The Diversity of Life
Fossils
Biology Diversity Of Life Notes
The word fossil means literally 'dug up.' More practically, they are remains or evidence of once living organisms. Fossils are of great value for geologists. They are used for stratigraphic correlation and for studying the evolution of life on Earth through time.
Define Diversity of life. Diversity of life synonyms, Diversity of life pronunciation, Diversity of life translation, English dictionary definition of Diversity of life. The number and variety of species found within a specified geographic region. The variability among living organisms on the earth, including the. The diversity of life. The biosphere supports between 3 and 30 million species of plants, animals, fungi, single-celled prokaryotes such as bacteria, and single-celled eukaryotes such as protozoans ( Figure 1 ). Of this total, only about 1.4 million species have been named so far, and fewer than 1 percent have been studied for their ecological relationships and their role in ecosystems. Fractionation meaning.
Fossil Preservation
Organisms are made up of organic matter ('soft parts') and inorganic skeletal materials ('hard parts'). There are various modes of fossil preservation:
preservation of hard parts is the most common. Shell, bones, and other skeletal materials may be preserved mostly unaltered or in varying degrees of alteration. Over time shell and bone material may be recrystallized, obscuring the finer structure.
preservation of soft parts is rare because organic matter is subject to decay (oxidation). Soft parts may be preserved for hundreds of thousands or millions of years if rapidly buried in an oxygen poor environment, such as in an organic rich swamp, or if frozen in ice, such as wooly mammoths and the recently found 'ice man' preserved in ice.
permineralization is the molecule by molecule replacement of an organisms original material for by stable inorganic materials. Petrified wood is a good example. Wood is organic matter that is subject to decay. But sometimes buried logs will have the woody organic matter replaced by silica (quartz) slowly as the groundwater seeps through the wood. Some of the woods structure is retained, such as the wood grain.
carbonization is another mode of preservation of organic matter. Sometimes as organic matter, say a leaf, slowly oxidizes, their may be a thin film of carbon left. There may also be a leaf impression.
molds and casts may be left if shell material dissolves before the mud that the shells were encased in. Molds are hollows in the shape of the shell left after the shell has dissolved. Casts are the mud left from the inside of the shell after the shell has dissolved.
trace fossils such as tracks and trails, burrows, and coprolites (feces) may tell us much about a fossil organisms habits and diet.
Diversity Of Life
The Six Kingdoms of Life (viruses not included)
Living things have the ability to maintain themselves and reproduce. Anything from the lowliest, single-cell bacterium to the most complex vertebrates and towering redwood trees have that ability. Viruses, on the other hand are only quasi living. They are not much more than bundles of DNA. To survive, they force host cells to carry out these functions for them.
Diversity Of Life Definition
There are millions of species of organisms living on the Earth today. Many millions of others that lived in the past are now extinct. Scientists and natural philosophers (such as Aristotle in ancient Greece) have recognized that organisms can be organized according to similarities and differences.
The most basic difference between organism is the distinction between prokaryotes and eukaryotes. Prokaryotes are the simplest, most primitive kinds of single-celled organisms. They are the bacteria. They lack a nucleus to hold their genetic material. The DNA (genetic material) in a prokaryotic cell lies in a bundle within the cell. Bacterial cells are quite small (microscopic) and very simple. Eukaryotes are more advanced organisms. They may be single celled, like amoebas and paramecia that you may have seen under a microscope in elementary school, or they may be complex, multicellular organisms like humans. Essentially, all living things on Earth besides bacteria are eukaryotes. Eukaryotic cells have a nucleus that contains the DNA on structures called chromosomes. Eukaryotic cells also contain many bodies called organelles that perform specialized functions to aid in energy processing, etc. Eukarytotic cells are larger than prokaryotic cells, though normally also microscopic.
Many kinds of organisms must obtain their energy by breaking down (digesting/metabolizing) organic matter. Animals, fungi, and some prokaryotic and eukaryotic single-celled organisms do this. Many other organisms capture energy by the process of photosynthesis in which sunlight is used to produce carbohydrate (energy store) from carbon dioxide and water. Plants, algae, and some kinds of bacteria do this. Some organisms obtain their energy from dissolved ions by a process known as chemosynthesis. Some of the most primitive bacteria do this.
The tree of life is organized from the most general (kingdoms) down to the most specific level (species). Kingdoms can be subdivided into phyla (phylum is the singular); phyla into classes; classes into orders; orders into families; families into genuses; genuses include many species.
For example, some of the phyla of Kindom Animalia are Phylum Chordata (including the vertebrates), Phylum Arthropoda (including insects, spiders, and crustaceans), and Phylum Porifera (the sponges). humans belong to Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Primates, Family Hominidae, Genus Homo, Species Homo sapiens.
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For now we will just introduce the kingdoms. Later, we will discuss the most important fossil groups from each kingdom.
Kingdom Archeobacteria
Archeobacteria are characterized by living in extreme conditions. Some kinds of archeobacteria live in extremely hot water, such as at hot water vents at the midocean ridges called black smokers or in hot springs. Others live in very acidic waters, or very salty waters, or in environments devoid of oxygen. They are considered primitive bacteria. Some of these conditions are similar to condition under which life may have first arisen on Earth. Perhaps the archeobacteria include the oldest kinds of organisms on Earth.
Kingdom Eubacteria
The oldest known living things on Earth are a type of eubacteria. The oldest fossils yet found are 3.5 billion year old cyanobacteria. These are photosynthetic bacteria formerly known as 'blue-green algae.' They are not true algae. True algae are eukaryotes. By about 3.2 billion years ago the fossil record contains the first large fossils called stromatolites. These formed from filamentous cyanobacteria that trapped sediments in mats that often grew into mounds.
(Under some schemes all bacteria are included in one kingdom)
Kingdom Protista
Protists are mostly single-celled (mostly microscopic) eukaryotes, though some simple multicellular organisms are also lumped in with the protists. Some protists secrete a shell and are important contributors to the fossil record.
- Protozoans ingest organic matter to obtain their energy. These include amoebas and paramecia. The most important microfossil protozoans are foraminifera (calcium carbonate shells) and radiolarians (silica shells).
- Algae are photosynthetic protists. Dinoflagellates form a tuff protein casing called a cyst when conditions are poor. These cysts often preserve as fossils. The oldest fossils that may represent eukaryotes are cysts found in rocks about 1.7 billion years old similar to those of the dinoflagellates. The most important algae microfossil are diatoms (silica shells) and calcareous nanoplankton (calcareous shells).
Kingdom Plantae
Plants are multicellular organisms that produce their own energy and via photosysnthesis. They are primary producers on the land. They include everything from mosses to ferns to conifers, like pine trees, to broad leaf trees, like oak trees, to grasses. Plants probably arose during the lower Paleozoic.
Kingdom Fungi
Fungi are multicellular and single-celled organisms that break down dead organic matter within their cells. The multicellular fungi are plant-like in that they lack senses and the ability to move about like animals, but they are incapable of photosynthesis. Mushrooms belong to the Fungus Kingdom. Fungi do not fossilize easily so they are poorly represented in the fossil record. The oldest fossil fungi are from the Cambrian Period.
Kingdom Animalia
Animals are multicellular organisms that ingest organic matter to obtain energy and materials for life. Animals run the gamut from simple sponges and corals, to complex invertebrates like insects and crustaceans, to complex vertebrates like reptiles and mammals. Animals arose during the late Proterozoic, around 600 million years ago or so.
Taxonomy
Taxonomy is the classification of living organisms. Taxonomy groups living things into Kingdoms, which are subdivided into phyla, classes, orders, families, genuses, and species. This was first established by Linneus in the 18th century.
The traditional means of organizing the various genera is with the phylogenetic tree or the branching tree of life. The groupings of similar genera implies relationships among organisms.
cladistics is a method of classification that assumes that living things have ancestral relationships derived from their evolution. A clade is a group of organism that all share a common set of 'primitive' traits (those acquired from some common ancestor).
E.O. Wilson, one of the world’s greatest scientists, is also a Pulitzer Prize-winning author who has published over twenty-five books. Here David Attenborough and Harrison Ford introduce the breadth of Wilson’s vision.
The following are excerpts from E.O. Wilson’s acclaimed book The Diversity of Life. In this 1992 work, Wilson reflects on the evolution of life and man’s destruction of the natural world.
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The sixth great extinction spasm of geological time is upon us, grace of mankind. Earth has at last acquired a force that can break the crucible of biodiversity. The creation of that diversity came slow and hard: 3 billion years of evolution to start the profusion of animals that occupy the seas, another 350 million years to assemble the rain forests in which half or more of the species on earth now live. There was a succession of dynasties.
White top pitcher plants, Splinter Hill Bog, Baldwin County, Alabama. Photograph by Alex Harris.
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[U]nlike the rest of science, the study of biodiversity has a time limit. Species are disappearing at an accelerating rate through human action, primarily habitat destruction but also pollution and the introduction of exotic species into residual natural environments. I have said that a fifth or more of the species of plants and animals could vanish or be doomed to early extinction by the year 2020 unless better efforts are made to save them. This estimate comes from the known quantitative relation between the area of habitats and the diversity that habitats can sustain. These area-biodiversity curves are supported by the general but not universal principle that when certain groups of organisms are studied closely, such as snails and fishes and flowering plants, extinction is determined to be widespread. And the corollary: among plant and animal remains in archaeological deposits, we usually find extinct species and races. As the last forests are felled in forest strongholds like the Philippines and Ecuador, the decline of species will accelerate even more. In the world as a whole, extinction rates are already hundreds or thousands of times higher than before the coming of man. They cannot be balanced by new evolution in any period of time that has meaning for the human race.
Sunset over the winter-season floodplain, Gorongosa National Park, Mozambique.
Why should we care? What difference does it make if some species are extinguished, if even half of all the species on earth disappear? Let me count the ways. New sources of scientific information will be lost. Troll cannon 2gaming potatoes. Vast potential biological wealth will be destroyed. Still undeveloped medicines, crops, pharmaceuticals, timber fibers, pulp, soil-restoring vegetation, petroleum substitutes, and other products and amenities will never come to light. It is fashionable in some quarters to wave aside the small and obscure, the bugs and weeds, forgetting that an obscure moth from Latin America saved Australia’s pastureland from overgrowth by cactus, that the rosy periwinkle provided the cure for Hodgkin’s disease and childhood lymphocytic leukemia, that the bark of the Pacific yew offers hope for victims of ovarian and breast cancer, that a chemical from the saliva of leeches dissolves blood clots during surgery, and so on down a roster already grown long and illustrious despite the limited research addressed to it.
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It is easy to overlook the services that conserved ecosystems provide humanity. They enrich the soil and create the very air we breathe. Without these amenities, the remaining tenure on Earth of the human race would be nasty and brief. The life-sustaining matrix is built of green plants with legions of microorganisms and mostly small, obscure animals—in other words, weeds and bugs. Such organisms support the world with efficiency because they are so diverse, allowing them to divide labor and swarm over every square meter of the earth’s surface. They run the world precisely as we would wish it to be run, because humanity evolved within living communities and our bodily functions are finely adjusted to the idiosyncratic environment already created. Mother Earth, lately called Gaia, is no more than the commonality of organisms and the physical environment they maintain with each passing moment, an environment that will destabilize and turn lethal if the organisms are disturbed too much. A near infinity of other mother planets can be envisioned, each with its own fauna and flora, all producing physical environments uncongenial to human life. To disregard the diversity of life is to risk catapulting ourselves into an alien environment. We will have become like the pilot whales that inexplicably beach themselves on New England shores.
Diversity Of Life Biology
The bees on this sagging colony are quite still until disturbed. Gorongosa National Park, Mozambique.
Diversity Of Life Lab
Humanity coevolved with the rest of life on this particular planet; other worlds are not in our genes. Because scientists have yet to put names on most kinds of organisms, and because they entertain only a vague idea of how ecosystems work, it is reckless to suppose that biodiversity can be diminished indefinitely without threatening humanity itself. Field studies show that as biodiversity is reduced, so is the quality of the services provided by ecosystems. Records of stressed ecosystems also demonstrate that the descent can be unpredictably abrupt. As extinction spreads, some of the lost forms prove to be keystone species, whose disappearance brings down other species and triggers a ripple effect. The loss of a keystone species is like a drill accidentally striking a power line. It causes lights to go out all over.