Taxo-signi.htm
by George H. M. Lawrence, Professor of Botany at the Bailey Hortorium, Cornell University, 1951
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Lawrence-indx.htm
Taxonomy and its significance
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Interrelationships with other sciences
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Problems in taxonomy
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Opportunities
Plant Taxonomy - a modern view:
presented by UKT from
www.herbarium.usu.edu/teaching
augmented by articles from other sources.
UKT notes
• Flora
• Ontology
• Speciation
• Teratology
• Tree of Life
[{p006}]
Taxonomic study has among its objectives
the learning of the kinds of plants on
the earth and their names, of their distinctions
and their affinities, their distributions
and habitat characteristics, and the correlation
of these facets of knowledge with pertinent
scientific data contributed by research activities
of related fields of botanical endeavor. [UKT ¶]
UKT, 121218: Lawrence's book is now half a century old, and to many there is no sense in going through it other than for old-time's sake. Yet, I feel that if I were to include a modern view (as collected from various articles including those from Wikipedia -- I am not a botanist) it would be well worth reading. At the bottom of this chapter, I have added my presentation.
See my note on Tree of Life
In the beginning of the science of taxonomy, small fragments of plants were collected, and they, together with the scant notations on their labels, provided the basis of cursory herbarium studies and of initial records of the floras of large areas. It is now recognized that competent taxonomic work is the product of a knowledge of the plant as it grows naturally, of study of an adequate series of specimens representing it and its immediate allies, and of a synthesis of these data with other available pertinent data collated from related fields. The information accumulated from these studies is fundamental to the scientific knowledge of the inventory of the earth's plant resources.
A secondary objective of taxonomy is the assemblage of knowledge gained. This is usually in the form of treatises useful to fellow scientists and to civilization in general. The mere acquisition of the knowledge, the mere possession of the inventories, is sterile unless it is made available to others; only then is it of use and an aid to the progress of civilization. [UKT ¶]
This conversion of taxonomic data from a status of sterility to fertility is accomplished in many ways. Floras are published to account for the plants of a given area; manuals are prepared that the plants of an area may be the more readily identified and named; revisions and monographs are published that one may know the extent and delimitations of a particular group and its components; distributional studies are published that others may know of range extensions, corrections, and interrelationships of the taxa within an area. [UKT ¶]
In addition to these, there are built up great collections of pressed specimens of the plants that serve as the basis of the scientific studies and publication, collections that become the [{p007}] cornerstones of the work published, for they are the proof and the evidence of the identity of the material concerned. All these products of taxonomic research add to the resources available to the scientist. They are essential to any study of the natural resources of an area, to studies of land potentials, to evaluations of resources of raw materials possibly suited to man's needs in a multiplicity of activities (as, for example, forest products, medicines, food, ornamentals, agricultural crops, and industry). As long as world populations increase and areas of low population density exist, man will demand an increasing quantity of biological data concerning those areas of low population density -- data that will serve as factors influencing human migrations. For purposes of comparison, he will demand also similar current information on the more densely populated areas.
A third, and scientifically basic, objective is the demonstration of the tremendous diversity of the plant world and its relation to man's understanding of evolution. An organized reconstruction of the plant kingdom as a whole can be made only after the inventory of its components (the plants) has been assembled. When this has been done, the charting of the degree and character of variation will demonstrate its diversity, and these data can then be integrated with other facets of evolutionary knowledge to produce a more accurate phylogenetic schema.
Taxonomy is dependent on many other sciences and they in turn are equally dependent on it. A taxonomist must have a knowledge of morphology; he must know not only the gross morphology of the plants with which he works, but if he is to comprehend the relationships of these plants he must often be conversant with studies of their embryology, floral anatomy, ontogenetical development, and teratological variations. [UKT ¶]
See my notes on Ontology and Teratology
Modern systematists place considerable value on the importance of cytogentic findings as criteria in delimiting the species and its elements; data of this character have proved to be of inestimable value in demonstrating the presence and taxonomic significance of exceptional chromosomal situations and of breeding behavior over successive generations. In this connection attention has been focused on the significance of the correlation of these studies with the responses of genetically uniform plants when grown simultaneously in an assortment of environments. [UKT ¶]
By means of these correlations, the less significant environmental characters may be segregated from the more fundamental characters of genetic origin. This segregation has resulted in a shift of emphasis from the viewpoint [{p008}] that the species is of morphological distinction only to that of its being a biological unit of combined morphological and genetical distinctions. In addition to an appreciation and understanding of the contributory value of morphological, anatomical, and cytogenetical findings, modern taxonomic studies reflect the significance of distributional patterns and of more detailed data concerning the extent of normal variation and its causes. All these wider viewpoints demonstrate the increasing dependence of taxonomy on the findings of related sciences; the product of modern taxonomic research is rapidly becoming one of synthesis rather than of individual conclusions.
Taxonomy is one of the older botanical sciences. Its development followed closely that of the exploration of the earth's surfaces. Prior to the explorations into the New World, man's knowledge of plants was restricted for the most part to the plants of the greater Mediterranean area and extensions from it. [UKT ¶]
UKT: You will note that the European mind which used to look up to the Orient, ceases to think of the older civilizations of India (and Myanmarpré), and China. The colonialists had completely ignored the very existence of much civilized people with far better philosophies. -- UKT121224
Communications with new lands accompanied exploration and colonization. Collections of natural resources were sent back to homelands. As the number of new plants received from these outlying areas multiplied and the information about them increased, the older systems for their classification and naming became inadequate. These were replaced by successively more adequate and at the same time more complex systems. During the eighteenth and early nineteenth centuries the studies we now call taxonomic dominated the field of botanical activity. However, it was not long before interest in the subject was surpassed by interest in the new and related fields. This was particularly true in those fields opened by Darwin's and Wallace's theories of evolution, by DeVries' theories of origin of mutation, by Mendel's laws of heredity, and by rapid developmental improvement in equipment and techniques, especially the microscope, whereby could be observed the nature of chromatin material within nuclei and more recently perhaps even the genes themselves. [UKT ¶]
A half century ago many biological workers believed that most of the vascular plants of the world were then known, that the taxonomist occupied himself with efforts to differentiate between twiddledum and twiddledee, and that when not so busied was annoying others and inflating his ego by changing names, splitting species, or merely "working over old hay." Recent decades have witnessed a revival of interest in the science; a revival engendered in part by renewed explorations, by the recognition that taxonomic groups are biological entities and [{p009}] not merely morphological aggregates, by a re-evaluation of phylogenetic criteria in which wholly new concepts of group relationships have materialized, by extended field studies correlating morphological variations with environmental and distributional factors, and by a realization of the significance of synthesis of all these related data toward the resolution of the problems of systematics in the world's vascular flora.
The vascular flora of the earth is not at all so well known as the many savants of a half century ago believed. Vast areas of South America, Africa, the large island groups that comprise Occeania, Australasia, and much of western Asia are recognized today as botanically little known. To bring the problem closer home, and despite the existence of published floras for some of the areas, the lands of Central America and of Mexico have not been well explored for their plants; every year finds literally scores of species wholly new to science being described from collections made in these regions. Domestically, the components of the vascular flora of the southeastern region of the United States are not adequately known, those of Alaska are only beginning to become known, and much territory in western Canada remains to be surveyed for its plants. In all these areas the problems of floristics are many and challenging.
The taxonomist is interested in the problems associated with the distribution of plants, for distributional data may be related closely to the migrations of plants. Knowledge of plant distributions is pertinent to the determination of geographic areas of origins of species, of genera, and often of families -- all factors that are important in determining matters of genetical relationships. These studies in distribution and geography bring taxonomy into the field of phytogeography, the inquiry into why a group occupies the area that it does, how long it has been there, how rapidly it is migrating, and what evolutionary trends it is showing. Studies with this wider viewpoint represent a synthesis of ecologic, genetic, and taxonomic aspects leading to a better understanding of a series of common problems.
The subject of speciation has always presented a problem to the taxonomist. The literature that has accumulated in the attempt to answer the question of "what is a species?" is voluminous, and by no means are the answers in accord. [UKT ¶ ]
UKT: See my note on Speciation
Long has it been said that species are judgments, which is another way of saying that there can be as many definitions and concepts of a species as there are taxonomists. The newer systematics, based on the premise that species are not judgments, but rather are biological units that have evolved from a series of often identifiable ancestors, [{p010}] has postulated certain hypotheses by which the smaller taxa of plants (genera, species, and their subdivisions) may be circumscribed by a combination of genetical, ecological, and morphological criteria. [UKT ¶ ]
A species is considered, by supporters of these views, to be an objective definitive unit. However, analysis of their work fails to reveal any application of complete objectivity, and the taxa they would label as species do represent judgments to a degree. Nonetheless, their efforts toward objectivity have produced noteworthy milestones in taxonomic progress. The application of their criteria has placed taxa of more or less equivalent biological significance in their respective categories. These categories take on a more definite meaning, they have a biological significance, and plants assigned to them can be expected to follow prescribed patterns of behavior; large and unwieldy groups can be reorganized into biologically related taxa, and order can be expected slowly but definitely to emerge from confusion. The application of these principles of biosystematics requires infinite time, care, and patience, and may represent the long-term and ultimate solution to many taxonomic problems concerning genera known to be genetically less stable than others. In the interim until such data are available, the older and more orthodox principles of taxonomy will remain in effect; they must remain in effect because there is as yet no substitute for them. [UKT ¶ ]
The scores of thousands of plants recognized today as species have been established by the application of existing and established principles of taxonomy. These principles are employed by the biosystematists in selecting the taxa with which they work and by which they measure -- to a degree -- the progress of their research. The use of orthodox and conventional principles is the only means whereby immediately useful and applicable results of taxonomic research can come to fruition. The problems awaiting the test of the principles of biosystematics are many, some are more acute than others, and in them the opportunities for basic taxonomic research are unlimited.
The resolution of the accumulated knowledge of the earth's flora is far from perfect, and will become, more perfect only by, first, exploration of its areas, collection of its components, their study and classification, and second, by the publishing of competently prepared floras, manuals, revisions, and monographs of elements of its flora. Large areas of our continents have no published accounting of their floras, others have none less than 50 to 100 years old, and the probability is that as many more [{p011}] plants have been discovered for these latter areas since the time of their publication as were accounted in them. In focusing attention on taxonomic problems that are close to home, it should be noted there is no flora of Mexico, nor of Canada, nor even of the United States. [UKT ¶]
Domestically, we do have floras accounting for the flowering plants of many of our states; many of these are old, others were based on herbarium collections and unsupported by careful field observations, some states have no flora published within the last century, and a few have no published flora at all. The problems in these fields of taxonomic activity are many and acute, and they are within the reach of every student of taxonomy. In this connection it should be noted also that some of our currently best local or county floras have been the result of assiduous field studies and collections by amateur botanists. Similar problems await resolution by the trained taxonomist who is interested in monographic work. There is a great need for competently prepared revisions and monographs of a large number of genera and families.
In addition to these problems open to and currently requiring the abilities of the trained and amateur taxonomist who is interested in the indigenous flora, there are equally important and abundant problems open the trained taxonomist who will work with cultivated plants. Too often the botanist will avoid the exotic or lowly cultivated plant, deprecating it as "rubbish" or not deigning to attempt to identify and name it because, not knowing where it was native, he does not know what flora or manual would account for it; another would consider it to be a monstrosity, a hybrid, or clonal selection and hence beyond the pale with respect to his abilities. [UKT ¶ ]
Despite and because of these ill-conceived defenses by many taxonomists the challenge to identify cultivated plants is paramount. Here is a fertile and too-long neglected field for taxonomists to enter. Few taxonomists have any degree of intimate acquaintance with the world's flora, but rather are inclined to become specialists in the flora of a particular region or for a particular group; it is an easier and surer path. [UKT ¶ ]
The cultivated flora has no geographic boundaries; it has been brought in by man from all of the continents. Surprisingly enough, of the scientifically named species current in the domestic trade, the great majority of them can be reasonably well aligned with their indigenous counterparts. To be sure, vernacularly named variants representing all manner of genetic potpourri and devoid of all vestiges of apparent relationship to indigenous ancestors, are found in some groups (such as chrysanthemums, wheat, corn, apples) but their generic affinities are [{p012}] readily recognized and their speciation -- if any -- is of minor concern. The solution to the problem of the systematics of cultivated plants would appear to lie with the production of more and better world monographs and revisions of families and genera, and by increased attention on the part of trained taxonomists to the needs of the economic botanist and horticulturist.
From: www.herbarium.usu.edu/teaching/4420/planttaxonomy.htm 121218
Last modified: 121218
author: unknown.
UKT note: The author writes in first person, and I am finding it confusing when his name is unknown. -- UKT121224
Plant taxonomy is about grouping plants. The primary goal of a plant taxonomist is to try and summarize the variation in the plant world and express it in a manner that reflects the phylogenetic relationships among the various taxa observed. Let us look at the last sentence in more detail.
The most obvious variation is the morphological variation, in other words, variation in size, shape, and color. But plants also vary in the chemical compounds that they produce (think how different our plant foods taste), their biosynthetic pathways, and reactions to stimuli. There is also variation in how their embryos develop, how they undergo meiosis, how they protect their leaves from sunburn, what triggers flowering, etc., etc., etc.
Taxonomists would like to include all aspects of a plant's variation in their considerations but, in practice, most concentrate on a particular set of characters. Those concerned with fieldwork and identification are apt to stress the variation in morphological and ecological characters; those involved in plant breeding will often focus on chromosome numbers, sizes, and shape; those concerned most with phylogeny currently focus on variation in gene sequences. That is because most of the preferred methods of numerical phylogenetic analysis are not well suited to examination of morphological characters.
In essence, the ancestor-descendant relationships of groups of organisms. Phylogenetic relationships are similar in concept to genealogical relationships, in that they are the relationships that exist among organisms as a consequence of their ancestor-descendant relationships. In practice, however, we use the term phylogenetic relationships when we are considering relationships among groups of organisms, and genealogical relationships when we are thinking of individuals, particularly human individuals.
There are, of course, a few small problems in trying to determine phylogenetic relationships among plants. For instance, plants do not keep genealogical records. We have to infer their genealogy from the variation we observe. We need to appreciate, however, that many plants have amazing reproductive versatility. Many can reproduce both asexually and sexually; the seeds developing in a single fruit may have more than one paternal parent; hybridization is not uncommon; polyploidy is normal in some groups; asexual reproducers can acquire strange genetic material and, eventually incorporate it into their own chromosome structure. Then, in a rare sexual event, pass it on to others of its kind. Current methods of phylogenetic analysis assume that hybridization rarely contributes to evolution. This is frequently untrue in plants.
An additional complication of trying to assess the phylogenetic relationships among groups of organisms, such as species or genera is that one must first be confident that one knows what entities belong to the group and that all members of one's group are descended from the same ancestor. If you think that you are working with one species (or one genus) when, in reality, you are working with two, your analyses will either yield very confusing results (possibly the safest kind of results because they will make you look further), suggest the wrong answer, or suggest the right answer - purely by chance.
At this point, let me introduce a new term: Taxon, the plural of which is taxa. A taxon is a taxonomic group [to be defined soon], rank unspecified. It can be used when you do not know the taxonomic rank involved or when the statements being made refer to all taxonomic ranks. It takes much less time to write, and say, 'taxon' than 'taxonomic group' or 'species, genera, and other ranks' so, from here on in, I shall use it.
Some botanists argue that taxonomy is about circumscribing the groups to be used whereas systematics is the study of relationships among groups. I consider this is a false dichotomy and consider both activities as falling within the purview of taxonomy, but I am in the minority so will defer to the majority. Keep in mind, however, that a systematic study cannot be better than the quality of taxonomy used. In this course we shall be concerned primarily with learning to recognize taxa and the processes usually used to determine what constitutes a good plant taxon rather than with the methods used in attempting to elucidate the phylogenetic relationships among taxa. Please note the restriction to plant taxa; the methods used vary with the organisms being studied.
A good taxon has predictive value. This means that, if you know to which taxon a plant belongs, you should be able to predict many of its characteristics, including characteristics that were not considered when the taxon was originally described.
Most of the taxa that we work with today were formed by looking at morphological characteristics. In other words, by considering how the plants looked. Plants that looked more like each other than other plants were placed in the same taxon. We still usually take this as a starting point, largely because we are visually oriented organisms. We can quickly assess, and describe, things that we can see. Dogs might place greater emphasis on smell.
This approach sometimes lead to arguments about whether it is more important to be alike in leaf shape or number of stamens. There is no objective means for deciding between the two. [UKT ¶ ]
What one does then is look at another character, one that, so far as one can tell is unrelated to the two conflicting characters. One might, for example, consider the ability to produce a particular kind of chemical or possession of a particular distribution of hairs. Let's consider the chemical compound character. If the chemical is common in individuals with a particular leaf shape, but absent from those with different leaf shapes, this would reinforce the notion that plants with the particular leaf shape and chemical constitute a good taxon even if they differ in the number of stamens that they have. It is not proof that these plants form a good taxon, just additional evidence that they do so.
Notice that I introduced a non-morphological character in the above paragraph, possession of a particular chemical compound. Taxonomists often consider non-morphological characters, but most of our work is with morphological characters because, as was stated above, we are visual organisms. It is easy, relatively quick, and inexpensive (often an important consideration) to assess morphological similarity.
Two other characters that are frequently given a lot of weight, particularly by field-oriented taxonomists, are ecology and geographic distribution. If what is thought to be one taxon is found growing in two distinct habitats, for instance beside streams and on dry mountain slopes, one might suspect that two different taxa are involved. Again, it is not proof that there are two different taxa involved, but it should stimulate further study. Similarly, if the same taxon is identified as growing in two widely separated locations (the two sides of North America or in North and South America), it is worth examining more closely whether other evidence supports their inclusion in a single taxon. Disjuncts exist, but it is also possible that some differences are being overlooked.
In a word, inheritance. Taxa inherit their characteristics from their ancestors. There are some mutations, both gain and loss, and chromosomal re-arrangements that can lead to changes in morphology, biochemistry, physiological (and hence ecological) abilities, but these changes occur in a pre-existing genetic make-up. So, just as children are generally more like their parents and close relations more like each other than distant relations, so species are usually more like their ancestral and closely related species than distantly related species. Yes, this is a simplistic statement, but it is a good place to start.
I have used the term 'character' fairly frequently in the above paragraphs. It is worth spending some time considering what a character is, and what it is not. Scientists do tend to use it in different ways. If you are aware of the different meanings that it may have, you will find it easier to determine how a particular author is using it.
As I use it, a character is a feature that can be measured, counted, described, or otherwise expressed. It is an abstract entity. Petal color is a character. Plant height is a character. Position 33 from the end of a gene is a character. Red is not a character; it is a character state.
UKT: The author uses two terms: character & state . As examples he states:
Color of petal, or petal-color is a character.
The color-red is a state .
I have hyphenated the words above. Thus, leaf-color would be a character, and in some plants, the color-yellow is the state of the leaf.
Characters have states. Red could be a character state for the character petal color; 3 cm could be a state for the character plant height 3 cm; cytosine is a possible character state for position 33 on a gene.
In taxonomy, some characters are more equal than other characters, but which characters these are varies from group to group. First of all, one needs to decide if a character is a good taxonomic character for the plants that one is studying. What makes a character a good taxonomic character? A good taxonomic character is one that is useful in determining to which group a plant belongs. Davis and Heywood (1973) suggested four criteria:
1. The character varies less within putative groups than between them. If this is not the case, either the character is not useful or the groups are bad.
2. The character is genetically determined but does not have a high intrinsic genetic variability. For instance, if the offspring of the same pair of parents can have different states for the character, the character is not taxonomically useful.
3. The expression of the character is not significantly modified by the environment.
4. The pattern of variation in the character being examined correlates with the pattern of variation in other characters.
UKT 121224:
Right now, my interest is in languages. Thus, I am comparing a language such as Bur-Myan to a vascular plant. Mon-Myan is another language. Bur-Myan belongs to the Tib-Bur linguistic group. What about Mon-Myan? Does it belong to Tib-Myan? It is stated that it belongs to Austro-Asiatic. I am comparing it to Skt-Dev of the IE linguistic group. I am using two lines of consonants, the r1 & r2: the shapes of glyphs and their pronunciation. The shape and pronunciation as character . Compare r1c3, r1c4, r1c5, & r2c1, r2c2, r2c3, r2c4, r2c5. -- UKT121224
As Davis and Heywood pointed out, there is circularity in taxonomy; it is inherent in criteria 1 and 4. But spiral staircases are circular; they are still an effective means (though somewhat giddymaking) of moving from one floor to another. Circularity in taxonomy is of the spiral staircase kind.
Good for what?
The above discussion refers to taxonomic characters. Characters are also used for other purposes than circumscribing taxa, for instance for identification, diagnosis, and description. What qualities would you look for in characters used for these purposes?
Everyone realizes that some plants are
more alike than others. I suspect that
most of you can distinguish a pine from
other conifers. This statement implies
that you can recognize two levels of
grouping - one that consists of different
kinds of pine and then a more inclusive
group, conifers, that includes pines plus
many other kinds of conifer. [UKT ¶ ]
One way to recognize such differences in degrees of similarity is to recognize groups as having different ranks. Taxa at the lowest ranks consist of plants that are very alike; taxa at the higher ranks include more plants but these plants are not as similar to each other as the plants within taxa at the lower ranks.
The highest rank recognized nowadays is the Domain. Plants belong to the Eukaryote Domain, as do humans. [UKT ¶]
UKT: The inset shows the Tree of Life separated into Three domains .
-- http://en.wikipedia.org/wiki/Tree_of_life 121224
Below this comes the kingdom. Plants belong to the kingdom of plants - surprise! Humans belong to the kingdom of animals. The kingdom of plants is now restricted to such things as flowering plants, gymnosperms, mosses, liverworts, and green algae. It used to include fungi and all the algae. There are then additional ranks until one gets to the lowest formal rank, one that is rarely ever used but is theoretically possible, a subform.
The rank to which a taxon belongs determines how its name is structured. For more on this, see botanical nomenclature.
AN IMPORTANT POINT
Taxonomy as we know it is a human endeavor. It represents our attempt to make sense of the biological diversity around us. Over the centuries it has been found that certain approaches to achieving this understanding are more productive than others. These approaches require an understanding of biological principles, but they also help us acquire a better understanding of biology. It is in this sense that taxonomy can be considered a science. It is, however, a science in which two individuals faced with the same information may draw different conclusions as to how much variation should be included in the same taxon. Taxonomists have to accept diversity of opinion as a fact of life.
You must also recognize that no one gave plants a set of instructions as to how they should behave, how they should restrict their reproductive endeavors, and how variable they could be. During the semester, you will become aware that plants are remarkable for their versatility and plasticity. This frequently frustrates the efforts of humans to place them in neat and tidy boxes. It is, however, these abilities that enables plants to grow in so many different habitats and to survive extremes of climate even though they cannot run away and hide in a cave or climate-controlled construction (aka a house).
UKT: End of article
From Wikipedia: http://en.wikipedia.org/wiki/Flora 121218
Flora
is the plant life occurring in a particular
region or time, generally the naturally
occurring or indigenous -- native plant life.
The corresponding term for animal life is
fauna. Flora, fauna
and other forms of life such as fungi are
collectively referred to as
biota. Bacterial organisms, algae,
and other organisms are sometimes referred
to as flora,
[1]
[2]
[3]
so that for example the terms bacterial flora
and plant flora are used separately.
"Flora" comes from the Latin name of Flora, the goddess of plants, flowers, and fertility in Roman mythology.
Plants are grouped into floras based on region, period, special environment, or climate. Regions can be geographically distinct habitats like mountain vs. flatland. Floras can mean plant life of a historic era as in fossil flora. Lastly, floras may be subdivided by special environments:
• Native flora. The native and indigenous flora of an area.
• Agricultural and Horticultural flora (garden flora). The plants that are deliberately grown by humans.
• Weed flora. Traditionally this classification was applied to plants regarded as undesirable, and studied in efforts to control or eradicate them. Today the designation is less often used as a classification of plant life, since it includes three different types of plants: weedy species, invasive species (that may or may not be weedy), and native and introduced non-weedy species that are agriculturally undesirable. Many native plants previously considered weeds have been shown to be beneficial or even necessary to various ecosystems.
UKT: More in the Wikipedia article
Go back flora-note-b
-- UKT 121224
Can we compare the development of a single
fertilized egg into a human embryo, to the
development of a civilization, of a country,
of a group of people, or of a language?
Ultimately, the developed unit matures, and
finally death ensues. The original Tibeto-Burman
Burmese-Myanmar language had been under
the influence of Magadhi, and then it was
assaulted by Sanskrit and Mon-Myan which
has strong parallels to Sanskrit. Then
starting from about 200 years ago, it came
under the strong influence of English, which
itself has been changing as it is becoming
international. Will the language of
our forefathers eventually die? And what
would be causes for its early demise?
From Wikipedia: http://en.wikipedia.org/wiki/Ontogeny 121224
Ontogeny (also ontogenesis or
morphogenesis) is the origin and
the development of an organism – for example:
from the fertilized egg to mature form. It
covers in essence, the study of an organism's
lifespan. The word "ontogeny"
comes from the Greek ὄντος,
ontos, present participle singular of
εἶναι, "to be";
and from the suffix -geny, which expresses
the concept of "mode of production".
[1] [UKT ¶]
In more general terms, ontogeny is defined as the history of structural change in a unity, which can be a cell, an organism, or a society of organisms, without the loss of the organization which allows that unity to exist. [2] More recently, the term ontogeny has been used in cell biology to describe the development of various cell types within an organism. [3]
Ontogeny
comprises a field of study in disciplines
such as developmental biology, developmental
psychology, developmental cognitive neuroscience,
and developmental psychobiology.
Within biology, ontogeny pertains to the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of species. In practice, writers on evolution often speak of species as "developing" traits or characteristics. This can be misleading. While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes [4] (see evolutionary developmental biology), individual organisms develop (ontogeny), while species evolve (phylogeny).
UKT: End of Wikipedia article
Go back ontology-note-b
From Wikipedia: http://en.wikipedia.org/wiki/Speciation 121224
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or "cladogenesis," as opposed to "anagenesis" or "phyletic evolution" occurring within lineages. [1] [2] Whether genetic drift is a minor or major contributor to speciation is the subject matter of much ongoing discussion.
There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments. Observed examples of each kind of speciation are provided throughout. [3]
UKT: More in the Wikipedia article
Go back speciation-note-b
From: Wikipedia: http://en.wikipedia.org/wiki/Teratology 121224
Teratology is the study of abnormalities of physiological development. It is often thought of as the study of human birth defects, but it is much broader than that, taking in other non-birth developmental stages, including puberty; and other non-human life forms, including plants. A newer term developmental toxicity includes all manifestations of abnormal development, not only frank terata. These may include growth retardation or delayed mental development without any structural malformations. [1]
UKT: More in the Wikipedia article.
Go back teratology-note-b
From Wikipedia: http://en.wikipedia.org/wiki/Tree_of_life 121224
The concept of a tree of life has been used in science, religion, philosophy, and mythology. A tree of life is a common motif in various world theologies, mythologies, and philosophies. A mystical concept alluding to the interconnection of all life on our planet; and a metaphor for common descent in the evolutionary sense. The term tree of life may also be used as a synonym for sacred tree. [1]
The tree of knowledge, connecting to heaven and the underworld, and the tree of life, connecting all forms of creation, are both forms of the world tree or cosmic tree, according to the Encyclopædia Britannica, [2] and are portrayed in various religions and philosophies as the same tree. [3]
UKT: Do the Theravada Buddhists of Myanmarpré believe in a tree of of life? Not that I know of -- but my knowledge is meagre. But I think it could still be compared to the idea of
{þän-þa.ya}, and the "beings" are either going upwards because of good deeds, and falling backwards because of misdeeds. I wait for comment from my peers. -- UKT121224
UKT: More in the Wikipedia article
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