Origin of life on earth evolution of life on earth adaptive radiation biological evolution origin and evolution of man timeline of evolution. Phylogeny and evolution of ferns monilophytes with a focus on the early leptosporangiate divergences. Scott 1900, eames 1936, however do not trace their origin from any particular group of algae. It is speculated that life began in the oceans, and through millions of years of evolution, life slowly adapted on to dry land. All these very large evolutionary jumps are discussed on the basis of the phyletic gradualist neodarwinian theory and other genetic evolutionary mechanisms. Pteridophytes or pteridophyta, in the broad interpretation of the term or sensu. Evolution of bryophytes according to these theories the evolution in bryophytes is as follows. Explanations for the diversity of reproductive systems in flowering plants in terms of a tradeoff between shortterm adaptive benefit and longterm flexibility were attractive, in part, because they emphasized the synergistic role of reproductive systems in plant evolution. There are two theories regarding evolution of bryophytes.
Demystifying the evolution and diversification of epiphytic ferns is essential to a full understanding of the leptosporangiate success story. Pteridophytes biology encyclopedia plant, body joilethbwinmi. Pteridophyte definition is any of a division pteridophyta of vascular plants such as a fern that have roots, stems, and leaves but lack flowers or seeds. Pteridophyta is the most highly evolved group among the cryptogams. Ferns, horsetails, and lycophytes are all pteridophytes. Stelar evolution in pteridophytes easy biology class.
Consider the evolution of the cregion gene agamous ag. However, they do not form a monophyletic group because ferns are more closely related to seed plants than to lycophytes. Pteridophytes may represent the closest living relatives sister group to the seed plants. They formed the dominant part of the earths during palaeozoic and mesozoic periods. Pteridophyte definition and meaning collins english. Charophyte evolution and the origin of land plants. The body of the sporophyte is well differentiated into roots, stem and leaves. Types of stele and its evolution in pteridophytes duration.
Pdf a short history about the evolution of gymnosperms. Another difference between pterophyta and higher plants is that many species belonging to the pterophyta have a vegetative 1 sorus plural sori. O stele is the central cylinder or core of vascular tissue in higher plants. Mar 05, 2016 origin of life on earth evolution of life on earth adaptive radiation biological evolution origin and evolution of man timeline of evolution. The pteridophytes ferns and fern allies pteridophytes are vascular plants and have leaves known as fronds, roots and sometimes true stems, and tree ferns have full trunks. As they produce neither flowers nor seeds, they are referred to as cryptogams. A pteridophyte is a vascular plant with xylem and phloem that disperses spores. The worlds quarter of a million vascular plant species display an incredible diversity of life histories, growth forms, and physiologies, but the diversity of their reproductive systems is at least as great. The stele is a real entity and present universally in all axis of higher plants. Stelar evolution in vascular plants origin and evolution of stele in pteridophytes and higher plants what is stele. It is our hope that it will inspire innovative research on these plants at this critical time where human activities are transforming biodiversity as we know it. Occurrence and evolution of pteridophytes biology boom. Pteridophytes, also known as vascular cryptogams and ferns and fern allies, comprise about 12 000 species of vascular plants that do not produce.
These genes are present even in pteridophytes, but the spread and diversity is many times higher in angiosperms. The evolution of the madsbox family has been extensively studied. The pteridophytes ferns and fern allies pteridophytes are vascular plants and have leaves known as fronds tertium organum pdf portugues, roots and sometimes true stems. Sporophylls the leaves that bear sporangia are known as sporophylls. Today this subject is controversial, and scarcely considered in textbooks and journals of botany, in spite of its importance. From a simple plant body consisting of only a few cells, land plants liverworts, hornworts, mosses and vascular plants evolved an elaborate twophase life cycle and an extraordinary array of complex organs and tissue. Although it is now widely accepted that the charophyceae are a sister group to the land plants, there is considerable disagreement over the systematics of different charophycean taxa and whether a chara or coleochaetelike alga was. Stelar theory also says that the cortex and the stele are the two fundamental.
Pith formed may be inter stellar in origin or by invasion of cortical tissue. A mono phyletic origin of wings is rejected since they. Ncert general science origin of life on earth the universe is very old almost billion years old. International research botany group 2017 international. A pteridophyte is a vascular plant that disperses spores. O the stele consists of xylem, phloem, pericycle and medullary rays and pith if present. Reproductive systems and evolution in vascular plants pnas. Such premolecular era evodevo approaches led to several hypotheses for the evolution of leaves. Sporophyte evolution one of the most important innovations of early bryophytes was a multicellular sporophyte fig. The origin of the sporophyte in land plants represents a fundamental phase in plant evolution.
In some pteridophytes the sporangia develop on stems i. The evolution of plants has resulted in a wide range of complexity, from the earliest algal mats, through multicellular marine and freshwater green algae, terrestrial bryophytes, lycopods and ferns, to the complex gymnosperms and angiosperms of today. This site is like a library, use search box in the widget to get ebook that you want. Seed bearing plants have been prominent in nearly all terrestrial ecosystems from the paleozoic era to today. As i see it, the change in our attitude to theories of evolution rests principally in a new. As in seed plants, the greatest diversity of pteridophytes is found in the tropics, with only about six hundred species adapted for life in temperate climates. Pteridophytes ferns and lycophytes are freesporing vascular plants that have a life cycle with alternating, freeliving gametophyte and sporophyte phases that are independent at maturity. This chapter describes how the elements that made up the solar nebula were formed. However, additional phylogenetic dilemmas are the evolution of bryophytes from algae and the transition from these first land plants to the pteridophytes. Pteridophytes as commonly defined have a longer evolutionary history with a fossil record of more than 400 million years. Seeds, pollen, and wood in the long evolutionary history of plants, few developments have had more profound consequences than the evolution of seeds and pollen.
In the past 10 years, with the use of all available ways, especially the advances in molecular systematics, many important progress toward a more complete understanding of the circumscription. The more primitive ferns are called eusporangiate ferns and their sori are made up of a clump of simple sporangia that release their spores by opening up a pore or slit see first pic. Problems of cytology and evolution in the pteridophyta. In some ferns, individual haploid gametophytes produce both eggs and sperm. The origin of the sporophyte in land plants represents a fundamental phase in plant. Types of stele and its evolution in pteridophytes youtube. As the first true land plants, they offer a very favourable material for the study of various adaptations that have made the colonization of land possible for the plants. Pdf molecular evolution of pteridophytes and their relationship to. The defining features of bryophytes are that their life cycle featuring alternating haploid and diploid generations with a dominant, branched gametophyte stage. Two simple steps can account for the evolution of this new structure. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as cryptogams, meaning that their means of reproduction is hidden.
Systematics and evolution of lycophytes and ferns schneider. This chapter considers the origin and evolution of the key innovations of seed plants and surveys the diversity of living gymnosperms. The primary components of stele are xylem and phloem. A monophyletic origin of the homosporous lycopodium and heterosporous lycopsid lineage selaginella, iso6tes is indicated in both anal yses, but only the. Pteridophytes continued to dominate most terrestrial floras long after the origin of seed plants tables 3 and 4. First, meiosis must be delayed in the zygote, which, as you recall, is retained on the parent gametophyte in land plant ancestors. Problems concerning the origin and evolution of any plant group have not been solved to date, to the satisfaction of all. They formed the dominant part of the earths during palaeozoic and mesozoic periods on soral evolution. Namboodiri and beck 1968c, and beck 1970 emphasize that this view of stelar evolution is at variance with that which suggests that the eustele of seed plants is derived by the lengthening and overlapping of leaf gaps in a. And among the first of the plants to truly live on land were the pteridophytes. Bryophytes are small, non vascular land plants, that require water for reproduction. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The following separation of the main growth forms of pteridophyta is proposed. Pdf the origin and early evolution of plants on land researchgate.
The plant body can be divided into a true root, stem, and leaves. This chapter describes how the elements that made up. Problems of origin and evolution by their very nature give ample scope for speculation and imaginative interpretation. Pteridophyta characteristics, life cycle, classification. Molecular evolution of pteridophytes and their relationship.
The megaspore and microspore germinate to give rise female and male gametophyte respectively. There appears to be quite a bit of pattern into how this family has evolved. Pteridophyte definition of pteridophyte by merriamwebster. Thus, these characteristics make them horticulturally important plants. Jan 23, 2017 reproduction the sporophytes reproduce by spores which are produced within sporangia. While many of the earliest groups continue to thrive, as exemplified by red and green algae in marine environments, more recently derived groups. The branching of the rhizome and formation of adventitious buds on rhizomes is.
Molecular evolution of pteridophytes and their relationship to seed. Welcome to this special issue of the journal of systematics and evolution focused on the systematics and evolution of lycophytes and ferns. Life forms of pteridophyta, their origin and evolution. Even more importantly, it can provide critical insight into the origin of the modern tropical rain forest biome in which these ferns are found. Chapter 22 bryophytes university of california, davis. There are two conflicting theories concerning the origin of the alternating generations in landplants. Origin and evolution of bryophytes linkedin slideshare. Reproduction the sporophytes reproduce by spores which are produced within sporangia. Each of these can be divided into life forms according to a series of morphological and other characters. Work on leaf evolution integrated all the data types available morphology, anatomy, development, phylogenetic hypotheses and the fossil record to produce consistent theories. Megaphylls, microphylls and the evolution of leaf development. Apr 10, 2006 another way you can look at sorus evolution is to consider the sporangia.
There are controversies regarding their origin and evolution. May 20, 2018 pith formed may be inter stellar in origin or by invasion of cortical tissue. According to one school of thought, the pteridophytes like bryophytes have been evolved from algae. Pteridophyta is thus no longer a widely accepted taxon, but the term pteridophyte remains in common parla. Ecology and evolution of pteridophytes in the era of. Pteridophyta download ebook pdf, epub, tuebl, mobi. The origin and early diversification of land plants marks an interval. The origin and early evolution of plants on land biology. Ferns, horsetails often treated as ferns, and lycophytes clubmosses, spikemosses, and quillworts are all pteridophytes. Pteridophytes ferns and fern allies the plant list. According to this view both the groups are parallel to each other in their origin and they are not connected phylogenetically. Tissues like pericycle, medullary rays and pith are also the components of stele. Pteridophytes constitute a significant and important group in the plant kingdom.
Pteridophytes or pteridophyta, in the broad interpretation of the term, are vascular plants plants with xylem and phloem that reproduce and disperse via spores. Molecular evolution of pteridophytes and their relationships to seed plants. Seed plants include the angiosperms, the conifers, and a smaller assortment of other plants. In others, individual gametophytes produce only one or the other. Occurrence and evolution of pteridophytes with its origin and economic importance in pteridophyta is a group of ancient plants. Many pteridophytes supplement their sexual cycles with various forms of vegetative reproduction yatskievych 2003. Origin and evolution of wings and flight in insects. Although this concept of bryophyte phylogeny has prevailed in general treat ments, bryologists have advanced alter nate hypotheses, both in past and recent times. Pteridophytes have a long geological history on our planet. Another way you can look at sorus evolution is to consider the sporangia.
Occurrence and evolution of pteridophytes pteridophyta is a group of ancient plants. Some of the species belonging to this division have small leaves called as the microphylls. Therefore pteridophytes are no longer considered to form a valid taxon, but the term is still used as an informal way to refer to ferns, horsetails, clubmosses and whisk ferns. Common pteridophytic life forms include rhizomatous herbs, rhizomatous clonal forms, epiphytic herbs, vines, shrubs, and a variety of canopy trees that achieved arborescence by gigantism, modular repetitive growth, and rhizomorphic. Economic importance of pteridophytes,several ferns such as angiopteris, asplenium, marattia, microsorium, nephrolepis, phymatodes, etc. Molecular evolution of pteridophytes and their relationship to seed plants.
The diversity of growth forms and life history patterns that have helped pteridophytes become successful throughout time is examined, and evidence for. They are preserved in the form of fossils or coal deposits. The origin and early evolution of plants on land pdf. Fronds in the largest species of ferns can reach some six metres in length. Pdf the origin and early evolution of land plants in the midpalaeozoic era, between about 480 and 360 million years ago, was an important. Of those, two prevailing hypotheses explained the origin of.
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