Plant Diversity, Biology tutorial

Introduction to Plant Diversity:

Plants belong to Plantae Kingdom. They are multicellular, have the rigid cell wall and make their own food. Many plants grow in soil and utilize energy from sun to make their own food. Dissimilar animals, they cannot move on their own and they do not have nervous systems. There are 2 large groups of plants: non-vascular plants or Bryophytes, such as moss; and vascular plants or tracheophytes, such as flowers, trees and grasses.

While species may not be exactly same, plants might look much related even on different continents. All places now mentioned include similar climates, so the plants share similarities which are adaptive in that climate. Separate development of similar traits is known as convergent evolution. Convergent evolution occurs when organisms which are not closely associated end up with related characteristics.

The good example of convergent evolution is cacti and euphorbias. Cacti dwell in Americas and euphorbias dwell in Africa. Both groups are desert plants, having juicy-looking stems and scary spikes. Although they look similar, cacti and euphorbias are not closely linked. They have alike qualities as natural selection favored traits which were adaptive in desert environments.

The significance of plant diversity:

Diversity of plant life is the necessary underpinning of most of the terrestrial ecosystems. Humans and most other animals are roughly completely dependent on plants, directly or indirectly, as the source of energy through their skill to convert sun's energy through photosynthesis. Worldwide tens of thousands of species of higher plants, and numerous hundred lower plants, are presently utilized by humans for the wide diversity of purposes as fuel, food, fibre, herbs, oil, spices, industrial crops and as forage and fodder for domesticated animals. In tropics it has been evaluated that 25,000-30,000 species are in use and approx 25,000 species have been utilized in traditional medicines. Additionally, several thousands of species are developed as ornamentals in parks, public and private gardens, as street trees and for shade and shelter. Significant role of plant life is provision of ecosystem services protection of watersheds, improvement of soils, stabilization of slopes, and moderation of climate and provision of habitat for much of the wild fauna.

While it is usually accepted today that conservation of biodiversity must be the goal, particularly through preservation and sustainable usage of natural habitats, this is the ideal which is unlikely to be attained and there are convincing economic, scientific and sociological explanation for providing main concern to conservation of major centers of plant diversity throughout world, particularly as this will very frequently also lead to conservation of much animal and micro-organism diversity also.  Concept of recognizing centers of diversity and endemism.

At times plants (and animals) develop rapidly and fill various niches in the communities. This is known as adaptive radiation and occurred after 5 mass extinction events in Earth's history. This kind of radiation doesn't cause superpowers, though. The adaptive radiation can also occur after change in climate, or if organisms are isolated on various islands like Galapagos or Hawaiian islands. Darwin's finches on Galapagos are the classic example of the adaptive radiation: associated finches developed different beaks which permitted them to specialize on changeable sizes of fruit and seeds. In Hawaii, the group of plants known as silversword descended from one ancestor which lived on islands five million years ago. Over time in the different environments, descendents of that one plant developed in very different plants, some short, tall, round, spiky.

The plant kingdom has multicellular phototrophs which generally live on land. Earliest plant fossils are from terrestrial deposits, though few plants have since returned to water. Every plant cells have cell wall having carbohydrate cellulose, and frequently have plastids in the cytoplasm. Plant life cycle has the alternation between haploid (gametophyte) and diploid (sporophyte) generations.

Plant genetic resources are source of food security and comprise of diversity of seeds and planting material of traditional diversities and new cultivars, crop wild relatives and wild plant species. These resources are utilized as food, feed for domesticated animals, clothing, fibre, shelter and energy. Conservation and sustainable use of PGRFA is necessary to make sure crop production and fulfill growing environmental demands and climate change. Loss of the resources or lack of sufficient connection between conservation and their use creates the cruel threat to world's food security in long term. Potential of plant genetic resources for food security, adequate nutrition, sustainable livelihoods, and adaptation to climate change is huge, if handled in the sustainable manner.

Threats to plant diversity:

  • It is evaluated that there are approx 400,000 plant species in world, and at least 25% are vulnerable with extinction. Humans are major reason of extinction and principle danger to species in danger of extinction.
  • Habitat loss and degradation are most important danger.
  • Introductions of alien species. Some of the worst include cats and rats, green crabs, zebra mussels, the African tulip tree and the brown tree snake. Beginning of alien species can occur intentionally or inadvertently, for instance, by organisms "hitch-hiking" in containers, soil, cars or ships.
  • Over-exploitation. Hunting, Resource removal, and fishing for food, pets, and medicine threaten several species.
  • Pollution and disease
  • Climate change made by humans is gradually more recognized as one of most severe danger. Climate change has several effects, from varying migratory species patterns to causing coral bleaching.

Diversity of life on earth is not limited to great number of species or abundance of individual species. There is great variety in size and form of organisms. The bacterium may be simply one thousandth of millimeter in length while a 30 metre tall palm tree is 30 million times longer that bacterium. Living things exhibit diversity in construction, from single celled organisms to those made up of trillions of cells. Few multicellular organisms are plain in structure whereas others exhibit high degree of discrimination. The green alga called as Ulva situated in the seas seems to be no more than thin and flat green structure. The distinctive flowering plant, in contrast, is discriminated in stems, roots, flowers branches, leaves, and other organs.

There is variety also in ways in which organisms get their food. Carbon is the all significant element in life of living things. Organic compounds of carbon give energy and materials for metabolism, development and reproduction. Green plants are autotrophs. Autotrophs get their carbon from inorganic carbon dioxide in procedure of photosynthesis. Heterotrophs are other organisms that carbon from presynthesised organic compounds. Animals are heterotrophs as their carbon source comes from plants or animals that they feed on. Parasites are heterotrophs which occupy living hosts and suck up carbon compounds. Several bacteria are parasites and fungi. Saprotrophs are as well heterotrophs as they get their carbon source from organic remains in the surroundings. Several fungi and bacteria are saprotrophs. Whatsoever means of getting the carbon, every species is able to elaborate simple carbon compounds in thousands of different compounds. This variety in chemical composition can be utilized to recognize numerous plant groups. Several insects selectively feed on some plants as their ability to use chemicals present in such plants for food, defense or reproduction.

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