Biological organisation

Last updated

A population of bees shimmers in response to a predator.

Biological organisation is the organisation of complex biological structures and systems that define life using a reductionistic approach. [1] The traditional hierarchy, as detailed below, extends from atoms to biospheres. The higher levels of this scheme are often referred to as an ecological organisation concept, or as the field, hierarchical ecology.

Contents

Each level in the hierarchy represents an increase in organisational complexity, with each "object" being primarily composed of the previous level's basic unit. [2] The basic principle behind the organisation is the concept of emergence —the properties and functions found at a hierarchical level are not present and irrelevant at the lower levels.

The biological organisation of life is a fundamental premise for numerous areas of scientific research, particularly in the medical sciences. Without this necessary degree of organisation, it would be much more difficult—and likely impossible—to apply the study of the effects of various physical and chemical phenomena to diseases and physiology (body function). For example, fields such as cognitive and behavioral neuroscience could not exist if the brain was not composed of specific types of cells, and the basic concepts of pharmacology could not exist if it was not known that a change at the cellular level can affect an entire organism. These applications extend into the ecological levels as well. For example, DDT's direct insecticidal effect occurs at the subcellular level, but affects higher levels up to and including multiple ecosystems. Theoretically, a change in one atom could change the entire biosphere.

Levels

The simplest unit in this hierarchy is the atom, like oxygen. Two or more atoms is a molecule, like a dioxide. Many small molecules may combine in a chemical reaction to make up a macromolecule, such as a phospholipid. Multiple macromolecules form a cell, like a club cell. A group of cells functioning together as a tissue, for example, Epithelial tissue. Different tissues make up an organ, like a lung. Organs work together to form an organ system, such as the Respiratory System. All of the organ systems make a living organism, like a lion. A group of the same organism living together in an area is a population, such as a pride of lions. Two or more populations interacting with each other form a community, for example, lion and zebra populations interacting with each other. Communities interacting not only with each other but also with the physical environment encompass an ecosystem, such as the Savanna ecosystem. All of the ecosystems make up the biosphere, the area of life on Earth. Levels of Organization.svg
The simplest unit in this hierarchy is the atom, like oxygen. Two or more atoms is a molecule, like a dioxide. Many small molecules may combine in a chemical reaction to make up a macromolecule, such as a phospholipid. Multiple macromolecules form a cell, like a club cell. A group of cells functioning together as a tissue, for example, Epithelial tissue. Different tissues make up an organ, like a lung. Organs work together to form an organ system, such as the Respiratory System. All of the organ systems make a living organism, like a lion. A group of the same organism living together in an area is a population, such as a pride of lions. Two or more populations interacting with each other form a community, for example, lion and zebra populations interacting with each other. Communities interacting not only with each other but also with the physical environment encompass an ecosystem, such as the Savanna ecosystem. All of the ecosystems make up the biosphere, the area of life on Earth.

The simple standard biological organisation scheme, from the lowest level to the highest level, is as follows: [1]

For levels smaller than atoms see Subatomic particle
Acellular level
and
Pre-cellular level		 Atoms
Molecule Groups of atoms
Biomolecular complex Groups of (bio)molecules
Sub-cellular level Organelle Functional groups of biomolecules, biochemical reactions and interactions
Cellular level Cell Basic unit of all life and the grouping of organelles
Super-cellular level
(Multicellular level)		 Tissue Functional groups of cells
Organ Functional groups of tissues
Organ system Functional groups of organs
Ecological levels Organism The basic living system, a functional grouping of the lower-level components, including at least one cell
Population Groups of organisms of the same species
Guild Interspecific groups of organisms carrying the same ecological function (i.e. herbivores).
Community
(or biocoenosis)		Guilds from all biological domains, and their interactions in a specific location.
Ecosystem Groups of organisms in conjunction with the physical (abiotic) environment.
Biome Continental scale (climatically and geographically contiguous areas with similar climatic conditions) grouping of ecosystems.
Biosphere or
Ecosphere 		All life on Earth or all life plus the physical (abiotic) environment [3]
For levels larger than Biosphere or Ecosphere, see Earth's location in the Universe

More complex schemes incorporate many more levels. For example, a molecule can be viewed as a grouping of elements, and an atom can be further divided into subatomic particles (these levels are outside the scope of biological organisation). Each level can also be broken down into its own hierarchy, and specific types of these biological objects can have their own hierarchical scheme. For example, genomes can be further subdivided into a hierarchy of genes. [4]

Each level in the hierarchy can be described by its lower levels. For example, the organism may be described at any of its component levels, including the atomic, molecular, cellular, histological (tissue), organ and organ system levels. Furthermore, at every level of the hierarchy, new functions necessary for the control of life appear. These new roles are not functions that the lower level components are capable of and are thus referred to as emergent properties .

Every organism is organised, though not necessarily to the same degree. [5] An organism can not be organised at the histological (tissue) level if it is not composed of tissues in the first place. [6]

Emergence of biological organisation

Biological organisation is thought to have emerged in the early RNA world when RNA chains began to express the basic conditions necessary for natural selection to operate as conceived by Darwin: heritability, variation of type, and competition for limited resources. Fitness of an RNA replicator (its per capita rate of increase) would likely have been a function of adaptive capacities that were intrinsic (in the sense that they were determined by the nucleotide sequence) and the availability of resources. [7] [8] The three primary adaptive capacities may have been (1) the capacity to replicate with moderate fidelity (giving rise to both heritability and variation of type); (2) the capacity to avoid decay; and (3) the capacity to acquire and process resources. [7] [8] These capacities would have been determined initially by the folded configurations of the RNA replicators (see "Ribozyme") that, in turn, would be encoded in their individual nucleotide sequences. Competitive success among different RNA replicators would have depended on the relative values of these adaptive capacities. Subsequently, among more recent organisms competitive success at successive levels of biological organisation, presumably continued to depend, in a broad sense, on the relative values of these adaptive capacities.

Fundamentals

Empirically, a large proportion of the (complex) biological systems we observe in nature exhibit hierarchical structure. On theoretical grounds we could expect complex systems to be hierarchies in a world in which complexity had to evolve from simplicity. System hierarchies analysis performed in the 1950s, [9] [10] laid the empirical foundations for a field that would be, from the 1980s, hierarchical ecology. [11] [12] [13] [14] [15]

The theoretical foundations are summarized by thermodynamics. When biological systems are modeled as physical systems, in its most general abstraction, they are thermodynamic open systems that exhibit self-organised behavior, [16] and the set/subset relations between dissipative structures can be characterized in a hierarchy.

A simpler and more direct way to explain the fundamentals of the "hierarchical organisation of life", was introduced in Ecology by Odum and others as the "Simon's hierarchical principle"; [17] Simon [18] emphasized that hierarchy "emerges almost inevitably through a wide variety of evolutionary processes, for the simple reason that hierarchical structures are stable".

To motivate this deep idea, he offered his "parable" about imaginary watchmakers.

Parable of the Watchmakers

There once were two watchmakers, named Hora and Tempus, who made very fine watches. The phones in their workshops rang frequently; new customers were constantly calling them. However, Hora prospered while Tempus became poorer and poorer. In the end, Tempus lost his shop. What was the reason behind this?

The watches consisted of about 1000 parts each. The watches that Tempus made were designed such that, when he had to put down a partly assembled watch (for instance, to answer the phone), it immediately fell into pieces and had to be reassembled from the basic elements.

Hora had designed his watches so that he could put together subassemblies of about ten components each. Ten of these subassemblies could be put together to make a larger sub-assembly. Finally, ten of the larger subassemblies constituted the whole watch. Each subassembly could be put down without falling apart.

See also

Notes

  1. 1 2 Solomon, Berg & Martin 2002 , pp. 9–10
  2. ↑ Pavé 2006 , p. 40
  3. ↑ Huggett 1999
  4. ↑ Pavé 2006 , p. 39
  5. ↑ Postlethwait & Hopson 2006 , p. 7
  6. ↑ Witzany, G (2014). "Biological Self-organization". International Journal of Signs and Semiotic Systems. 3 (2): 1–11. doi:10.4018/IJSSS.2014070101.
  7. 1 2 Bernstein, H; Byerly, HC; Hopf, FA; Michod, RA; Vemulapalli, GK (1983). "The Darwinian Dynamic". Quarterly Review of Biology. 58 (2): 185–207. doi:10.1086/413216. JSTOR   2828805. S2CID   83956410.
  8. 1 2 Michod RE. (2000) Darwinian Dynamics: Evolutionary Transitions in Fitness and Individuality. Princeton University Press, Princeton, New Jersey ISBN   0691050112
  9. ↑ Evans 1951
  10. ↑ Evans 1956
  11. ↑ Margalef 1975
  12. ↑ O'Neill 1986
  13. ↑ Wicken & Ulanowicz 1988
  14. ↑ Pumain 2006
  15. ↑ Jordan & Jørgensen 2012
  16. ↑ Pokrovskii, Vladimir (2020). Thermodynamics of Complex Systems: Principles and applications. IOP Publishing, Bristol, UK.
  17. ↑ Simon 1969 , pp. 192–229
  18. ↑ Simon's texts at doi : 10.1207/S15327809JLS1203_4, polaris.gseis.ucla.edu/pagre/simon Archived July 5, 2015, at the Wayback Machine or johncarlosbaez/2011/08/29 transcriptions Archived 2015-05-31 at the Wayback Machine

Related Research Articles

<span class="mw-page-title-main">Outline of biology</span>

Biology – The natural science that studies life. Areas of focus include structure, function, growth, origin, evolution, distribution, and taxonomy.

<span class="mw-page-title-main">Ecology</span> Study of organisms and their environment

Ecology is the natural science of the relationships among living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely related sciences of biogeography, evolutionary biology, genetics, ethology, and natural history.

<span class="mw-page-title-main">Theoretical ecology</span>

Theoretical ecology is the scientific discipline devoted to the study of ecological systems using theoretical methods such as simple conceptual models, mathematical models, computational simulations, and advanced data analysis. Effective models improve understanding of the natural world by revealing how the dynamics of species populations are often based on fundamental biological conditions and processes. Further, the field aims to unify a diverse range of empirical observations by assuming that common, mechanistic processes generate observable phenomena across species and ecological environments. Based on biologically realistic assumptions, theoretical ecologists are able to uncover novel, non-intuitive insights about natural processes. Theoretical results are often verified by empirical and observational studies, revealing the power of theoretical methods in both predicting and understanding the noisy, diverse biological world.

The metabolic theory of ecology (MTE) is the ecological component of the more general Metabolic Scaling Theory and Kleiber's law. It posits that the metabolic rate of organisms is the fundamental biological rate that governs most observed patterns in ecology. MTE is part of a larger set of theory known as metabolic scaling theory that attempts to provide a unified theory for the importance of metabolism in driving pattern and process in biology from the level of cells all the way to the biosphere.

<span class="mw-page-title-main">Unit of selection</span> Biological entity within the hierarchy of biological organization

A unit of selection is a biological entity within the hierarchy of biological organization that is subject to natural selection. There is debate among evolutionary biologists about the extent to which evolution has been shaped by selective pressures acting at these different levels.

The philosophy of biology is a subfield of philosophy of science, which deals with epistemological, metaphysical, and ethical issues in the biological and biomedical sciences. Although philosophers of science and philosophers generally have long been interested in biology, philosophy of biology only emerged as an independent field of philosophy in the 1960s and 1970s, associated with the research of David Hull. Philosophers of science then began paying increasing attention to biology, from the rise of Neodarwinism in the 1930s and 1940s to the discovery of the structure of DNA in 1953 to more recent advances in genetic engineering. Other key ideas include the reduction of all life processes to biochemical reactions, and the incorporation of psychology into a broader neuroscience.

A metasystem transition is the emergence, through evolution, of a higher level of organization or control.

<span class="mw-page-title-main">Functional ecology</span>

Functional ecology is a branch of ecology that focuses on the roles, or functions, that species play in the community or ecosystem in which they occur. In this approach, physiological, anatomical, and life history characteristics of the species are emphasized. The term "function" is used to emphasize certain physiological processes rather than discrete properties, describe an organism's role in a trophic system, or illustrate the effects of natural selective processes on an organism. This sub-discipline of ecology represents the crossroads between ecological patterns and the processes and mechanisms that underlie them.

<span class="mw-page-title-main">Ecological stoichiometry</span>

Ecological stoichiometry considers how the balance of energy and elements influences living systems. Similar to chemical stoichiometry, ecological stoichiometry is founded on constraints of mass balance as they apply to organisms and their interactions in ecosystems. Specifically, how does the balance of energy and elements affect and how is this balance affected by organisms and their interactions. Concepts of ecological stoichiometry have a long history in ecology with early references to the constraints of mass balance made by Liebig, Lotka, and Redfield. These earlier concepts have been extended to explicitly link the elemental physiology of organisms to their food web interactions and ecosystem function.

Simon Asher Levin is an American ecologist and the James S. McDonnell Distinguished University Professor in Ecology and Evolutionary Biology and the director of the Center for BioComplexity at Princeton University. He specializes in using mathematical modeling and empirical studies in the understanding of macroscopic patterns of ecosystems and biological diversities.

Bacteriophages (phages), potentially the most numerous "organisms" on Earth, are the viruses of bacteria. Phage ecology is the study of the interaction of bacteriophages with their environments.

The following outline is provided as an overview of and topical guide to ecology:

<span class="mw-page-title-main">Biology</span> Science that studies life

Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments.

The evolution of biological complexity is one important outcome of the process of evolution. Evolution has produced some remarkably complex organisms – although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of cell types or morphology all proposed as possible metrics.

The Ramon Margalef Prize in Ecology is a prize awarded annually by the Generalitat de Catalunya to recognize an exceptional scientific career or discovery in the field of ecology or other environmental sciences. The award was created to honor the life and work of Ramon Margalef. The award has been presented every year since 2004 and comes with an honorarium of €80,000 and a sculpture representing a microalga, called Picarola margalefii. It is open to ecologists from anywhere in the world.

Living systems are life forms treated as a system. They are said to be open self-organizing and said to interact with their environment. These systems are maintained by flows of information, energy and matter. Multiple theories of living systems have been proposed. Such theories attempt to map general principles for how all living systems work.

A social-ecological system consists of 'a bio-geo-physical' unit and its associated social actors and institutions. Social-ecological systems are complex and adaptive and delimited by spatial or functional boundaries surrounding particular ecosystems and their context problems.

This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology, Glossary of environmental science and Glossary of scientific naming, or any of the organism-specific glossaries in Category:Glossaries of biology.

Hierarchy theory is a means of studying ecological systems in which the relationship between all of the components is of great complexity. Hierarchy theory focuses on levels of organization and issues of scale, with a specific focus on the role of the observer in the definition of the system. Complexity in this context does not refer to an intrinsic property of the system but to the possibility of representing the systems in a plurality of non-equivalent ways depending on the pre-analytical choices of the observer. Instead of analyzing the whole structure, hierarchy theory refers to the analysis of hierarchical levels, and the interactions between them.

Eco-evolutionary dynamics refers to the reciprocal effects that ecology and evolution have on each other. The effects of ecology on evolutionary processes are commonly observed in studies, but the realization that evolutionary changes can be rapid led to the emergence of eco-evolutionary dynamics. The idea that evolutionary processes can occur quickly and on one timescale with ecological processes led scientists to begin studying the influence evolution has on ecology along with the affects ecology has on evolution. Recent studies have documented eco-evolutionary dynamics and feedback, which is the cyclic interaction between evolution and ecology, in natural and laboratory systems at different levels of biological organization, such as populations, communities, and ecosystems.

References

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.