PubMed Health⌕ Search

Biomedical subjects

E E Werner

Publications and source records attributed to E E Werner.

At least 19 recordsLinked to original sources
PubMed2001

The contribution of trait-mediated indirect effects to the net effects of a predator.

Many prey modify traits in response to predation risk and this modification of traits can influence the prey's resource acquisition rate. A predator thus can have a "nonlethal" impact on prey that can lead to indirect effects on other community members. Such indirect interactions are termed trait-mediated indirect interactions because they arise from a predator's influence on prey traits, rather than prey density. Because such nonlethal predator effects are immediate, can influence the entire prey population, and can occur over the entire prey lifetime, we argue that nonlethal predator effects are likely to contribute strongly to the net indirect effects of predators (i.e., nonlethal effects may be comparable in magnitude to those resulting from killing prey). This prediction was supported by an experiment in which the indirect effects of a larval dragonfly (Anax sp.) predator on large bullfrog tadpoles (Rana catesbeiana), through nonlethal effects on competing small bullfrog tadpoles, were large relative to indirect effects caused by density reduction of the small tadpoles (the lethal effect). Treatments in which lethal and nonlethal effects of Anax were manipulated independently indicated that this result was robust for a large range of different combinations of lethal and nonlethal effects. Because many, if not most, prey modify traits in response to predators, our results suggest that the magnitude of interaction coefficients between two species may often be dynamically related to changes in other community members, and that many indirect effects previously attributed to the lethal effects of predators may instead be due to shifts in traits of surviving prey.

Animals↗
PubMed1997

Vulnerable but invincible: high-risk children from birth to adulthood.

This report summarizes the major findings of a 40-year longitudinal study of a multi-racial cohort of children who had been exposed to poverty, perinatal stress, parental psychopathology and family discord. Individuals are members of the Kauai Longitudinal Study, which followed all children born in 1955 on a Hawaiian island from the prenatal period to middle age. Several clusters of protective factors were identified that enabled most of the high-risk individuals to develop into competent, confident and caring adults. Implications of the findings for developmental theory were discussed and issues for future research identified.

Adaptation, Psychological↗
PubMed1994

Overcoming the odds.

Explore the source record for details and available documents.

Adaptation, Psychological↗
PubMed1989

High-risk children in young adulthood: a longitudinal study from birth to 32 years.

The developmental courses of high-risk and resilient children were analyzed in a follow-up study of members of a 1955 birth cohort on the island of Kauai, Hawaii. Relative impact of risk and protective factors changed at various life phases, with males displaying greater vulnerability than females in their first decade and less during their second; another shift appears under way at the beginning of their fourth decade. Certain protective factors seem to have a more general effect on adaptation than do specific risk factors.

Achievement↗
PubMed1986

Resilient offspring of alcoholics: a longitudinal study from birth to age 18.

This study focuses on child characteristics and on the qualities of the caregiving environment that differentiated between offspring of alcoholics who did and those who did not develop serious coping problems by age 18. The 49 subjects (22 male) are members of a multiracial cohort of 698 children born in 1955 on the island of Kauai, Hawaii, who were followed at ages 1, 2, 10 and 18. In this group, males and the offspring of alcoholic mothers had higher rates of psychosocial problems in childhood and adolescence than females and the offspring of alcoholic fathers. Children of alcoholics who developed no serious coping problems by age 18 differed from those who did in characteristics of temperament, communication skills, self-concept and locus of control. They had also experienced fewer stressful life events disrupting their family unit in the first two years of life. Results of the study support a transactional model of human development and demonstrate bidirectionality of child-caregiver effects.

Adaptation, Psychological↗
PubMed1983

Juvenile idiopathic haemochromatosis: a life-threatening disorder presenting as hypogonadotropic hypogonadism.

It is generally believed that idiopathic haemochromatosis is exclusively a disease of middle age, affecting primarily men. We describe here four cases of idiopathic haemochromatosis having onset of symptoms before or around the age of 20 years. Other similar cases have previously been reported. In this juvenile form, males and females appear to be equally affected. These subjects may have a history of unexplained abdominal pain, present with hypogonadotropic hypogonadism, and, unless proper treatment is started, die early because of cardiac dysfunction. In this regard, their clinical course is very similar to that of well-transfused thalassemia major. Thus, early diagnosis is even more important in the juvenile form than in the adult form of idiopathic haemochromatosis. We suggest that evaluation of body iron stores should be performed as a screening procedure in young subjects with hypogonadotropic hypogonadism and/or cardiac dysfunction.

Adult↗
PubMed1976

Niche shifts in sunfishes: experimental evidence and significance.

Three species of sunfishes segregate ecologically when stocked together in small ponds. When each species is stocked separately in replicate ponds, it exhibits competitive release through increases in growth rate and average food size. Niche shifts are indicated by convergence of these species to the same food habits in the absence of competitors. These shifts are due to phenotypic (behavioral) plasticity. The significance of niche flexibility is related to seasonal patterns in resource availability.

Animals↗