Friday, 16 May 2014

GE 141 : SPATIAL ORGANIZATION ----- UNIVERSITY OF DAR---ES--SALAAM, TANZANIA.

GE  141:  SPATIAL   ORGANIZATION.


INTRODUCTION.

Spatial organization can be observed when components of an abiotic or biological group are arranged non-randomly in space. Abiotic patterns, such as the ripple formations in sand dunes or the oscillating wave patterns of the Belousov-Zhabotinsky reaction[1] emerge after thousands of particles interact millions of times. On the other hand, individuals in biological groups may be arranged non-randomly due to selfish behavior, dominance interactions, or cooperative behavior. W. D. Hamilton (1971) proposed that in a non-related "herd" of animals, spatial organization is likely a result of the selfish interests of individuals trying to acquire food or avoid predation.[2] On the other hand, spatial arrangements have also been observed among highly related members of eusocial groups, suggesting that the arrangement of individuals may provide some advantage for the group.[3]

Spatial organization in eusocial insects


Spatial patterns exhibited by ants (Temnothorax rugatulus) can be determined after each individual is painted with a distinguishing mark.
Individuals in a social insect colony can be spatially organized, or arranged non-randomly inside the nest. These miniature territories, or spatial fidelity zones have been described in honey bees (Apis mellifera[4]), ants (Odontomachus brunneus;[5] Temnothorax albipennis;[6] Pheidole dentata[3]), and paper wasps (Polistes dominulus,[7] Ropalidia revolutionalis[8]). While residing in these zones, workers perform the task appropriate to the area they reside. For example, individuals that remain in the center of an ant nest are more likely to feed larvae, whereas individuals found at the periphery of the nest are more likely to forage.[5][6] E. O. Wilson proposed that by remaining in small, non-random areas inside the nest, the distance an individual moves between tasks may be minimized, and overall colony efficiency would increase.[3]

Spatial organization in the nest

"Foraging-for-work"

There are a variety of ways in which individuals can divide space inside a nest. According to the “foraging-for-work” hypothesis, adult workers begin performing tasks in the area of the nest where they emerged, and gradually move towards the periphery of the nest as demands to perform particular tasks change. This hypothesis is based on two observations: "(1) that there is spatial structure in the layout of tasks in social insect colonies and (2) that workers first become adults in or around the center of the nest".[9] Individuals can remain in an area for an extended period of time, as long as tasks need to be performed there. Over time, an individual’s zone may shift as tasks are accomplished and workers search for other areas where tasks need to be performed. Honey bees, for example, begin their adult life caring for brood located in the area near where they emerged (i.e. nurse bees). Eventually, workers move away from the brood rearing area and begin to perform other tasks, such as food storage, guarding, or foraging.[4]

Dominance hierarchy


The dominant paper wasp (Polistes flavus) remains in the center of the nest while subordinate wasps are often at the edge or off the nest.
Space inside the nest may also be divided as a result of dominance interactions. For example, in paper wasp colonies, a single inseminated queen may found (initiate) a colony after waking up from hibernation (overwintering). However, it is common in many species that multiple inseminated females join these foundresses instead of founding their own nest.[10] When multiple inseminated females found a colony together, the colony grows quickly, yet only one individual will become the primary egg-layer.[11] Through a series of dominance interactions, the most aggressive wasp will emerge as the dominant individual and will become the primary egg-layer for the group (the prime role for ensuring your genes are passed on to subsequent generations), whereas the remaining subordinate wasps will perform other tasks, such as nest construction or foraging.[8] There is evidence that these dominance interactions affect the spatial zones individuals occupy as well. In paper wasps (Ropalidia revolutionalis), as well as in the ant species Odontomachus brunneus,[5] dominant individuals are more likely to reside in the central areas of the nest, where they take care of brood, while the subordinate individuals are pushed towards the edge, where they are more likely to forage. It is unknown whether division of space or establishment of dominance occurs first and if the other is a result of it.

Spatial organization outside the nest


Bumble bees, Bombus impatiens individually marked with plastic number tags
There is also evidence that foragers, which are the insects that leave the nest to collect the valuable resources for the developing colony, can divide space outside the nest. Makino & Sakai showed that bumble bee foragers maintain foraging zones in flower patches, which means that bees consistently return to the same areas within a patch and there is little overlap between individuals.[12] These zones can expand and contract when neighboring foragers are removed or introduced, respectively.[13] By dividing foraging patches into miniature ‘foraging territories’, individuals can maximize the number of flowers visited with minimal interruptions or competition between foragers. These ‘foraging territories’ divided among individuals from the same colony are the result of self-organization among the foragers; that is, there is no lead forager dictating where the bees will forage. Instead, the maintenance of these foraging zones is due to simple rules followed by each individual forager. Studies to determine these “rules” are an important area of research in computer science, basic biology, behavioral ecology, and mathematic modeling.

Spatial organization as an emergent property of a self-organized system

The self-organization observed in foraging territories is a microcosm for the self-organization seen in the entire colony. Spatial organization observed across social insect colonies can be considered an emergent property of a self-organized complex system. It is self-organized because there is no leader dictating where each individual will reside, nor which task an individual will perform once they get there.[14] Instead, zones may be a by-product of division of labor, whereby individuals end up in a particular location for a period of time based on the task they perform,[9] or dominance interactions, whereby dominant individuals are granted access to the most desirable places inside the nest.[5][8] Spatial patterns exhibited by individuals of social insect colonies are not obvious, because it is difficult to observe and differentiate among individuals inside a nest cavity or flying across a foraging patch. However, when careful attention is given to the individual worker, the spatial organization of workers in the nest becomes apparent.

See also

References

  1. Ball, P. The Self-Made Tapestry: Pattern formation in nature. Oxford: Oxford University Press. ISBN 0-19-850244-3.
  2. Hamilton, W.D. (1971). "Geometry for the selfish herd". Journal of Theoretical Biology 31 (2): 295–311. doi:10.1016/0022-5193(71)90189-5. PMID 5104951.
  3. Wilson, E. O. (1976). "Behavioral discretization and the number of castes in an ant species". Behavioral Ecology and Sociobiology 1 (2): 141–154. doi:10.1007/BF00299195.
  4. Seeley, T. D. (1982). "Adaptive significance of the age polyethism schedule in honeybee colonies". Behavioral Ecology and Sociobiology 11 (4): 287–293. doi:10.1007/BF00299306.
  5. Powell, S.; Tschinkel, W. R. (1999). "Ritualized conflict in Odontomachus brunneus and the generation of interaction-based task allocation: a new organizational mechanism in ants". Animal Behaviour 58 (5): 965–972. doi:10.1006/anbe.1999.1238. PMID 10564598.
  6. Sendova-Franks, A. B.; Franks, N. R. (1995). "Spatial relationships within nests of the ant Leptothorax unifasciatus (Latr.) and their implications for the division of labour". Animal Behaviour 50: 121–136. doi:10.1006/anbe.1995.0226.
  7. Baracchi, D; Zaccaroni, M, Cervo R, Turillazzi S (2010). "Home Range Analysis in the Study of Spatial Organization on the Comb in the Paper Wasp Polistes Dominulus". Ethology 116 (7): 579–587. doi:10.1111/j.1439-0310.2010.01770.x.
  8. Robson, SKA; Bean, K, Hansen, J, Norling, K, Rowe, RJ, White, D (2000). "Social and spatial organization in colonies of a primitively eusocial wasp Ropalidia revolutionalis (de Saussure) (Hymenoptera: Vespidae)". Aust J Entomol 39: 20–24. doi:10.1046/j.1440-6055.2000.00135.x.
  9. Franks, NR; Tofts, C. (1994). "Foraging for work: how tasks allocate workers". Animal Behaviour 48 (2): 470–472. doi:10.1006/anbe.1994.1261.
  10. Wilson, E. O. (1971). The Insect Societies. Cambridge, MA: Harvard University Press.
  11. West-Eberhard, M. J. (1969). "The social biology of Polistine wasps". Miscellaneous Publications Museum of Zoology, University of Michigan 140: 1–101.
  12. Makino, TT; Sakai, S (2004). "Findings on spatial foraging patterns of bumblebees (Bombus ignitus) from a bee-tracking experiment in a net cage". Behav Ecol Sociobiol 56 (2): 155–163. doi:10.1007/s00265-004-0773-x.
  13. Makino, TT,; Sakai, S. (2005). "Does interaction between bumblebees (Bombus ignitus) reduce their foraging area?: Bee-removal experiments in a net cage". Behav Ecol Sociobiol 57 (6): 617–622. doi:10.1007/s00265-004-0877-3.
  14. Camazine, S.; Deneubourg, J.-L., Franks, N. R., Sneyd, J., Theraulaz, G., & Bonabeau, E. (2001). Self-Organization in Biological Systems. Princeton: Princeton University Press.

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WHAT IS PHYSICAL GEOGRAPHY ?



WHAT   IS   PHYSICAL  GEGRAPHY ?

INTRODUCTION
Physiography redirects here. It is also an obsolete term for "geomorphology"
True-color image of the Earth's surface and atmosphere. NASA Goddard Space Flight Center image.
Physical geography (also known as geosystems or physiography) is one of the two major sub-fields of geography.[1] Physical geography is that branch of natural science which deals with the study of processes and patterns in the natural environment like the atmosphere, hydrosphere, biosphere, and geosphere, as opposed to the cultural or built environment, the domain of human geography.
Within the body of physical geography, the Earth is often split either into several spheres or environments, the main spheres being the atmosphere, biosphere, cryosphere, geosphere, hydrosphere, lithosphere and pedosphere. Research in physical geography is often interdisciplinary and uses the systems approach.

Sub-branches

A natural arch.
Physical Geography can be divided into several sub-fields, as follows:
  • Geomorphology is the field concerned with understanding the surface of the Earth and the processes by which it is shaped, both at the present as well as in the past. Geomorphology as a field has several sub-fields that deal with the specific landforms of various environments e.g. desert geomorphology and fluvial geomorphology, however, these sub-fields are united by the core processes which cause them; mainly tectonic or climatic processes. Geomorphology seeks to understand landform history and dynamics, and predict future changes through a combination of field observation, physical experiment, and numerical modeling (Geomorphometry). Early studies in geomorphology are the foundation for pedology, one of two main branches of soil science.
Meander formation.
  • Hydrology is predominantly concerned with the amounts and quality of water moving and accumulating on the land surface and in the soils and rocks near the surface and is typified by the hydrological cycle. Thus the field encompasses water in rivers, lakes, aquifers and to an extent glaciers, in which the field examines the process and dynamics involved in these bodies of water. Hydrology has historically had an important connection with engineering and has thus developed a largely quantitative method in its research; however, it does have an earth science side that embraces the systems approach. Similar to most fields of physical geography it has sub-fields that examine the specific bodies of water or their interaction with other spheres e.g. limnology and ecohydrology.
Alpine glacier.
  • Glaciology is the study of glaciers and ice sheets, or more commonly the cryosphere or ice and phenomena that involve ice. Glaciology groups the latter (ice sheets) as continental glaciers and the former (glaciers) as alpine glaciers. Although, research in the areas are similar with research undertaken into both the dynamics of ice sheets and glaciers the former tends to be concerned with the interaction of ice sheets with the present climate and the latter with the impact of glaciers on the landscape. Glaciology also has a vast array of sub-fields examining the factors and processes involved in ice sheets and glaciers e.g. snow hydrology and glacial geology.
Wallace line.
  • Biogeography is the science which deals with geographic patterns of species distribution and the processes that result in these patterns. Biogeography emerged as a field of study as a result of the work of Alfred Russel Wallace, although the field prior to the late twentieth century had largely been viewed as historic in its outlook and descriptive in its approach. The main stimulus for the field since its founding has been that of evolution, plate tectonics and the theory of island biogeography. The field can largely be divided into five sub-fields: island biogeography, paleobiogeography, phylogeography, zoogeography and phytogeography
Climate trends.
  • Climatology is the study of the climate, scientifically defined as weather conditions averaged over a long period of time. Climatology examines both the nature of micro (local) and macro (global) climates and the natural and anthropogenic influences on them. The field is also sub-divided largely into the climates of various regions and the study of specific phenomena or time periods e.g. tropical cyclone rainfall climatology and paleoclimatology.
  • Meteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and short term forecasting (in contrast with climatology). Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century. Meteorological phenomena are observable weather events which illuminate and are explained by the science of meteorology.
Nitrogen cycle.
High-energy coastline.
  • Coastal geography is the study of the dynamic interface between the ocean and the land, incorporating both the physical geography (i.e. coastal geomorphology, geology and oceanography) and the human geography of the coast. It involves an understanding of coastal weathering processes, particularly wave action, sediment movement and weathering, and also the ways in which humans interact with the coast. Coastal geography although predominantly geomorphological in its research is not just concerned with coastal landforms, but also the causes and influences of sea level change.
Thermohaline circulation.
  • Oceanography is the branch of physical geography that studies the Earth's oceans and seas. It covers a wide range of topics, including marine organisms and ecosystem dynamics (biological oceanography); ocean currents, waves, and geophysical fluid dynamics (physical oceanography); plate tectonics and the geology of the sea floor (geological oceanography); and fluxes of various chemical substances and physical properties within the ocean and across its boundaries (chemical oceanography). These diverse topics reflect multiple disciplines that oceanographers blend to further knowledge of the world ocean and understanding of processes within it.
  • Quaternary science is an inter-disciplinary field of study focusing on the Quaternary period, which encompasses the last 2.6 million years. The field studies the last ice age and the recent interstadial the Holocene and uses proxy evidence to reconstruct the past environments during this period to infer the climatic and environmental changes that have occurred.
Habitat fragmentation.
  • Landscape ecology is a sub-discipline of ecology and geography that address how spatial variation in the landscape affects ecological processes such as the distribution and flow of energy, materials and individuals in the environment (which, in turn, may influence the distribution of landscape "elements" themselves such as hedgerows). The field was largely founded by the German geographer Carl Troll. Landscape ecology typically deals with problems in an applied and holistic context. The main difference between biogeography and landscape ecology is that the latter is concerned with how flows or energy and material are changed and their impacts on the landscape whereas the former is concerned with the spatial patterns of species and chemical cycles.
Digital elevation model.
  • Geomatics is the field of gathering, storing, processing, and delivering of geographic information, or spatially referenced information. Geomatics includes geodesy (scientific discipline that deals with the measurement and representation of the earth, its gravitational field, and other geodynamic phenomena, such as crustal motion, oceanic tides, and polar motion) and GIS (a computer based system for capturing, storing, analyzing and managing data and associated attributes which are spatially referenced to the earth) and remote sensing (the short or large-scale acquisition of information of an object or phenomenon, by the use of either recording or real-time sensing devices that are not in physical or intimate contact with the object).
Salinization.
  • Environmental geography is a branch of geography that analyzes the spatial aspects of interactions between humans and the natural world. The branch bridges the divide between human and physical geography and thus requires an understanding of the dynamics of geology, meteorology, hydrology, biogeography, and geomorphology, as well as the ways in which human societies conceptualize the environment. Although the branch was previously more visible in research than at present with theories such as environmental determinism linking society with the environment. It has largely become the domain of the study of environmental management or anthropogenic influences.

Journals and literature

Physical geography and Earth Science journals communicate and document the results of research carried out in universities and various other research institutions. Most journals cover a specific field and publish the research within that field, however unlike human geographers, physical geographers tend to publish in inter-disciplinary journals rather than predominantly geography journal; the research is normally expressed in the form of a scientific paper. Additionally, textbooks, books, and magazines on geography communicate research to laypeople, although these tend to focus on environmental issues or cultural dilemmas. Examples of journals that publish articles from physical geographers are:

Historical evolution of the discipline

From the birth of geography as a science during the Greek classical period and until the late nineteenth century with the birth of anthropogeography (human geography), geography was almost exclusively a natural science: the study of location and descriptive gazetteer of all places of the known world. Several works among the best known during this long period could be cited as an example, from Strabo (Geography), Eratosthenes (Geographika) or Dionisio Periegetes (Periegesis Oiceumene) in the Ancient Age to the Alexander von Humboldt (Kosmos) in the nineteenth century, in which geography is regarded as a physical and natural science, of course, through the work Summa de Geografía of Martín Fernández de Enciso from the early sixteenth century, which indicated for the first time the New World.
During the eighteenth and nineteenth centuries, a controversy exported from geology, between supporters of James Hutton (uniformitarianism thesis) and Georges Cuvier (catastrophism) strongly influenced the field of geography, because geography at this time was a natural science since Human Geography or Antropogeography had just developed as a discipline in the late nineteenth century.
Two historical events during the nineteenth century had a great effect in the further development of physical geography. The first was the European colonial expansion in Asia, Africa, Australia and even America in search of raw materials required by industries during the Industrial Revolution. This fostered the creation of geography departments in the universities of the colonial powers and the birth and development of national geographical societies, thus giving rise to the process identified by Horacio Capel as the institutionalization of geography.
One of the most prolific empires in this regard was Russia. In the mid-eighteenth century many geographers were sent by the Russian altamirazgo different opportunities to perform geographical surveys in the area of Arctic Siberia. Among these is who is considered the patriarch of Russian geography: Mikhail Lomonosov who in the mid-1750s began working in the Department of Geography, Academy of Sciences to conduct research in Siberia, their contributions are notable in this regard, shows the soil organic origin, develops a comprehensive law on the movement of the ice that still governs the basics, thereby founding a new branch of Geography: Glaciology. In 1755 his initiative was founded Moscow University where he promotes the study of geography and the training of geographers. In 1758 he was appointed director of the Department of Geography, Academy of Sciences, a post from which would develop a working methodology for geographical survey guided by the most important long expeditions and geographical studies in Russia. Thus followed the line of Lomonosov and the contributions of the Russian school became more frequent through his disciples, and in the nineteenth century we have great geographers as Vasily Dokuchaev who performed works of great importance as a "principle of comprehensive analysis of the territory" and "Russian Chernozem" latter being the most important where introduces the geographical concept of soil, as distinct from a simple geological strata, and thus founding a new geographic area of study: the Pedology. Climatology also receive a strong boost from the Russian school by Wladimir Köppen whose main contribution, climate classification, is still valid today. However, this great geographer also contributed to the Paleogeography through his work "The climates of the geological past" which is considered the father of Paleoclimatology. Russian geographers who made great contributions to the discipline in this period were: NM Sibirtsev, Pyotr Semyonov, K. D. Glinka, Neustrayev, among others.
The second important process is the theory of evolution by Darwin in mid-century (which decisively influenced the work of Ratzel, who had academic training as a zoologist and was a follower of Darwin's ideas) which meant an important impetus in the development of Biogeography.
Another major event in the late nineteenth and early twentieth centuries will give a major boost to development of geography and will take place in United States. It is the work of the famous geographer William Morris Davis who not only made important contributions to the establishment of discipline in his country, but revolutionized the field to develop geographical cycle theory which he proposed as a paradigm for Geography in general, although in actually served as a paradigm for Physical Geography. His theory explained that mountains and other landforms are shaped by the influence of a number of factors that are manifested in the geographical cycle. He explained that the cycle begins with the lifting of the relief by geological processes (faults, volcanism, tectonic upheaval, etc.). Geographical factors such as rivers and runoff begins to create the V-shaped valleys between the mountains (the stage called "youth"). During this first stage, the terrain is steeper and more irregular. Over time, the currents can carve wider valleys ("maturity") and then start to wind, towering hills only ("senescence"). Finally, everything comes to what is a plain flat plain at the lowest elevation possible (called "baseline") This plain was called by Davis' "peneplain" meaning "almost plain" Then the rejuvenation occurs and there is another mountain lift and the cycle continues. Although Davis's theory is not entirely accurate, it was absolutely revolutionary and unique in its time and helped to modernize and create Geography subfield of Geomorphology. Its implications prompted a myriad of research in various branches of Physical Geography. In the case of the Paleogeography this theory provided a model for understanding the evolution of the landscape. For Hydrology, Glaciology and Climatology as a boost investigated as studying geographic factors shape the landscape and affect the cycle. The bulk of the work of William Morris Davis led to the development of a new branch of Physical Geography: Geomorphology whose contents until then did not differ from the rest of Geography. Shortly after this branch would present a major development. Some of his disciples made significant contributions to various branches of physical geography such as Curtis Marbut and his invaluable legacy for Pedology, Mark Jefferson, Isaiah Bowman, among others.

Notable physical geographers

Main article: List of geographers
Alexander von Humboldt, considered to be the founding father of physical geography.

See also

Book icon

References

  1. Fundamentals of Physical Geography, 2nd Edition, by M. Pidwirny, 2006
  2. Eratosthenes (2010). Eratosthenes' "Geography". Fragments collected and translated, with commentary and additional material by Duane W. Roller. Princeton University Press. ISBN 978-0-691-14267-8.
  3. Avraham Ariel, Nora Ariel Berger (2006)."Plotting the globe: stories of meridians, parallels, and the international". Greenwood Publishing Group. p.12. ISBN 0-275-98895-3
  4. Jennifer Fandel (2006)."The Metric System". The Creative Company. p.4. ISBN 1-58341-430-4
  5. Akbar S. Ahmed (1984). "Al-Beruni: The First Anthropologist", RAIN 60, p. 9-10.
  6. H. Mowlana (2001). "Information in the Arab World", Cooperation South Journal 1.
  7. S. P. Scott (1904), History of the Moorish Empire, pp. 461-2:
    The compilation of Edrisi marks an era in the history of science. Not only is its historical information most interesting and valuable, but its descriptions of many parts of the earth are still authoritative. For three centuries geographers copied his maps without alteration. The relative position of the lakes which form the Nile, as delineated in his work, does not differ greatly from that established by Baker and Stanley more than seven hundred years afterwards, and their number is the same.

Further reading

  • Smithson, Peter; et al. (2002). Fundamentals of the Physical Environment. Routledge, London.
  • Holden, Joseph (2004). Introduction to Physical Geography and the Environment. Prentice-Hall, London.
  • Summerfield, Mike (1991). Global Geomorphology. Longman, London.
  • Wainwright, John; Mulligan, M. (2003). Environmental Modelling: Finding Simplicity in Complexity. John Wiley and Sons Ltd, London.
  • Strahler, Alan; Strahler Arthur (2006). Introducing Physical Geography. Wiley,New York.
  • Inkpen, Robert (2004). Science, Philosophy and Physical Geography. Routledge, London.

External links

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