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In ecology, a biological interaction is the effect that a pair of organisms living together in a . Parasitism is a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is. Looking for online definition of octoploid in the Medical Dictionary? octoploid Meaning of octoploid medical term. Collins Dictionary of Biology, 3rd ed. reflect close relationships (Stebbins and Tobgy, ; Stebbins, , ; Hall , ; octonary · octonary · octonary number system · octonary signaling · Octonion. Evolutionary developmental biology is inevitably a comparative subject. The approach taken below in relation to both examples is to compare the Minelli and Bortoletto () devised an “octonary” model in which each.
Plants that produce grains, fruits and vegetables form humankinds basic foodstuffs, Plants play many roles in culture. They are used as ornaments and, until recently and in variety, they have served as the source of most medicines. The scientific study of plants is known as botany, a branch of biology, Plants are one of the two groups into which all living things were traditionally divided, the other is animals. The division goes back at least as far as Aristotle, who distinguished between plants, which generally do not move, and animals, which often are mobile to catch their food.
Much later, when Linnaeus created the basis of the system of scientific classification. Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, however, these organisms are still often considered plants, particularly in popular contexts.
When the name Plantae or plant is applied to a group of organisms or taxon. The evolutionary history of plants is not yet settled. Those which have been called plants are in bold, the way in which the groups of green algae are combined and named varies considerably between authors. Algae comprise several different groups of organisms which produce energy through photosynthesis, most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble land plants, but are classified among the brown, red and green algae.
Each of these groups also includes various microscopic and single-celled organisms 3. Flowering plant — The flowering plants, also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants, with families, approx.
The term angiosperm comes from the Greek composite word meaning enclosed seeds, the ancestors of flowering plants diverged from gymnosperms in the Triassic Period, during the range to million years ago, and the first flowering plants are known from mya. They diversified extensively during the Lower Cretaceous, became widespread by mya, angiosperms differ from other seed plants in several ways, described in the table. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants, the amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms.
The vascular bundles of the stem are arranged such that the xylem and phloem form concentric rings, in the dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex.
In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium, the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial.
Among the monocotyledons, the bundles are more numerous in the stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases, the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species, the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds.
The floral apparatus may arise terminally on a shoot or from the axil of a leaf, occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. There are two kinds of cells produced by flowers. Microspores, which divide to become pollen grains, are the male cells and are borne in the stamens. The female cells called megaspores, which divide to become the egg cell, are contained in the ovule.
The flower may consist only of parts, as in willow. Usually, other structures are present and serve to protect the sporophylls, the individual members of these surrounding structures are known as sepals and petals.
The outer series is usually green and leaf-like, and functions to protect the rest of the flower, the inner series is, in general, white or brightly colored, and is more delicate in structure.
It functions to attract insect or bird pollinators, attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower 4.
Cultivar — The term cultivar most commonly refers to an assemblage of plants selected for desirable characteristics that are maintained during propagation. More generally, cultivar refers to the most basic classification category of cultivated plants governed by the ICNCP, most cultivars have arisen in cultivation, but a few are special selections from the wild. Popular ornamental garden plants like roses, camellias, daffodils, rhododendrons, trees used in forestry are also special selections grown for their enhanced quality and yield of timber.
Cultivars form a part of Liberty Hyde Baileys broader grouping. Cultivar was coined by Bailey and it is regarded as a portmanteau of cultivated and variety.
A cultivar is not the same as a variety, a taxonomic rank below subspecies. In recent times, the naming of cultivars has been complicated by the use of statutory plant patents, the International Union for the Protection of New Varieties of Plants offers legal protection of plant cultivars to people or organisations who introduce new cultivars to commerce.
UPOV requires that a cultivar be distinct, uniform and stable, to be distinct, it must have characteristics that easily distinguish it from any other known cultivar.
Relationships Between Organisms
To be uniform and stable, the cultivar must retain these characteristics under repeated propagation, a cultivar is given a cultivar name, which consists of the scientific Latin botanical name followed by a cultivar epithet. The cultivar epithet is usually in a vernacular language, for example, the full cultivar name of the King Edward potato is Solanum tuberosum King Edward.
The King Edward part of the name is the cultivar epithet, the origin of the term cultivar arises from the need to distinguish between wild plants and those with characteristics that have arisen in cultivation. This distinction dates back to the Greek philosopher Theophrastus, the Father of Botany, botanical historian Alan Morton notes that Theophrastus in his Enquiry into Plants had an inkling of the limits of culturally induced changes and of the importance of genetic constitution.
In Species Plantarum, Linnaeus listed all the known to him. Most of the listed by Linnaeus were of garden origin rather than being wild plants. Over time there was an increasing need to distinguish between plants growing in the wild, and those with variations that had produced in cultivation. In the nineteenth century many garden-derived plants were given names, sometimes in Latin.
In the twentieth century an improved international terminology was proposed for the classification and it is essentially the equivalent of the botanical variety except in respect to its origin.
However, Bailey was never explicit about the etymology of the word, and it has suggested that it is a contraction of the words cultigen and variety 5. Skimmia — Skimmia is a genus of four species of evergreen shrubs and small trees in the Rue family, Rutaceae, all native to warm temperate regions of Asia.
The leaves are clustered at the ends of the shoots, simple, lanceolate, cm long and cm broad, the flowers are in dense panicle clusters, each flower small, mm diameter, with petals. The fruit is red to black, mm diameter, a drupe containing a single seed. All parts of the plant have a pungent aroma when crushed, the botanical name, Skimmia, is a Latinization of shikimi, which is the Japanese name for Illicium religiosum as well as an element in miyama shikimi, the Japanese name for Skimmia japonica.
Shrub or small tree to 15 m, shrub or small tree to 13 m. Skimmia reevesiana Skimmias are fed on by aphids, Horse Chestnut Scale, Garden Leafhopper, Skimmias are grown as garden plants for their foliage, flowers, and showy red fruits. They are grown in shade, with moist, well-drained, humus-rich soils and they are tolerant of both drought and air pollution.
Skimmia anquetilia - WikiVisually
Rutaceae — The Rutaceae are a family, commonly known as the rue or citrus family, of flowering plants, usually placed in the order Sapindales. Species of the family generally have flowers that divide into four or five parts and they range in form and size from herbs to shrubs and small trees.
The most economically important genus in the family is Citrus, which includes the orange, lemon, grapefruit, Boronia is a large Australian genus, some members of which are plants with highly fragrant flowers and are used in commercial oil production. Other large genera include Zanthoxylum, Melicope, and Agathosma, about genera are in the family Rutaceae, List of Rutaceae genera.
Most species are trees or shrubs, a few are herbs, the leaves are usually opposed and compound, and without stipules. Flowers are bractless, solitary or in cyme, rarely in raceme and they are radially or laterally symmetric, and generally hermaphroditic.
They have four or five petals and sepals, sometimes three, mostly separate, eight to ten stamen, usually separate or in several groups, usually a single stigma with 2 to 5 united carpels, sometimes ovaries separate but styles combined. The fruit of the Rutaceae are very variable, berries, drupes, hesperidia, samaras, capsules, and follicles all occur.
The family is related to the Sapindaceae, Simaroubaceae, and Meliaceae. The families Flindersiaceae and Ptaeroxylaceae are sometimes separate, but nowadays generally are placed in the Rutaceae.
The subfamilial organization has not been resolved, but the subfamily Aurantioideae is well supported. Non-citrus fruits include the White sapote, Orangeberry, Clymenia, Limeberry, other plants are grown in horticulture, Murraya and Skimmia species, for example.
Ruta, Zanthoxylum and Casimiroa species are medicinals, several plants are also used by the perfume industry, such as the Western Australian Boronia megastigma. The genus Pilocarpus has species from which the medicine pilocarpine, used to treat glaucoma, is extracted, spices are made from a number of species in the genus Zanthoxylum, notably Sichuan pepper.
Kallunki, phylogenetic relationships of Rutaceae, a cladistic analysis of the subfamilies using evidence from RBC and ATP sequence variation. Eudicots — The eudicots, Eudicotidae or eudicotyledons are a monophyletic clade of flowering plants that had been called tricolpates or non-magnoliid dicots by previous authors. The close relationships among flowering plants with tricolpate pollen grains was initially seen in studies of shared derived characters. These plants have a trait in their pollen grains of exhibiting three colpi or grooves paralleling the polar axis.
Later molecular evidence confirmed the basis for the evolutionary relationships among flowering plants with tricolpate pollen grains. The term means true dicotyledons, as it contains the majority of plants that have been considered dicots and have characteristics of the dicots, the term eudicots has subsequently been widely adopted in botany to refer to one of the two largest clades of angiosperms, monocots being the other.
The remaining angiosperms are sometimes referred to as basal angiosperms or paleodicots, the other name for the eudicots is tricolpates, a name which refers to the grooved structure of the pollen. Members of the group have tricolpate pollen, or forms derived from it and these pollens have three or more pores set in furrows called colpi. In contrast, most of the seed plants produce monosulcate pollen. The name tricolpates is preferred by some botanists to avoid confusion with the dicots, numerous familiar plants are eudicots, including many common food plants, trees, and ornamentals.
However, so far evolutionary developmental biology has had a relatively minor input into the traditional territory of population genetics, namely comparisons within species—both within and between geographic populations.
Yet this area is crucial, as all evolutionary novelties ultimately arise from intraspecific variation. Here, I address this issue, focusing on the question of how early in development novelties arise. To shed light on this question, I discuss two examples of developmental polymorphism within species involving two of the main body axes: A few of them will be major, many trivial. In the morphological domain, examples of novelties include the origin of feathers Brush,new cusp patterns in mammalian teeth Hunter and Jernvall, ; Jernvall, and altered numbers of antennule segments in copepod crustaceans Galassi and De Laurentiis, These are just a few of very many examples in the literature that are explicitly discussed as novelties.
Biological interaction - Wikipedia
Although the origin of novelties can be taken for granted, and although countless examples can be given, there is no universally accepted definition of evolutionary novelty, and those definitions that have been attempted often conflict with each other. For example, Mayrp.
Also, in my view, both definitions are too restrictive. Here, I will instead follow the more inclusive approach where novelties and apomorphies are regarded as essentially the same. I have previously put forward the hypothesis that there is a statistical but not absolute link between earliness of onset in development and magnitude of change in the adult: The examples discussed in the present paper—changes in centipede segment number and switches in gastropod chirality—lend support to this idea, but there is an important caveat relating to heterochrony.
Here, it is impossible to classify the change as either early or late. The shift from anamorphic to epimorphic groups see below involved the addition of segments plus a major heterochronic change from late to early development of the full complement of segments.
In contrast, the evolution of new segment numbers within the derived epimorphic groups has always involved early developmental changes. This variation may be persistent or fleeting. In either event, at the phenotypic level it can take any one of three well-known forms—continuous, meristic, or polymorphic discrete.
The examples of novelty that I discuss below tend to fall into the polymorphic category. However, there is a complication in the case of segment number. If the number of segments varies over only two or three values within a species, then the variation is polymorphic. However, if it varies over say fifty values then it may be more appropriate to consider it as meristic. Since examples of both are known in centipedes, respectively Brachygeophilus truncorum Arthur and Blackburn, and Hymantarium gabrielis Minelli, et al.
The relationship between developmental and genetic polymorphism deserves a brief mention here. In genetic polymorphism, these are usually different alleles at a given locus. In developmental polymorphism, they are different morphological forms—e. In some cases of genetic polymorphism e. Where developmental polymorphisms are indeed heritable, a relationship with genetic polymorphism necessarily exists but may be simple or complex, depending on whether the two or more morphological forms have their origin in allelic variation at a single major-effect locus or in a more complex, polygenic system.
Gastropod chirality is an example of the former see below. Centipede segmentation may well be an example of the latter, but this remains to be established. The approach taken below in relation to both examples is to compare the phylogenetic distributions of a clades characterized by particular novelties and b the existence of related intraspecific variation, in the form of developmental polymorphism. This approach reveals the extent to which the two can be connected and, complementary to this, the difficulties that remain in attempting to understand how novelties arise.
This pattern, in which the long, thin, subterranean geophilomorphs are derived, is the opposite of the pattern which found favour before a cladistic approach was used, in which the geophilomorphs were considered to be primitive. However, the pattern shown in Figure 1 now appears to be well founded, as it has been produced independently through three morphological cladistic analyses Dohle ; Shear and Bonamo, ; Borucki, and one molecular cladistic analysis based on rDNA: It should be noted that Shear and Bonamo describe an extinct sixth order of centipedes—Devonobiomorpha—but due to the fragmentary nature of the specimens it is not possible to ascertain their number of trunk segments.
Curiously, the number of trunk segments in centipedes is always odd Minelli and Bortoletto, ; Arthur and Farrow, However, it is possible that the total number of segments is always even. Also, it is possible that the head and genital areas, taken together, constitute a further 8 segments add 9 to all numbers shown in Fig. Further, it may be that segment anlagen are produced in a multiplicative manner, with the result that the final number of total segments is always even.
Variation in the number of such primordia might explain a large part of the pattern shown in Figure 1. Starting with a craterostigmomorph-like ancestor, addition of a single primordium would cause a shift from 15 to 23 scolopendromorphwhile a further such addition would cause a shift to 31 geophilomorphand subsequent additions could take the number of segments to progressively higher numbers within the geophilomorph range.
It is apparent from Minelli and Bortoletto's presentation of the data that the pattern of distribution in many families of geophilomorphs shows an excess of octonary forms, which supports their model. Intraspecific variation Intraspecific variation in segment number occurs only in the Geophilomorpha, and so is itself a novelty of that group. The only exception is the geophilomorph family Mecistocephalidae, whose species are invariant and which may be the cladistic outgroup to the rest of the order: It is thus the Geophilomorpha that provides possible model systems for studying the link between intra- and inter-specific variation.
An example of how congeners vary in trunk segment number is given in Table 1 for British species of the genus Geophilus compiled from Eason As can be seen, some species overlap extensively while others e. This suggests that some speciation events involve no shifts in segment number, others slight shifts, yet others major shifts perhaps again by 4 or 8 units.