Multiple Episodes of Convergence in Genes of the Dim Light Vision Pathway in Bats

The molecular basis of the evolution of phenotypic characters is very complex and is poorly understood with few examples documenting the roles of multiple genes. Considering that a single gene cannot fully explain the convergence of phenotypic characters, we choose to study the convergent evolution of rod vision in two divergent bats from a network perspective. The Old World fruit bats (Pteropodidae) are non-echolocating and have binocular vision, whereas the sheath-tailed bats (Emballonuridae) are echolocating and have monocular vision; however, they both have relatively large eyes and rely more on rod vision to find food and navigate in the night. We found that the genes CRX, which plays an essential role in the differentiation of photoreceptor cells, SAG, which is involved in the desensitization of the photoactivated transduction cascade, and the photoreceptor gene RH, which is directly responsible for the perception of dim light, have undergone parallel sequence evolution in two divergent lineages of bats with larger eyes (Pteropodidae and Emballonuroidea). The multiple convergent events in the network of genes essential for rod vision is a rare phenomenon that illustrates the importance of investigating pathways and networks in the evolution of the molecular basis of phenotypic convergence

Association Patterns in Saproxylic Insect Networks in Three Iberian Mediterranean Woodlands and Their Resistance to Microhabitat Loss

The assessment of the relationship between species diversity, species interactions and environmental characteristics is indispensable for understanding network architecture and ecological distribution in complex networks. Saproxylic insect communities inhabiting tree hollow microhabitats within Mediterranean woodlands are highly dependent on woodland configuration and on microhabitat supply they harbor, so can be studied under the network analysis perspective. We assessed the differences in interacting patterns according to woodland site, and analysed the importance of functional species in modelling network architecture. We then evaluated their implications for saproxylic assemblages’ persistence, through simulations of three possible scenarios of loss of tree hollow microhabitat. Tree hollow-saproxylic insect networks per woodland site presented a significant nested pattern. Those woodlands with higher complexity of tree individuals and tree hollow microhabitats also housed higher species/interactions diversity and complexity of saproxylic networks, and exhibited a higher degree of nestedness, suggesting that a higher woodland complexity positively influences saproxylic diversity and interaction complexity, thus determining higher degree of nestedness. Moreover, the number of insects acting as key interconnectors (nodes falling into the core region, using core/periphery tests) was similar among woodland sites, but the species identity varied on each. Such differences in insect core composition among woodland sites suggest the functional role they depict at woodland scale. Tree hollows acting as core corresponded with large tree hollows near the ground and simultaneously housing various breeding microsites, whereas core insects were species mediating relevant ecological interactions within saproxylic communities, e.g. predation, competitive or facilitation interactions. Differences in network patterns and tree hollow characteristics among woodland sites clearly defined different sensitivity to microhabitat loss, and higher saproxylic diversity and woodland complexity showed positive relation with robustness. These results highlight that woodland complexity goes hand in hand with biotic and ecological complexity of saproxylic networks, and together exhibited positive effects on network robustness.The research Projects I+D CGL2011-23658 y CGL2012-31669 of the Spanish Minister of Science provided economic support

Bat Eyes Have Ultraviolet-Sensitive Cone Photoreceptors

Mammalian retinae have rod photoreceptors for night vision and cone photoreceptors for daylight and colour vision. For colour discrimination, most mammals possess two cone populations with two visual pigments (opsins) that have absorption maxima at short wavelengths (blue or ultraviolet light) and long wavelengths (green or red light). Microchiropteran bats, which use echolocation to navigate and forage in complete darkness, have long been considered to have pure rod retinae. Here we use opsin immunohistochemistry to show that two phyllostomid microbats, Glossophaga soricina and Carollia perspicillata, possess a significant population of cones and express two cone opsins, a shortwave-sensitive (S) opsin and a longwave-sensitive (L) opsin. A substantial population of cones expresses S opsin exclusively, whereas the other cones mostly coexpress L and S opsin. S opsin gene analysis suggests ultraviolet (UV, wavelengths <400 nm) sensitivity, and corneal electroretinogram recordings reveal an elevated sensitivity to UV light which is mediated by an S cone visual pigment. Therefore bats have retained the ancestral UV tuning of the S cone pigment. We conclude that bats have the prerequisite for daylight vision, dichromatic colour vision, and UV vision. For bats, the UV-sensitive cones may be advantageous for visual orientation at twilight, predator avoidance, and detection of UV-reflecting flowers for those that feed on nectar

Evidence for 'critical slowing down' in seagrass:a stress gradient experiment at the southern limit of its range

The theory of critical slowing down, i.e. the increasing recovery times of complex systems close to tipping points, has been proposed as an early warning signal for collapse. Empirical evidence for the reality of such warning signals is still rare in ecology. We studied this on Zostera noltii intertidal seagrass meadows at their southern range limit, the Banc d'Arguin, Mauritania. We analyse the environmental covariates of recovery rates using structural equation modelling (SEM), based on an experiment in which we assessed whether recovery after disturbances (i.e. seagrass & infauna removal) depends on stress intensity (increasing with elevation) and disturbance patch size (1 m(2) vs. 9 m(2)). The SEM analyses revealed that higher biofilm density and sediment accretion best explained seagrass recovery rates. Experimental disturbances were followed by slow rates of recovery, regrowth occurring mainly in the coolest months of the year. Macrofauna recolonisation lagged behind seagrass recovery. Overall, the recovery rate was six times slower in the high intertidal zone than in the low zone. The large disturbances in the low zone recovered faster than the small ones in the high zone. This provides empirical evidence for critical slowing down with increasing desiccation stress in an intertidal seagrass system

Sea Urchins Predation Facilitates Coral Invasion in a Marine Reserve

Macroalgae is the dominant trophic group on Mediterranean infralittoral rocky bottoms, whereas zooxanthellate corals are extremely rare. However, in recent years, the invasive coral Oculina patagonica appears to be increasing its abundance through unknown means. Here we examine the pattern of variation of this species at a marine reserve between 2002 and 2010 and contribute to the understanding of the mechanisms that allow its current increase. Because indirect interactions between species can play a relevant role in the establishment of species, a parallel assessment of the sea urchin Paracentrotus lividus, the main herbivorous invertebrate in this habitat and thus a key species, was conducted. O. patagonica has shown a 3-fold increase in abundance over the last 8 years and has become the most abundant invertebrate in the shallow waters of the marine reserve, matching some dominant erect macroalgae in abundance. High recruitment played an important role in this increasing coral abundance. The results from this study provide compelling evidence that the increase in sea urchin abundance may be one of the main drivers of the observed increase in coral abundance. Sea urchins overgraze macroalgae and create barren patches in the space-limited macroalgal community that subsequently facilitate coral recruitment. This study indicates that trophic interactions contributed to the success of an invasive coral in the Mediterranean because sea urchins grazing activity indirectly facilitated expansion of the coral. Current coral abundance at the marine reserve has ended the monopolization of algae in rocky infralittoral assemblages, an event that could greatly modify both the underwater seascape and the sources of primary production in the ecosystem

A diferença na qualidade de vida de pacientes com doença venosa crônica leve e grave Differences in the quality of life of patients with mild and severe chronic venous disease

CONTEXTO: A doença venosa crônica atinge os indivíduos em sua fase mais produtiva da vida, acarretando dor, perda de mobilidade e afastamento de atividades, podendo interferir diretamente na qualidade de vida. Seus sintomas clínicos decorrem de um estado de hipertensão venosa, causada por refluxo e/ou obstrução venosa. OBJETIVO: Determinar a diferença na qualidade de vida de pacientes com doença venosa crônica leve e grave. MÉTODOS: Foi realizado estudo transversal analítico comparativo na unidade de saúde durante 8 meses. A amostra foi calculada em 88 pacientes e dividida em dois grupos: Grupo A (CEAP clínico 1, 2 e 3) e Grupo B (CEAP clínico 4, 5 e 6). Foi usado o questionário genérico Medical Outcomes Study - 36-Item Short-Form Health Survey (SF-36). A análise estatística para verificar se havia diferença foi através do teste t de Student, com intervalo de confiança de 95% e p < 0,05. RESULTADOS: Foram analisados 88 indivíduos, sendo 47 no grupo A e 41 no grupo B. Do total, 87,5% (77) eram mulheres. Com relação à idade, 34% (30) tinham entre 30 e 40 anos. As alterações subcutâneas (CEAP clínico 4) foram os sintomas mais presentes, em 28,4%. Com exceção do domínio estado geral da saúde, todos os outros mostraram que o grupo B apresentava escores inferiores quando comparado ao grupo A. CONCLUSÕES: A qualidade de vida dos pacientes com doença venosa crônica leve e grave é diferente, apresentando-se mais afetada de acordo com a gravidade.<br>BACKGROUND: Chronic venous disease afflicts individuals in their most productive years, resulting in pain and loss of mobility and independence in performing routine daily activities, which may directly interfere with the patient's quality of life. Clinical symptoms result from venous hypertension caused by reflux and/or venous blockage. OBJECTIVE: To determine differences in the quality of life of patients with mild and severe chronic venous disease. METHODS: A cross-sectional comparative study was conducted in a health care facility during an 8-month period. The sample was composed of 88 patients divided into two groups: group A (clinical CEAP class 1, 2 and 3) and group B (clinical CEAP class 4, 5 and 6). The Medical Outcomes Study - 36-Item Short-Form Health Survey (SF-36) questionnaire was used. Statistical analysis was conducted using the Student t test, with a 95% confidence interval and a level of significance set at p < 0.05. RESULTS: We analyzed 88 subjects, 47 in group A and 41 in group B. Of the total, 87.5% (77) were women and 34% (30) were aged 30 to 40 years. Subcutaneous changes (CEAP class 4) were the most common symptoms, observed in 28.4% of the individuals. Except for the general health perceptions domain, group B showed lower scores than group A in all other domains. CONCLUSIONS: The quality of life of patients with mild and severe chronic venous disease proved to be different according to disease severity