Effective conservation requires efficient population monitoring, which can be challenging for rare species like the desert tortoise (Gopherus agassizii). We compared two alternative survey methods that can be used to monitor tortoise populations: distance sampling and site occupancy estimation. In 2005 and 2006 combined, we surveyed 120 1-km transects to estimate density and 40 3-ha plots with five presence-“absence” surveys to estimate occupancy of Sonoran desert tortoises in two mountain ranges in southern Arizona. We found that monitoring programs based on an occupancy framework were more efficient and had greater power to detect linear trends. We also found that habitat use by Sonoran desert tortoises was influenced most by slope and aspect, contrasting with patterns observed in the Mojave Desert. Given its efficiency, power, and ability to gauge changes in distribution while accounting for variation in detectability, occupancy offers a promising alternative for long-term monitoring of Sonoran desert tortoise populations.

Sonoran Desert Drosophila mettleri breeds in soil soaked by the necrotic cacti juices from saguaro (Carnegiea gigantea) and cardon (Pachycereus pringlei). An isolated population on Santa Catalina Island, 300 kilometers NW of the Sonoran Desert limit, was discovered breeding in several Opuntia cacti species. Host shifts are associated with the speciation process in phytophagous insects. I tested for evidence of premating isolation, postmating isolation, and ecological differences among allopatric populations of Drosophila mettleri using a variety of approaches. No sexual isolation was detected. However, Drosophila mettleri from Santa Catalina Island shows significant behavioral and physiological differences compared with Sonoran Desert populations. Furthermore, Drosophila mettleri from Santa Catalina Island was significantly genetically differentiated from all other populations in the study. Finally, I observed sufficiently significant F1 male sterility in crosses involving the Santa Catalina Island population to consider it indicative of early postzygotic isolation.

No description available.

The geology, topography, soils and climate of the Namib Desert Park south of 23 S. Lat. are described briefly. The vegetation was investigated using the techniques of the Zurich - Montpellier school of phytosociology. Floristic and other site data were collected from 472 sites in the standard Braun - Blanquet manner and the techniques are described in some detail. These data are presented by means of phytosociological tables and detailed descriptions of each community. A total of 34 noda, communities and sub-communities, were delimited in the study area and the floristic and ecological relationships of these are discussed. Only a few of the communities can be assigned to syntaxa from other parts of the world or southern Africa because most of the Namib Desert communities seemed too different to be compared to associations from North Africa, the Middle East, South America or Australia on more than a superficial, structural basis. Very few data from other arid or semi-arid areas in southern Africa have received formal phytosociological treatment and there is therefore insufficient material to draw meaningful comparisons. The "foam structure" described by Volk & Geyger (1970) was found to be widely distributed in soils of the plains of the Namib Desert, and it was shown to have a profound influence on water penetration. The effects on vegetation development are discussed. The study generated a number of questions about the vegetation and ecosystems of the Namib Desert and some recommendations are made concerning future synecological and autecological studies. A list of species and synonyms of the names of all higher plants recorded in the study area are given in Appendix I. It is concluded that the Braun - Blanquet method is efficient in terms of time required to collect data which can be used for a number of purposes, but that a classification of vegetation ' should be followed up by autecological and detailed synecological studies of species (particularly those which characterize communities) and individual communities to determine the controlling factors more precisely and to enable more accurate predictions concerning the effects of management programmes to be made. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1976.

The sidewinder rattlesnake is found only in the low hot deserts of the southwestern United States and northwestern Mexico. It has adapted to this environment in various ways and thus is able to live under extremely demanding conditions. Previously published information on sidewinders is quite complete in certain respects and totally lacking in others. The present study represents an attempt to integrate the various aspects of sidewinder biology into a more cohesive unit. A large sidewinder population at Kelso Dunes, Mojave Desert, California, was intensively studied for three years. A number of parameters - physical, clmatic, behavioral and population - were investigated. Activity cycles are most closely tied to thermal regimes and considerably less so to rainfall and wind. An abundance of small mammal burrows on most of the study area provide thermal refugia on hot days and hibernacula during the winter. Because of the insulating properties of sand and the general lack of frost at Kelso, sidewinder hibernacula are probably scattered over the entire study area and appear to be rather superficial. Mating occurs generally in the spring and the young are born alive in early autumn. Whether the sidewinder reproductive cycle is annual or biennial was not determined. During warm weather sidewinders become active at dusk and may wander over the sand in any direction for over 1200 meters - mostly by sidewinding. The average distance travelled is much shorter, however. This nocturnal wandering probably serves as a dispersal mechanism, since mark and release studies showed no tendency towards homing or territorality. By midnight, however, even the most active sidewinders have formed resting craters and remain coiled therein until sunrise or later. Among rattlesnakes cratering is a feature unique to sidewinders. During the day the crater serves primarily for thermoregulation and less so for concealment, whereas at night this order of importance is reversed. Sidewinders prey upon any small reptile or mammal they can overpower and may actually do a considerable amount of feeding from ambush during the day. After feeding they become sedentary until digestion is largely completed, shifting position only to warm the food bolus during the day. Bio-telemetry studies indicated that the rate of heating or cooling may be more important in thermoregulatory behavior than the simple attainment of absolute thermal thresholds. On cool evenings sidewinders often bask on asphalt roads or railroad rails, using these surfaces as sources of reradiated heat. The sidewinder population is not uniformly distributed on the Kelso study area. More trackways were recorded in dune areas dotted with large clumps of vegetation with stable sand hummocks beneath them. In rockier areas with low vegetation and little sand, sidewinder trackways were few and mostly those of juveniles. This was attributed to inadequate burrows and the general lack of shade in such areas.

Kanyirninpa, or holding, exists as a deeply embedded value amongst desert Aboriginal peoples (Puntu). It is disclosed as authority with nurturance, where older generations assume the responsibility to care for and look after younger people. Kanyirninpa also holds in balance two other key cultural patterns of desert life, autonomy and relatedness. These values are transmitted across generations where they provide desert society with identity, cohesion and strength. While kanyirninpa can be identified in the nurturance provided a child after birth, its presence and power is particularly disclosed at ceremonial time. Here, the meanings of the ancestral tjukurrpa (dreaming) are celebrated and renewed. Desert society is reproduced as the deeper, social and cosmic meanings around ngurra (land), walytja (family) and tjukurrpa are gathered, ritualised and re-enacted. The older generations of men and women enable this holding to occur. When boys (marnti) become men (wati) the manner of kanyirninpa changes. No longer do young men seek to be held by their mothers and female relations. Instead, they seek to be held by older men: brothers, uncles and other males. By holding them older men induct younger men into the social meanings and behaviours of desert, male adulthood. A generative and generational male praxis is disclosed.

Thesis (M.A.)--St. Vladimir's Orthodox Theological Seminary, Crestwood, NY, 2007. / Abstract. Includes bibliographical references (leaves 31-32).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 353-373).

Thesis (M.A.)--St. Vladimir's Orthodox Theological Seminary, Crestwood, NY, 2007. / Abstract. Includes bibliographical references (leaves 31-32).