The systematic significance of flavonoids in Persea of the Southeastern United States

The systematic significance of flavonoid distribution in the southeastern United States taxa of Persea is discussed. The compounds thus far elucidated are glycosides based on quercetin, kaempferol, apigenin or luteolin.     

Impact on plant communities by white-tailed deer in Mississippi,USA

Background: The abundance of white-tailed deer (Odocoileus virginianus) in the eastern United States has escalated during the twentieth century, potentially impacting plant communities.

Methods: We measured understorey plant cover and biomass five years after excluding deer from mature forests of three ecological regions in Mississippi, USA. We extended the significance of P values to 0.10 to detect developing impacts.

Results: Deer impacts were limited and varied by ecological region. We recorded 151 species in cover transects. Consistent exclosure treatment effects were detected in two regions where there was greater cover of two deer forages and less cover of three non-forages. Species richness was greater in exclosures in one region, but otherwise species richness and diversity indices did not differ. We recorded 127 species in biomass quadrats. Exclosure treatment effects on biomass were inconsistent. Out of five species with significant differences, three had more biomass in controls, including two deer forages. Except for greater total biomass in controls of one region, there were no differences by growth form or total vegetation for canopy coverage or biomass. Ordination of community canopy cover demonstrated similarity of paired exclosure and controls.

Conclusions: Exclosure treatment effects on canopy cover and species richness in two regions indicated limited negative impacts from deer foraging. A time frame of more than five years may be required for exclusion to allow recovery of vegetation, even with relatively open canopies and a long growing season.     

American Anthropology in the Middle Decades: A View from Hollywood

North American anthropology had an earlier interest in studies of the United States and in critical approaches than is often recognized. Such interests were pursued before World War II but were set aside during the war and in anthropology's postwar expansion. This perspective on anthropological history was inspired by the work of Hortense Powdermaker, specifically the disjunction between her 1930s research in segregated Mississippi and her pioneering study of Hollywood in the late 1940s. Reexamining that study highlights the theoretical framework that led to omissions in her account of Hollywood, while her explanation of movie content invites a more diachronic approach. Parallels between the history of the movies and that of cultural anthropology from the 1930s through the 1960s suggest how both were shaped by the Depression, World War II, and the Cold War.     

Effects of Forest Regrowth and Urbanization on Ecosystem Carbon Storage in a Rural–Urban Gradient in the Southeastern United States

Forest regrowth after cropland abandonment and urban sprawl are two counteracting processes that have influenced carbon (C) sequestration in the southeastern United States in recent decades. In this study, we examined patterns of land-use/land-cover change and their effect on ecosystem C storage in three west Georgia counties (Muscogee, Harris, and Meriwether) that form a rural–urban gradient. Using time series Landsat imagery data including MSS for 1974, TM for 1983 and 1991, and ETM for 2002, we estimate that from 1974 to 2002, urban land use in the area has increased more than 380% (that is, 184 km²). Most newly urbanized land (63%) has been converted from forestland. Conversely, cropland and pasture area has decreased by over 59% (that is, 380 km²). Most of the cropland area was converted to forest. As a result, the net change in forest area was small over the past 29 years. Based on Landsat imagery and agricultural census records, we reconstructed an annual gridded data set of land-cover change for the three counties for the period 1850 to 2002. These data sets were then used as input to the Terrestrial Ecosystem Model (TEM) to simulate land-use effects on C fluxes and storage for the study area. Simulated results suggest that C uptake by forest regrowth (approximately 23.0 g C m⁻² y⁻¹) was slightly greater than the amount of C released due to deforestation (approximately 18.4 g C m⁻² y⁻¹), thus making the three counties a weak C sink. However, the relative importance of different deforestation processes in this area changed significantly through time. Although agricultural deforestation was generally the most important C-release process, the amount of C release attributable to urbanization has increased over time. Since 1990, urbanization has accounted for 29% of total C loss from the study area. We conclude that balancing urban development and forest protection is critically important for C management and policy making in the southeastern United States.     

Fat frogs,mobile genes: unexpected phylogeographic patterns for the ornate chorus frog (Pseudacris ornata)

The southeastern coastal plain of the United States is a region marked by extraordinary phylogeographic congruence that is frequently attributed to the changing sea levels that occurred during the glacial‐interglacial cycles of the Pleistocene epoch. A phylogeographic break corresponding to the Apalachicola River has been suggested for many species studied to date that are endemic to this region. Here, we used this pattern of phylogeographic congruence to develop and test explicit hypotheses about the genetic structure in the ornate chorus frog (Pseudacris ornata). Using 1299 bp of mtDNA sequence and seven nuclear microsatellite markers in 13 natural populations of P. ornata, we found three clades corresponding to geographically distinct regions; one spans the Apalachicola River (Southern Clade), one encompasses Georgia and South Carolina (Central Clade) and a third comprises more northerly individuals (Northern Clade). However, it does not appear that typical phylogeographic barriers demarcate these clades. Instead, isolation by distance across the range of the entire species explained the pattern of genetic variation that we observed. We propose that P. ornata was historically widespread in the southeastern United States, and that a balance between genetic drift and migration was the root of the genetic divergence among populations. Additionally, we investigated fine‐scale patterns of genetic structure and found the spatial scale at which there was significant genetic structure varied among the regions studied. Furthermore, we discuss our results in light of other phylogeographic studies of southeastern coastal plain organisms and in relation to amphibian conservation and management.     

Cranial variation in the Iberian Peninsula and the Balearic Islands: Inferences about the history of the population

A multivariate analysis of four prehistoric and nine historic populations from the Iberian Peninsula and Balearic Islands with large sample sizes (n > 30 individuals for the neurocranium and n > 15 for the facial skeleton) is presented, considering 874 male and 557 female skulls and using 20 craniometric measurements. Cluster analyses have been undertaken using the squared Euclidean distance as a measure of proximity and the average linkage between groups (UPGMA), and neighbor-joining algorithms as a branching method, and a bootstrap analysis was used to assess the robustness of the clustering topology. The study was complemented with a principal coordinate analysis and with the application of the Mantel test to measure the degree of correspondence between the information furnished by the female and the male samples. The analyses show that the main source of morphometric variability in the Iberian Peninsula is the Basque population. The second source of variation is provided by two populations (Muslims and Jews), different from the rest from an archaeological and cultural point of view, and can probably be attributed to influences from sub-Saharan Africa. The massive deportations of the Jews in 1492 and of the Moors between the 15th and 17th centuries may have erased this source of variability from the present population of the Iberian Peninsula. The remaining studied populations, including samples from Castile, Cantabria, Andalusia, Catalonia and Balearic Islands, are grouped together, showing a notable morphological homogeneity, despite their temporal and geographic heterogeneity. These results are in general agreement with those obtained in synthetic maps, by analyzing multiple genetic markers. In such studies, the Basque population is described as the main source of genetic variability, not only in the Iberian Peninsula, but also in Western Europe. © 1996 Wiley-Liss, Inc.