The Development of Integration in Marsupial and Placental Limbs.

The morphological interdependence of traits, or their integration, is commonly thought to influence their evolution. As such, study of morphological integration and the factors responsible for its generation form an important branch of the field of morphological evolution. However, most research to date on post-cranial morphological integration has focused on adult patterns of integration. This study investigates patterns of correlation (i.e., morphological integration) among skeletal elements of the fore- and hind limbs of developing marsupial and placental mammals. The goals of this study are to establish how patterns of limb integration vary over development in marsupials and placentals, and identify factors that are likely responsible for their generation. Our results indicate that although the overall pattern of correlation among limb elements is consistent with adult integration throughout mammalian development, correlations vary at the level of the individual element and stage. As a result, the relative integration among fore- and hind limb elements varies dynamically between stages during development in both marsupial and placental mammals. Therefore, adult integration studies of the limbs may not be indicative of developmental integration. Results are also consistent with integration during early limb development being more heavily influenced by genetic and developmental factors, and later by function. Additionally, results are generally consistent with a constraint on marsupial forelimb evolution caused by the functional requirements of the crawl to the teat that operates by limiting morphological variation before and at the time of birth, and not after

Bringing agroforestry technology to farmers in the Philippines: Identifying constraints to the success of extension activities using systems modelling

This paper presents a systems modelling approach to evaluating the success of an agroforestry extension program in Leyte, the Philippines. During the program, variables which are intrinsic to farmers’ socio-economic and farming systems were found to have influenced the uptake and acceptance of extension advice. Evaluation of the program therefore depended on identifying the variables and their interdependencies and assessing their relative influence on program outputs. For this purpose, a systems approach which encourages breaking systems into component variables, but also acknowledges the context of problems, assisted construction of models. Using both empirical data collected during program activities and input from stakeholders, Bayesian Belief Network software was used to predict critical success factors for four aspects of the overall extension system, namely recruitment, use of written extension materials, farmers’ self-efficacy and retention of participating farmers throughout the program. A key predicted constraint to program recruitment is farmers’ perception of harvest security and while this variable can be partly addressed through dissemination of information on harvesting legislation, title security cannot. Differing levels of farmers’ education result in differences in predicted reading ability, comprehension of extension literature and possible misconstrual of information. The variable most critical to the development of farmers’ self-efficacy is extended on-farm technical assistance and support