M. L. Maublanc ◽  
J. M. Gaillard ◽  
J. M. Cugnasse
Keyword(s):  
Sexual Selection ◽  
Environmental Conditions ◽  
Resource Limitation ◽  
Density Dependent ◽  
Annual Survival ◽  
Survival Probabilities ◽  
Capture Recapture ◽  
Stochastic Events ◽  
The Impact ◽  
Dimorphic Species

We estimated survival probabilities over a 9-year period for an introduced population of Mediterranean mouflon (Ovis gmelini), applying capture – recapture models to resighting data from individually marked animals. Survival was high and constant among lambs, yearling males, and adults of both sexes, and we were unable to detect senescence among old animals. Survival of female yearlings varied widely among years. No difference in survival probabilities between the sexes was detected, indicating that the survival costs of sexual selection were low in this dimorphic species. We suggest that these results may be explained by a lack of limiting conditions on this study site. An outbreak of keratoconjunctivitis during the rut of 1993 caused a marked fall in annual survival for both sexes. Among males, this decline was constant for all ages (approximately 23%), but for females the impact of the disease varied in relation to age, with young ewes particularly affected. Otherwise, the population appears to be stable and we hypothesise that the removal of animals for export and through hunting, together with stochastic events such as periodic epizootics, maintains mouflon numbers at a level where the influence of density-dependent resource limitation on survival is limited.

scholarly journals Thiotrophic bacterial symbiont induces polyphenism in giant ciliate host Zoothamnium niveum

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Monika Bright ◽  
Salvador Espada-Hinojosa ◽  
Jean-Marie Volland ◽  
Judith Drexel ◽  
Julia Kesting ◽  
...  
Keyword(s):  
Evolutionary Theory ◽  
Environmental Conditions ◽  
Life Style ◽  
Growth Form ◽  
Colony Growth ◽  
Bacterial Symbiont ◽  
Unstable Environment ◽  
Experimental Approaches ◽  
Chemical Conditions ◽  
Potential Shifts

Abstract Evolutionary theory predicts potential shifts between cooperative and uncooperative behaviour under fluctuating environmental conditions. This leads to unstable benefits to the partners and restricts the evolution of dependence. High dependence is usually found in those hosts in which vertically transmitted symbionts provide nutrients reliably. Here we study host dependence in the marine, giant colonial ciliate Zoothamnium niveum and its vertically transmitted, nutritional, thiotrophic symbiont from an unstable environment of degrading wood. Previously, we have shown that sulphidic conditions lead to high host fitness and oxic conditions to low fitness, but the fate of the symbiont has not been studied. We combine several experimental approaches to provide evidence for a sulphide-tolerant host with striking polyphenism involving two discrete morphs, a symbiotic and an aposymbiotic one. The two differ significantly in colony growth form and fitness. This polyphenism is triggered by chemical conditions and elicited by the symbiont’s presence on the dispersing swarmer. We provide evidence of a single aposymbiotic morph found in nature. We propose that despite a high fitness loss when aposymbiotic, the ciliate has retained a facultative life style and may use the option to live without its symbiont to overcome spatial and temporal shortage of sulphide in nature.

Sign in / Sign up

Export Citation Format

Share Document