scholarly journals Maladaptive learning and memory in hybrids as a reproductive isolating barrier

2018 ◽  
Vol 285 (1879) ◽  
pp. 20180542 ◽  
Author(s):  
Amber M. Rice ◽  
Michael A. McQuillan

Selection against hybrid offspring, or postzygotic reproductive isolation, maintains species boundaries in the face of gene flow from hybridization. In this review, we propose that maladaptive learning and memory in hybrids is an important, but overlooked form of postzygotic reproductive isolation. Although a role for learning in premating isolation has been supported, whether learning deficiencies can contribute to postzygotic isolation has rarely been tested. We argue that the novel genetic combinations created by hybridization have the potential to impact learning and memory abilities through multiple possible mechanisms, and that any displacement from optima in these traits is likely to have fitness consequences. We review evidence supporting the potential for hybridization to affect learning and memory, and evidence of links between learning abilities and fitness. Finally, we suggest several avenues for future research. Given the importance of learning for fitness, especially in novel and unpredictable environments, maladaptive learning and memory in hybrids may be an increasingly important source of postzygotic reproductive isolation.

2017 ◽  
Author(s):  
Michael A. McQuillan ◽  
Timothy C. Roth ◽  
Alex V. Huynh ◽  
Amber M. Rice

AbstractIdentifying the phenotypes underlying postzygotic reproductive isolation is crucial for fully understanding the evolution and maintenance of species. One potential postzygotic isolating barrier that has not yet been examined is learning and memory ability in hybrids. Learning and memory are important fitness-related traits, especially in scatter-hoarding species, where accurate retrieval of hoarded food is vital for winter survival. Here, we test the hypothesis that learning and memory ability can act as a postzygotic isolating barrier by comparing these traits among two scatter-hoarding songbird species, black-capped (Poecile atricapillus), Carolina chickadees (Poecile carolinensis), and their naturally occurring hybrids. In an outdoor aviary setting, we find that hybrid chickadees perform significantly worse on an associative learning spatial task and are worse at solving a novel problem compared to both parental species. Deficiencies in learning and memory abilities could therefore contribute to postzygotic reproductive isolation between chickadee species. Given the importance of learning and memory for fitness, our results suggest that these traits may play an important, but as yet overlooked, role in postzygotic reproductive isolation.


2008 ◽  
Vol 363 (1506) ◽  
pp. 3009-3021 ◽  
Author(s):  
David B Lowry ◽  
Jennifer L Modliszewski ◽  
Kevin M Wright ◽  
Carrie A Wu ◽  
John H Willis

Speciation is characterized by the evolution of reproductive isolation between two groups of organisms. Understanding the process of speciation requires the quantification of barriers to reproductive isolation, dissection of the genetic mechanisms that contribute to those barriers and determination of the forces driving the evolution of those barriers. Through a comprehensive analysis involving 19 pairs of plant taxa, we assessed the strength and patterns of asymmetry of multiple prezygotic and postzygotic reproductive isolating barriers. We then reviewed contemporary knowledge of the genetic architecture of reproductive isolation and the relative role of chromosomal and genic factors in intrinsic postzygotic isolation. On average, we found that prezygotic isolation is approximately twice as strong as postzygotic isolation, and that postmating barriers are approximately three times more asymmetrical in their action than premating barriers. Barriers involve a variable number of loci, and chromosomal rearrangements may have a limited direct role in reproductive isolation in plants. Future research should aim to understand the relationship between particular genetic loci and the magnitude of their effect on reproductive isolation in nature, the geographical scale at which plant speciation occurs, and the role of different evolutionary forces in the speciation process.


2020 ◽  
Vol 375 (1806) ◽  
pp. 20190535 ◽  
Author(s):  
Sina J. Rometsch ◽  
Julián Torres-Dowdall ◽  
Axel Meyer

Cichlid fishes are exceptionally species-rich, speciated at explosive rates and, hence, are a model system in speciation research. Yet, their reproductive isolating barriers have, so far, not been comprehensively studied. Here, we review current knowledge on pre- and postzygotic mechanisms in cichlids. While premating isolation is the norm in cichlids, its strength varies across lineages and with the geographical setting. Moreover, manipulations of ambient conditions tended to reduce assortative mating among closely related species, suggesting that premating isolation in cichlids is often fragile and context dependent. The observed lack of complete reproductive isolation is supported by past and present hybridization events that have contributed to diversity by creating novel allelic combinations. On the other hand, our meta-analysis highlights that intrinsic postzygotic isolation might accumulate faster than assumed. Mild forms of genetic incompatibilities, such as sex ratio distortion, can already be observed among closely related species. Therefore, cessation of gene flow by strong reproductive isolation in cichlids requires a combination of premating prezygotic isolation supplemented with intrinsic and extrinsic postzygotic barriers. Further, we suggest crucial next steps to improve our knowledge about reproductive barriers in cichlids to understand the evolutionary dynamics of pre- and postzygotic isolation mechanisms during adaptive radiations. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.


Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 690
Author(s):  
Desanka Lazic ◽  
Andrew L. Hipp ◽  
John E. Carlson ◽  
Oliver Gailing

Adaptive divergence is widely accepted as a contributor to speciation and the maintenance of species integrity. However, the mechanisms leading to reproductive isolation, the genes involved in adaptive divergence, and the traits that shape the adaptation of wild species to changes in climate are still largely unknown. In studying the role of ecological interactions and environment-driven selection, trees have emerged as potential model organisms because of their longevity and large genetic diversity, especially in natural habitats. Due to recurrent gene flow among species with different ecological preferences, oaks arose as early as the 1970s as a model for understanding how speciation can occur in the face of interspecific gene flow, and what we mean by “species” when geographically and genomically heterogeneous introgression seems to undermine species’ genetic coherence. In this review, we provide an overview of recent research into the genomic underpinnings of adaptive divergence and maintenance of species integrity in oaks in the face of gene flow. We review genomic and analytical tools instrumental to better understanding mechanisms leading to reproductive isolation and environment-driven adaptive introgression in oaks. We review evidence that oak species are genomically coherent entities, focusing on sympatric populations with ongoing gene flow, and discuss evidence for and hypotheses regarding genetic mechanisms linking adaptive divergence and reproductive isolation. As the evolution of drought- and freezing-tolerance have been key to the parallel diversification of oaks, we investigate the question of whether the same or a similar set of genes are involved in adaptive divergence for drought and stress tolerance across different taxa and sections. Finally, we propose potential future research directions on the role of hybridization and adaptive introgression in adaptation to climate change.


2016 ◽  
Vol 25 (1) ◽  
pp. 96-109
Author(s):  
Kristen Marangoni

The enigmatic setting of Beckett's novel Watt has been compared to places as diverse as an insane asylum, a boarding school, a womb, and a concentration camp. Watt's experience at Knott's house does seem suggestive of all of these, and yet it may more readily conform to the setting of a monastery. The novel is filled with chants, meditations, choral arrangements, hierarchical classifications, and even silence, all highly evocative of a monastic lifestyle. Some of Watt's dialogue (such as his requests for forgiveness or reflections on the nature of mankind) further echoes various Catholic liturgies. Watt finds little solace in these activities, however. He feels that they are largely rote and purposeless as they are focused on Knott, a figure who in many ways defies linguistic description and physical know-ability. Watt's meditations and rituals become, then, empty catechisms without answers, something that is reflected in the extreme difficulty that Watt has communicating. In the face of linguistic and liturgical instability, the Watt notebooks present a counter reading that can be found in the thousand plus doodles that line its pages. The drawings reinforce as well as subvert their textual counterpart, and they function in many ways as the images in medieval illuminated manuscripts. The doodles in Watt often take the form of decorative letters, elaborate marginal drawings, and depictions of a variety of people and animals, and many of its doodles offer uncanny resemblances in form or theme to those in illuminated manuscripts like The Book of Kells. Doodles of saints, monks, crosses, and scribes even give an occasional pictorial nod to the monastic setting in which illuminated manuscripts were usually produced (and remind us of the monastic conditions in which Beckett found himself writing much of Watt). Beckett's doodles not only channel this medium of illuminated manuscripts, they also modernize its application. Instead of neat geometric shapes extending down the page, his geometric doodle sequences are often abstracted, fragmented, and nonlinear. Beckett also occasionally modernized the content of illuminated manuscripts: instead of the traditional sacramental communion table filled with candles, bread and wine, Beckett doodles a science lab table where Bunsen burners replaces candles and wine glasses function as beakers. It is through these modernized images that Watt attempts to draw contemporary relevance from a classic art form and to restore (at least partial) meaning to rote traditions.


2020 ◽  
Vol 06 ◽  
Author(s):  
Parul Kamboj ◽  
Ajit Kumar Thakur

Background: Glycyrrhiza glabra Linn. (Family: Fabaceae) has been known to very useful medicinal plant in the Traditional Medicinal Systems from the centuries. With ethnopharmacological values, it is well-reported plant for their traditional uses for anti-inflammatory, antioxidant, anxiolytic, expectorant activities, and antidepressant activities. Objective: Although it is described for memory enhancing activity, the present study was focused to examine the comparative effect of Glycyrrhiza glabra extracts viz. flavonoid rich (GGFE) and glycyrrhizin rich (GGGE) in stress triggered rats and to provide future research insight for this herbal drug, for which no scientific justification has been reported till now. Methods: Male Wister rats divided into 7 different groups (n= 6 per group) were given chronic foot-shock stress for 21 successive days with scheduled administration of the extracts (50 and 100 mg/kg) and standard drug (10 mg/kg) for 28 days. Elevated Plus Maze, Rectangular Maze, Morris Water Maze, and Locomotor activity were performed to test behavioral alteration and learning ability of stressed rats. Further, rats were sacrificed to assay acetylcholinesterase activity and antioxidant activity in brain samples for the mechanistic role in learning and memory. Results: Extracts of Glycyrrhiza glabra were indicated a significant alteration in stress induced learning and memory deficiency in behavioral parameters studied. These extracts were also modulated significant changes in acetylcholinesterase and antioxidant enzyme activity to improve the learning and memory of stressed rats. Conclusions: It is concluded that both extracts of Glycyrrhiza glabra (GGFE and GGGE) possess memory enhancing property in stress triggered rats. Moreover, these comparative results provided information and confirmed the high potential of GGGE in comparison to GGFE might be due to rich glycyrrhizin content present in GGGE responsible for acetylcholinesterase and antioxidant enzyme modulatory activity. Therefore, GGGE could be used as a promising lead for further mechanistic and molecular study for defining the role of glycyrrhizin of Glycyrrhiza glabra.


Author(s):  
Jane Austen ◽  
Jane Stabler

‘Me!’ cried Fanny … ‘Indeed you must excuse me. I could not act any thing if you were to give me the world. No, indeed, I cannot act.’ At the age of ten, Fanny Price leaves the poverty of her Portsmouth home to be brought up among the family of her wealthy uncle, Sir Thomas Bertram, in the chilly grandeur of Mansfield Park. There she accepts her lowly status, and gradually falls in love with her cousin Edmund. When the dazzling and sophisticated Henry and Mary Crawford arrive, Fanny watches as her cousins become embroiled in rivalry and sexual jealousy. As the company starts to rehearse a play by way of entertainment, Fanny struggles to retain her independence in the face of the Crawfords’ dangerous attractions; and when Henry turns his attentions to her, the drama really begins… This new edition does full justice to Austen’s complex and subtle story, placing it in its Regency context and elucidating the theatrical background that pervades the novel.


2021 ◽  
Vol 11 (4) ◽  
pp. 426
Author(s):  
Lydia Giménez-Llort ◽  
Mikel Santana-Santana ◽  
Míriam Ratia ◽  
Belén Pérez ◽  
Pelayo Camps ◽  
...  

A new hypothesis highlights sleep-dependent learning/memory consolidation and regards the sleep-wake cycle as a modulator of β-amyloid and tau Alzheimer’s disease (AD) pathologies. Sundowning behavior is a common neuropsychiatric symptom (NPS) associated with dementia. Sleep fragmentation resulting from disturbances in sleep and circadian rhythms in AD may have important consequences on memory processes and exacerbate the other AD-NPS. The present work studied the effect of training time schedules on 12-month-old male 3xTg-AD mice modeling advanced disease stages. Their performance in two paradigms of the Morris water maze for spatial-reference and visual-perceptual learning and memory were found impaired at midday, after 4 h of non-active phase. In contrast, early-morning trained littermates, slowing down from their active phase, exhibited better performance and used goal-directed strategies and non-search navigation described for normal aging. The novel multitarget anticholinesterasic compound AVCRI104P3 (0.6 µmol·kg−1, 21 days i.p.) exerted stronger cognitive benefits than its in vitro equipotent dose of AChEI huprine X (0.12 μmol·kg−1, 21 days i.p.). Both compounds showed streamlined drug effectiveness, independently of the schedule. Their effects on anxiety-like behaviors were moderate. The results open a question of how time schedules modulate the capacity to respond to task demands and to assess/elucidate new drug effectiveness.


2021 ◽  
Vol 54 (4) ◽  
pp. 1-37
Author(s):  
Azzedine Boukerche ◽  
Xiren Ma

Vision-based Automated Vehicle Recognition (VAVR) has attracted considerable attention recently. Particularly given the reliance on emerging deep learning methods, which have powerful feature extraction and pattern learning abilities, vehicle recognition has made significant progress. VAVR is an essential part of Intelligent Transportation Systems. The VAVR system can fast and accurately locate a target vehicle, which significantly helps improve regional security. A comprehensive VAVR system contains three components: Vehicle Detection (VD), Vehicle Make and Model Recognition (VMMR), and Vehicle Re-identification (VRe-ID). These components perform coarse-to-fine recognition tasks in three steps. In this article, we conduct a thorough review and comparison of the state-of-the-art deep learning--based models proposed for VAVR. We present a detailed introduction to different vehicle recognition datasets used for a comprehensive evaluation of the proposed models. We also critically discuss the major challenges and future research trends involved in each task. Finally, we summarize the characteristics of the methods for each task. Our comprehensive model analysis will help researchers that are interested in VD, VMMR, and VRe-ID and provide them with possible directions to solve current challenges and further improve the performance and robustness of models.


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