Chloroplast DNA phylogeography of Alnus glutinosa (L.) Gaertn.

Traditionally, information on the postglacial history of plant species has been gained from the analysis of fossil pollen data. More recently, surveys of present patterns of genetic variation have given valuable insights into species phylogeography. The genus Alnus , based on fossil data, is known to have had at least four glacial refugia. A survey of chloroplast DNA (cpDNA) diversity in populations of black alder ( A. glutinosa ) was undertaken in order to gain more insight into its postglacial history. This revealed a high degree of structuring of 13 cpDNA haplotypes on a European scale which indicated that most of northern and central Europe was colonized from a refuge in the Carpathian Mountains. Based on the distribution of two common cpDNA haplotypes, colonization routes from this refuge can be determined. The locations of other previously identified refugia are confirmed and two formerly unconfirmed refugial areas for alder (southern Spain and Turkey) are proposed.     

Root disturbance of common ash, Fraxinus excelsior (Oleaceae), leads to reduced foliar toughness and increased feeding by a folivorous weevil, Stereonychus fraxini (Coleoptera, Curculionidae)

Abstract.

• 1 Bioassays were carried out to examine differences in the feeding of a folivorous weevil, Stereonychus fraxini De Geer, on leaves from ash saplings with undamaged roots, and those with damaged roots. Beetles ate significantly more of the leaves of root-damaged saplings in a choice experiment.
• 2 A separate study of the effect of root damage on leaf toughness was carried out on a second group of ash saplings. Saplings with damaged roots had less tough leaves than control saplings. Decreased leaf toughness in hypothesized as a mechanism to explain the preference of weevils for leaves from damaged trees.
• 3 Both chemical and physical changes may occur in the tissues of ash trees in response to environmental stress such as drought and root damage.
• 4 Root damage caused by agricultural disturbance is hypothesized as a mechanism making mature ash trees in hedgerow ecosystems more susceptible to insect herbivores.

     

Landscapes of Power and Identity: Comparative Histories in the Sonoran Desert and the Forests of Amazonia from Colony to Republic

Landscapes of Power and Identity: Comparative Histories in the Sonoran Desert and the Forests of Amazonia from Colony to Republic . Cynthia Radding. Durham, NC: Duke University Press, 2005. 431 pp.     

Studying metapopulation effects in predator-prey systems

It has been suggested that many predator-prey systems persist, despite unstable local interactions, due to metapopulation processes: movement of individuals among largely independent local populations. I review 13 possible examples of this phenomenon all I could find in the literature—and find that each either lacks convincing data or is not a true metapopulation. Most of the examples rely on evidence of local extinction and recolonization, only a few using direct experimental methods; I discuss the advantages and disadvantages of these methods, as well as alternatives.
I also consider the ways these systems deviate from having pure metapopulation structures, and conclude that most large-scale spatial population structures will not fit cleanly into a metapopulation vs. within-population dichotomy, but rather combine features of both. This will necessitate use of powerful and focused methodology (in particular, experimentation) to directly describe movement rates and patterns, rather than use of crude observational data (e.g. extinctions) to make inferences about movement.     

Studies of Diurnal Acid Fluctuations in British Isoetid-type Submerged Aquatic Macrophytes

British isoetid species are examined for the presence of diurnalfluctuations in tritratable acidity (to pH 6·4), in plantscollected directly from a small lake and in plants grown inconstant conditions in the laboratory. Wide diurnal fluctuationsare present in Isoetes lacustris and in both submerged and terrestrialpopulations of Littorella uniflora. They are absent in Lobeliadortmanna, Subularia aquatica, Eriocaulon septangulare, Ranunculusflammula and Pilularia globulifera. The significance of submerged CAM is discussed in relation toother carbon accumulating mechanisms in isoetids and in considerationof their general ecology. Crassulacean acid metabolism, photosynthesis, isoetid, oligotrophic lakes     

Population regulation and dispersion of the smoky mouse,Pseudomys fumeus II. Spring decline,breeding success and habitat heterogeneity

The smoky mouse (Pseudomys fumeus) undergoes large annual fluctuations in abundance, characterized by a dramatic decline in numbers just before the summer breeding season. The population on Mount William has two components which are differentially affected by this decline. The first, consisting of animals living in preferred microhabitat, have high breeding success and are unaffected by the decline. Females normally breed in two seasons, and in the second season breed earlier than first year females. The second component lives in non-preferred microhabitat, is severely affected by the decline and shows high levels of fighting during the decline period. This difference may result from the lack of high quality food resources in non-preferred microhabitat following the seasonal cessation of production of fungal sporocarps. The role of spatial and temporal heterogeneity in the availability of food resources in the population processes of small mammals is discussed.