Revealing hidden evolutionary capacity to cope with global change

The extent to which global change will impact the long‐term persistence of species depends on their evolutionary potential to adapt to future conditions. While the number of studies that estimate the standing levels of adaptive genetic variation in populations under predicted global change scenarios is growing all the time, few studies have considered multiple environments simultaneously and even fewer have considered evolutionary potential in multivariate context. Because conditions will not be constant, adaptation to climate change is fundamentally a multivariate process so viewing genetic variances and covariances over multivariate space will always be more informative than relying on bivariate genetic correlations between traits. A multivariate approach to understanding the evolutionary capacity to cope with global change is necessary to avoid misestimating adaptive genetic variation in the dimensions in which selection will act. We assessed the evolutionary capacity of the larval stage of the marine polychaete Galeolaria caespitosa to adapt to warmer water temperatures. Galeolaria is an important habitat‐forming species in Australia, and its earlier life‐history stages tend to be more susceptible to stress. We used a powerful quantitative genetics design that assessed the impacts of three temperatures on subsequent survival across over 30 000 embryos across 204 unique families. We found adaptive genetic variation in the two cooler temperatures in our study, but none in the warmest temperature. Based on these results, we would have concluded that this species has very little capacity to evolve to the warmest temperature. However, when we explored genetic variation in multivariate space, we found evidence that larval survival has the potential to evolve even in the warmest temperatures via correlated responses to selection across thermal environments. Future studies should take a multivariate approach to estimating evolutionary capacity to cope with global change lest they misestimate a species’ true adaptive potential.     

Pouzolzia saxophila sp. nov. (Urticaceae tribe Boehmerieae) from Bahia,Brazil

The paper supplements a taxonomic revision of the New World species of Pouzolzia by Wilmot‐Dear and Friis in 1996 and a supplement in 2011 with an additional new species. Here another new species of Pouzolzia, P. saxophila Friis, Wilmot‐Dear & A. K. Monro, is described from a restricted area of xerophytic scrub vegetation on rocky outcrops in the Boa Nova National Park, Bahia, Brazil. The new species is somewhat similar to P. pringlei, a Mexican endemic, and to P. amambaiensis from the Brazil–Paraguay border, but also to the widespread Asiatic P. zeylanica. However, the similarities with these species are probably due to adaptation to similar dry habitats on rocky outcrops.     

The respiration of insects at reduced pressures I. The expiration of carbon dioxide by Tenebrioides mauritanicus (L.)

Carbon dioxide expiration of larvae of Tenebrioides mauritanicus (L.) exposed to reduced pressures in air is increased temporarily during the initial period of change from atmospheric pressure down to 35 mm Hg.During this time there is evidence of irritation of the insects shown by increased locomotor activity. After the required low pressure is reached the insects soon assume an activity and CO₂ expiration characteristic for that pressure. At 35 mm, the lowest pressure attainable before fatal desiccation starts, CO₂ expiration and visible activity are at their lowest. At 100 mm both phenomena are at about the same level as at atmospheric pressure. When oxygen is substituted for air the responses are similar, but at pressures of 35 mm and 50 mm there is slightly more visible activity and more CO₂ production than at the corresponding pressure in air.

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Zusammenfassung Monro (1959) beobachtete, dass bei der Reaktion von T. mauritanicus und anderen Insekten auf Vakuum-begasung mit Methylbromid die Sterblichkeit bei 35 mm Quecksilberdruck geringer war als bei 100 mm. Unter 35 mm trat eine erhebliche Sterblichkeit durch Austroknung ein. Um diese Ergebnisse auf einen möglichen Atmungseffekt zu beziehen, wurde die Kohlensäureausatmung der Larven von T. mauritanicus zwischen 35 und 750 mm gemessen.Die Kohlensäureausatmung wuchs vorübergehend während der Anfangsphase der Druckverringerung von 750 auf 35 mm an. Während dieses Stadiums wurde auch die sichtbare Aktivität der Insekten gesteigert. Nachdem der erforderliche niedere Druck erreicht war, nahmen die Insekten eine für diesen Druck charakteristischen CO₂-Ausatmung und Aktivität an. Bei 100 mm befanden sich beide Erscheinungen etwa auf der gleichen Höhe wie bei atmosphärischen Druck und sie verringerten sich dann zunehmend, bis sie beide bei 35 mm ihren niedrigsten Wert erreichten. Wenn die Luft durch Sauerstoff ersetzt wurde, waren die Reaktionen ähnlich, aber bei einem Druck von 35 oder 50 mm in Sauerstoff war etwas mehr sichtbare Aktivität und mehr CO₂-Ausatmung als bei den entsprechenden Werten in Luft.Die Bedeutung dieser Befunde wird besprochen. Bei einem Druck unter 100 mm besteht eine bemerkenswerte Ähnlichkeit zwischen CO₂-Ausatmung und Methylbromidempfindlichkeit (Monro 1959). Es wird vermutet, dass hier ein direkter Zusammenhang zwischen herabgesetzter Atmung und gesteigerter Resistentz gegen Giftgase besteht. Weitere Studien sind erforderlich, um den wirklichen Sauersoffverbrauch festzustellen, so dass entsprechende Respirationsquotienten für reduzierte Druckverhältnisse aufgestellt werden können. In dieser Richtung laufen bereits Laboruntersuchungen.

     

The organization and growth of primary cell walls of lupin hypocotyl

Models of the primary cell wall are discussed in relation to results obtained by the present authors from studies of the primary cell wall of lupin and mung bean hypocotyls. A structure of the primary cell wall is suggested that differs in several respects from structures already proposed. It has a non-covalent interaction of much of the pectin, hemicellulose and glycoprotein, and a more direct interaction of the glycoprotein and cellulose microfibrils. An idea of scale is introduced through a consideration of degree of polymerization and monomer size of polymers, and of the volume of the cellulose microfibrils. Wall structure is discussed in relation to polymer orientation and elongation of the primary cell wall.     

Predicting evolutionary responses to climate change in the sea

An increasing number of short‐term experimental studies show significant effects of projected ocean warming and ocean acidification on the performance on marine organisms. Yet, it remains unclear if we can reliably predict the impact of climate change on marine populations and ecosystems, because we lack sufficient understanding of the capacity for marine organisms to adapt to rapid climate change. In this review, we emphasise why an evolutionary perspective is crucial to understanding climate change impacts in the sea and examine the approaches that may be useful for addressing this challenge. We first consider what the geological record and present‐day analogues of future climate conditions can tell us about the potential for adaptation to climate change. We also examine evidence that phenotypic plasticity may assist marine species to persist in a rapidly changing climate. We then outline the various experimental approaches that can be used to estimate evolutionary potential, focusing on molecular tools, quantitative genetics, and experimental evolution, and we describe the benefits of combining different approaches to gain a deeper understanding of evolutionary potential. Our goal is to provide a platform for future research addressing the evolutionary potential for marine organisms to cope with climate change.     

Selection in modular organisms: is intraclonal variation in macroalgae evolutionarily important?

Theoretical and practical difficulties occur when defining the units of selection in modular organisms that grow by iteration of repeated parts (modules). Modules may become physically autonomous through fragmentation and may vary because of genetic variation arising in somatic cell lineages. Since cells destined for gamete production are not sequestered in early development, heritable variation and selection among asexual progeny are possible. We used the branching red macroalgae Delisea pulchra and Asparagopsis armata to test whether modules fulfill three fundamental criteria for units of selection: that they replicate, that they display heritable variation, and that selective agents distinguish among the variants. We detected significant phenotypic variation among modules for fitness-related traits (growth, secondary metabolite concentrations, and rates of tissue loss to herbivory) in each species and significant heritability estimates for secondary metabolite production and tissue loss to herbivory in D. pulchra. Variation in growth rate among A. armata modules was largely phenotypic with small but important estimates of genetic variation. Our results indicate that selection may indeed act on phenotypic variation among modules within individuals and that this process may effect evolutionary change within asexual lineages given sufficient genetic variation in the traits examined.     

The CO2 sense of the moth Cactoblastis cactorum and its probable role in the biological control of the CAM plant Opuntia stricta

The interaction between the moth, Cactoblastis cactorum, and the cactus, Opuntia stricta, is used as a model to examine the question of whether the CO₂ sense of a herbivorous insect can detect the CO₂ gradients associated with a plant's metabolic activity. Both the anatomical and the electrophysiological characteristics of CO₂-sensitive receptor neurons in C. cactorum indicate an adaptation to the detection of small fluctuations around the atmospheric background. Evidence is provided that further rises in background will impair the function of the sensory organ. In the habitat of the plant, during the diurnal window of the moth's activity, two types of CO₂ gradients occur that are detectable by the moth's sensors. The first gradient, associated with soil respiration, is vertical and extends from the soil surface to an altitude of approximately 1 m. Its magnitude is well above the detectability limit of the sensors. The notion that this gradient provides, to a flying insect, a cue for the maintenance of a flight altitude favourable for host detection is supported by field observations of behaviour. The second gradient, associated with CO₂ fixation by the plant, extends from the surfaces of photosynthetic organs (cladodes) over a boundary layer distance of approximately 5 mm. Again, its magnitude is well above the detectability limit. The notion that this gradient provides, to a walking insect, a cue to the physiological condition of the plant is supported by the observation that females of C. cactorum, prior to oviposition, actively probe the plant surface with their CO₂ sensors. In a simulation of probing, pronounced responses of the sensors to the CO₂-fixing capacity of O. stricta are observed. We propose that by probing the boundary layer, females of C. cactorum can detect the healthiest, most active O. stricta cladodes, accounting for earlier observations that the most vigorous plants attract the greatest density of egg sticks.     

Cardiac surgery in Wessex.

The results of 3000 consecutive operations using cardio-pulmonary bypass show that the overall early mortality was 6.1%, dropping from 8.9% in the first 1000 to 4.4% in the third 1000. Operations for valve disease have been the most common, the early mortality for aortic valve replacement being 3.1% and for mitral valve replacement 2.9%. Combined aortic and mitral valve replacement had an early mortality of 4.4%. The number of patients undergoing isolated coronary artery bypass grafting has increased from 59 in the first 1000 to 292 in the third 1000 operations, with an overall early mortality of 1.3%. Six hundred and ninety seven patients underwent surgery for congenital heart disease with an overall early mortality of 10.9% (7.5% in the last 2000 cases). The patients have been followed up from one to 8.5 years. A high proportion have returned to work and enjoy a normal life. At the time of review, 87% of the 3000 patients were alive. Long waiting times for outpatient and inpatient care indicate underprovision of facilities relative to regional demand.