Plant structural traits and their role in anti-herbivore defence

We consider the role that key structural traits, such as spinescence, pubescence, sclerophylly and raphides, play in protecting plants from herbivore attack. Despite the likelihood that many of these morphological characteristics may have evolved as responses to other environmental stimuli, we show that each provides an important defence against herbivore attack in both terrestrial and aquatic ecosystems. We conclude that leaf-mass–area is a robust index of sclerophylly as a surrogate for more rigorous mechanical properties used in herbivory studies. We also examine herbivore counter-adaptations to plant structural defence and illustrate how herbivore attack can induce the deployment of intensified defensive measures. Although there have been few studies detailing how plant defences vary with age, we show that allocation to structural defences is related to plant ontogeny. Age-related changes in the deployment of structural defences plus a paucity of appropriate studies are two reasons why relationships with other plant fitness characteristics may be obscured, although we describe studies where trade-offs between structural defence and plant growth, reproduction, and chemical defences have been demonstrated. We also show how resource availability influences the expression of structural defences and demonstrate how poorly our understanding of plant structural defence fits into contemporary plant defence theory. Finally, we suggest how a better understanding of plant structural defence, particularly within the context of plant defence syndromes, would not only improve our understanding of plant defence theory, but enable us to predict how plant morphological responses to climate change might influence interactions at the individual (plant growth trade-offs), species (competition), and ecosystem (pollination and herbivory) levels.     

Physical anthropology and the biobehavioral approach to child growth and development

Recent progress in primatology, neurology and psychology has made it possible to begin to synthesize and combine the data and concepts from these fields into the physical anthropological approach to child growth and development. This paper attempts to conceptualize this new biobehavioral approach, reviewing two studies which exemplify it, already under research at the Krogman Growth Center. The first, which deals with mother-newborn social interaction, explores neonate attachment behaviors and predictable maternal response. The methodology of this study relies heavily on ethological techniques. The second study, involving pre-pubescent and post-pubescent same sex twins, aims to delineate the genetic and environmental components of certain human behavioral qualities, such as intelligence, using the genetic approach to human variation. The problem of how this possibly interacts with the secular trend is also discussed.