Developmental Ecology Research Articles

Family Dynamics, Supportive Relationships, and Educational Resilience During Adolescence

If problematic relationships with parents are an academic risk factor during adolescence, then nonparental sources of support (e.g., friends, siblings, and teachers) may be arenas of comfort that promote educational resilience in the face of such risk. In a series of structural models using the National Longitudinal Study of Adolescent Health, the authors found that nonparental relationships are more likely to be directly associated with academic behavior than to interact with parent-related risk. Protective interactions occur only among certain subgroups. For example, close relationships with teachers and involvement with friends protect against parent-related academic risk among Asian American adolescents, whereas support from friends operates similarly for younger girls. In other subgroups, parental and nonparental relationships interact but not in a protective way. These patterns demonstrate the complex interplay of developmental ecology and larger social structures during the adolescent stage of life as well as the context-specific nature of resilience.

Holism, contextual variability, and the study of friendships in adolescent development.

This study treated a key relationship in the developmental ecology of adolescence, friendships, as multidimensional and context specific. First, it examined 4 characteristics of friends (academic achievement, alcohol use, emotional distress, and extracurricular participation) as independent factors and as components in holistic friendship group profiles. Longitudinal analyses of 9,224 adolescents (ages 12-20) revealed that multiple characteristics of friends predicted adolescent behavioral problems, as did membership in the best adjusted group profile. Second, the study examined whether the associations between friendship factors and adolescent behavior varied as a function of the larger peer network and school context, finding that network centrality, school academic press, and intergenerational bonding in schools conditioned the role of friends' characteristics and group profiles in positive and negative ways.

Parent Perspectives on Early Intervention: The Paradox of Needs and Rights

The aim of this study is to describe conceptions of support in early intervention in Sweden, as perceived by parents to young children with disabilities. Data were collected through in-depth interviews with eight parents and were analyzed with a qualitative approach. The theoretical framework is based on developmental ecology and empowerment and the results are discussed in relation to theory and empirical studies. The results show that parents experience discrepancies between their needs and received support. The paradoxical effects of need fulfillment and empowerment that occur in parent-professional interaction are highlighted and points to needs for future research about filling needs and providing support through encounters between parents to children with disabilities and professionals. Collaboration in the intervention process using the expertise of both parents and professionals is also discussed.The aim of this study is to describe conceptions of support in early intervention in Sweden, as perceived by parents to young children with disabilities. Data were collected through in-depth interviews with eight parents and were analyzed with a qualitative approach. The theoretical framework is based on developmental ecology and empowerment and the results are discussed in relation to theory and empirical studies. The results show that parents experience discrepancies between their needs and received support. The paradoxical effects of need fulfillment and empowerment that occur in parent-professional interaction are highlighted and points to needs for future research about filling needs and providing support through encounters between parents to children with disabilities and professionals. Collaboration in the intervention process using the expertise of both parents and professionals is also discussed.

Understanding the Identities of Mixed-Race College Students Through a Developmental Ecology Lens

Using an ecology model of human development (Bronfenbrenner, 1979, 1993), I frame the exploration of racial identities of 38 college students with multiple racial heritages. I map the influence of interactions within and between specific environments on students' decisions to identify in one or more of five patterns of mixed race identity found in a previous study.

The developmental ecology of urban males' youth violence.

The developmental ecology of urban males' youth violence.

The developmental ecology of urban males' youth violence.

Data from a longitudinal study of 294 African American and Latino adolescent boys and their caregivers living in poor urban communities were used to test a developmental-ecological model of violence. Six annual waves of data were applied to evaluate the relations between microsystem influences of parenting and peer deviance (peer violence and gang membership), macrosystem influences of community structural characteristics and neighborhood social organization, and individual involvement in violence (level and growth). Structural equation modeling analyses showed that community structural characteristics significantly predicted neighborhood social processes. Parenting practices partially mediated the relation between neighborhood social processes and gang membership. Parenting practices was fully mediated in its relation to peer violence by gang membership. Gang membership was partially mediated by peer violence level in its relation to individual violence level. Although the overall set of relations does not satisfy mediation requirements fully in all instances, the model was validated for the most part, supporting a focus on a multilevel ecological model of influences on risk development.

Larval stages, developmental ecology, and distribution of Scyllarus sp. Z (probably Scyllarus aoteanus Powell, 1949) (Decapoda: Scyllaridae)

Phyllosomata and nistos of Scyllarus sp. Z taken from plankton around and offshore northern New Zealand and in the Tasman Sea are presumed to be those of S. aoteanus Powell, 1949, the most common Scyllarus species in this area. The full larval and postlarval development of this species are described. Three features are characteristic of Scyllarus sp. Z phyllosomata; a dorsal crest on the cephalic shield, dorsal thoracic spines, and a forked telson in middle stages persisting as two prominent spines outreaching the telson posterior margin in the final stage. Scyllarus sp. Z's closest affinities are with a group of Scyllarus species whose phyllosomata have forked telsons in middle stages and medium to strong posterolateral telson spines in the final stage. The nisto is low in profile but distinctive in its armature. Too few Scyllarus sp. nistos have been described to suggest any group to which that of Scyllarus sp. Z can be assigned. The spatial and temporal distribution of the larvae and postlarvae of Scyllarus sp. Z are also described. Although early larval stages and postlarvae are found close to New Zealand, mid‐ and late‐stage larvae are widely distributed, some well beyond the known latitudinal range of the adults. There is probably an extended egg‐bearing and hatching period as early stage larvae are caught in most months. Variable rates of development of the larvae and/or delayed metamorphosis, are also possible.

How I Play: Roles and Relations in the Play Situations of Children with Restricted Mobility

The purpose of this grounded theory study was to gain knowledge and understanding of how children with restricted mobility play in different play situations. The group investigated consisted of 10 children with restricted mobility, aged from 6 to 12 years, living in northern Sweden. In this study, the child with restricted mobility is defined as a child unable to move around without the aid of a wheelchair, walking trolley, crutches or other walking device. The children were interviewed about play and were observed in different play situations. The transcribed interviews and observations were analysed according to the constant comparative method of grounded theory described by Glaser and Strauss (1967). The analysis resulted in a model (How I play, core category) describing the child's relations in different play situations, the factors that gave rise to different types of play and the consequences of the play. The different types of play were: (A) play with friends - (a) interactive play and (b) onlooker play; (B) play alone; and (C) play with adults. Most play came to be placed in categories B and C, that is the children played mostly alone or with adults. The results were discussed on the basis of Mead's theory of identity development and Bronfenbrenner's theory of developmental ecology, that is how children's play influences their development when adults are so often present.

Developmental Disharmonies and Pre‐school Setting Adaptation of Children

The aim of the investigations was to examine the course of adaptation process to the pre‐school setting and to establish the effect of developmental disharmonies on this process. The conceptual framework for the research was the Piaget's developmental theory and Bronfenbrenner's ecology of human development theory. The data was gathered in a longitudinal study design. Indicators of developmental level in four areas (motor characteristics, adaptive behaviour, language and personal‐social development) evaluated with the Gesell Developmental Schedules were used as developmental quotients. Adaptation to pre‐school setting was measured with the aid of Schaefer and Aaronson's Classroom Inventory Preschool to Primary Scale (CBI) and observations of children and interviews with parents and pre‐school teachers. The sample included 76 children aged 3 to 4 years of age (39 boys, 37 girls). The results show that children display some behaviour disorders during the entry phase to pre‐school setting and that serious developmental disharmonies were accompanied by these disorders.

Developmental Ecology of Mayapple: Effects of Rhizome Severing, Fertilization and Timing of Shoot Senescence

Mayapple (Podophyllum peltatum (L.)) is a perennial herb that forms rhizome systems, each terminated by a vegetative or sexual shoot. Such systems consist of previously formed annual segments, that are kept alive for many years. By severing rhizomes and fertilizing shoots, we have investigated whether new rhizome growth depends on nutrients acquired by roots of older segments. The treatments were imposed in spring and the effects evaluated in the following autumn, when formation of new rhizomes was complete. Neither severing alone, nor the combination of severing and fertilization significantly affected rhizome branching, determination of the new rhizome bud type, rhizome length or dry weight. Fertilization and even severing alone increased the accumulation of nutrients in new rhizomes. Timing of shoot senescence had a major impact, with later senescing shoots producing longer and heavier new rhizomes. Later senescence also increased the biomass increment of the penultimate rhizomes, i.e. those immediately preceding the current year's shoot. We conclude that in mayapple nutrient uptake by older roots does not contribute, at least immediately, to new rhizome growth. The lack of fertilization effects and the presence of strong effects of the timing of shoot senescence upon new rhizome growth indicate that light rather than nutrients was the limiting factor in this growth phase. The increased nutrient accumulation in response to fertilization suggests, however, that growth of the t Present address: Dr H. de Kroon, Department of Plant Ecology and Evolutionary Biology, University of Utrecht, PO Box 800, 84 3508 TB Utrecht, The Netherlands. rhizome system may be affected by nutrient availability over a longer period of time. Data are presented that suggest that rhizome segments store nutrients that are needed to support the growth of developing shoots in subsequent years. Given the capability of dormant buds on old rhizome segments to form new shoots after damage, an important function of rhizome longevity in mayapple may be to maintain the potential to regenerate. Key-words: Clonal plants, dormant bud bank, fertilization, mayapple, nutrient translocation, phenology, physiological integration, Podophyllum peltatum, rhizome severing, senescence

Developmental Ecology of Mayapple: Seasonal Patterns of Resource Distribution in Sexual and Vegetative Rhizome Systems

Mayapple (Podophyllum peltatum L.), a clonal perennial herb, produces shoots that are distinctly vegetative or sexual. To determine whether shoot type was correlated with rhizome size or nutrient distribution, we compared size and N and P levels of organs of both shoot types in March, May and August. Buds, leaves and current rhizome segments were significantly larger for sexual than vegetative shoots at all sampling dates, but there was substantial overlap. Shoot types differed little in N and P concentrations, but did differ in N and P contents and in distributions of N and P among organs. N and P levels were highest in buds and green leaves; nutrient levels in rhizomes decreased from March to May but increased again by August. Rhizome size may be important for the amount of future storage capacity provided, as well as for amounts of stored carbon and/or nutrients available for release. However, rhizome size may be a consequence of bud type, rather than determining bud type, because buds are recognizably sexual or vegetative by late spring, before new rhizome growth is complete. Sexual buds may be stronger sinks for resources than are vegetative buds, leading to increased growth of their associated rhizomes. Key-words: Allocation patterns, clonal plants, developmental ecology, mayapple, nutrient distribution, plant reproduction, Podophyllum peltatum, rhizome systems

Simulating forest shade to study the developmental ecology of tropical plants: juvenile growth in three vines in India

ABSTRACTBoth light quantity and quality affect the development and autoecology of plants under shade conditions, as in the understorey of tropical forests. However, little research has been directed towards the relative contributions of lowered photosynthetic photon flux density (PPFD) versus altered spectral distributions (as indicated by quantum ratios of 660 to 730 nm, or R:FR) of radiation underneath vegetation canopies. A method for constructing shade enclosures to study the contribution of these two variables is described. Three tropical leguminous vine species (Abrus precatonusL.,Caesalpinia bondicelaFleming andMucuna prunens(L.) DC) were grown in two shade enclosures with 3–4% of solar PPFD with either the R:FR of sunlight (1.10) or foliage shade (0.33), and compared to plants grown in sunlight. Most species treated with low R:FR differed from those treated with high R:FR in (1) percent allocation to dry leaf weight, (2) internode length, (3) dry stem weight/length, (4) specific leaf weight, (5) leaf size, and (6) chlorophyll a/b ratios. However, these plants did not differ in chlorophyll content per leaf dry weight or area. In most cases the effects of low R:FR and PPFD were additional to those of high R:FR and low PPFD. Growth patterns varied among the three species, but both low PPFD and diminished R:FR were important cues in their developmental responses to light environments. This shadehouse system should be useful in studying the effects of light on the developmental ecology of other tropical forest plants.

New Perspectives on the Pelagic Stage of Sea Turtle Development

Abstract: An original difficulty in accepting the idea of a pelagic diwelopmental period for sea turtles was to explain bow food could be found in reliable supply in the open ocean The uncertainty that this introduced was removed when I belatedly came to appreciate the prevalence and diversity of convergences where downwelling gathers and aligns buoyant material, including the dispersed food mources of the surface waters. Thus, it now seems clear that an essential factor in the survival of young sea turtles–and of other elements of the epipelagic; open‐ocean fauna as well–is the accessibility of a front; where inanimate debris and any floating animal or plant will be gathered to.This new evidence of complexity in the lost‐year ecology of sea turtles has important implications for their conservation and management. It is now obvious that when young cultured sea turtles are released in so‐called bead‐starting projects, the release sites ought to be chosen with the greatest care. Shores located at a distance from any major current or its eddy ought to be avoided. It is also necessary to avoid release localities where the convergence habitat may carry heavy loads of pollutants.Results of the present work reveal an urgent need for further study of sea turtle life cycles, with special attention to their developmental ecology The growing evidence for a more protracted pelagic stage, during which the juvenile turtles are passive migrants in fronts that are increasingly invaded by debris and toxic wastes, emphasizes the need for a better understanding by marine biologists of the organization of the driftline habitat and the behavioral ecology of its occupants Until these studies of the oceanography and biology of driftlines are done, we are bound to remain peculiarly ignorant of the ecologic organization of three‐fifths of the surface of the earth.

Impact of nondegradable marine debris on the ecology and survival outlook of sea turtles

Sea turtles of all kinds are peculiarly prone to eat plastic scraps and other buoyant debris and to tangle themselves in lines and netting discarded by fishermen, and records of such mishaps have increased markedly in recent years. Advances in our understanding of the developmental ecology of sea turtles shed new light on the impact of buoyant wastes on the juvenile stages. The initial developmental stages of all species are passed in the open sea. In the case of the loggerhead Caretta this period of pelagic life is likely to include 3–5 years of planktonic open-ocean travel, which may involve multiple transatlantic crossings. During this time both the young turtles and their buoyant food are drawn by advection into fronts (convergences, rips, driftlines) and the same process also brings in and aligns persistent plastics and lost fishing gear. This effect exacerbates survival problems for sea turtles that are dependent on driftlines for their food supply or shelter.

Current research on the developmental ecology of lead exposure during childhood

A model for understanding the effects of lead on child development, which focuses on the ecology of childhood is presented. The methods used in 10 prospective, longitudinal studies of the effects of lead are summarized and preliminary results presented. Differences between studies lead to a conclusion that there should be more interinvestigator collaboration to ensure greater comparability across studies.

Human Biology in Britain

Human Biology in Britain

Effects of Early Experience on Substrate Pattern Selection in Rana aurora Tadpoles

Rana aurora tadpoles from laboratory-hatched eggs were reared in artificial habitats to examine the effects of early experience on their response to substrate patterns. Tadpoles reared in featureless environments showed no preference for either square-patterned or striped substrate types. Similarly, tadpoles reared in a square-patterned environment showed no differential response to the two substrate patterns, but stripereared individuals showed a significant preference for the striped substrate. This preference was apparently established during the first 14-17 days in the striped rearing habitat, and continued exposure to this pattern through metamorphosis effected little improvement in this expression of preference. Other experiments indicated that the preference was retained through a period of isolation from the rearing substrate type, and could rapidly be established in old and in young tadpoles. The relationship of these results to the developmental ecology of R. aurora is discussed.