A comparison of the changes in the non‐neuronal cell populations of the superior cervical ganglia following decentralization and axotomy

Transecting the axons of neurons in the adult superior cervical ganglion (SCG; axotomy) results in the survival of most postganglionic neurons, the influx of circulating monocytes, proliferation of satellite cells, and changes in neuronal gene expression. In contrast, transecting the afferent input to the SCG (decentralization) results in nerve terminal degeneration and elicits a different pattern of gene expression. We examined the effects of decentralization on macrophages in the SCG and compared the results to those previously obtained after axotomy. Monoclonal antibodies were used to identify infiltrating (ED1+) and resident (ED2+) macrophages, as well as macrophages expressing MHC class II molecules (OX6+). Normal ganglia contained ED2+ cells and OX6+ cells, but few infiltrating macrophages. After decentralization, the number of infiltrating ED1+ cells increased in the SCG to a density about twofold greater than that previously seen after axotomy. Both the densities of ED2+ and OX6+ cells were essentially unchanged after decentralization, though a large increase in OX6+ cells occurred after axotomy. Proliferation among the ganglion's total non‐neuronal cell population was examined and found to increase about twofold after decentralization and about fourfold after axotomy. Double‐labeling experiments indicated that some of these proliferating cells were macrophages. After both surgical procedures, the percentage of proliferating ED2+ macrophages increased, while neither procedure altered the proliferation of ED1+ macrophages. Axotomy, though not decentralization, increased the proliferation of OX6+ cells. Future studies must address what role(s) infiltrating and/or resident macrophages play in regions of decentralized and axotomized neurons and, if both are involved, whether they play distinct roles. © 2002 Wiley Periodicals, Inc. J Neurobiol 53: 68–79, 2002     

PHYLOGENETIC ANALYSIS OF THE EVOLUTION OF ALTERNATIVE SOCIAL BEHAVIOR IN THE MANAKINS (AVES: PIPRIDAE)

Phylogenetic analyses of lekking, lek spatial organization, and cooperative and coordinated lek display in the manakins (Aves: Pipridae) demonstrate that variation in social behavior in the group has a strong, phylogenetic component. Two of the three classes of social behavior examined also show significant phylogenetic constraints. Current adaptive plasticity models are insufficient to explain the phylogenetic variation in these behaviors in the manakins. These findings support the conclusion that vertebrate reproductive social behavior has an evolutionary history, and that it is not determined solely by adaptive individual plasticity to current conditions. The evolution of social behavior, particularly through sexual selection, can have historical consequences that can limit subsequent behavioral adaptation.     

Evolution as a cognition process: Towards an evolutionary epistemology

Recently, biologist and philosophers have been much attracted by an evolutionary view of knowledge, so-called evolutionary epistemology. Developing this insight, the present paper argues that our cognitive abilities are the outcome of organic evolution, and that, conversely, evolution itself may be described as a cognition process. Furthermore, it is argued that the key to an adequate evolutionary epistemology lies in a system-theoretical approach to evolution which grows from, but goes beyond, Darwin's theory of natural selection.     

The Effect of Traffic Density on Lead Contents in Roadside Soils: An Analysis of Published Data

Data from eight published studies were combined to show that the influence of traffic density on Pb contents in roadside soils increases with proximity to the road.     

CHROMOSOME NUMBERS IN THE GENUS ANTHURIUM (ARACEAE) II

Chromosome numbers were determined for 86 Anthurium species. Fifty-one of these were newly determined with counts ranging from 2n = 24 to 66 and 30 being the most common. All known Anthurium chromosome numbers were summarized, and 43 taxonomic changes were made in the previous reports to reflect current taxonomy. In terms of somatic chromosome numbers, the numbers form four polyploid series of 20–40–60, 24–30–48–84, 28–56 and 30–60–90–ca. 124. Paleoaneuploidy, polyploidy and B-chromosomes are basic features of the genus, but subsequent recent aneuploidy is not. The exact nature of chromosome evolution in Anthurium remains to be elucidated.     

Predicting Effects of Water Regime Changes on Waterbirds: Insights from Staging Swans

Predicting the environmental impact of a proposed development is notoriously difficult, especially when future conditions fall outside the current range of conditions. Individual-based approaches have been developed and applied to predict the impact of environmental changes on wintering and staging coastal bird populations. How many birds make use of staging sites is mostly determined by food availability and accessibility, which in the case of many waterbirds in turn is affected by water level. Many water systems are regulated and water levels are maintained at target levels, set by management authorities. We used an individual-based modelling framework (MORPH) to analyse how different target water levels affect the number of migratory Bewick’s swans Cygnus columbianus bewickii staging at a shallow freshwater lake (Lauwersmeer, the Netherlands) in autumn. As an emerging property of the model, we found strong non-linear responses of swan usage to changes in water level, with a sudden drop in peak numbers as well as bird-days with a 0.20 m rise above the current target water level. Such strong non-linear responses are probably common and should be taken into account in environmental impact assessments.