Diversity of Living Things

What is diversity?

In order to discuss diversity in living organisms it is firstly important to discuss what diversity actually is. By dictionary definition biodiversity, the diversity of living organisms, is "the variety of plant and animal life in the world or a particular habitat."

Living Things:

Living things include many kinds of organisms, from the plants, animals, fungi, and algae that can be readily seen in nature to the multitude of tiny creatures known as protozoa, bacteria, and archaea that can be seen only with a microscope.

Diversity in Living Things:

Life on Earth is incredibly diverse. Take a walk in a park, and you will see trees, birds, insects, and maybe fish in a stream. All of these organisms are living, but they are all very different from one another. How do scientists organize this variety into categories they can understand? Most scientists classify organisms into six kingdoms, based on different characteristics. Members of the six kingdoms get their food in different ways and are made up of different types of cells, the smallest unit of biological organization. The cells of animals, plants, fungi, and protests contain a nucleus which consists of a membrane that surrounds a cell’s genetic material. A characteristic shared by bacteria, fungi, and plants is the cell wall, a structure that surrounds a cell and provides it with rigid support.

Diversity of living things also called Biodiversity in Science and biology. Biodiversity is the variety of different types of life found on earth.  It is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species) within an area, biome, or planet. Terrestrial biodiversity tends to be highest near the equator, which seems to be the result of the warm climate and high primary productivity. Biodiversity is not distributed evenly on Earth. It is the richest in the tropics. Marine biodiversity tends to be highest along coasts in the Western Pacific, where sea surface temperature is highest and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time but will be likely to slow in the future.

Rapid environmental changes typically cause mass extinctions.  More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct, Estimates on the number of Earth's current species range from 10 million to 14 million of which about 1.2 million have been documented and over 86 percent have not yet been described.

"Biodiversity" is most commonly used to replace the more clearly defined and long established terms, species diversity and species richness. Biologists most often define biodiversity as the "totality of genes, species, and ecosystems of a region". An advantage of this definition is that it seems to describe most circumstances and presents a unified view of the traditional types of biological variety previously identified:

·                    taxonomic diversity (usually measured at the species diversity level)

·                    ecological diversity often viewed from the perspective of ecosystem diversity

·                    morphological diversity which stems from genetic diversity

Biodiversity is the result of 3.5 billion years of evolution. The origin of life has not been definitely established by science, however some evidence suggests that life may already have been well-established only a few hundred million years after the formation of the Earth. Until approximately 600 million years ago, all life consisted of archaea, bacteria, protozoans and similar single-celled organisms.

Bacteria:

Bacteria are microscopic, single-celled organisms that usually have cell walls and reproduce by dividing in half. Bacteria also lack nuclei, unlike all other organisms. Scientists have found two main kinds of bacteria, archaebacterial and eubacteria. Most bacteria, including the kinds that cause disease and those found in garden soil, are eubacteria. Bacteria live in every habitat on Earth, from hot springs to the bodies of animals.

Bacteria and the Environment:  Bacteria play many important roles in the environment. Some kinds of bacteria break down the remains and wastes of other organisms and return nutrients to the soil. Others recycle mineral nutrients, such as nitrogen and phosphorous. For example, certain kinds of bacteria play a very important role by converting nitrogen in the air into a form that plants can use. Nitrogen is important because it is a main component of proteins and genetic material.

Fungi:

A (plural, fungi) is an organism whose cells have nuclei, cell walls, and no chlorophyll (the pigment that makes plants green). Cell walls act like miniature skeletons that allow fungi, such as the mushrooms, to stand upright. A mushroom is the reproductive structure of a fungus. The rest of the fungus is an underground network of fibers. These fibers absorb food from decaying organisms in the soil. Indeed, all fungi absorb their food from their surroundings. Fungi get their food by releasing chemicals that help break down organic matter, and then absorbing the nutrients. The bodies of most fungi are a huge network of threads that grow through the soil, dead wood, or other material on which the fungi are feeding. Like bacteria, fungi play an important role in the environment by breaking down the bodies and body parts of dead organisms. Like bacteria, some fungi cause diseases, such as athlete’s foot. Other fungi add flavor to food. The fungus in blue cheese, gives the cheese its strong flavor. And fungi called yeasts produce the gas that makes bread rise.

Protists:

Most people have some idea what bacteria and fungi are, but few could define a protist. Protists are a diverse group of organisms that belong to the kingdom Protista. Some, such as amoebas, are animal like. Others are plantlike. Still others are more like fungi. Most protists are one-celled microscopic organisms. This group includes amoebas and diatoms (DIE uh TAHMS). Diatoms, float on the ocean surface. The most infamous protist is Plasmodium, the one-celled organism that causes the disease malaria. From an environmental standpoint, the most important protists are probably algae. Algae are plantlike protists that can make their own food using the sun’s energy. Green pond “scum” and seaweed are examples of algae. They range in size from the giant kelp to the one-celled phytoplankton, which are the initial source of food in most ocean and freshwater ecosystems.

Plants:

Plants are many-celled organisms that make their own food using the sun’s energy and have cell walls. Most plants live on land, where the resources a plant needs are separated between the air and the soil. Sunlight, oxygen, and carbon dioxide are in the air, and minerals and water are in the soil. Plants have roots that tap resources underground and leaves that intercept light and gases in the air. Leaves and roots are connected by vascular tissue, a system of tubes that carries water and food. Vascular tissue has thick cell walls, so a wheat plant or a tree is like a building supported by its plumbing.

Lower Plants: The first land plants had no vascular tissue, and they also had swimming sperm. As a result, these early plants could not grow very large and had to live in damp places. Their descendants alive today are small plants such as mosses. Ferns and club mosses were the first vascular plants. Some of the first ferns were as large as small trees, and some of these tree ferns live in the tropics and in New Zealand today

Gymnosperms:

Pine trees and other evergreens are common examples of gymnosperms (JIM noh SPUHRMZ). Gymnosperms are woody plants whose seeds are not enclosed in fruits. Gymnosperms such as pine trees are also called conifers because they bear cones, Gymnosperms have several adaptations that allow them to live in drier conditions than lower plants can. Gymnosperms produce pollen, which protects and moves sperm between plants. These plants also produce seeds, which protect developing plants from drying out. And a conifer’s needle-like leaves lose little water. Much of our lumber and paper comes from gymnosperms.

Animals:

Animals cannot make their own food like plants can. They have to take in food from their environment. In addition, animal cells have no cell walls, so animals’ bodies are soft and flexible. Some animals have evolved hard skeletons against which their muscles can pull to move the body. As a result, animals are much more mobile than plants and all animals move around in their environments during at least one stage in their lives.

More insects exist on Earth than any other type of animal. They are successful for several reasons. Insects have a waterproof external skeleton, they move quickly, and they reproduce quickly. Also, most insects can fly. Their small size allows them to live on little food and to hide from enemies in small spaces, such as a seed or in the hair of a mammal. Many insects and plants have evolved together and depend on each other to survive. Insects carry pollen from male parts of flowers to fertilize a plant’s egg, which develops into a fruit. Without insect pollinators, we would not have tomatoes, cucumbers, apples, and many other crops. Insects are also valuable because they eat other insects that we consider to be pests. But, humans and insects are often enemies. Bloodsucking insects transmit human diseases, such as malaria, sleeping sickness, and West Nile virus. Insects probably do more damage indirectly, however, by eating our crops.

Vertebrates: Animals that have backbones are called Members of three vertebrate groups are shown in Figure 19. The first vertebrates were fish, but today most vertebrates live on land. Amphibians, which include toads, frogs, and salamanders, are partially aquatic. Nearly all amphibians must return to water to lay their eggs. The first land vertebrates were the reptiles, which today include turtles, lizards, snakes, and crocodiles. These animals were successful because they have an almost waterproof egg, which allows the egg to hatch on land, away from predators in the water. Birds are warm-blooded vertebrates with feathers. Bird eggs have hard shells. Adult birds keep their eggs and young warm until they develop insulating layers of fat and feathers. Mammals are warm-blooded vertebrates that have fur and feed their young milk. The ability to maintain a high body temperature allows birds and mammals to live in cold areas, where other animals cannot survive.

Biodiversity and Agriculture:

Agricultural diversity can be divided into two categories: intraspecific diversity, which includes the genetic variety within a single species, like the potato (Solanum tuberosum) that is composed of many different forms and types (e.g.: in the U.S. we might compare russet potatoes with new potatoes or purple potatoes, all different, but all part of the same species, S. tuberosum).

The other category of agricultural diversity is called interspecific diversity and refers to the number and types of different species. Thinking about this diversity we might note that many small vegetable farmers grow many different crops like potatoes, and also carrots, peppers, lettuce etc.

Agricultural diversity can also be divided by whether it is ‘planned’ diversity or ‘associated’ diversity. This is a functional classification that we impose and not an intrinsic feature of life or diversity. Planned diversity includes the crops which a farmer has encouraged, planted or raised (e.g.: crops, covers, symbionts and livestock, among others), which can be contrasted with the associated diversity that arrives among the crops, uninvited (e.g.: herbivores, weed species and pathogens, among others).

The control of associated biodiversity is one of the great agricultural challenges that farmers face. On monoculture farms, the approach is generally to eradicate associated diversity using a suite of biologically destructive pesticides, mechanized tools and transgenic engineering techniques, then to rotate crops. Although some polyculture farmers use the same techniques, they also employ integrated pest management strategies as well as strategies that are more labor-intensive, but generally less dependent on capital, biotechnology and energy.

Interspecific crop diversity is, in part, responsible for offering variety in what we eat. Intraspecific diversity, the variety of alleles within a single species, also offers us choice in our diets. If a crop fails in a monoculture, we rely on agricultural diversity to replant the land with something new. If a wheat crop is destroyed by a pest we may plant a hardier variety of wheat the next year, relying on intraspecific diversity. We may forgo wheat production in that area and plant a different species altogether, relying on interspecific diversity. Even an agricultural society which primarily grows monocultures, relies on biodiversity at some point.

 

 

Biodiversity and human health:

Biodiversity's relevance to human health is becoming an international political issue, as scientific evidence builds on the global health implications of biodiversity loss. This issue is closely linked with the issue of climate change, as many of the anticipated health risks of climate change are associated with changes in biodiversity (e.g. changes in populations and distribution of disease vectors, scarcity of fresh water, impacts on agricultural biodiversity and food resources etc.) This is because the species most likely to disappear are those that buffer against infectious disease transmission, while surviving species tend to be the ones that increase disease transmission, such as that of West Nile Virus, Lyme disease and Hantavirus, according to a study done co-authored by Felicia Keesing, an ecologist at Bard College, and Drew Harvell, associate director for Environment of the Atkinson Center for a Sustainable Future (ACSF) at Cornell University.

The growing demand and lack of drinkable water on the planet presents an additional challenge to the future of human health. Partly, the problem lies in the success of water suppliers to increase supplies, and failure of groups promoting preservation of water resources. While the distribution of clean water increases, in some parts of the world it remains unequal. According to 2008 World Population Data Sheet, only 62% of least developed countries are able to access clean water.

Some of the health issues influenced by biodiversity include dietary health and nutrition security, infectious disease, medical science and medicinal resources, social and psychological health. Biodiversity is also known to have an important role in reducing disaster risk, and in post-disaster relief and recovery efforts.

Climate Change:

Global warming is also considered to be a major potential threat to global biodiversity in the future. For example coral reefs - which are biodiversity hotspots - will be lost in 20 to 40 years if global warming continues at the current trend. Climate change has seen many claims about potential to affect biodiversity but evidence supporting the statement is tenuous. Increasing atmospheric carbon dioxide certainly affects plant morphology, and is acidifying oceans, and temperature affects species ranges, phenology, and weather, but the major impacts that have been predicted are still just potential impacts. We have not documented major extinctions yet, even as climate change drastically alters the biology of many species.

Human Overpopulation:

From 1950 to 2011, world population increased from 2.5 billion to 7 billion and is forecast to reach a plateau of more than 9 billion during the 21st century. Sir David King, former chief scientific adviser to the UK government, told a parliamentary inquiry: "It is self-evident that the massive growth in the human population through the 20th century has had more impact on biodiversity than any other single factor." At least until the middle of the 21st century, worldwide losses of pristine biodiverse land will probably depend much on the worldwide human birth rate.

According to a 2014 study by the World Wildlife Fund, the global human population already exceeds planet's biocapacity - it would take the equivalent of 1.5 Earths of biocapacity to meet our current demands. The report further points that if everyone on the planet had the Footprint of the average resident of Qatar, we would need 4.8 Earths, and if we lived the lifestyle of a typical resident of the USA, we would need 3.9 Earths.