Divergent Outcomes of Reinforcement Speciation: The Relative Importance of Assortative Mating and Migration Modification

2006 ◽  
Vol 167 (5) ◽  
pp. 638
Author(s):  
Yukilevich ◽  
True
Keyword(s):  
Assortative Mating ◽  
Relative Importance ◽  
And Migration

Divergent Outcomes of Reinforcement Speciation: The Relative Importance of Assortative Mating and Migration Modification

2006 ◽  
Vol 167 (5) ◽  
pp. 638-654 ◽  
Author(s):  
Roman Yukilevich ◽  
John R. True
Keyword(s):  
Assortative Mating ◽  
Relative Importance ◽  
And Migration

scholarly journals Out of Africa by spontaneous migration waves

2018 ◽  
Author(s):  
Paul D. Bons ◽  
Catherine C. Bauer ◽  
Hervé Bocherens ◽  
Tamara de Riese ◽  
Dorothée G. Drucker ◽  
...  
Keyword(s):  
Assortative Mating ◽  
Current Model ◽  
Source Region ◽  
Regional Differentiation ◽  
Power Law Distribution ◽  
Modern Humans ◽  
Large Wave ◽  
Anatomically Modern Humans ◽  
Out Of Africa ◽  
And Migration

AbstractHominin evolution is characterized by progressive regional differentiation, as well as migration waves, leading to anatomically modern humans that are assumed to have emerged in Africa and spread over the whole world. Why or whether Africa was the source region of modern humans and what caused their spread remains subject of ongoing debate. We present a spatially explicit, stochastic numerical model that includes ongoing mutations, demic diffusion, assortative mating and migration waves. Diffusion and assortative mating alone result in a structured population with relatively homogeneous regions bound by sharp clines. The addition of migration waves results in a power-law distribution of wave areas: for every large wave, many more small waves are expected to occur. This suggests that one or more out-of-Africa migrations would probably have been accompanied by numerous smaller migration waves across the world. The migration waves are considered “spontaneous”, as the current model excludes environmental or other factors. Large waves preferentially emanate from the central areas of large, compact inhabited areas. During the Pleistocene, Africa was the largest such area most of the time, making Africa the statistically most likely origin of anatomically modern humans, without a need to invoke additional environmental or ecological drivers.

Process Responsible for Temporal Changes in the Percentages of Pelage Color Types Among the Young Recruited Into a House Mouse-Population in an Outdoor Pen

1990 ◽  
Vol 38 (2) ◽  
pp. 105
Author(s):  
PR Pennycuik ◽  
AH Reisner ◽  
NH Westwood
Keyword(s):  
House Mouse ◽  
Total Population ◽  
Temporal Changes ◽  
Relative Importance ◽  
Population Bottlenecks ◽  
Mouse Population ◽  
Colour Type ◽  
Pelage Color ◽  
Males And Females ◽  
And Migration

In populations of the house mouse, Mus musculus, temporal changes in allelic frequencies have been attributed to both selective and non-selective processes. During a 12-year study on a mouse population carrying recessive alleles at loci affecting the colour of the pelage, the percentages of homozygous recessive mice among the young recruited were found to change with time. These changes occurred in both the total population living in the experimental pen and in the subpopulations living in the five shelters housing the mice. In the total population, bottlenecks preceded changes in the percentages of recessive homozygotes among the mice recruited each year. In the subpopulations, changes in the percentages of recessive homozygotes were preceded by bottlenecks and by movements of mice between shelters. When the data for the males and females of each pelage colour were pooled, the males of all colour types appeared to be equally fit, and females of only one colour type appeared to be slightly less fit than the other three. We concluded that the temporal changes in the percentages of mice homozygous for the recessive alleles were due largely, if not wholly, to drift and migration rather than to natural selection, and that the relative importance of these non-selective processes was determined by the degree to which the populations were isolated from one another.

scholarly journals The effects of assortative mating and migration on cytonuclear associations in hybrid zones.

Genetics ◽  
1989 ◽  
Vol 122 (4) ◽  
pp. 923-934 ◽  
Author(s):  
M A Asmussen ◽  
J Arnold ◽  
J C Avise
Keyword(s):  
Assortative Mating ◽  
Hybrid Zone ◽  
Evolutionary Dynamics ◽  
Initial Conditions ◽  
Likelihood Method ◽  
Hybrid Population ◽  
Hybrid Zones ◽  
Gene Frequencies ◽  
Nonrandom Mating ◽  
And Migration

Abstract We examine the influence of nonrandom mating and immigration on the evolutionary dynamics of cytonuclear associations in hybrid zones. Recursion equations for allelic and genotypic cytonuclear disequilibria were generated under models of (1) migration alone, assuming hybrid zone matings are random with respect to cytonuclear genotype; and (2) migration in conjunction with refined epistatic mating, in which females of the pure parental species preferentially mate with conspecific males. Major results are as follows: (a) even the slightest migration removes the dependency of the final outcome on initial conditions, producing a unique equilibrium in which both pure parental genotypes are maintained in the hybrid zone; (b) in contrast to nuclear genes, the dynamics of cytoplasmic allele frequencies appear robust to changes in the assumed mating system, yet are particularly sensitive to gene flow; (c) continued immigration can generate permanent cytonuclear disequilibria, whether mating is random or assortative; and (d) the order of population censusing (before versus after reproduction by immigrants) can have a dramatic effect on the magnitude but not the pattern of cytonuclear disequilibria. Using the maximum likelihood method, the parameter space of migration rates and assortative mating rates was examined for best fit to observed cytonuclear disequilibria data in a hybrid population of Hyla tree frogs. An epistatic mating model with a total immigration rate of about 32% per generation produces equilibrium gene frequencies and cytonuclear disequilibria consistent with the empirical observations.

Population Dynamics of the Australian Plague Locust, Chortoicetes Terminifera (Walker), in Central Western New South Wales. I. Reproduction and Migration in Relation to Weather.

1979 ◽  
Vol 27 (5) ◽  
pp. 717 ◽  
Author(s):  
RA Farrow
Keyword(s):  
New South ◽  
New South Wales ◽  
Population Fluctuations ◽  
Relative Importance ◽  
Net Migration ◽  
South Wales ◽  
Reproductive Rates ◽  
And Migration ◽  
Australian Plague Locust

On three adjacent experimental plots in central western New South Wales, from 1971 to 1974, population fluctuations of the Australian plague locust were interpreted in terms of the interactions between reproductive rates (Ro) between generations and net migration losses or gains (M plus or minus ) within generations. Changes due to variations in net migration fluctuated over a greater range than those due to variations in reproductive rates, and were the major cause of the population fluctuations during the 16 generations studied. Variations in rainfall during breeding accounted for nearly 90% of the variance in reproductive rates, provided rain followed relatively dry periods. Changes caused by migration resulted from episodic, often long-range and generally southward displacements of adults at night in the gradient wind during disturbed weather. The frequency and intensity of migration depended primarily on the availability of potential emigrants and secondarily on the incidence of weather favourable for takeoff and prolonged flight. The incidence of rainfall before periods of migration was higher than expected. Adults thus migrated into areas already favourable for successful breeding. Long-term median rainfall during breeding at Trangie gave mean reproductive rates greater than 1 per generation. Hence, population surpluses tend to be produced and generally disperse south to areas less favourable for breeding. There was close correspondence between the occurrence of heavy drought-breaking rains, leading to substantial population increases and migrations, and the observed incidence of outbreaks in this area. Changes in the relative importance of reproduction and migration in the drier breeding areas further inland are discussed in relation to historical changes in the distribution and abundance of the plague locust.

Movement and Migration

2017 ◽  
Author(s):  
Catherine M. Cameron ◽  
Scott G. Ortman
Keyword(s):  
Native American ◽  
Fifteenth Century ◽  
Population Distribution ◽  
American Southwest ◽  
Relative Importance ◽  
Population Movements ◽  
Native Peoples ◽  
The Past ◽  
And Migration ◽  
P Movement

Movement is a fundamental concept among Native peoples of the American Southwest, and early archaeologists adopted a strong interest in migration from Native groups with whom they interacted. Over the past two decades, southwest archaeologists have made significant contributions to method and theory in migration studies, including ways of identifying migrants as they move across the landscape, the ways in which migrants interact with Indigenous residents, and the size of migrating groups. Study has focused especially on the vast thirteenth- through fifteenth-century population movements that resulted in dramatic changes in population distribution, particularly in the northern Southwest. The passage of the Native American Graves Protection and Repatriation Act (NAGPRA) initiated a re-engagement with contemporary Native peoples that has transformed perspectives on the relative importance of movement (and sedentism) and has produced new understandings of how social identity was constructed in the ancient Southwest.

Have Migrants Bought a "Round Trip Ticket"? Determinants in Probability of Immigrants' Return in Spain

2012 ◽  
Vol 12 (2) ◽  
pp. 1850258 ◽  
Author(s):  
Rafael de Arce ◽  
Ramon Mahia
Keyword(s):  
Cox Model ◽  
Relative Importance ◽  
Round Trip ◽  
Host Countries ◽  
Factors Affecting ◽  
Strategic Design ◽  
Elapsed Time ◽  
And Migration ◽  
The Moment

Understanding the extent to which immigration is a predominantly permanent or transitory phenomenon is essential for host countries insofar as it affects the strategic design of their admission, reception, and integration policies. Beyond the determination of the volume of returns, it is crucial to also determine which covariates connect better with a greater or lesser propensity of return. An adequate approach to the dynamics of the return requires considering this decision conditioned by the time elapsed since the arrival of the immigrant. From this perspective, the variable of interest would not be the intention of return, but the elapsed time between the arrival of the immigrant and the moment that return is considered as an option, as well as what are the factors affecting a greater or lesser duration of the stay. In this context, the article explores the relative importance of various personal and migration characteristics in the intention of return of immigrants conditional at the time of residence through the application of a Cox model of duration.

Laboratory and Field Data Needs for Site-Specific Repository Modeling

1983 ◽  
Vol 26 ◽  
Author(s):  
M.J. Apted
Keyword(s):  
Slow Release ◽  
Environmental Parameters ◽  
Nuclear Waste Repository ◽  
Relative Importance ◽  
Geochemical Processes ◽  
Laboratory Studies ◽  
Site Specific ◽  
Simple Matrix ◽  
And Migration ◽  
Efficient Program

ABSTRACTThe relative importance of material properties, geochemical processes, and environmental parameters affecting containment and release of radionuclides vary strongly as a function of time and spatial position within a nuclear waste repository located in basalt (NWRB). A simple matrix of spatial regions (Engineered-Barrier System, Disturbed-Rock Zone, Site System of the Controlled Access Zone) and time periods (Pre-emplacement, Containment, Isolation/Slow-release)can be used to identify the dominant processes that affect the containment, release, and migration of radionuclides. From this analysis, a directed and efficient program of field and laboratory studies can be conducted to obtain the data required to assess the feasibility of an NWRB and compliance with Federal regulatory criteria.

scholarly journals Cytonuclear Theory for Haplodiploid Species and X-Linked Genes. I. Hardy-Weinberg Dynamics and Continent-Island, Hybrid Zone Models

Genetics ◽  
1997 ◽  
Vol 147 (1) ◽  
pp. 321-338
Author(s):  
Michael A D Goodisman ◽  
Marjorie A Asmussen
Keyword(s):  
Assortative Mating ◽  
Hybrid Zone ◽  
Random Mating ◽  
Diploid Species ◽  
Specific Gene ◽  
Hybrid Zones ◽  
Pure Type ◽  
Special Cases ◽  
Source Populations ◽  
And Migration

Abstract We develop models that describe the cytonuclear structure for either a cytoplasmic and nuclear marker in a haplodiploid species or a cytoplasmic and X-linked marker in a diploid species. Sex-specific disequilibrium statistics that summarize nonrandom cytonuclear associations in such systems are defined, and their basic Hardy-Weinberg dynamics and admixture formulae are delimited. We focus on the context of hybrid zones and develop continent-island models whereby individuals from two genetically differentiated source populations migrate into and mate within a single zone of admixture. We examine the effects of differential migration of the sexes, assortative mating by pure type females, and census time (relative to mating and migration), as well as special cases of random mating and migration subsumed under the general models. We show that pure type individuals and nonzero cytonuclear disequilibria can be maintained within a hybrid zone if there is continued migration from both source populations, and that females generally have a greater influence over these cytonuclear variables than males. The resulting theoretical framework can be used to estimate the rates of assortative mating and sex-specific gene flow in hybrid zones and other zones of admixture involving haplodiploid or sex-linked cytonuclear data.

Demonstration of Retinal Glycogen with Silver Methenamine

1971 ◽  
Vol 29 ◽  
pp. 564-565
Author(s):  
A. W. Sedar ◽  
G. H. Bresnick
Keyword(s):  
Lactic Acid ◽  
Chromic Acid ◽  
Periodic Acid ◽  
Müller Cell ◽  
External Limiting Membrane ◽  
Electron Microscope Level ◽  
Reactive Process ◽  
Inner Limiting Membrane ◽  
Muller Cell ◽  
And Migration

After experimetnal damage to the retina with a variety of procedures Müller cell hypertrophy and migration occurs. According to Kuwabara and others the reactive process in these injuries is evidenced by a marked increase in amount of glycogen in the Müller cells. These cells were considered originally supporting elements with fiber processes extending throughout the retina from inner limiting membrane to external limiting membrane, but are known now to have high lactic acid dehydrogenase activity and the ability to synthesize glycogen. Since the periodic acid-chromic acid-silver methenamine technique was shown to demonstrate glycogen at the electron microscope level, it was selected to react with glycogen in the fine processes of the Müller cell that ramify among the neural elements in various layers of the retina and demarcate these cells cytologically. The Rhesus monkey was chosen as an example of a well vascularized retina and the rabbit as an example of a avascular retina to explore the possibilities of the technique.

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