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Host Traits (host + trait)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Shiny Cowbird parasitism of a low quality host: effect of host traits on a parasite's reproductive success

JOURNAL OF FIELD ORNITHOLOGY, Issue 3 2009
Andrea A. Astié
ABSTRACT The reproductive success of parasitic cowbirds (Molothrus spp.) varies among host species and is influenced by the degree of synchronization in timing of egg laying, the duration of parasite and host incubation periods, and the ability of hosts to incubate and rear parasite young. We studied the reproductive success of Shiny Cowbirds (Molothrus bonariensis) that parasitized the nests of Creamy-bellied Thrushes (Turdus amaurochalinus) in the Monte desert region of Argentina. Shiny Cowbirds frequently parasitized Creamy-bellied Thrush nests (60%), and most cowbirds synchronized egg laying with that of thrushes (79%). Most parasitic eggs (80%) hatched within 1 d of the hatching of the first host egg, and more than 91% of the eggs survived until the end of the incubation. However, only 60% of the cowbird eggs hatched and 52% of young survived. The proportion of Shiny Cowbirds eggs laid in Creamy-bellied Thrush nests that resulted in fledged young was 0.03, including eggs and young lost due to predation or desertion. Despite this low reproductive success, Creamy-bellied Thrushes were heavily parasitized by Shiny Cowbirds in our study area. Shiny Cowbirds may continue to parasitize these thrushes because of diffuse selection or because Shiny Cowbird chicks are more likely to fledge from Creamy-bellied Thrush nests in years or areas with greater food availability when brood reduction does not occur. SINOPSIS El éxito reproductivo del los tordos parásitos (Molothrus spp.) varía entre sus especies hospedadoras y está afectado por el grado de sincronización en el momento de la puesta de huevos, la duración de los períodos de incubación del hospedador y el parásito y la habilidad del hospedador para incubar y criar a los pichones parásitos. Nosotros estudiamos el éxito reproductivo del Tordo Renegrido (Molothrus bonariensis) en nidos del Zorzal Chalchalero (Turdus amaurochalinus) en la región del desierto del Monte de Argentina. El Tordo Renegrido parasita frecuentemente los nidos del Zorzal Chalchalero (60%) y la mayoría de los tordos sincroniza su puesta con la de los zorzales (79%). La mayoría de los huevos parásitos (80%) eclosionan entre 1 día antes y un día después del primer huevo del hospedador y más del 91% de los huevos sobreviven hasta el final de la incubación. Sin embargo, solo el 60% de los huevos de tordo eclosionan y el 52% de los pichones sobreviven. La proporción de huevos de Tordo Renegrido puestos en nidos de Zorzal Chalchalero que resultan en volantones fue 0.03, incluyendo los huevos y los pichones perdidos por depredación o abandono. A pesar de este bajo éxito reproductivo, el Zorzal Chalchalero es intensamente parasitado por el Tordo Renegrido en nuestra área de estudio. Es posible que el Tordo Renegrido continúe parasitando a estos zorzales debido a un proceso de selección difusa o porque los pichones de tordo tienen mayores posibilidades de llegar a volantones en nidos de Zorzal Chalchalero en años o en áreas con mayor disponibilidad de alimento, donde no ocurra reducción de nidada. [source]

Infestation of trees by lianas in a tropical forest in Amazonian Peru

JOURNAL OF VEGETATION SCIENCE, Issue 6 2008
Geertje M.F. van der Heijden
Abstract Question: In Amazonian moist forest, four questions arose: 1. Do tree species differ in their susceptibility to lianas? 2. What host tree traits (branch-free bole height, growth rate, bark type, leaf length and adult stature) are correlated with the susceptibility of tree species to lianas infesting the trunk and the crown? 3. To what extent do spatial variables (proximity to liana-infested trees and the light environment of the tree crown) affect the likelihood of liana infestation? 4. Are spatial variables or tree traits relatively more important in influencing the susceptibility of trees to lianas? We address all questions separately for trunk and crown infestation. Location: Tambopata Nature Reserve, Peru. Methods: We collected information on liana infestation, tree morphological traits, growth, light-environment and position for 3675 trees in seven 1-ha permanent sample plots. We separated trunk from crown infestation and used correlation and logistic regression analyses for tree species and individual tree-level analyses, respectively. Results: Half of all trees were colonised by at least one liana. Of 41 relatively common dicot tree species, at least five have significantly greater and three significantly lower crown infestation rates than expected by chance. Trunk and crown infestation are influenced by different host traits , trunk infestation was only affected by bark type, while crown infestation is reduced when trees are fast-growing, tall, have low-density wood, long branch-free boles and long leaves. The likelihood of both trunk and crown infestation increases for trees growing in close proximity to another liana-infested tree, but is invariant with the light environment of tree crowns. Conclusion: Crown and trunk infestation have not been properly distinguished before; it is important to do so as the factors determining the different modes of infestation differ fundamentally. The association between crown infestation and tree traits suggests that increases in liana dominance in Amazonian forests could cause changes in forest composition, including favouring faster growing tree species with low density wood, potentially reducing the carbon stored by mature forests. [source]

Gall insects can avoid and alter indirect plant defenses

NEW PHYTOLOGIST, Issue 3 2008
John F. Tooker
Summary ,,Parasitic species can dramatically alter host traits. Some of these parasite-induced changes can be considered adaptive manipulations that benefit the parasites. Gall-inducing insects are parasites well known for their ability to alter host-plant morphology and physiology, including the distribution of plant defensive compounds. Here it was investigated whether gall-inducing species alter indirect plant defenses, involving the release of volatile compounds that are attractive to foraging natural enemies. ,,Using field and factorial laboratory experiments, volatile production by goldenrod (Solidago altissima) plants was examined in response to attack by two gall-inducing species, the tephritid fly Eurosta solidaginis and the gelechiid moth Gnorimoschema gallaesolidaginis, as well as the meadow spittlebug, Philaenus spumarius, and the generalist caterpillar Heliothis virescens. ,,Heliothis virescens elicited strong indirect defensive responses from S. altissima, but the gall-inducing species and spittlebugs did not. More significantly, infestation by E. solidaginis appeared to suppress volatile responses to subsequent attack by the generalist caterpillar. ,,The extensive control that E. solidaginis apparently exerts over host-plant defense responses may reduce the predation risk for the gall inducer and the subsequent herbivore, and could influence community-level dynamics, including the distribution of herbivorous insect species associated with S. altissima parasitized by E. solidaginis. [source]

Host intrinsic determinants and potential consequences of parasite infection in free-ranging red-fronted lemurs (Eulemur fulvus rufus)

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010
Dagmar Clough
Abstract Parasites and infectious diseases represent ecological forces shaping animal social evolution. Although empirical studies supporting this link abound in various vertebrate orders, both the study of the dynamics and impact of parasite infections and infectious diseases in strepsirrhine primates have received little empirical attention. We conducted a longitudinal parasitological study on four groups of wild red-fronted lemurs (Eulemur fulvus rufus) at Kirindy Forest, Madagascar, during two field seasons in consecutive years to investigate i) the degree of gastrointestinal parasite infection on population and individual levels and ii) factors potentially determining individual infection risk. Using a comprehensive dataset with multiple individually assignable parasite samples as well as information on age, sex, group size, social rank, and endocrine status (fecal androgen and glucocorticoid), we examined parasite infection patterns and host traits that may affect individual infection risk. In addition, we examined whether parasite infection affects mating and reproductive success. Our results indicated high variability in parasite infection on individual and population levels. Time of year and group size was important determinants of variability in parasite infection. Variation in hormone levels was also associated with parasite species richness and parasite infection intensity. Differences in parasite infection between years indicate a potential immune-enhancing function of steroid hormones on nematode infections, which has not been reported before from other vertebrates studied under natural conditions. Male mating and reproductive success were not correlated to any measure of parasite infection, which suggests a nonfunctional role of the parasites we examined in primate sexual selection. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source]