Elongated tails are elaborate plumage traits possessed by a variety of bird species. Sexual selection has long been the dominant hypothesis for explaining why certain species possess such long tails. ...During the past three decades, however, alternative hypotheses have been proposed and tested. Here, we review evidence, and the lack thereof, for four hypothesised functions of elongated tails in birds: sexual selection, aerodynamic enhancement, anti‐predation signalling and perch balancing. Sexual selection has received the most attention, though with inconsistent support. The other three hypothesised functions, in contrast, have gained less attention, with perch balancing remaining largely speculative. After reviewing and synthesizing information about these functions, we show that our current knowledge of avian elongated tails is not comprehensive. To advance our understanding of this topic, we suggest (1) devising a uniform definition of elongated tails that can be applied to a wide variety of bird species, (2) further investigation of less‐studied functions of such tails, (3) conducting meta‐analyses to discover the origins and trait correlates of elongated tails, (4) considering the possibility that elongated tails serve multiple functions simultaneously, and (5) testing unexplored functions of elongated tails.
Antibody-drug conjugates (ADCs) have developed rapidly in recent decades. However, it is complicated to map out a perfect ADC that requires optimization of multiple parameters including antigens, ...antibodies, linkers, payloads, and the payload-linker linkage. The therapeutic targets of the ADCs are expected to express only on the surface of the corresponding target tumor cells. On the contrary, many antigens usually express on normal tissues to some extent, which could disturb the specificity of ADCs and limit their clinical application, not to mention the antibody is also difficult to choose. It requires to not only target and have affinity with the corresponding antigen, but it also needs to have a linkage site with the linker to load the payloads. In addition, the linker and payload are indispensable in the efficacy of ADCs. The linker is required to stabilize the ADC in the circulatory system and is brittle to release free payload while the antibody combines with antigen. Also, it is a premise that the dose of ADCs will not kill normal tissues and the released payloads are able to fulfill the killing potency in tumor cells at the same time. In this review, we mainly focus on the latest development of key factors affecting ADCs progress, including the selection of antibodies and antigens, the optimization of payload, the modification of linker, payload-linker linkage, and some other relevant parameters of ADCs.
English has a significant role in every state in the school curriculum, and several scholars have researched the status of teaching English at secondary level. The purpose of teaching English is to ...build multilingual languages that can enrich our entire language; this has been an ongoing national vision. The weak status of teaching English and the use of conventional teaching methods are found in the study of literature. It is ironic, however, that while English enjoys a high status in the wake of globalization, it is quite inadequate and unproductive to teach and learn in educational institutions. Present strategies of teaching English in the classroom are no longer viable, but they can be 'communicatively' driven. The key disadvantages are the low status of teaching English, non-availability of professionally trained and educated teachers, less weighting provided for teaching English and no proper transactional strategies adopted for teaching. In this sense, the extent of the pedagogical processes of learning the English language must be examined. The target population of the current study in the South district of Sikkim was limited to 90 teachers teaching English in 30 secondary schools. Classroom observation schedule covering the aspects like engage, explore, explain, elaborate, evaluate was used for collection of data. Classroom observation is also one of the powerful methods of monitoring the success of the instructor in the classroom. Through this study, attempt has been made to see the extent as to how constructivist approach is used by the teachers in the teaching learning processes. Conversely, study has explored the teaching processes used by English teachers in the classroom towards learning English language at secondary schools in Sikkim. The sequential processes are mainly used to link up the connection between past and the present learning experience, designising activities for students engagement, assess learning outcomes, type of resource used in learning, identifying and developing concepts, reconstructing students knowledge, assessing students current level of understanding in listening, speaking, reading and writing, elaboration through recapitulative questions, development of higher order thinking, evaluation of students of key concepts and skills, identifying and motivating the students to identify future learning goals and evaluating students knowledge through quiz, debate, role play, recitation, tests, observation and performance dialogue, essay and summary writing and projects, respectively.
In order to meet the urgent needs of target image data in the testing of close-range space target situational awareness algorithm, an elaborate image simulation method that fully considers the target ...surface texture structure is proposed. First, the physical mechanism is analysed by constructing a radiation transmission model. Then, Phong and five-parameters BRDF models are adopted to characterize the optical properties of the material. The geometric characteristic of texture structure is also characterized through displacement mapping. Finally, the sequence images of the space target are obtained by simulation based on the designed simulation process and given imaging conditions. The CPU multi-core parallel acceleration based on the Embree engine is taken to compensate for the speed reduction caused by the increase in the number of model faces. Compared with the measured image in orbit for verification, the image simulation similarity is above 80%. The results show that the simulation method in this article can better describe the characteristics of the target in the actual on-orbit environment and meet the near real-time simulation requirements of the system, providing a more realistic image data source for the ground test of the on-orbit service technology.
Elaborate petals are present in many flowering plants lineages and have greatly promoted the success and evolutionary radiation of these groups. How elaborate petals are made, however, remains ...largely unclear. Petals of Nigella (Ranunculaceae) have long been recognized as elaborate and can thus be an excellent model for the study of petal elaboration.
Here, by conducting detailed morphological, micromorphological, anatomical, developmental and evolutionary studies on the petals of Nigella species, we explored the processes, general patterns and underlying mechanisms of petal elaboration.
We found that petals of Nigella are highly complex, and the complexity can be reflected at various levels. We also found that evolutionary elaboration of the Nigella petals is a gradual process, involving not only modifications of pre-existing structures but also de novo origination of new characters. Further investigations indicated that the elaboration and diversification of Nigella petals were accomplished by modifying the ancestral trajectory of petal development, a process known as developmental repatterning.
Our results not only provide new insights into the development and evolution of elaborate petals, but also highlight the necessity of conducting multiple-level investigations for understanding the processes, patterns and underlying mechanisms of plant evolution.
Ranunculaceae comprise
ca.
2,500 species (
ca.
55 genera) that display a broad range of floral diversity, particularly at the level of the perianth. Petals, when present, are often referred to as ...“elaborate” because they have a complex morphology. In addition, the petals usually produce and store nectar, which gives them a crucial functional role in the interaction with pollinators. Its morphological diversity and species richness make this family a particularly suitable model group for studying the evolution of complex morphologies. Our aims are (1) to reconstruct the ancestral form of the petal and evolutionary stages at the scale of Ranunculaceae, (2) to test the hypothesis that there are morphogenetic regions on the petal that are common to all species and that interspecific morphological diversity may be due to differences in the relative proportions of these regions during development. We scored and analyzed traits (descriptors) that characterize in detail the complexity of mature petal morphology in 32 genera. Furthermore, we described petal development using high resolution X-Ray computed tomography (HRX-CT) in six species with contrasting petal forms (
Ficaria verna, Helleborus orientalis, Staphisagria picta, Aconitum napellus, Nigella damascena, Aquilegia vulgaris
). Ancestral state reconstruction was performed using a robust and dated phylogeny of the family, allowing us to produce new hypotheses for petal evolution in Ranunculaceae. Our results suggest a flat ancestral petal with a short claw for the entire family and for the ancestors of all tribes except Adonideae. The elaborate petals that are present in different lineages have evolved independently, and similar morphologies are the result of convergent evolution.
Traits are often caught in a dynamic tension of countervailing evolutionary pressures. Trade-offs can be imposed by predators evolutionarily curtailing the conspicuousness of a sexually selected ...trait, or acting in opposition to another natural selection pressure, for instance, a different predator with a divergent hunting strategy. Some moon moths (Saturniidae) have long hindwing tails that thwart echolocating bat attacks at night, allowing the moth to escape. These long tails may come at a cost, however, if they make the moth's roosting form more conspicuous to visually foraging predators during the day. To test this potential trade-off, we offered wild-caught Carolina wrens (
) pastry dough models with real
wings that were either intact or had tails experimentally removed. We video recorded wrens foraging on models and found that moth models with tails did not experience increased detection and attack by birds. Thus, this elaborate trait, while obvious to human observers, does not seem to come at a cost of increased avian predator attention. The evolution of long hindwing tails, likely driven by echolocating predators at night, does not seem to be limited by opposing diurnal constraints. This study demonstrates the importance of testing presumed trade-offs and provides hypotheses for future testing.
Summary
Superior physical competence is vital to the adaptive behavioural routines of many animals, particularly those that engage in elaborate sociosexual displays. How such traits evolve across ...species remains unclear.
Recent work suggests that activation of sex steroid receptors in neuromuscular systems is necessary for the fine motor skills needed to execute physically elaborate displays. Thus, using passerine birds as models, we test whether interspecific variation in display complexity predicts species differences in the abundance of androgen and oestrogen receptors (AR and ER‐α) expressed in the forelimb musculature and spinal cord.
We find that small‐scale evolutionary patterns in physical display complexity positively predict expression of AR in the main muscles that lift and retract the wings. No such relationship is detected in the spinal cord, and we do not find a correlation between display behaviour and neuromuscular expression of ER‐α. Also, we find that AR expression levels in different androgen targets throughout the body – namely the wing muscles, spinal cord and testes – are not necessarily correlated, providing evidence that evolutionary forces drive AR expression in a tissue‐specific manner.
These results suggest co‐evolution between the physical prowess necessary for display performance and levels of AR expression in avian forelimb muscles. Moreover, this relationship appears to be both specific to muscle and AR‐mediated signalling.
Given that prior work suggests that activation of muscular AR is a necessary component of physical display performance, our current data support the hypothesis that sexual selection shapes levels of AR expressed in the forelimb skeletal muscles to help drive the evolution of adaptive motor abilities.
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