Evolution has resulted incredible diversity and adaptations found in the natural world
Evolutionary biology is understanding of how organisms evolve through natural selection, is an area of science with many practical applications. The most compelling evidence for evolution comes from the study of genes. It is important to recognize that evolutionary biology has implications to a new century of medicine, agriculture, biotechnology, and even law. Students educated with this knowledge will have an edge in most of the areas in Biology.
Evolutionary Bioinformatics is a computational biology in the study of evolution. Advances in technology have given us tools that have dramatically advanced our understanding of how evolution occurs. Bioinformatics made possible to trace the evolution of a large number of organisms by measuring changes in their DNA.
Ecology reveals the richness of the biosphere
From tiny viruses and bacteria, to blue whales weighing 200 tons, and fungi that spread for hundreds of hectares underground, the diversity and extent of life on Earth is dazzling. In its life and reproduction, every organism is shaped by, and in turn shapes, its environment. Ecological scientists study organism-environment interactions across ecosystems of all sizes, ranging from microbial communities to the Earth as a whole.
Biodiversity - A degree of variation of life forms
Biodiversity is the variety and differences among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are a part. This includes genetic diversity within and between species and of ecosystems. Thus, in essence, biodiversity represents all life.
A Laboratory For Global Ecology – Closed Ecological systems
Closed ecological systems (CES) are ecosystems that do not rely on matter exchange with any part outside the system. The term is most often used to describe man made ecosystems. Such systems are scientifically interesting and can potentially serve as a life support system during space flights, in space stations or space habitats. (Example- Biosphere 2). Biosphere 2 is an unprecedented, on-going ecological experiment, built as a laboratory for global ecology.
Evolutionary biology is the study of how organisms evolve in response to changing variables in the environment, as well as how things are related to each other. The great variety of species that exist today on our planet evolved over a period of time.
The environment and the biological evolution are closely related leading to rich diversity of life. The evolution of photosynthetic organisms that released oxygen into the air, followed by emergence of Homo sapiens transformed the life on earth.
Some of the important properties and processes that associate with life are ordered structure, evolutionary adaptation, response to the environment, regulation, energy processing, growth and development and reproduction. Flow of energy from sunlight and the feedback mechanisms in biological systems sustain life.
Exploring life in its entirety starts from the microscopic molecules and cells that make up organisms to the macroscopic view of entire planet including the biosphere and ecosystems. Biosphere includes most regions of land, bodies of water such as lakes, rivers and oceans and the atmosphere to an altitude of several miles.
Diversity is the hallmark of life as the total species count range between 10 million to 200 million while biologists have so far named about 1.8 million species which can be grouped under three domains or five kingdoms.
Even though there is so much of diversity we can also find remarkable unity especially at molecular and cellular levels. The universal genetic language of DNA is common to organisms as different as bacteria and animals.
Darwin’s theory of evolution by way of descent with modification and natural selection explains this unity and diversity. The rain forest orchids reflect the unity in diversity through variations in their form and color while all of them belong to the same species with common characteristics such as lip like petals that attract pollinating insects and provides a landing platform for the pollinators.
Exploring life in its entirety helps us to have a panoramic view of the unity in the diversity of life. In order for evolution to occur, there must be genetic variation. Genetic variation brings about evolution. Without it there will be no evolution. There are two major mechanisms that drive evolution. First is natural selection. Individuals with advantageous traits are more likely to reproduce successfully, passing these traits to the next generation. This kind of evolution driven by natural selection is called adaptive evolution. Another mechanism involves genetic drift, which produces random changes in the frequency of traits in a population. Evolution that arises from genetic drift is called neutral evolution.
Ecology is the study of connections in nature encompassing wide spectrum of interactions among organisms, populations, communities, ecosystems and the biosphere. An organism is any form of life. Organisms are classified as either eukaryotic or prokaryotic depending on their cell structure. They are also classified into species or groups of organisms that resemble one another in appearance, behavior, chemistry and genetic makeup.
A population consists of a group of interacting individuals of the same species that occupy a specific area at the same time. Populations of the different species occupying a particular place make up a community. Biological community is a complex interacting network of matter and energy. An ecosystem is a community of different species interacting with one another and with their nonliving environment of matter and energy. The biosphere is the portion of the earth in which living organisms exist and interact with their nonliving environment.
Troposphere, the inner layer of atmosphere of earth extending for about 11 miles above the sea level, contains most of the planet’s air, mostly nitrogen(78%) and oxygen(22%). The next layer stretching between 11-30 miles above the earth’s surface is the stratosphere. Its lower portion contains enough ozone to filter out most of the sun’s harmful ultraviolet radiation. The hydrosphere consists of earth’s water and water vapor in the atmosphere. Lithosphere is the earth’s crust and upper mantle. The crust contains non renewable fossil fuels and minerals as well as renewable soil nutrients needed for plant life. The biosphere includes most of the hydrosphere and parts of the lower atmosphere and upper lithosphere. It reaches to the deepest ocean floor, about 12 miles below sea level, to the tops of the highest mountains.
If the earth were an apple, the biosphere would be no thicker than the apple’s skin.
The goal of ecology is to understand the interconnections in this thin, life supporting membrane of air, water, soil and organisms. Life on earth is sustained mainly by flow of high quality energy from Sun and the cycling of matter needed for survival by organisms.
Biodiversity includes a rich variety of genes, species, ecological diversity (variety of forests, streams, lakes, oceans, coral reefs, wetlands and other biological communities) and functional diversity in processes or functions such as energy flow and matter cycling needed for the survival of species.
Biodiversity provides us not only food, energy and materials but also free recycling, purification and natural pest control services. Insects that eat other insects help control the population of at least half of the insect species we classify as pests. Without pollinating insects, very few fruits and vegetables would be available for us as a large portion of earth’s plant species depend on insects to pollinate their flowers.
Most of the earth’s microbes are harmless and play a very important role in our lives. Some of them are useful in producing food such as bread, yogurt, cheese, vinegar, tofu, beer and wine. They convert nitrogen gas in the atmosphere into forms that plant can take as nutrients. Bacteria and fungi in the soil decompose organic wastes into nutrients that can be taken up by plants. Bacteria in intestinal tract break down the food we eat. Microbes also have been the source of disease fighting antibiotics including penicillin, erythromycin and streptomycin.
What powers life? How do sunlight and nutrients affect the plants we depend on? How do greenhouse gases and other contaminants degrade the interactions among the plant, animal, and microbial populations that comprise ecosystems? Understanding how ecosystems work begins with an understanding of how sunlight is converted into usable energy, the importance of nutrient cycling, and the impact mankind has on the environment. Plants convert sunlight into usable forms of energy that are carbon based. Primary and secondary production in populations can be used to determine energy flow in ecosystems.
The nutrients, atoms, ions and molecules that organisms need to live, grow, and reproduce are continuously cycled from the non living environment (air, water, soil and rock) to living organisms and then back again in what are called nutrient cycles or biogeochemical cycles. These cycles, driven directly or indirectly by incoming solar energy and gravity include the carbon, oxygen, nitrogen, phosphorous and water cycles. They also connect past, present and future forms of life. The natural ecosystems and the biosphere achieve sustainability by using solar energy and recycling the chemical nutrients its organisms need for survival, growth and reproduction. To develop a rich understanding of ecosystems, begin with this introductory overview, and then explore the other summaries you’ll find further.