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Diversity of Organisms

Bioblitz Bioblitz – Biological inventory A bioblitz is an event that focuses on finding and identifying as many species as possible in a specific area over a short period of time. The primary goal of a bioblitz is to get an overall count of the plants, animals, fungi, and other organisms that live in a place. A group spearheaded by Arizona State University taxonomists wants to launch a NASA – style mission to identify and describe all the world's 10 million species in the next 50 years. Come....let's explore more about diversity of organisms.

Learning Objectives

After completing the topic, the student will be able to:

  • Define the term diversity and explore where does life’s diversity come from.
  • Develop a conceptual frame work of Panspermia theory.
  • Understand the conditions on early Earth made the origin of life possible (chemical evolution).
  • Define, describe and distinguish the terms prokaryotes and eukaryotes.
  • Explore how prokaryotes and eukaryotes evolved.
  • Define and describe the terms taxonomy and binomial nomenclature.
  • Classify organisms according to five – Kingdom and three – Domain classification systems.
How life originated How life emerged from non-life is an extremely challenging question. As a prelude to the details, let’s review the distinguishing features of living systems in the context of this question.
Origin and Diversity of Life

Life is a continuum extending from the earliest organisms to the great variety of species that exist today. It is difficult for us to appreciate exactly how far back life has existed on Earth.

In this unit, we will survey the diversity of life and trace the evolution of this diversity. Throughout this unit, we will see examples of the connection between biological history and biological evolution.

If we calculate Earth to be about 4 billion years old and we know that there were stromatolite–forming bacteria by 3.5 billion years ago, we must assume that living organisms arose sometime in between.

Where did these living organisms come from?The conditions on Earth are very different than they were 4 billion years ago. In Earth's early years the atmosphere was essentially devoid of oxygen and the planet was subjected to more lightning, UV radiation, and falling meteorites (A stony or metallic mass of matter that has fallen to the earth's surface from outer space ). Somehow life managed to arise under these conditions, and various hypotheses attempt to explain how this might have happened.

Stromatolites Stromatolites – Earth's oldest fossils 1. Stromatolite. Example of a layered stromatolite from the Ozarks (Precambrian era). Most often stromatolites appear as variously sized arches, spheres or domes.
2. A Microbial Mat. A hypersaline microbial mat from Baja California.
Early life on earth

Information about early life forms has been deduced by looking at modern–day microbial communities. Some bacteria and cyanobacteria, found in certain types of marshes and lagoons, collect sediment on their sticky outer coats. These microbes migrate upward when they are clogged with sediments, thereby producing a banded pattern.

This banded pattern is extremely similar to the pattern seen in stromatolites(stromatolites are Earth's oldest fossils, formations of sedimentary rock with a characteristic pattern). Stromatolites are thought to be the fossilized remains of ancient microbial communities that grew in layered mats and pillars.

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