Search results for "Müller"

The importance of pattern similarity between Müllerian mimics in predator avoidance learning

2004

Müllerian mimicry, where unpalatable prey share common warning patterns, has long fascinated evolutionary biologists. It is commonly assumed that Müllerian mimics benefit by sharing the costs of predator education, thus reducing per capita mortality, although there has been no direct test of this assumption. Here, we specifically measure the selection pressure exerted by avian predators on unpalatable prey with different degrees of visual similarity in their warning patterns. Using wild-caught birds foraging on novel patterned prey in the laboratory, we unexpectedly found that pattern similarity did not increase the speed of avoidance learning, and even dissimilar mimics shared the educatio…

2018

Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency-dependent learning. However, widespread variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: …

Eye position tunes the contribution of allocentric and egocentric information to target localization in human goal-directed arm movements.

1997

Subjects were required to point to the distant vertex of the closed and the open configurations of the Muller-Lyer illusion using either their right hand (experiment 1) or their left hand (experiment 2). In both experiments the Muller-Lyer figures were horizontally presented either in the left or in the right hemispace and movements were executed using either foveal or peripheral vision of the target. According to the illusion effect, subjects undershot and overshot the vertex location of the closed and the open configuration, respectively. The illusion effect decreased when the target was fixated and when the stimulus was positioned in the right hemispace. These results confirm the hypothe…

Surgical planning after sleep versus awake techniques in patients with obstructive sleep apnea

2013

Objective/Hypothesis This study examined correlations between surgical recommendations based on either drug-induced sleep endoscopy (DISE) or common awake examination methods in patients with obstructive sleep apnea syndrome (OSAS). Study Design Prospective, blinded, clinical trial at a university hospital. Methods An otorhinolaryngologist designed surgical plans for patients with OSAS after clinical examination, lateral cephalometry, the Muller maneuver, and Friedman staging. A second otorhinolaryngologist blinded to the previous plans made surgical recommendations after DISE. A third person tested agreement between the two sets of plans using Cohen's kappa statistic and the chi-squared te…

How Did the Cuckoo Get Its Polymorphic Plumage?

2012

One hundred and fifty years ago, the English naturalist Henry Walter Bates first developed the theory of mimicry ( 1 ). Based on his field observations in the Amazon, he argued that the uncanny likeness of unrelated butterflies is an evolutionary adaptation whereby edible butterflies avoid predation by imitating the coloration of venomous butterfly species without paying the cost of arming themselves. Such “Batesian mimicry” is a dynamic parasitic game between three players, in which a harmless species (the mimic) escapes predation by imitating the warning signals of harmful species (the model) that a shared predator (the dupe) has learned to avoid. On page 578 of this issue, Thorogood and …

Investigating Müllerian mimicry: predator learning and variation in prey defences

2006

Inexperienced predators are assumed to select for similarity of warning signals in aposematic species (Mullerian mimicry) when learning to avoid them. Recent theoretical work predicts that if co-mimic species have unequal defences, predators attack them according to their average unpalatability and mimicry may not be beneficial for the better defended co-mimic. In this study, we tested in a laboratory environment whether a uniform warning signal is superior to a variable one in promoting predator learning, and simultaneously whether co-mimics are preyed upon according to their average unpalatability. There was an interaction of signal variation and unpalatability but inexperienced birds did…

Malformaciones uterinas (anomalías müllerianas): posibilidades diagnósticas con ecografía 3D/4D y ecografía de alta definición en tiempo real

2019

El sistema reproductivo femenino se forma a partir de los conductos müllerianos, que durante el desarrollo embrionario se fusionan para crear las trompas de Falopio, el útero, el cérvix y la porción superior de la vagina. Su desarrollo está inducido por los conductos de Wolf que actúan como elementos guía. Este proceso tiene lugar entre la semana sexta y la vigésima de vida fetal. Las malformaciones uterinas constituyen un grupo heterogéneo de anomalías congénitas que resultan de un fallo en una de las tres fases del desarrollo de los conductos paramesonéfricos o de Müller: fase de organogénesis o desarrollo, fase de fusión y fase de reabsorción del septo. Muchas mujeres con estas anomalías…

Geographic mosaic of selection by avian predators on hindwing warning colour in a polymorphic aposematic moth

2020

AbstractWarning signals are predicted to develop signal monomorphism via positive frequency-dependent selection (+FDS) albeit many aposematic systems exhibit signal polymorphism. To understand this mismatch, we conducted a large-scale predation experiment in four locations, among which the frequencies of hindwing warning coloration of aposematic Arctia plantaginis differ. Here we show that selection by avian predators on warning colour is predicted by local morph frequency and predator community composition. We found +FDS to be strongest in monomorphic Scotland, and in contrast, lowest in polymorphic Finland, where different predators favour different male morphs. +FDS was also found in Geo…

Characterization of a new murine retinal cell line (MU-PH1) with glial, progenitor and photoreceptor characteristics

2013

Unlike fish and amphibians, mammals do not regenerate retinal neurons throughout life. However, neurogenic potential may be conserved in adult mammal retina and it is necessary to identify the factors that regulate retinal progenitor cells (RPC) proliferative capacity to scope their therapeutic potential. Müller cells can be progenitors for retinal neuronal cells and can play an essential role in the restoration of visual function after retinal injury. Some members of the Toll-like receptor (TLR) family, TLR2, TLR3 and TLR4, are related to progenitor cells proliferation. Müller cells are important in retinal regeneration and stable cell lines are useful for the study of retinal stem cell bi…

Teichmuller Space and Related Topics : Proceedings of the workshop on Geometry, January 20, 2011, JOSAI UNIVERSITY

2012

The theory of geometric structures on a surface with nonempty boundary can be developed by using a decomposit,ion of such a surface into hexagons, in the same way as the theory of geometric structures on a surface without boundary is developed using the decomposition of such a surface into pairs of pants. The basic elements of the theory for surfaces with boundary include the study of measured foliations and of hyperbolic structures on hexagons. It turns out that there is an interesting space of measured foliations on a hexagon, which is equipped with a piecewise-Iinear structure (in fact, a natural cell-decomposition), and this space is a natural boundary for the space of hyperbolic struct…