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Rapid Adaptation (rapid + adaptation)
Selected AbstractsSEQUENTIAL RAPID ADAPTATION OF INDIGENOUS PARASITOID WASPS TO THE INVASIVE BUTTERFLY PIERIS BRASSICAEEVOLUTION, Issue 8 2007Shingo Tanaka The introduction of a new species can change the characteristics of other species within a community. These changes may affect discontiguous trophic levels via adjacent trophic levels. The invasion of an exotic host species may provide the opportunity to observe the dynamics of changing interspecific interactions among parasitoids belonging to different trophic levels. The exotic large white butterfly Pieris brassicae invaded Hokkaido Island, Japan, and quickly spread throughout the island. Prior to the invasion, the small white butterfly P. rapae was the host of the primary parasitoid Cotesia glomerata, on which both the larval hyperparasitoid Baryscapus galactopus and the pupal hyperparasitoid Trichomalopsis apanteroctena depended. At the time of the invasion, C. glomerata generally laid eggs exclusively in P. rapae. During the five years following the invasion, however, the clutch size of C. glomerata in P. rapae gradually decreased, whereas the clutch size in P. brassicae increased. The field results corresponded well with laboratory experiments showing an increase in the rate of parasitism in P. brassicae. The host expansion of C. glomerata provided the two hyperparasitoids with an opportunity to choose between alternative hosts, that is, C. glomerata within P. brassicae and C. glomerata within P. rapae. Indeed, the pupal hyperparasitoid T. apanteroctena shifted its preference gradually to C. glomerata in P. brassicae, whereas the larval hyperparasitoid B. galactopus maintained a preference for C. glomerata in P. rapae. These changes in host preference may result from differential suitability of the two host types. The larval hyperparasitoid preferred C. glomerata within P. rapae to C. glomerata within P. brassicae, presumably because P. brassicae larvae attacked aggressively, thereby hindering the parasitization, whereas the pupal hyperparasitoid could take advantage of the competition-free resource by shifting its host preference. Consequently, the invasion of P. brassicae has changed the host use of the primary parasitoid C. glomerata and the pupal hyperparasitoid T. apanteroctena within a very short time. [source] Rapid evolution in introduced species, ,invasive traits' and recipient communities: challenges for predicting invasive potentialDIVERSITY AND DISTRIBUTIONS, Issue 4 2008Kenneth D. Whitney ABSTRACT The damaging effects of invasive organisms have triggered the development of Invasive Species Predictive Schemes (ISPS). These schemes evaluate biological and historical characteristics of species and prioritize those that should be the focus of exclusion, quarantine, and/or control. However, it is not clear how commonly these schemes take microevolutionary considerations into account. We review the recent literature and find that rapid evolutionary changes are common during invasions. These evolutionary changes include rapid adaptation of invaders to new environments, effects of hybridization, and evolution in recipient communities. Strikingly, we document 38 species in which the specific traits commonly associated with invasive potential (e.g. growth rate, dispersal ability, generation time) have themselves undergone evolutionary change following introduction, in some cases over very short (, 10 year) timescales. In contrast, our review of 29 ISPS spanning plant, animal, and microbial taxa shows that the majority (76%) envision invading species and recipient communities as static entities. Those that incorporate evolutionary considerations do so in a limited way. Evolutionary change not only affects the predictive power of these schemes, but also complicates their evaluation. We argue that including the evolutionary potential of species and communities in ISPS is overdue, present several metrics related to evolutionary potential that could be incorporated in ISPS, and provide suggestions for further research on these metrics and their performance. Finally, we argue that the fact of evolutionary change during invasions begs for added caution during risk assessment. [source] Variability in responses to thermal stress in parasitoidsECOLOGICAL ENTOMOLOGY, Issue 6 2008GAËLLE AMICE Abstract 1.,To study phenotypic effects of stress, a stress is applied to cohorts of organisms with an increasing intensity. In the absence of mortality the response of traits will be a decreasing function of stress intensity because of increasing physiological costs. We call such decreasing functions type A responses. 2.,However, when stress caused mortality, some studies have found that for high stress intensities, survivors performed as well as control individuals (type B responses). We proposed that type A responses are caused by the physiological cost of stress whereas type B responses are caused by a mixture of physiological costs and selection. 3.,The present study exposed Aphidius picipes wasps to an increasing duration of cold storage (cold stress), and obtained variable responses as predicted when both physiological costs and selection of resistant individuals determine the outcome. 4.,When cold storage of parasitoids for biological control is desirable, research should be carried out to find (i) the temperature regime and duration of storage and (ii) the least sensitive stage for storage to minimise losses from mortality and reduction of fitness of survivors. 5.,Selection by cold stress as observed in the present study could result in rapid adaptation of populations exposed to such stress. [source] Rapid evolution in crop-weed hybrids under artificial selection for divergent life historiesEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 2 2009Lesley G. Campbell Abstract When species hybridize, offspring typically exhibit reduced fitness and maladapted phenotypes. This situation has biosafety implications regarding the unintended spread of novel transgenes, and risk assessments of crop-wild hybrids often assume that poorly adapted hybrid progeny will not evolve adaptive phenotypes. We explored the evolutionary potential of early generation hybrids using nontransgenic wild and cultivated radish (Raphanus raphanistrum, Raphanus sativus) as a model system. We imposed four generations of selection for two weedy traits , early flowering or large size , and measured responses in a common garden in Michigan, USA. Under selection for early flowering, hybrids evolved to flower as early as wild lineages, which changed little. These early-flowering hybrids also recovered wild-type pollen fertility, suggesting a genetic correlation that could accelerate the loss of crop traits when a short life cycle is advantageous. Under selection for large size at reproduction, hybrids evolved longer leaves faster than wild lineages, a potentially advantageous phenotype under longer growing seasons. Although early generation hybrid offspring have reduced fitness, our findings provide novel support for rapid adaptation in crop-wild hybrid populations. Biosafety risk assessment programs should consider the possibility of rapid evolution of weedy traits from early generations of seemingly unfit crop-wild hybrids. [source] The rapidly adapting receptors in mammalian airways and their responses to changes in extravascular fluid volumeEXPERIMENTAL PHYSIOLOGY, Issue 4 2006C. Tissa Kappagoda In this short review, we shall focus on some recent findings on the physiological stimulus for the rapidly adapting receptors (RAR) of the airways. They are readily activated by a sustained inflation of the lungs and they are usually identified by their rapid adaptation to this stimulus. They are also activated by both tactile stimuli and irritant gases applied to the epithelium of the airways. The investigations reviewed here suggest that these receptors are activated by changes in extravascular fluid volume. The principal factors governing fluid flux from the microcirculation are identified in the Starling equation. These are the hydrostatic pressure, plasma oncotic pressure and capillary permeability. Findings from recent studies suggest that all these factors increase the activity of RAR. In addition, these receptors are also activated by obstruction of lymph drainage from the lung. Evidence is presented to show that manipulation of Starling forces also increases the extravascular fluid volume of the airways in areas where the RAR are located. On the basis of these findings, it is suggested that, along with mechanosensitivity to stimuli such as stretch, inflation and deflation, another physiological stimulus to the RAR is a change in extravascular fluid volume in the regions of the airways where these receptors are located. [source] Selective acquisition of novel mating type and vegetative incompatibility genes via interspecies gene transfer in the globally invading eukaryote Ophiostoma novo-ulmiMOLECULAR ECOLOGY, Issue 1 2006MATHIEU PAOLETTI Abstract The Dutch elm disease fungus Ophiostoma novo-ulmi, which has destroyed billions of elm trees worldwide, originally invaded Europe as a series of clonal populations with a single mating type (MAT-2) and a single vegetative incompatibility (vic) type. The populations then rapidly became diverse with the appearance of the MAT-1 type and many vegetative incompatibility types. Here, we have investigated the mechanism using isolates from sites in Portugal at which the rapid evolution of O. novo-ulmi populations from clonality to heterogeneity was well established. We show by genetic mapping of vic and MAT loci with AFLP markers and by sequence analysis of MAT loci that this diversification was due to selective acquisition by O. novo-ulmi of the MAT-1 and vic loci from another species, Ophiostoma ulmi. A global survey showed that interspecies transfer of the MAT-1 locus occurred on many occasions as O. novo-ulmi spread across the world. We discuss the possibility that fixation of the MAT-1 and vic loci occurred in response to spread of deleterious viruses in the originally clonal populations. The process demonstrates the potential of interspecies gene transfer for facilitating rapid adaptation of invasive organisms to a new environment. [source] Rate-sensitive contractile responses of lymphatic vessels to circumferential stretchTHE JOURNAL OF PHYSIOLOGY, Issue 1 2009Michael J. Davis Phasic contractile activity in rat portal vein is more sensitive to the rate of change in length than to absolute length and this response is widely assumed to be a general characteristic of myogenic behaviour for vascular smooth muscle. Previously, we found that rat lymphatic vessels exhibit phasic contractile behaviour similar to that of portal vein. In the present study, we hypothesized that lymphatic muscle would exhibit rate-sensitive contractile responses to stretch. The hypothesis was tested on rat mesenteric lymphatics (90,220 ,m, i.d.) using servo-controlled wire- and pressure-myograph systems to enable ramp increases in force or pressure at different rates. Under isometric conditions in wire-myograph preparations, both the amplitude and the frequency of phasic activity were enhanced at more optimal preloads, but superimposed upon this effect were bursts of contractions that occurred only during fast preload ramps. In such cases, the ratio of contraction frequency during the ramp to that at the subsequent plateau (at optimal preload) was > 1. Further, the frequency ratio increased as a function of the preload ramp speed, consistent with a rate-sensitive mechanism. In contrast, the amplitude ratio was < 1 and declined further with higher ramp speeds. Downward preload ramps produced corresponding rate-sensitive inhibition of contraction frequency but not amplitude. Similar findings were obtained in pressurized lymphatics in response to pressure ramps and steps. Our results suggest that lymphatics are sensitive to the rate of change in preload/pressure in a way that is different from portal vein, possibly because the pacemaker for generating electrical activity is rate sensitive but lymphatic muscle is not. The behaviour may be widely present in collecting lymphatic vessels and is probably an important mechanism for rapid adaptation of the lymphatic pump to local vascular occlusion. [source] | ||||||||||