scholarly journals Comparative Phylogeography of Some Aridland Bird Species

The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Robert M. Zink ◽  
Ann E. Kessen ◽  
Theresa V. Line ◽  
Rachelle C. Blackwell-Rago
Keyword(s):  
Dna Sequences ◽  
Baja California ◽  
General Pattern ◽  
Bird Species ◽  
Phylogeographic Structure ◽  
Comparative Phylogeography ◽  
Current Range ◽  
Long Term Stability ◽  
Long Period

Abstract We compared mitochondrial DNA sequences for six species distributed across the aridlands of North America to document phylogeographic patterns and assess levels of congruence. The Curve-billed Thrasher (Toxostoma curvirostre) and Canyon Towhee (Pipilo fuscus) show genetic divisions between the Sonoran and Chihuahuan Deserts, whereas the Cactus Wren (Campylorhynchus brunneicapillus), Black-tailed Gnatcatcher (Polioptila melanura), and Verdin (Auriparus flaviceps) do not. Most likely, species without phylogeographic structure only recently colonized their entire current range. Therefore, although these species are today part of a widespread avifauna, species' distributions were historically different from today. In Baja California, the Cactus Wren and the Verdin show phylogeographic breaks at 28°–30°N, consistent with a division previously described in the LeConte's Thrasher (Toxostoma lecontei) and in some members of the herpetofauna. These genetic divisions were likely caused by isolation resulting from a mid-peninsular seaway that existed one million years ago. Hence, these species appear to have been broadly sympatric for at least one million years. In contrast, the California Gnatcatcher (Polioptila californica) lacks such a phylogeographic division, and apparently only recently expanded into the northern part of its current range. Thus, not all species in Baja California have had similar histories, although further sampling might reveal a general pattern. Comparative phylogeography therefore provides an indirect method of evaluating the long-term stability of faunas via assessment of levels of phylogeographic congruence, and can show whether particular species are likely to have had a long period of co-association.

scholarly journals Ultraviolet-sensitive vision in long-lived birds

2010 ◽  
Vol 278 (1702) ◽  
pp. 107-114 ◽  
Author(s):  
Livia S. Carvalho ◽  
Ben Knott ◽  
Mathew L. Berg ◽  
Andrew T. D. Bennett ◽  
David M. Hunt
Keyword(s):  
Uv Light ◽  
Bird Species ◽  
Visual Sensitivity ◽  
Opsin Gene ◽  
Uv Sensitivity ◽  
Long Period ◽  
Lens Transparency ◽  
Avian Order

Long-term exposure to ultraviolet (UV) light generates substantial damage, and in mammals, visual sensitivity to UV is restricted to short-lived diurnal rodents and certain marsupials. In humans, the cornea and lens absorb all UV-A and most of the terrestrial UV-B radiation, preventing the reactive and damaging shorter wavelengths from reaching the retina. This is not the case in certain species of long-lived diurnal birds, which possess UV-sensitive (UVS) visual pigments, maximally sensitive below 400 nm. The Order Psittaciformes contains some of the longest lived bird species, and the two species examined so far have been shown to possess UVS pigments. The objective of this study was to investigate the prevalence of UVS pigments across long-lived parrots, macaws and cockatoos, and therefore assess whether they need to cope with the accumulated effects of exposure to UV-A and UV-B over a long period of time. Sequences from the SWS1 opsin gene revealed that all 14 species investigated possess a key substitution that has been shown to determine a UVS pigment. Furthermore, in vitro regeneration data, and lens transparency, corroborate the molecular findings of UV sensitivity. Our findings thus support the claim that the Psittaciformes are the only avian Order in which UVS pigments are ubiquitous, and indicate that these long-lived birds have UV sensitivity, despite the risks of photodamage.

Comparative phylogeography of two co-distributed species of lizards of the genus Liolaemus (Squamata: Tropiduridae) from Southern Chile

2012 ◽  
Vol 33 (1) ◽  
pp. 55-67 ◽  
Author(s):  
Marcela A. Vidal ◽  
Juan Carlos Ortiz ◽  
Juan Carlos Marín ◽  
Elie Poulin ◽  
Patricio I. Moreno
Keyword(s):  
Dna Sequences ◽  
Middle Pleistocene ◽  
Phylogeographic Structure ◽  
Evolutionary Divergence ◽  
Southern Chile ◽  
Historical Events ◽  
Lizard Species ◽  
Comparative Phylogeography ◽  
Evolutionary Pattern ◽  
The Times

Comparative phylogeography describes the patterns of evolutionary divergence and whether or not they are congruent, in co-distributed populations of different taxa. If the populations of these taxa have been co-distributed for a prolonged time, and if the times between processes of perturbation or vicariance have been more or less stable, it is expected that patterns of divergence will be congruent in closely related species, for example because of similar biological and demographic characteristics. Liolaemus pictus and L. cyanogaster are widely co-distributed lizard species in southern Chile, occurring in a region with a complex topology. We analyzed the phylogeographic structure of the two lizard species using Cytochrome b DNA sequences to estimate their genetic structure in response to historical events. Our results suggest an evolutionary pattern of genetic diversity for each species that is consistent with the geomorphological history of the region, suggesting a complex phylogeographic history in Liolaemus species. Also, the high levels of divergence among haplotypes in several populations suggest the possibility that their origin might predate the middle Pleistocene in both species. Finally, our results are consistent with our hypothesis that two species have responded to historical events in parallel, where historical process have been sufficient to influence their phylogeographical structure (0.80 congruency between topologies).

The Khāliṣah of Varamin

1993 ◽  
Vol 25 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Mansoureh Ettehadieh Nezam-Mafi
Keyword(s):  
Civil War ◽  
Land Tenure ◽  
General Pattern ◽  
Land Ownership ◽  
Climatic Conditions ◽  
The State ◽  
Regional Variations ◽  
Long Period ◽  
The Government

The history and development of land tenure in Iran have been affected by many factors, including climatic conditions, scarcity of water, lack of security, widespread tribalism, and legal and administrative confusion. In addition to limitations in resources, political instability in the premodern period molded systems of land tenure in Iran. Changes of dynasty were frequent and usually followed by the confiscation and redistribution of land. The Qajar dynasty (1788–1925), which came to power after a long period of anarchy and civil war, continued that general pattern. There were three classes of land ownership in Iran in this period: waqfs (religious endowments), arbābī (land owned by large landlords), and khāliṣah (state-owned lands). This last category was composed of lands confiscated by the government as punishment for rebellion or failure to pay taxes. As land was often the only form of wealth landlords had, the threat of government confiscation was an instrument of control as well as a source of revenue for the state. The khāliṣah were usually rented out on long-term leases or were granted as ṭuyul, that is in lieu of services rendered or salaries deferred. The khāliṣah were also in some instances farmed directly by the government. These lands were cultivated by peasants under conditions similar to those of the arbābī lands. They were scattered throughout the country and were also subject to various local and regional variations in agricultural taxes.

scholarly journals Assembly in G1 phase and long-term stability are unique intrinsic features of CENP-A nucleosomes

2013 ◽  
Vol 24 (7) ◽  
pp. 923-932 ◽  
Author(s):  
Dani L. Bodor ◽  
Luis P. Valente ◽  
João F. Mata ◽  
Ben E. Black ◽  
Lars E. T. Jansen
Keyword(s):  
Cell Cycle ◽  
Dna Sequences ◽  
Protein A ◽  
G1 Phase ◽  
Term Stability ◽  
Nucleosome Core ◽  
Long Term Stability ◽  
Centromere Position ◽  
Centromere Protein A

Centromeres are the site of kinetochore formation during mitosis. Centromere protein A (CENP-A), the centromere-specific histone H3 variant, is essential for the epigenetic maintenance of centromere position. Previously we showed that newly synthesized CENP-A is targeted to centromeres exclusively during early G1 phase and is subsequently maintained across mitotic divisions. Using SNAP-based fluorescent pulse labeling, we now demonstrate that cell cycle–restricted chromatin assembly at centromeres is unique to CENP-A nucleosomes and does not involve assembly of other H3 variants. Strikingly, stable retention is restricted to the CENP-A/H4 core of the nucleosome, which we find to outlast general chromatin across several cell divisions. We further show that cell cycle timing of CENP-A assembly is independent of centromeric DNA sequences and instead is mediated by the CENP-A targeting domain. Unexpectedly, this domain also induces stable transmission of centromeric nucleosomes, independent of the CENP-A deposition factor HJURP. This demonstrates that intrinsic properties of the CENP-A protein direct its cell cycle–restricted assembly and induces quantitative mitotic transmission of the CENP-A/H4 nucleosome core, ensuring long-term stability and epigenetic maintenance of centromere position.

scholarly journals Sensing with Chirality Pure near Infrared Fluorescent Carbon Nanotubes

2020 ◽  
Author(s):  
Robert Nißler ◽  
Larissa Kurth, ◽  
Han Li ◽  
Alexander Spreinat ◽  
Ilyas Kuhlemann ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Dna Sequences ◽  
Near Infrared ◽  
Single Wall Carbon Nanotubes ◽  
Term Stability ◽  
Long Term Stability ◽  
Sensing Applications ◽  
Main Challenge ◽  
The Impact

Semiconducting single wall carbon nanotubes (SWCNTs) fluoresce in the near infrared (NIR) and the emission wavelength depends on their chirality (n,m). Interactions with the environment affect the fluorescence and can be tailored by functionalizing SWCNTs with biopolymers such as DNA, which is the basis for fluorescent biosensors. So far, such biosensors were mainly assembled from mixtures of SWCNT chiralities with large spectral overlap, which affects sensitivity as well as selectivity and prevents multiplexed sensing. The main challenge to gain chirality pure sensors has been to combine approaches to isolate specific SWCNTs and generic (bio)functionalization approaches. Here, we created chirality pure SWCNT-based NIR biosensors for important analytes such as neurotransmitters and investigated the impact of SWCNT chirality/handedness as well as long-term stability and sensitivity. For this purpose, we used aqueous two-phase extraction (ATPE) to gain chirality pure (6,5)-, (7,5)-, (9,4)- and (7,6)- SWCNTs (emission at ~ 990, 1040, 1115 and 1130 nm). Exchange of the surfactant sodium deoxycholate (DOC) to specific singlestranded (ss)DNA sequences yielded monochiral sensors for small analytes (dopamine, riboflavin, ascorbic acid, pH). DOC used in the separation process was completely removed because residues impaired sensing. The assembled monochiral sensors were up to 10 times brighter than their non-purified counterparts and the ssDNA sequence affected absolute fluorescence intensity as well as colloidal (long-term) stability and selectivity for the analytes. (GT)40-(6,5)-SWCNTs displayed the maximum fluorescence response to the neurotransmitter dopamine (+140 %, Kd = 1.9 x10-7 M) and a long-term stability > 14 days. Furthermore, the specific ssDNA sequences imparted selectivity to the analytes independent of SWCNT chirality and handedness of (+/-) (6,5)-SWCNTs. These monochiral/single-color SWCNTs enabled ratiometric/multiplexed sensing of dopamine, riboflavin, H2O2 and pH. In summary, we demonstrated the assembly, characteristics and potential of monochiral (single-color) SWCNTs for multiple NIR fluorescent sensing applications.

scholarly journals Sensing with Chirality Pure near Infrared Fluorescent Carbon Nanotubes

2020 ◽  
Author(s):  
Robert Nißler ◽  
Larissa Kurth, ◽  
Han Li ◽  
Alexander Spreinat ◽  
Ilyas Kuhlemann ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Dna Sequences ◽  
Near Infrared ◽  
Single Wall Carbon Nanotubes ◽  
Term Stability ◽  
Long Term Stability ◽  
Sensing Applications ◽  
Main Challenge ◽  
The Impact

Semiconducting single wall carbon nanotubes (SWCNTs) fluoresce in the near infrared (NIR) and the emission wavelength depends on their chirality (n,m). Interactions with the environment affect the fluorescence and can be tailored by functionalizing SWCNTs with biopolymers such as DNA, which is the basis for fluorescent biosensors. So far, such biosensors were mainly assembled from mixtures of SWCNT chiralities with large spectral overlap, which affects sensitivity as well as selectivity and prevents multiplexed sensing. The main challenge to gain chirality pure sensors has been to combine approaches to isolate specific SWCNTs and generic (bio)functionalization approaches. Here, we created chirality pure SWCNT-based NIR biosensors for important analytes such as neurotransmitters and investigated the impact of SWCNT chirality/handedness as well as long-term stability and sensitivity. For this purpose, we used aqueous two-phase extraction (ATPE) to gain chirality pure (6,5)-, (7,5)-, (9,4)- and (7,6)- SWCNTs (emission at ~ 990, 1040, 1115 and 1130 nm). Exchange of the surfactant sodium deoxycholate (DOC) to specific singlestranded (ss)DNA sequences yielded monochiral sensors for small analytes (dopamine, riboflavin, ascorbic acid, pH). DOC used in the separation process was completely removed because residues impaired sensing. The assembled monochiral sensors were up to 10 times brighter than their non-purified counterparts and the ssDNA sequence affected absolute fluorescence intensity as well as colloidal (long-term) stability and selectivity for the analytes. (GT)40-(6,5)-SWCNTs displayed the maximum fluorescence response to the neurotransmitter dopamine (+140 %, Kd = 1.9 x10-7 M) and a long-term stability > 14 days. Furthermore, the specific ssDNA sequences imparted selectivity to the analytes independent of SWCNT chirality and handedness of (+/-) (6,5)-SWCNTs. These monochiral/single-color SWCNTs enabled ratiometric/multiplexed sensing of dopamine, riboflavin, H2O2 and pH. In summary, we demonstrated the assembly, characteristics and potential of monochiral (single-color) SWCNTs for multiple NIR fluorescent sensing applications.

From Gaul to Francia

2020 ◽  
pp. 33-51
Author(s):  
Paul Fouracre
Keyword(s):  
Middle Ages ◽  
Balance Of Power ◽  
Political Conflict ◽  
Seventh Century ◽  
Economic Resources ◽  
Long Term Stability ◽  
Long Period ◽  
High Level ◽  
The Church

The ways in which “Gaul” became “Francia” have been regarded as key to the development of Europe as a whole during the Middle Ages and beyond. This has led to a “Francocentric” view of west European history. This chapter considers how that view was constructed from a canon of narrative and normative sources. It examines the emergence of a Frankish polity and asks why that polity was so large. It then considers why the Frankish kingdoms did not disintegrate over the course of the seventh century, given the political conflict evident in the later narrative sources. The aristocracy and the church were considered cohesive as well as disruptive forces. A high level of social, political, cultural, and religious integration against a background of diminishing economic resources is seen as central to long-term stability in the polity. Shorter-term outbreaks of violence are analyzed in terms of factional politics that ultimately worked to restore balance. The chapter closes with a discussion of how the balance of power was finally upset, leading to the demise of the Merovingian dynasty and the rise of the Carolingians. Emphasis, however, is given to the strong cultural and religious continuities that were the fruit of a long period of stability and that became the basis of Carolingian power.

scholarly journals Comparative phylogenomic patterns in the Baja California avifauna, their conservation implications, and the stages in lineage divergence

2021 ◽  
Author(s):  
Hernan Vazquez-Miranda ◽  
Robert M. Zink ◽  
Brendan J Pinto
Keyword(s):  
Baja California ◽  
Bird Species ◽  
Intermediate Stage ◽  
Molecular Data ◽  
Baja California Peninsula ◽  
Phylogeographic Structure ◽  
Individual Species ◽  
Conservation Implications ◽  
Snp Data ◽  
Genotype By Sequencing

Comparative phylogeography explores the historical congruence of individual species phylogeographic histories to understand the factors that led to their current genetic and phenotypic structures. Various factors can result in currently co-distributed species exhibiting different phylogeographic patterns. The Baja California peninsula and adjacent desert regions provide several potential biogeographic barriers, which have left phylogeographic patterns in some but not all species. We discuss data from bird species found in this region that are relevant to understanding potential biogeographic barriers provided by the Vizcaino Desert. One goal is to compare different sources of molecular data. We show that previous work using mitochondrial markers and single-locus nuclear markers are concordant with similar analyses conducted with genome-wide SNP data (genotype-by-sequencing (GBS) for four bird species found along the Baja California peninsula and adjacent mainland, cactus wren, Gila woodpecker, California gnatcatcher, and LeContes thrasher. The cactus wren and LeContes thrasher show a concordant historical division at or near the Vizcaino Desert in north-central Baja California, the Gila woodpecker appears to be at an intermediate stage of divergence, whereas the California gnatcatcher lacks comparable phylogeographic structure. None of the species we analyzed are classified taxonomically in a way that captures their evolutionary history, with the exception of the LeContes thrasher. The evolutionary division at the Vizcaino desert is well known in other vertebrate species, and our study further corroborates the extent and importance of this biogeographic boundary. The areas north and south of the Vizcaino Desert, which contains considerable diversity, should be recognized as historically significant areas for conservation.

Stability and Change in Emotional Intelligence: Exploring the Transition to Young Adulthood

2005 ◽  
Vol 26 (2) ◽  
pp. 100-106 ◽  
Author(s):  
James D.A. Parker ◽  
Donald H. Saklofske ◽  
Laura M. Wood ◽  
Jennifer M. Eastabrook ◽  
Robyn N. Taylor
Keyword(s):  
High School ◽  
Emotional Intelligence ◽  
Postsecondary Education ◽  
Life Transition ◽  
Full Time ◽  
Major Life ◽  
Long Term Stability ◽  
Time Period ◽  
Transition From High School

Abstract. The concept of emotional intelligence (EI) has attracted growing interest from researchers working in various fields. The present study examined the long-term stability (32 months) of EI-related abilities over the course of a major life transition (the transition from high school to university). During the first week of full-time study, a large group of undergraduates completed the EQ-i:Short; 32 months later a random subset of these students (N = 238), who had started their postsecondary education within 24 months of graduating from high school, completed the measures for a second time. The study found EI scores to be relatively stable over the 32-month time period. EI scores were also found to be significantly higher at Time 2; the overall pattern of change in EI-levels was more than can be attributed to the increased age of the participants.

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