scholarly journals Genealogical structure changes as range expansions transition from pushed to pulled

2021 ◽  
Vol 118 (34) ◽  
pp. e2026746118
Author(s):  
Gabriel Birzu ◽  
Oskar Hallatschek ◽  
Kirill S. Korolev
Keyword(s):  
Growth Dynamics ◽  
High Growth ◽  
Invasion Biology ◽  
Population Bottlenecks ◽  
Broad Distribution ◽  
High Fecundity ◽  
Structure Changes ◽  
Wave Models ◽  
Accelerate Evolution ◽  
And Control

Range expansions accelerate evolution through multiple mechanisms, including gene surfing and genetic drift. The inference and control of these evolutionary processes ultimately rely on the information contained in genealogical trees. Currently, there are two opposing views on how range expansions shape genealogies. In invasion biology, expansions are typically approximated by a series of population bottlenecks producing genealogies with only pairwise mergers between lineages—a process known as the Kingman coalescent. Conversely, traveling wave models predict a coalescent with multiple mergers, known as the Bolthausen–Sznitman coalescent. Here, we unify these two approaches and show that expansions can generate an entire spectrum of coalescent topologies. Specifically, we show that tree topology is controlled by growth dynamics at the front and exhibits large differences between pulled and pushed expansions. These differences are explained by the fluctuations in the total number of descendants left by the early founders. High growth cooperativity leads to a narrow distribution of reproductive values and the Kingman coalescent. Conversely, low growth cooperativity results in a broad distribution, whose exponent controls the merger sizes in the genealogies. These broad distribution and non-Kingman tree topologies emerge due to the fluctuations in the front shape and position and do not occur in quasi-deterministic simulations. Overall, our results show that range expansions provide a robust mechanism for generating different types of multiple mergers, which could be similar to those observed in populations with strong selection or high fecundity. Thus, caution should be exercised in making inferences about the origin of non-Kingman genealogies.

scholarly journals Genealogical structure changes as range expansions transition from pushed to pulled

2020 ◽  
Author(s):  
Gabriel Birzu ◽  
Oskar Hallatschek ◽  
Kirill S. Korolev
Keyword(s):  
Genetic Diversity ◽  
Spatial Dynamics ◽  
Growth Dynamics ◽  
High Growth ◽  
Invasion Biology ◽  
Expansion Velocity ◽  
Broad Distribution ◽  
High Fecundity ◽  
Accelerate Evolution ◽  
Expanding Population

AbstractRange expansions accelerate evolution through multiple mechanisms including gene surfing and genetic drift. The inference and control of these evolutionary processes ultimately relies on the information contained in genealogical trees. Currently, there are two opposing views on how range expansions shape genealogies. In invasion biology, expansions are typically approximated by a series of population bottlenecks producing genealogies with only pairwise mergers between lineages—a process known as the Kingman coalescent. Conversely, traveling-wave models predict a coalescent with multiple mergers, known as the Bolthausen–Sznitman coalescent. Here, we unify these two approaches and show that expansions can generate an entire spectrum of coalescent topologies. Specifically, we show that tree topology is controlled by growth dynamics at the front and exhibits large differences between pulled and pushed expansions. These differences are explained by the fluctuations in the total number of descendants left by the early founders. High growth cooperativity leads to a narrow distribution of reproductive values and the Kingman coalescent. Conversely, low growth cooperativity results in a broad distribution, whose exponent controls the merger sizes in the genealogies. These broad distribution and non-Kingman tree topologies emerge due to the fluctuations in the front shape and position and do not occur in quasi-deterministic simulations. Overall, our results show that range expansions provide a robust mechanism for generating different types of multiple mergers, which could be similar those observed in populations with strong selection or high fecundity. Thus, caution should be exercised in making inferences about the origin of non-Kingman genealogies.Significance statementSpatial dynamics are important for understanding genetic diversity in many contexts, such as cancer and infectious diseases. Coalescent theory offers a powerful framework for interpreting and predicting patters of genetic diversity in populations, but incorporating spatial structure into the theory has proven difficult. Here, we address this long-standing problem by studying the coalescent in a spatially expanding population. We find the topology of the coalescent changes depending on the growth dynamics at the front. Using analytical arguments, we show that the transition between coalescent topologies is universal and is controlled by a parameter related to the expansion velocity. Our theory makes precise predictions about the effects of population dynamics on genetic diversity at the expansion front, which we confirm in simulations.

scholarly journals ESTIMATION OF EFFICIENCY OF FISH GROWING IN WATER WITH NEGATIVE OXIDATION-REDUCTION POTENTIAL

2020 ◽  
Vol 2020 (3) ◽  
pp. 103-110
Author(s):  
Anna Aleksandrovna Bakhareva ◽  
Yulia Nikolaevna Grozesku ◽  
Adelya Dzumaniyashevna Zhandalgarova ◽  
Leonid Matveevich Slavin ◽  
Aleksandr Nevalennyy
Keyword(s):  
Redox Potential ◽  
Physiological State ◽  
Electrical Potential ◽  
High Growth ◽  
High Growth Rate ◽  
Oxidation Reduction ◽  
Structure Changes ◽  
Oxidation Reduction Potential ◽  
Standard Values ◽  
And Control

The paper outlines the problems of fish rearing in the water with negative redox potential. Water is known to consist of supermolecules, the so-called clusters and cells, connected by a special molecular structure. This structure changes when exposed to water in different ways: chemical, electromagnetic, mechanical. Under these influences the water molecules rearrange forming the structured living water. The effectiveness of activated water is explained by the fact that in the process of electrolysis the dead water acquires a positive electric potential, and living water – a negative electrical potential. It becomes a weak electrolyte which quickly interacts with body fluids (gastric juice, blood, lymph, intercellular fluid, etc.). As a result of the studies carried out on juvenile tilapia, it has been found that the hydrochemical parameters in the experimental (growing in structured water) and control variants were within the standard values. Concentration of O2 made 7 mg/l, pH of the medium was 7.2, and nitrite concentration was 0.3 mg/l. It has been inferred that the redox potential (redox) of the blood of young tilapia has a negative value (–96 mV). It has been recorded that at a water temperature of 21°C that is sufficiently low for thermophilic tilapia and at a negative redox (–212 mV) there has been observed a high growth rate of fish. It was found that the use of redox water (–100 mV) is most effective, because the linear-weight gain of juveniles increases by 41% in comparison with the control. Negatively charged (cathode) water increases the efficiency of rearing tilapia fry and does not affect the physiological state of fish. Tilapia fry reared in the structured water have the highest hemoglobin content (62-64 g/l) and total protein (13.3-14.3 g/l).

GROWTH OF PIKE-PERCH SANDER LUCIOPERCA (L., 1758) (PERCIDAE) IN RESERVOIRS OF K. SATPAYEV’S CHANNEL

2018 ◽  
pp. 59-68
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Vladimir Nickolaevich Krainyuk
Keyword(s):  
Growth Rates ◽  
Growth Dynamics ◽  
High Growth ◽  
Water Bodies ◽  
Volga River ◽  
Trophic Resources ◽  
Pike Perch ◽  
The Amur River ◽  
Back Calculation ◽  
Abiotic And Biotic Factors

Pike-perch is an invader for the water basins of Central Kazakhstan. These species have stable self-reproductive populations in the regional waters. Back calculation method was used to investigate pike-perch growth rates in reservoirs of K. Satpayev’s channel. For comparison, the data from the other water bodies (Vyacheslavsky and Sherubay-Nurinsky water reservoirs) were used, as well as literature data. Pike-perch species from the investigated waters don’t show high growth rates. The populations from the reservoirs of K. Satpayev’s channel have quite similar growth rates with populations from the Amur river, from a number of reservoirs in the Volga river basin and from the reservoir in Spain. Sexual differences in growth have not been observed. Evaluating possible influence of various abiotic and biotic factors on the growth rate of pike-perch in the reservoirs of K. Satpayev’s channel was carried out. It has been stated that the availability of trophic resources cannot play a key role in growth dynamics because of their high abundance. Morphology of water bodies also does not play a role, as well as chromaticity, turbidity and other optical water indicators. It can be supposed that the main factor influencing growth of pike perch is the habitat’s temperature. This factor hardly ever approaches optimal values for the species in reservoirs of K. Satpaev’s channel. The possible influence of fishing selectivity on pike-perch growth rates was also evaluated. Currently, there has been imposed a moratorium on pike-perch catch. However, pike-perch is found in by-catches and in catches of amateur fishermen. It should be said that such seizures have an insignificant role in the dynamics of growth rates.

Invasion biology and control of invasive woody plants in eastern forests

2007 ◽  
Vol 8 (2) ◽  
pp. 97-106 ◽  
Author(s):  
Christopher R. Webster ◽  
Michael A. Jenkins ◽  
Shibu Jose
Keyword(s):  
Woody Plants ◽  
Invasion Biology ◽  
And Control

scholarly journals Resource-efficient infrastructure for fast growing cities – realization of a Resource Recovery Center

2018 ◽  
Vol 13 (3) ◽  
pp. 513-523 ◽  
Author(s):  
J. Tolksdorf ◽  
P. Cornel ◽  
M. Wagner
Keyword(s):  
Urban Areas ◽  
Source Separation ◽  
Growth Dynamics ◽  
High Growth ◽  
Resource Recovery ◽  
Resource Scarcity ◽  
Design Data ◽  
Fast Growing ◽  
Treatment Processes ◽  
Design Values

Abstract The SEMIZENTRAL approach is an infrastructure solution for the challenges of high growth dynamics and resource scarcity in fast growing urban areas. The integration of water, wastewater, waste, and energy in one system increases resource efficiency. District-wise realization enables the infrastructure system to grow at the same rate as the city. The concept has been realized for the first time on a scale of 12,000 population equivalent in Qingdao, China. Greywater and blackwater are collected separately; treated greywater is reused for toilet flushing. Reclaimed blackwater is used for irrigation. The analyses of the wastewater composition reveal significant differences in comparison to design values as well as to literature values for greywater and blackwater. Unexpected user behaviour, as well as cross-connections, are likely reasons. The greywater and blackwater treatment processes in the Resource Recovery Center were adapted to the influent's characteristics, so that legal effluent limits are fulfilled, despite changes in influent quality. Small systems often show higher influent variability. Design data for systems with source separation are still lacking. Measurement campaigns in areas similar to the planning area are recommendable, but might not always be possible. In addition, there is a risk of cross-connections between blackwater and greywater, though this can be reduced. For these reasons, there is (possibly high) uncertainty regarding design values for greywater and blackwater. Correspondingly, the treatment processes need to be designed flexibly. For future implementation, technical risks deriving from source separation have to be weighed against the expected higher acceptance of reuse of treated greywater in households. Intra-urban reuse of total wastewater, in combination with extensive public relations programs, might be an alternative.

Post-Secondary Institution Level and Control: Effect on Women’s Proportion of Entrepreneurship Degrees

2020 ◽  
pp. 251512742096043
Author(s):  
Desarae Mueller-Fichepain ◽  
Cheryl McConnell ◽  
Myles P. Gartland
Keyword(s):  
Postsecondary Education ◽  
Repeated Measures ◽  
High Growth ◽  
Growth Potential ◽  
Control Effect ◽  
Post Secondary ◽  
Gender Biases ◽  
Post Secondary Institution ◽  
Human And Social Capital ◽  
And Control

This study examines the influence U.S. college/university level (2-year/4-year) and control (public/private) have on the female-awarded proportion of their entrepreneurship degrees and certificates (EDCs). It also examines trends over a decade, 2006-2016. Integrated Postsecondary Education Data System (IPEDS) data on U.S. institutions awarding Classification of Instructional Programs (CIP) 52.07 (Entrepreneurship and Small Business degrees/certificates) in 2006, 2011, and/or 2016 is analyzed using ANOVA/ANCOVA/repeated measures methods. Surprisingly, even with the growing focus on female entrepreneurship, results did not show significant increases in the female-awarded proportion of EDCs over the ten years. Closer examination of 2016 data shows 2-year public institutions confer a significantly larger percentage of their EDCs to women compared to both 4-year public and private institutions providing evidence that institution level and control influence the proportion and suggesting that 4-year institutions may still be gendered in terms of entrepreneurship. Entrepreneurship education has been empirically shown to augment entrepreneurial human and social capital, which is of key importance in entrepreneurship, particularly high-growth potential female businesses. For this reason, these results have important implications for post-secondary institution leaders and entrepreneurship educators, and serves as a call to action to pro-actively assess their environments and curriculum for potential gender biases. Suggestions provided.

Incorporating fungal community ecology into invasion biology: challenges and opportunities

2018 ◽  
Vol 39 (1) ◽  
pp. 56
Author(s):  
Eleonora Egidi ◽  
Ashley E Franks
Keyword(s):  
Community Ecology ◽  
Plant Species ◽  
Fungal Community ◽  
Invasive Plant ◽  
Invasion Biology ◽  
Invasive Plant Species ◽  
Native Communities ◽  
Challenges And Opportunities ◽  
And Control

Recently, the role of the plant-associated mycobiome (i.e. the fungal community) in influencing the competitive success of invasive plant species has received increasing attention. Fungi act as primary drivers of the plant invasion process due to their ability to form both beneficial and detrimental relationships with terrestrial plant species. Here we review the role of the plant mycobiome in promoting or inhibiting plant species invasion into foreign ecosystems. Moreover, the potential to exploit these relationships for invasive plant control and restoration of native communities is discussed. Incorporating fungal community ecology into invasion and restoration biology will aid in the management and control of invasive plant species in Australia.

Two-Axis Solid-State Microgyroscope on Surface Acoustic Waves

2019 ◽  
Vol 20 (5) ◽  
pp. 299-307
Author(s):  
V. P. Sizov ◽  
V. N. Pogorelov ◽  
Yu. V. Vakhtin
Keyword(s):  
Solid State ◽  
Elastic Waves ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Oscillation Amplitude ◽  
Substrate Layer ◽  
Production Technologies ◽  
Wave Models ◽  
And Control ◽  
High Degree

This article focuses on the development of a two-axis solid state micro gyroscope (SMG) on surface acoustic waves (SAW). The described gyroscope belongs to the category of inexpensive sensing elements featuring a high degree of longtime overload stability. This advantage seems to make SAW SMGs a priority choice for navigation and control systems functioning in severe overload environments of up to 65,000 g. As of today SAW SMGs are designed according to a number of known principles. Such SMGs may also operate on standing SAWs or traveling SAWs. This article addresses the first gyro type. Unfortunately, the existing standing SAW SMGs share a common limitation of measuring angular rates in relation to one axis only. This research attempts to introduce an innovative two-axis standing SAW SMG. The influence of the basis rotation on the parameters of the elastic waves traveling within the substrate layer was carefully studied. Incident and reflected wave models were also elaborated. The numerical simulation results demonstrate the effects of the basis rotation on the complex factors of the volume waves reflected by the substrate layer and on the phase velocity and frequency thereof as well as on the oscillation amplitude of the particles involved in SAW transition, and on the elliptical particle movement path configuration. Also, the SAW SMG is compared to the existing micromechanical gyroscopes, and the basic SAW SMG production technologies are reviewed.

High-growth firms and the use of formalised planning and control systems

2014 ◽  
Vol 13 (3) ◽  
pp. 266 ◽  
Author(s):  
Leona Achtenhagen ◽  
Anders Melander ◽  
Alexandra Rosengren ◽  
Andrea Standoft
Keyword(s):  
Control Systems ◽  
High Growth ◽  
Planning And Control ◽  
Growth Firms ◽  
And Control

EFFECTS OF FORMAL PLANNING AND CONTROL ON GROWTH: A CASE STUDY APPROACH

1995 ◽  
Vol 03 (02) ◽  
pp. 161-195
Author(s):  
CLAUDIO A. ROMANO ◽  
JANEK RATNATUNGA
Keyword(s):  
Small Business ◽  
Control Systems ◽  
Small Firms ◽  
Firm Growth ◽  
Control Process ◽  
High Growth ◽  
Exploratory Research ◽  
Contextual Variables ◽  
Planning And Control ◽  
And Control

While planning and control and their impact on small firm growth are implicit in many academic discussions, much of our understanding of these phenomena are based on speculation and opinion. Thus, they seem neglected areas of small business research. This paper seeks to improve the understanding of formal planning and control systems and their relationship to the growth of small business in Australian manufacturing. First, a framework is developed which incorporates the main contextual variables which independently and simultaneously have been shown to have a major relationship with growth. Second, the study provides empirically-based qualitative evidence to further the understanding of causality in the growth of small business by focusing on how formal planning and control systems are embedded within the external or internal contextual variables of small business and the characteristics of their management. Evidence is also provided as to the conditions and circumstances under which formal planning and control are likely to be most effective in controlling the effects of contextual variables, and to the differences between high growth and low growth firms in the use of formal planning and control. The findings of this study are important for two principal reasons. First, it has provided the opportunity to conduct exploratory research into how a small business is managed within the context in which the processes are applied. Second, it has provided the opportunity to identify factors which encourage or discourage small firms to plan, thus providing a better understanding of the planning and control process adopted by small firms.

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