Potato Diversity in the Andean Center of Crop Domestication

The diversity and population structure of potato landraces ( Solanum spp.) within their center of domestication was studied using isozyme surveys of four polymorphic loci. The objective in assessing the distribution of genetic diversity was to assist in planning conservation strategies of crop genetic resources that are threatened by genetic erosion. In situ conservation methods depend on this type of analysts. Research was conducted in the region of Cusco, Peru. Eight fields spread among two microregions were randomly sampled, and 610 tubers were studied from this sample. In addition, 503 tubers were collected from markets in seven different meso-regions (provinces) surrounding the regional center of Cusco. Thirty genotypes were identified in the field sample and 82 in the regional sample. The frequency and distribution of genotypes and alleles are described. A high degree of genotype endemism was found at both the field and regional levels. Genotypes were unevenly distributed, and most of the genotypic diversity was between rather than within populations. At the allele level, however, we found that a very high percentage of the diversity was within rather than between populations. The genotype is the key unit for maintaining the population of potato landraces. Our findings suggest that collections need to be both geographically extensive and intensive. Because farmers are able to maintain most alleles on relatively small portions of their land, in situ conservation is a viable strategy.     

Threats to Avifauna on Oceanic Islands

Abstract:  Results of the study by Blackburn et al. (2004 a ) of avifauna on oceanic islands suggest that distance from the mainland and time since European colonization have major influences on species extinctions and that island area is a significant but secondary contributing factor. After augmenting the data of the study on geographical properties for some of the islands they examined, we used a causal analysis approach with structural equation modeling to reexamine their conclusions. In our model geographical properties of islands, such as island area and isolation, were considered constraints on biological factors, such as the number of introduced mammalian predators and existing number of avifauna, that can directly or indirectly influence extinction. Of the variables we tested, island area had the greatest total influence on the threat of extinction due to its direct and indirect effects on the size of island avifauna. Larger islands had both a greater number of threatened bird species and more avifauna, increasing the number of species that could become threatened with extinction. Island isolation also had a significant, positive, and direct effect on threats to island avifauna because islands farther from the mainland had fewer current extant avifauna. Time since European colonization had a significant negative, but relatively weaker, influence on threats compared with the traditional biogeographic factors of island area and distance to the mainland. We also tested the hypothesis that the amount of threat is proportionally lower on islands that have had more extinctions (i.e., there is a "filter effect"). Because the proportion of bird extinctions potentially explained only 2.3% of the variation in the proportion of threatened species on islands, our results did not support this hypothesis. Causal modeling provided a powerful tool for examining threat of extinction patterns of known and hypothesized pathways of influence.     

PRIVACY REGULATION AND PLACE ATTACHMENT: PREDICTING ATTACHMENTS TO A STUDENT FAMILY HOUSING FACILITY

Although similar processes and functions have been proposed for privacy regulation and place attachment, little theoretical or empirical work encompasses both constructs. In the present study, a theoretical model relates privacy regulation to place attachment in the home. According to this model, the home setting may either facilitate or inhibit privacy regulation with family. When regulation is facilitated, family functioning and feelings of control should be enhanced, promoting attachments to the home.Questionnaire data from student family apartment residents supported this model. Residents who reported greater ease in regulating privacy with family also reported greater apartment attachment. Analyses suggested that this relationship was mediated by family functioning and feelings of control. Similar relationships were found for three different types of attachment.By bridging across concepts often treated separately, the model supported in this study suggests new directions for theoretical and empirical study, and new applications for housing policy and design.     

Regeneration of Native Trees in the Presence of Invasive Saltcedar in the Colorado River Delta, Mexico

Abstract:  Many riparian zones in the Sonoran Desert have been altered by elimination of the normal flood regime; such changes to the flow regime have contributed to the spread of saltcedar ( Tamarix ramosissma Ledeb.), an exotic, salt-tolerant shrub. It has been proposed that reestablishment of a natural flow regime on these rivers might permit passive restoration of native trees, without the need for aggressive saltcedar clearing programs. We tested this proposition in the Colorado River delta in Mexico, which has received a series of large-volume water releases from U.S. dams over the past 20 years. We mapped the vegetation of the delta riparian corridor through ground and aerial surveys (1999–2002) and satellite imagery (1992–2002) and related vegetation changes to river flood flows and fire events. Although saltcedar is still the dominant plant in the delta, native cottonwood (  Populus fremontii S. Wats.) and willow ( Salix gooddingii C. Ball) trees have regenerated multiple times because of frequent flood releases from U.S. dams since 1981. Tree populations are young and dynamic (ages 5–10 years). The primary cause of tree mortality between floods is fire. Biomass in the floodplain, as measured by the normalized difference vegetation index on satellite images, responds positively even to low-volume (but long-duration) flood events. Our results support the hypothesis that restoration of a pulse flood regime will regenerate native riparian vegetation despite the presence of a dominant invasive species, but fire management will be necessary to allow mature tree stands to develop.     

The Role of Botanic Gardens in the Science and Practice of Ecological Restoration

Abstract: Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing institutional strengths, such as plant‐based research and knowledge transfer, would enable many more botanic gardens worldwide to provide effective science‐based support to restoration efforts. We recommend botanic gardens widen research to include ecosystems as well as species, increase involvement in practical restoration projects and training practitioners, and serve as information hubs for data archiving and exchange.