Home About us Contact
|
Home About us Contact | ||
|
|
||
Defensive Strategy (defensive + strategy)
Selected AbstractsEvolution of latex and its constituent defensive chemistry in milkweeds (Asclepias): a phylogenetic test of plant defense escalationENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2008Anurag A. Agrawal Abstract A tremendous diversity of plants exude sticky and toxic latex upon tissue damage, and its production has been widely studied as a defensive adaptation against insect herbivores. Here, we address variation in latex production and its constituent chemical properties (cardenolides and cysteine proteases) in 53 milkweeds [Asclepias spp. (Apocynaceae)], employing a phylogenetic approach to test macroevolutionary hypotheses of defense evolution. Species were highly variable for all three traits, and they showed little evidence for strong phylogenetic conservatism. Latex production and the constituent chemical defenses are thus evolutionarily labile and may evolve rapidly. Nonetheless, in phylogenetically independent analyses, we show that the three traits show some correlations (and thus share a correlated evolutionary history), including a positive correlation between latex exudation and cysteine protease activity. Conversely, latex exudation and cysteine protease activity both showed a trade-off with cardenolide concentrations in latex. We also tested whether these traits have increased in their phenotypic values as the milkweeds diversified, as predicted by plant defense escalation theory. Alternative methods of testing this prediction gave conflicting results , there was an overall negative correlation between amount of evolutionary change and amount of latex exudation; however, ancestral state reconstructions indicated that most speciation events were associated with increases in latex. We conclude by (i) summarizing the evidence of milkweed latex itself as a multivariate defense including the amount exuded and toxin concentrations within, (ii) assessing the coordinated evolution of latex traits and how this fits with our previous notion of ,plant defense syndromes', and finally, (iii) proposing a novel hypothesis that includes an ,evolving community of herbivores' that may promote the escalation or decline of particular defensive strategies as plant lineages diversify. [source] Young infants' triangular communication with their parents in the context of maternal postpartum psychosis: Four case studies,INFANT MENTAL HEALTH JOURNAL, Issue 4 2009Diane Philipp With increasing data on the dynamics of normative couples as they transition to parenthood and become a triad, the need for greater understanding of the impact of parental psychopathology on this transition has become clear. The goal of the current article is to begin exploring this area that has received little attention to date, by describing case examples from a study of clinical families as they transitioned to parenthood. Four representative cases were selected from a pool of 13 mother,father,baby triads, for whom the mother had been hospitalized conjointly with her infant due to a psychotic episode during the postpartum period. The families were observed as part of a clinical consultation that included a semistructured play paradigm known as the Lausanne Trilogue Play (LTP; E. Fivaz-Depeursinge, & A. Corboz-Warnery, 1999). Interactions were scored using standardized measures as well as clinical impressions. All families from the clinical sample were noted to struggle and frequently failed to achieve the goals of play. The impact on the infants in terms of their developing sense of self as well as their defensive strategies in this context are discussed, with clinical implications explored. [source] Light dependent shift in the anti-predator response of a pyralid mothOIKOS, Issue 2 2003A. Monica Svensson Male small china-mark moth Cataclysta lemnata (Pyralidae) swarming over shallow water show a flight activity that peaks during the afternoon but which sometimes is extended into the night. We exposed wild, naturally flying C. lemnata to simulated predator attacks consisting of a) bursts of ultrasound (26 kHz, simulating a bat) and b) a thrown stick (rapid movement, simulating a small bird), during day and night, respectively. We thus investigated the possibility that these moths are able to switch between defensive strategies as the predator regime shifts from insectivorous birds to bats in the evening. The defensive response differed qualitatively between day and night, as expected, but it was independent of the kind of stimulus. We thus demonstrate a previously unknown flexibility in the defensive strategy of moths. [source] Applying an Emotion Regulation Framework to Integrative Approaches to Generalized Anxiety DisorderCLINICAL PSYCHOLOGY: SCIENCE AND PRACTICE, Issue 1 2002Douglas S. Mennin Integrative conceptualizations like that proposed by Roemer and Orsillo provide exciting new directions for understanding and treating generalized anxiety disorder (CAD). However, these approaches may be further strengthened by adoption of an emotion regulation perspective. Persons with CAD may have difficulty understanding their emotional experience and may possess few skills to modulate their emotions. They may experience emotions as subjectively aversive and use worry and maladaptive interpersonal behaviors as defensive strategies to control, avoid, or blunt emotional experience. An emotion regulation perspective suggests adding treatment components to help clients become more comfortable with arousing emotional experience, more able to access and utilize emotional information in adaptive problem solving, and better able to modulate emotional experience and expression according to contextual demands. [source] Symbiont-mediated changes in Lolium arundinaceum inducible defenses: evidence from changes in gene expression and leaf compositionNEW PHYTOLOGIST, Issue 3 2007Terrence J. Sullivan Summary ,,Plants have multiple strategies to deal with herbivory, ranging from chemical or physical defenses to tolerating damage and allocating resources for regrowth. Grasses usually tolerate herbivory, but for some cool-season grasses, their strategy may depend upon their interactions with intracellular symbionts. Neotyphodium endophytes are common symbionts in pooid grasses, and, for some host species, they provide chemical defenses against both vertebrate and invertebrate herbivores. ,,Here, it was tested whether defenses provided by Neotyphodium coenophialum in Lolium arundinaceum (tall fescue) are inducible by both mechanical damage and herbivory from an invertebrate herbivore, Spodoptera frugiperda (fall armyworm), via a bioassay and by quantifying mRNA expression for lolC, a gene required for loline biosysnthesis. ,,Both mechanical and herbivore damage had a negative effect on the reproduction of a subsequent herbivore, Rhopalosiphum padi (bird cherry-oat aphid), and herbivore damage caused an up-regulation of lolC. Uninfected grass hosts also had significantly higher foliar N% and lower C : N ratio compared with infected hosts, suggesting greater allocation to growth rather than defense. ,,For L. arundinaceum, N. coenophialum appears to switch its host's defensive strategy from tolerance via compensation to resistance. [source] Cadmium hyperaccumulation protects Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis)NEW PHYTOLOGIST, Issue 3 2005R. F. Jiang Summary ,,Metal hyperaccumulation has been proposed as a plant defensive strategy. Here, we investigated whether cadmium (Cd) hyperaccumulation protected Thlaspi caerulescens from leaf feeding damage by thrips (Frankliniella occidentalis). ,,Two ecotypes differing in Cd accumulation, Ganges (high) and Prayon (low), were grown in compost amended with 0,1000 mg Cd kg,1 in two experiments under glasshouse conditions. F2 and F3 plants from the Prayon × Ganges crosses were grown with 5 mg Cd kg,1. Plants were naturally colonized by thrips and the leaf feeding damage index (LFDI) was assessed. ,,The LFDI decreased significantly with increasing Cd in both ecotypes, and correlated with shoot Cd concentration in a log-linear fashion. Prayon was more attractive to thrips than Ganges, but the ecotypic difference in the LFDI was largely accounted for by the shoot Cd concentration. In the F2 and F3 plants, the LFDI correlated significantly and negatively with shoot Cd, but not with shoot zinc (Zn) or sulphur (S) concentrations. ,,We conclude that Cd hyperaccumulation deters thrips from feeding on T. caerulescens leaves, which may offer an adaptive benefit to the plant. [source] Light dependent shift in the anti-predator response of a pyralid mothOIKOS, Issue 2 2003A. Monica Svensson Male small china-mark moth Cataclysta lemnata (Pyralidae) swarming over shallow water show a flight activity that peaks during the afternoon but which sometimes is extended into the night. We exposed wild, naturally flying C. lemnata to simulated predator attacks consisting of a) bursts of ultrasound (26 kHz, simulating a bat) and b) a thrown stick (rapid movement, simulating a small bird), during day and night, respectively. We thus investigated the possibility that these moths are able to switch between defensive strategies as the predator regime shifts from insectivorous birds to bats in the evening. The defensive response differed qualitatively between day and night, as expected, but it was independent of the kind of stimulus. We thus demonstrate a previously unknown flexibility in the defensive strategy of moths. [source] Defending the Beachhead: Telstra versus OptusBUSINESS STRATEGY REVIEW, Issue 1 2001John H. Roberts Much less has been written about market defence strategy than about market attack. This article focuses on one aspect of defensive strategy, defending against a new market entrant , though much of the thinking would also apply to other competitive assaults, like a major new product launch. The article outlines a model of the response of the Australian telecoms incumbent, Telstra, after deregulation. The authors conclude that market leaders should avoid price wars, understand the points in the consumer decision process that are defendable and use inertial strategies. Consumers' views of the incumbent can dramatically change their perceptions of the new entrant too. [source] Stress Regulation in Adolescents: Physiological Reactivity During the Adult Attachment Interview and Conflict InteractionCHILD DEVELOPMENT, Issue 6 2008Mariëlle D. Beijersbergen The current study examined whether adolescents' attachment representations were associated with differences in emotion regulation during the Adult Attachment Interview (AAI; C. George, N. Kaplan, & M. Main, 1996) and during a mother,adolescent conflict interaction task (Family Interaction Task [FIT]; J. P. Allen et al., 2003). Participants were one hundred and fifty-six 14-year-old adolescents. Dismissing adolescents showed less interbeat interval (IBI) reactivity (indicating less stress) during the AAI than secure adolescents. However, during the FIT, dismissing adolescents showed more IBI reactivity. No differences in physiological reactivity were found between individuals with resolved or unresolved loss or trauma during the AAI or FIT. The results indicate that dismissing adolescents may effectively use a defensive strategy during the AAI but less so in direct conflict interaction with their attachment figure. [source] | |||||||||||||