scholarly journals Reproductive Success Across The Black-Capped Chickadee (Poecile Atricapillus) and Carolina Chickadee (P. Carolinensis) Hybrid Zone in Ohio

The Auk ◽  
2005 ◽  
Vol 122 (3) ◽  
pp. 759-772 ◽  
Author(s):  
C. L. Bronson ◽  
Thomas C. Grubb ◽  
Gene D. Sattler ◽  
Michael J. Braun
Keyword(s):  
Reproductive Success ◽  
Hybrid Zone ◽  
Past Century ◽  
Genetic Introgression ◽  
Genetic Composition ◽  
Poecile Atricapillus ◽  
Relative Paucity ◽  
Carolina Chickadee ◽  
The Face ◽  
East West

AbstractBlack-capped Chickadees (Poecile atricapillus) and Carolina Chickadees (P. carolinensis) hybridize in an east-west band from New Jersey to Kansas. Within the past century, the Ohio portion of this hybrid zone and the Carolina Chickadee range to the south have been moving northward, whereas the Black-capped Chickadee range has retracted. In Ohio, we characterized the genetic composition of the hybrid zone using five diagnostic molecular loci. Although there was no evidence of assortative mating in the center of the hybrid zone, we found a relative paucity of genetically intermediate breeding females as compared with breeding males. That suggests viability selection against female hybrids, in line with Haldane’s rule. On the basis of reproductive variables (number of nestlings, reproductive success), we found a decrease in productivity of breeding pairs in the hybrid zone that is significantly and positively related to their probability of producing homozygous offspring at each autosomal or sex-linked locus. We also found that the decrease in productivity was significantly and positively related to the genetic composition of the male of the pair (i.e. pure male chickadees more productive). These data strongly suggest that hybrids are at a selective disadvantage. Because the zone of reduced reproductive success was considerably narrower than the zone of introgression, our results demonstrate that genetic introgression is occurring in the face of substantial selection against hybrids.Éxito Reproductivo a través de la Zona de Hibridación de Poecile atricapillus y P. carolinensis en Ohio

scholarly journals Structure and Dynamics of The Hybrid Zone Between Black-Capped Chickadee (Poecile Atricapillus) and Carolina Chickadee (P. Carolinensis) in Southeastern Pennsylvania

The Auk ◽  
2007 ◽  
Vol 124 (2) ◽  
pp. 463-478 ◽  
Author(s):  
Matthew W. Reudink ◽  
Stephen G. Mech ◽  
Sean P. Mullen ◽  
Robert L. Curry
Keyword(s):  
Hybrid Zone ◽  
Selective Advantage ◽  
Genetic Introgression ◽  
Poecile Atricapillus ◽  
Large Numbers ◽  
Starting Point ◽  
Carolina Chickadee ◽  
Northern Edge ◽  
Historical Accounts ◽  
Carolina Chickadees

AbstractAnalysis of the structure and stability of a hybrid zone can serve as a starting point for examining mechanisms that influence spatial and evolutionary relationships between species. Recent studies of the hybrid zone between Black-capped Chickadee (Poecile atricapillus) and Carolina Chickadee (P. carolinensis) have suggested that genetic introgression is limited to a narrow zone, while also reinforcing the conclusion that the line of contact between these parapatrically distributed species is now shifting northward. We investigated the structure, position, and recent movement of the chickadee hybrid zone in southeastern Pennsylvania. Using selectively neutral microsatellite DNA markers, along with mitochondrial DNA haplotypes, we documented large differences in genetic composition among three populations ≤65 km apart where we sampled large numbers of breeding residents during 1998–2003. Genetic results indicate that the three sites support a population of Carolina Chickadees (Great Marsh), a population in which most individuals exhibit evidence of hybridization (Nolde Forest), and a population comprising mostly Black-capped Chickadees but with evidence of hybridization now taking place (Hawk Mountain). The patterns within the Nolde Forest population suggest that selection against hybrids may not be as strong as has been concluded from studies in other parts of the chickadee hybrid zone. Comparison of mitochondrial and nuclear genotypes between samples collected ≈15 years apart suggest that the northern edge of the hybrid zone shifted by ≈20 km over this interval, with hybridization now occurring as far north as the Kittatinny Ridge and beyond, where only Black-capped Chickadee genotypes were previously detectable. Our data and historical accounts suggest that the hybrid zone, now ≈50 km wide, may have become wider while also shifting northward. These results support the hypothesis that Carolina Chickadees enjoy a selective advantage during hybridization with Black-capped Chickadees, but both the proximate mechanisms and ultimate causes remain to be investigated.Structure et dynamique de la zone d'hybridation entre Poecile atricapillus et P. carolinensis dans le sud-est de la Pennsylvanie

scholarly journals An Assessment of Song Admixture as an Indicator of Hybridization in Black-Capped Chickadees (Poecile Atricapillus) and Carolina Chickadees (P. Carolinensis)

The Auk ◽  
2007 ◽  
Vol 124 (3) ◽  
pp. 926-944 ◽  
Author(s):  
Gene D. Sattler ◽  
Patricia Sawaya ◽  
Michael J. Braun
Keyword(s):  
Contact Zone ◽  
Ecological Factors ◽  
Principal Component ◽  
Song Type ◽  
Genetic Introgression ◽  
Genetic Composition ◽  
Poecile Atricapillus ◽  
Quantitative Analyses ◽  
Different Levels ◽  
Carolina Chickadees

AbstractVocal admixture often occurs where differentiated populations or species of birds meet. This may entail song sympatry, bilingually singing birds, and songs with intermediate or atypical characteristics. Different levels of vocal admixture at the range interface between Black-capped Chickadees (Poecile atricapillus) and Carolina Chickadees (P. carolinensis) have been interpreted as indicating that hybridization is frequent at some locations but not others. However, song ontogeny in these birds has a strong nongenetic component, so that inferences regarding hybridization based on vocal admixture require confirmation. We used diagnostic genetic markers and quantitative analyses of song to characterize population samples along two transects of the chickadee contact zone in the Appalachian Mountains. More than 50% of individuals at the range interface were of hybrid ancestry, yet only 20% were observed to be bilingual or to sing atypical songs. Principal component analysis revealed minimal song intermediacy. This result contrasts with an earlier analysis of the hybrid zone in Missouri that found considerable song intermediacy. Re-analysis of the Missouri data confirmed this difference. Correlation between an individual’s genetic composition and its song type was weak in Appalachian hybrid populations, and genetic introgression in both forms extended far beyond the limits of vocal admixture. Therefore, song is not a reliable indicator of levels of hybridization or genetic introgression at this contact zone. Varying ecological factors may play a role in producing variable levels of song admixture in different regions of the range interface.Una Evaluación de la Mixtura de Cantos como Indicador de Hibridación en Poecile atricapillus y P. carolinensis

Die harte Schule der neuen Gewalt

2021 ◽  
Author(s):  
Bernhard Rinke
Keyword(s):  
Cold War ◽  
Thought Processes ◽  
The World ◽  
The Face ◽  
The Cold War ◽  
Violent Conflicts ◽  
East West

This study examines the fundamental new direction in German theological peace ethics since the end of the East–West conflict. It guides the reader through the thought processes and discoveries of leading Catholic and Protestant peace ethicists and, in doing so, through the significant developments in theological peace ethics in Germany amid the tough new realities that have emerged since the end of the Cold War. In addition, the book discusses the normative premises for conduct conducive to peace which German theological peace ethics has devised in order to fulfil its responsibility to the world in the face of today’s new, violent conflicts.

Organizations are people: reflections, obstacles and learning opportunities

2020 ◽  
Vol 27 (6) ◽  
pp. 535-548
Author(s):  
Graham Robinson
Keyword(s):  
Organizational Learning ◽  
Learning Organization ◽  
Community Action ◽  
Past Century ◽  
Content Type ◽  
Personal Mastery ◽  
The Face ◽  
Effective Community ◽  
German Sociology

Purpose The purpose of this paper is to place the idea of the learning organization in a historical, multidisciplinary context with the aim of identifying obstacles and opportunities for its greater realization in practice. Design/methodology/approach Marking the 30th anniversary of publication of Peter Senge's “The Fifth Discipline”, the paper reflects on approaches to the study and analysis of organizations over the past century from German sociology, human relations, organization development, the learning organization to responses to the Covid-19 pandemic. Findings It is suggested that distributed leadership is critical to the realization of organizational learning and its absence is a major inhibitor of such learning. Following Argyris, it is argued that high levels of skill (personal mastery) may, in some circumstances, provide a barrier to organizational learning in the face of contextual uncertainty and change. Research limitations/implications While no specific areas of research are proposed, questions are raised which may only be answered in the wake of appropriate (interdisciplinary) research. Practical implications The reflective nature of the paper suggests that significant reform is required in the legislation that encourages short-term thinking on the part of institutional investors to the detriment of strategic thinking and long-term planning. Social implications The Covid-19 pandemic seems to have provided an opportunity to redress a perceived imbalance between traditional organizational thinking and opportunities demonstrated by effective community action, for reappraisal of organizations as communities of people as well as being formalized structures, systems and processes. Originality/value This paper seeks to synthesize diverse theories of organization with the aim of stimulating further innovation in approaches to organizational learning.

Indicators of population viability in red spruce, Picea rubens. I. Reproductive traits and fecundity

2000 ◽  
Vol 78 (7) ◽  
pp. 928-940 ◽  
Author(s):  
A Mosseler ◽  
J E Major ◽  
J D Simpson ◽  
B Daigle ◽  
K Lange ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Natural Populations ◽  
Population Viability ◽  
Height Growth ◽  
Picea Rubens ◽  
Red Spruce ◽  
Past Century ◽  
Seedling Height ◽  
Seed Traits ◽  
General Validity

Red spruce (Picea rubens Sarg.) has experienced a substantial decline across most of its range in eastern North America over the past century and probably also in the disjunct Ontario populations where it now occurs only in small isolated stands. Measurements of cone and seed traits from natural populations were used as indicators of the reproductive and genetic status of red spruce across the northern margins of its range in Canada. Cone and seed traits were quantified to provide reproductive benchmarks for assessing and monitoring population viability. Reduced fecundity and seedling height growth were observed in some of the smallest Ontario populations, suggesting some inbreeding depression in both vegetative and reproductive components of fitness. Nevertheless, the reproductive status of these small isolated Ontario populations compared favorably with the much larger, more extensive Maritime populations in Nova Scotia and New Brunswick. Significantly higher proportions of aborted (nonpollinated) seeds and lower proportions of filled seeds suggested poorer pollination conditions in the Maritimes in 1996. The proportion of empty seed, which was used to estimate inbreeding levels, was significantly and negatively related to seedling height growth. In the short-term, the Ontario populations, which probably represent relatively recent remnants of a broader past distribution, generally appeared to be quite resilient to the effects of small population size on fecundity and progeny fitness. In the longer term, continuing decline in population sizes and numbers may be expected to erode reproductive success and genetic diversity through the effects of inbreeding, genetic drift, and changes in mating behavior. The reproductive indicators described here have general validity for assessing and monitoring reproductive and genetic aspects of population viability in conifers.Key words: Picea rubens, reproductive success, reproductive fitness indicators, inbreeding, population viability, conservation.

scholarly journals School Consolidation and Notions of Progress: Why Community Actors Almost Always Lose the Fight to Keep Local Schools and How They Can Turn the Tables

in education ◽  
2012 ◽  
Vol 18 (1) ◽  
Author(s):  
Patricia Elliott
Keyword(s):  
Essential Role ◽  
Local Community ◽  
Community Action ◽  
School Consolidation ◽  
Power Dynamics ◽  
Past Century ◽  
The Past ◽  
Local Schools ◽  
The Face ◽  
Effective Community

Supported by a growing body of research, the idea that schools have an essential role to play in local community cohesion and development has gained currency among urban and rural school advocates alike. Yet moving theory into action often grinds to a halt in the face of a recalcitrant bureaucracy. To understand why, it is important to step back and examine the theoretical framework of progress that has driven school consolidation and bureaucratization over the past century. Knowing these underlying power dynamics will help community advocates understand where their power is weakest, and where it is strongest, leading to more effective community action in defence of local schools.Keywords: school consolitation; community action; community school

scholarly journals Radical women in social work: A historical prespective from North America

2018 ◽  
Vol 30 (3) ◽  
pp. 45-56
Author(s):  
Therese Jennissen ◽  
Colleen Lundy
Keyword(s):  
Social Justice ◽  
Social Workers ◽  
Armed Conflict ◽  
Status Quo ◽  
Past Century ◽  
The Past ◽  
The Status ◽  
The Face ◽  
Politically Active ◽  
Very High

INTRODUCTION: Many challenges that confront social workers today are similar to problems they have faced over the past century – inequality, poverty, unemployment, militarisation and armed conflict, and the challenges of refugee resettlement, to name a few. It is instructive for contemporary social workers to revisit this history and to determine if there are lessons to inform our current struggles.METHOD: This paper explores the issues faced and strategies employed by radical, politically active social workers, most of them women. These social workers had visions of social justice and were not afraid to challenge the status quo, often at very high personal costs. The radical social workers were expressly interested in social change that centred on social justice, women’s rights, anti-racism, international peace, and they worked in close alliance and solidarity with other progressive groups.CONCLUSIONS: This article highlights the work of five radical female social workers. Radical social workers were in the minority but they were extraordinarily active and made important contributions in the face of formidable challenges.

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