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[News] Acid Precipitation

[News] Acid Precipitation

forest damaged by acid rain Acid precipitation is rain, snow, or mist which has a pH lower than unpolluted precipitation. Increased levels o...

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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/03/hydrologic-cycle.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Water lilies, a kind of adaptations" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWTO3UCEkP1k5D48BJHCJvoeXTZc97nCrruOZZ3KfCGeK-o-nTBXYpt__JEwN9tbLw1Fa94JIzRBEvM4310jvGSk1yKGPov9sQSDi3MbMnmIond6Zzi805CMx0qodO1PQJmLNznXbLxOax/s1600/water-lilies.jpg" title="Water lilies, a kind of adaptations" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Water lilies, a kind of adaptations</td></tr></tbody></table> The results of natural selection in which succeeding generations of organisms become better able to live in their environments are called adaptations. Many of the features that are most interesting and beautiful in biology are adaptations. Specialized structures, physiological processes, and behaviors are all adaptations when they allow organisms to cope successfully with the special features of their environments. Adaptations ensure that individuals in populations will reproduce and leave well-adapted offspring, thus ensuring the survival of the <a href="http://gogreen-now.blogspot.com/2011/01/spedies-and-speciation.html" target="_blank" title="Species and Speciation">species</a>. Adaptations arise through mutations—inheritable changes in an organism’s genetic material. These rare events are usually harmful, but occasionally they give specific survival advantages to the mutated organism and its offspring. When certain individuals in a population possess advantageous <a href="http://gogreen-now.blogspot.com/2011/03/genetics-mutations.html" target="_blank" title="Genetics: Mutations">mutations</a>, they are better able to cope with their specific environmental conditions and, as a result, will contribute more offspring to future generations than those individuals that lack the mutation. <a name="more"></a><table align="center" border="0"><tbody><tr> <td align="center"><a href="http://www.amazon.com/gp/product/0881922870/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0881922870&linkCode=as2&tag=natureplant-20&linkId=AYEWYL5WPTMBKQ4N" rel="nofollow"><img border="0" src="http://ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0881922870&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="http://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=as2&o=1&a=0881922870" style="border: none !important; margin: 0px !important;" width="1" /><a href="https://www.amazon.com/gp/product/0198707894/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=natureplant-20&linkId=d05afc534bf7c0d716da6435c0d9f2ea" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0198707894&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=li3&o=1&a=0198707894" style="border: none !important; margin: 0px !important;" width="1" /></td> </tr></tbody></table> Over time, the number of individuals that have the advantageous mutation will increase in the <a href="http://gogreen-now.blogspot.com/2011/02/population-genetics.html" target="_blank" title="Population Genetics">population</a> at the expense of those that do not have it. Individuals with an advantageous mutation are said to have a higher fitness than those without it, because they tend to have comparatively higher survival and reproductive rates. This is natural selection. Natural Selection <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/03/hydroponics.html" imageanchor="1" style="margin-left: 1em; margin-right: 1em;" target="_blank"><img alt="Growing on poisonous environtment" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDO5GlmcoArVdz7rUqB_rmUPaqcT50FnHW02nTuuyIT5LAOM9z5fPHmTwr8JPT1Jzm7rnwjmKBbWVqoPRYiYP17Q79bbTtEBM4JlXJ-9q7BsopXgcMfg7YrkP6dudeTwzlAoJzzT2jz3ec/s1600/poisonous-environtment.jpg" title="Growing on poisonous environtment" width="470" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Growing on poisonous environtment</td></tr></tbody></table> Over very long periods of time, evolution by natural selection results in increasingly better adaptations to environmental circumstances. Natural selection is the primary mechanism of evolutionary change, and it is the force that either favors or selects against mutations. Although natural selection acts on individuals, a population gradually changes as those with adaptations become better represented in the total population. Most flowering plants, for example, are unable to grow in <a href="http://gogreen-now.blogspot.com/2011/01/soil.html" target="_blank" title="Soil">soil</a> containing high concentrations of certain elements (for example, heavy metals) commonly found in mine tailings. Therefore, an adaptation that conferred resistance to these elements would open up a whole new habitat where <a href="http://gogreen-now.blogspot.com/2011/05/competition.html" target="_blank" title="Competition">competition</a> with other plants would be minimal. Natural selection would favor the mutations, which confer specific survival advantages to those that carry them and impose limitations on individuals lacking these advantages. Thus, plants with special adaptations for resistance to the <a href="http://gogreen-now.blogspot.com/2011/02/poisonous-and-noxious-plants.html" target="_blank" title="Poisonous and Noxious Plants">poisonous</a> effects of heavy metals would have a competitive advantage over those that find heavy metals toxic. These attributes would be passed to their more numerous offspring and, in evolutionary time, resistance to heavy metals would increase in the population. Types of Adaptations Although natural selection serves as the instrument of change in shaping organisms to very specific environmental features, highly specific adaptations may ultimately be a disadvantage. Adaptations that are specialized may not allow sufficient flexibility (generalization) for survival in changing environmental conditions. The degree of adaptative specialization is ultimately controlled by the nature of the environment. Environments, such as the tropics, that have predictable, uniform climates and have had long, uninterrupted periods of climatic stability are biologically complex and have high species diversity. <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/03/inflorescence.html" imageanchor="1" style="margin-left: 1em; margin-right: 1em;" target="_blank"><img alt="Tropical rain forest" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXlJcPhIfRWEVJt-N2dp5-naXPfdrHafnLQWVQzcQ5bndAaKhzXZtggtgQfbdTeD6WT-Fh35yTcddvCgztNnYRGyWGq_N7Eiw_fW-ZhlrM5tbF4csRQYtNoemPrIpj24-DHKoh-KHT_sJG/s1600/tropical-forest.jpg" title="Tropical rain forest" width="470" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Tropical rain forest, complex competition for resources and intense predator-prey relationships</td></tr></tbody></table> Scientists generally believe that this diversity results, in part, from complex competition for resources and from intense predator-prey relationships. Because of these factors, many narrowly specialized adaptations have evolved when environmental stability and predictability prevail. By contrast, harsh physical environments with unpredictable or erratic climates seem to favor organisms with general adaptations, or adaptations that allow flexibility. Regardless of the environment type, organisms with both general and specific adaptations exist because both types of adaptation enhance survival under different environmental circumstances. Metabolism is the sum of all chemical reactions taking place in an organism, whereas physiology consists of the processes involved in an organism carrying out its function. Physiological adaptations are changes in the <a href="http://gogreen-now.blogspot.com/2011/03/microbial-nutrition-and-metabolism.html" target="_blank" title="Microbial Nutrition and Metabolism">metabolism</a> or physiology of organisms, giving them specific advantages for a given set of environmental circumstances. <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/03/irrigation.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="harsh physical environments, enhance survival under different environmental circumstances" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhE7lOyyS5Q5QZSZSXR76lUsoDbxPJEf31FaehzvaLiKJSDjom-0KDIBhp9bUgL_jUGYStcicyP-rWc97HYHThIASCqeHhwk9GU1hfrvX8dNlXXRKSCv-u05Q8dSO9SZDcVREhOk3xwzv2X/s1600/harsh-environtment.jpg" title="harsh physical environments, enhance survival under different environmental circumstances" width="470" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">harsh environments, enhance survival under different environmental circumstances</td></tr></tbody></table> Because organisms must cope with the rigors of their physical environments, physiological adaptations for temperature regulation, <a href="http://be-eco-friendly.blogspot.com/2010/02/water-conservation-water-purification.html" rel="nofollow" target="_blank" title="Water Conservation, Water Purification And Clean D...">water conservation</a>, varying metabolic rate, and dormancy allow organisms to adjust to the physical environment or respond to changing environmental conditions. Adaptations and Environment Desert environments, for example, pose a special set of problems for organisms. Hot, dry environments require physiological mechanisms that enable organisms to conserve water and resist prolonged periods of high temperature. Evolution has favored a specialized form of photosynthesis in cacti and other succulents inhabiting arid regions. Crassulacean acid metabolism (CAM) photosynthesis allows plants with this physiological adaptation to absorb carbon dioxide at night, when relative humidity is comparatively high and air temperatures relatively low. <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/03/leaf-abscission.html" imageanchor="1" style="margin-left: 1em; margin-right: 1em;" target="_blank"><img alt="✯ A Beavertail cactus in Henderson Canyon - CA" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4pT7HvPFESsmNv9NY9INxj70z1hcPPBtITTF33UHZ0qJQH9K9wQY6ffE92NjeZaXozMWOSey2cAhup-wNaSad4MTBUS9M-Gm6pCUi3MbDp8O68-H6w0Q7Najxvp3dWlQFZCJ1IgyQLu6x/s1600/desert-cactus.jpg" title="Adaptations and Environment" width="470" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Adaptations and Environment</td></tr></tbody></table> Taking in carbon dioxide during the day would dehydrate plants, because opening the pores through which gas exchange takes place allows water to escape from the plant. <a href="http://gogreen-now.blogspot.com/2011/10/c4-and-cam-photosynthesis.html" target="_blank" title="C4 and CAM Photosynthesis">CAM photosynthesis</a>, therefore, allows these plants to exchange the atmospheric gases essential for their metabolism at night, when the danger of dehydration is minimized. Because organisms must also respond and adapt to an environment filled with other organisms— including potential predators and competitors— adaptations that minimize the negative effects of biological interactions are favored by natural selection. Often the interaction among species is so close that each species strongly influences the others and serves as the selective force causing change. Under these circumstances, species evolve together in a process called <a href="http://gogreen-now.blogspot.com/2011/05/coevolution.html" target="_blank" title="Coevolution">coevolution</a>. The adaptations resulting from coevolution have a common survival value to all the species involved in the interaction. The coevolution of flowers and their pollinators is a classic example of these tight associations and their resulting adaptations. Speciation Adaptations can be general or highly specific. General adaptations define broad groups of organisms whose lifestyles are similar. At the species level, however, adaptations are more specific and give narrow definition to those organisms that are more closely related to one another. Slight variations in a single <a href="http://amazingrainbow.blogspot.com/2009/12/characteristics-of-good-leader.html" rel="nofollow" target="_blank">characteristic</a>, such as bill size in the seed-eating Galapágos finches, are adaptive in that they enhance the survival of several closely related species. An understanding of how adaptations function to make species distinct also furthers the knowledge of how species are related to one another. Why so many species exist is one of the most intriguing questions of biology. The study of adaptations offers biologists an explanation. Because there are many ways to cope with the environment, and because natural selection has guided the course of evolutionary change for billions of years, the vast variety of species existing on the earth today is simply an extremely complicated variation on the theme of survival.

[News] Adaptations

Water lilies, a kind of adaptations The results of natural selection in which succeeding generations of organisms become better able to live...

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[News] Active Transport

<div class="separator" style="clear: both; text-align: center;"><a href="http://watersome.blogspot.com/2011/11/recreation-in-and-on-oceans.html" imageanchor="1" rel="nofollow" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;" target="blank"><img border="0" src="https://3.bp.blogspot.com/-7UGgDLlXCWQ/Tvl_ATAt5iI/AAAAAAAAC40/H-4_kmg9te8/s1600/active-transport-1.jpg" /></a></div>Active transport is the process by which cells expend energy to move atoms or molecules across membranes, requiring the presence of a protein carrier, which is activated by ATP. Cotransport is active transport that uses a carrier that must simultaneously transport two substances in the same direction. Countertransport is active transport that employs a carrier that must transport two substances in opposite directions at the same time. Biologists in nearly every field of study have discovered that one of the major methods by which organisms regulate their metabolisms is by controlling the <a href="http://gogreen-now.blogspot.com/2010/12/water-and-solute-movement-in-plants.html" target="_blank" title="Water and Solute Movement in Plants">movement</a> of molecules into cells or into organelles such as the nucleus. This regulation is possible because of the semipermeable nature of cellular membranes. The membranes of all living cells are fluid mosaic structures composed primarily of lipids and <a href="http://gogreen-now.blogspot.com/2011/01/proteins-and-amino-acids.html" target="_blank" title="Proteins and Amino Acids">proteins</a>. The lipid molecules are aliphatic, which means that their molecular structure exhibits both a hydrophilic (water-attracted) and a hydrophobic (water-repelling) portion. These aliphatic molecules form a double layer: The hydrophilic heads are arranged opposite one another on the inner and outer surfaces, and the hydrophobic tails are aligned across from one another within the interior, sandwiched between the hydrophilic heads. The protein in the <a href="http://gogreen-now.blogspot.com/2011/03/membrane-structure.html" target="_blank" title="Membrane Structure">membrane</a> is interspersed periodically throughout the lipid bilayer. <a name="more"></a><table align="center" border="0"><tbody><tr> <td align="center"><a href="http://www.amazon.com/gp/product/0815344546/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0815344546&linkCode=as2&tag=natureplant-20&linkId=3YDWWFQAC45KID2S" rel="nofollow"><img border="0" src="http://ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0815344546&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="http://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=as2&o=1&a=0815344546" style="border: none !important; margin: 0px !important;" width="1" /><a href="http://www.amazon.com/gp/product/0470430664/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0470430664&linkCode=as2&tag=natureplant-20&linkId=5M7R7NIT3C5ENJFB" rel="nofollow"><img border="0" src="http://ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0470430664&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="http://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=as2&o=1&a=0470430664" style="border: none !important; margin: 0px !important;" width="1" /></td> </tr></tbody></table> Some of the protein, referred to as peripheral protein, penetrates only one of the lipid layers. The integral protein, as the remaining protein is called, extends through both layers of lipid to interface with the environment on both the internal and external surfaces of the membrane. These integral proteins can serve as transport <a href="http://marketingatoz.blogspot.com/2011/04/distribution-and-channels.html" rel="nofollow" target="_blank" title="Distribution and Channels">channels</a> and carriers. Cellular Energy Transport across the membrane is accomplished by three different mechanisms: simple diffusion, facilitated diffusion, and active transport. The first two mechanisms are referred to as passive processes because they do not require the direct input of cellular energy, and they involve transport down a concentration gradient, that is, from the side with a higher <a href="http://amazingrainbow.blogspot.com/2009/10/your-power-of-real-concentration.html" rel="nofollow" target="_blank" title="Your Power of Real Concentration">concentration</a> to the side with a lower concentration of the substance being transported. In many instances, however, substances are transported across a membrane from the side with a low concentration to the side containing a greater concentration. This "uphill" movement across membranes is called active transport, and it requires the expenditure of cellular <a href="http://be-eco-friendly.blogspot.com/2010/01/solar-energy-basic-facts.html" rel="nofollow" target="_blank" title="Solar Energy Basic Facts">energy</a>. Cellular energy, produced by the biological oxidation of fuels such as carbohydrates, is stored as adenosine triphosphate (ATP). When this high-energy phosphate is hydrolyzed, the stored energy is released to drive cellular reactions such as active transport. The ATPase protein located in membranes belongs to one of the groups of enzymes which hydrolyze ATP. The mechanism has not been completely deciphered, but it appears as though a protein carrier molecule binds with the substance to be transported at the surface on one side of the membrane. This binding occurs at a specific activated region on the carrier protein called the active site. After combining with the carrier, the substance is moved across the membrane and released at the surface on the other side of the membrane. ATP is then hydrolyzed by an ATPase, and the energy released in this reaction prepares the protein carrier for attachment to another molecule to be transported by reactivating the active site. There is some question as to whether ATPase is a component of the carrier molecule or functions separately from it. Regardless of the spatial arrangement, the two molecules are intimately related in the active transport process. Cotransport and Countertransport There are two important modifications of the active transport process: cotransport and countertransport. Cotransport, or symport, involves a specialized protein molecule referred to as a symport carrier. Asymport carrier has two attachment sites. One site is for the attachment of the molecule to be transported, and the other is for the attachment of a second molecule, which can be referred to as the synergist. Both the molecule to be transported and the synergist must be bound to the symport carrier before transport across the membrane can take place. The synergist is moved down a concentration gradient, and this downhill flow of the synergist drives the carrier to transport both molecules. In order to keep the synergist moving down a concentration gradient when attached to the symport carrier, the synergist must be pumped back across the membrane. This movement of the synergist in the opposite direction is mediated by a protein carrier activated by the energy released from the hydrolysis of ATP by an ATPase. Countertransport, or antiport, also utilizes a specialized carrier with two attachment sites. This antiport carrier binds with the molecule to be transported at one of the attachment sites, and a second molecule, which can be called the antagonist, binds at the other. The carrier moves the molecule to be transported across the membrane while simultaneously moving the antagonist in the opposite direction. Again, both molecules must be attached to the antiport carrier before either can be transported, and the flow of the antagonist down a concentration gradient drives the transport by the carrier in both directions. The antagonist is pumped back across the membrane by a protein carrier activated by the energy released from the hydrolytic action of an ATPase on ATP. This action maintains a concentration gradient favorable for transport when the antagonist is attached to the antiport carrier. Transport in Action The presence of these three active transport mechanisms has been well documented. Calcium, for example, has been shown to be pumped from the cell by a carrier protein activated by the hydrolysis of ATP. <a href="http://gogreen-now.blogspot.com/2011/01/sugars.html" target="_blank" title="Sugars">Sugars</a> for energy and carbohydrate structure must be cotransported into the cell by a symport carrier that utilizes the sodium ion as a synergist. At least two countertransport ion pumps have been identified. One pumps the potassium ion into the cell at the same time that it pumps the hydrogen ion out. The second pumps the potassium ion into the cell while the antagonist, sodium, is moved in the opposite direction. It is likely that numerous other active transport systems exist that have not yet been positively identified. A protein carrier is one of the basic components of any active transport mechanism. Although no specific carrier molecule has yet been positively identified, there is ample indirect evidence to support the presence of such a protein. Much of this evidence comes from studies showing that active transport exhibits saturation kinetics. This means that the transport of a specific ion will increase as the concentration increases, up to a certain point. At this point, further increases in concentration will have no effect on transport. These results strongly suggest that the ion is binding with another molecule in the membrane, such as a carrier protein, which is limited in concentration and becomes saturated. Studies have also shown the transport of some substances to be competitively inhibited by the presence of another, very similar, substance. This indicates that both substances are competing for the same site on a membrane molecule, such as a protein carrier. Role of Active Transport The ability to accumulate substances against a concentration gradient is necessary for the normal function and survival of cells. There are numerous examples, however, of active transport being intimately involved in the regulation of some important biological processes. In the plant kingdom, sugar is produced by <a href="http://gogreen-now.blogspot.com/2011/03/photosynthesis.html" target="_blank" title="Photosynthesis">photosynthesis</a> in the green leaves. This sugar must be transported out of the leaves and into nonphotosynthetic tissues, such as <a href="http://gogreen-now.blogspot.com/2011/01/roots.html" target="_blank" title="Roots">roots</a> or fruit, through specialized transport cells in the phloem. The loading of sugars into the phloem is dependent on an active cotransport mechanism. Almost every field of life science is concerned with gene regulation. Genes are continually being induced (activated) or repressed (deactivated) as organisms develop and change from the time of their conception until their death. Repression is usually caused by the presence of a protein molecule in the cell nucleus, but induction may very often be the result of metabolites being actively transported into the cell or <a href="http://gogreen-now.blogspot.com/2011/03/nucleus.html" target="_blank" title="Nucleus">nucleus</a>. Hence, the active transport mechanisms may be a very important component of gene regulation.

[News] Active Transport

Active transport is the process by which cells expend energy to move atoms or molecules across membranes, requiring the presence of a protei...

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[News] Adaptive Radiation

<div class="separator" style="clear: both; text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/05/coal.html" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;" target="_blank"><img border="0" src="https://1.bp.blogspot.com/-cZ6t4tVfZog/Tvlt6Z_vAFI/AAAAAAAAC4c/5rnGrrL2tfk/s1600/Adaptive-Radiation-1.jpg" /></a></div>In adaptive radiation, numerous species evolve from a common ancestor introduced into an environment with diverse ecological niches. The progeny evolve genetically into customized variations of themselves, each adapting to survive in a particular niche. In 1898 Henry F. Osborn identified and developed the evolutionary phenomenon known as adaptive radiation, whereby different forms of a <a href="http://gogreen-now.blogspot.com/2011/01/spedies-and-speciation.html" target="_blank" title="Species and Speciation">species</a> evolve, quickly in evolutionary terms, from a common ancestor. According to the principles of natural selection, organisms that are the best adapted (most fit) to compete will live to reproduce and pass their successful traits on to their offspring. The process of adaptive radiation illustrates one way in which natural selection can operate when members of one <a href="http://be-eco-friendly.blogspot.com/2010/10/population.html" target="_blank" title="Population">population</a> of a species are cut off or migrate to a different environment that is isolated from the first. Such isolation can occur from one patch of plantings to another, from one <a href="http://be-eco-friendly.blogspot.com/2011/03/mountain-pygmy-possum.html" rel="nofollow" target="_blank" title="Mountain Pygmy Possum">mountain</a> top or hillside to another, from pond to pond, or from island to island. Faced with different environments, the group will diverge from the original population and in time become different enough to form a new species. <a name="more"></a><table align="center" border="0"><tbody><tr> <td align="center"><a href="http://www.amazon.com/gp/product/0198505221/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0198505221&linkCode=as2&tag=natureplant-20&linkId=TFC4TQXR44DPFRU7" rel="nofollow"><img border="0" src="http://ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0198505221&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="http://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=as2&o=1&a=0198505221" style="border: none !important; margin: 0px !important;" width="1" /><a href="http://www.amazon.com/gp/product/019929223X/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=019929223X&linkCode=as2&tag=natureplant-20&linkId=2QY2URXNND7CNWYT" rel="nofollow"><img border="0" src="http://ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=019929223X&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="http://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=as2&o=1&a=019929223X" style="border: none !important; margin: 0px !important;" width="1" /></td> </tr></tbody></table> Genetic Changes In a divergent population, the relative numbers of one form of allele (characteristic) decrease, while the relative numbers of a different allele increase. New environmental pressures will select for favorable alleles that may not have been favored in the old environment. Over successive generations, therefore, a new gene created by random mutation (change) may replace the original form of the gene if, for example, the trait encoded by that gene allows the divergent group to cope better with environmental factors, such as food sources, predators, or temperature. The result in the long term is that deoxyribonucleic acid (<a href="http://gogreen-now.blogspot.com/2011/04/dna-in-plants.html" target="_blank" title="DNA in Plants">DNA</a>) changes sufficiently through the growth of divergent populations to allow new generations to become significantly different from the original population. In time, they are unable to reproduce with members of the original species and become a new species. Galápagos Islands Case Study Adaptive radiation occurs dramatically when a species migrates from one landmass to another. This may occur between islands or between continents and islands. A classic example of adaptive radiation is the <a href="http://gogreen-now.blogspot.com/2011/04/evolution-of-cells.html" target="_blank" title="Evolution of Cells">evolution</a> of finches noted by <a href="http://historyworldsome.blogspot.com/2013/12/charles-darwin.html" rel="nofollow" target="_blank">Charles Darwin</a> during his trips to the Galápagos Islands off the west coast of South America. Several species of plants and animals had migrated to these islands from the South American mainland by means of flight, wind, ocean debris, or other means of transport. Finches from the mainland—perhaps aided by winds—settled on fifteen of the islands in the Galápagos group and began to adapt to the various unoccupied ecological niches on those islands, which differed. Over several generations, natural selection favored a variety of finch species with beaks adapted for the different types of foods available on the different islands. As a result, several species of different finches evolved, roughly simultaneously, on these islands. Hawaiian Silversword Alliance <div class="separator" style="clear: both; text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/05/cloning-of-plants.html" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;" target="_blank"><img border="0" src="https://3.bp.blogspot.com/-gJIkPUt-htE/TvlujyMt1BI/AAAAAAAAC4o/xkjMCplgDw4/s1600/Adaptive-Radiation-2.jpg" /></a></div>Although plants seem unable to "migrate" as birds and other animals do, adaptive radiation occurs in the plant world as well. In the Hawaiian Islands, for example, twenty-eight species of the Asteraceae family are known together as the Hawaiian silversword alliance. The entire group appears to be traceable to one ancestor, thought to have arrived on the island of Kauai from western <a href="http://historyworldsome.blogspot.com/2013/12/financial-panics-in-north-america.html" rel="nofollow" target="_blank">North America</a>. The silverswords—which compose three genera, Argyroxiphium, Dubautia, and Wilkesia— have since evolved into twenty-eight species, and this speciation came about due to major ecological shifts. These plants are therefore prime examples of adaptive radiation. Within the silversword alliance, different species have adapted to widely varying <a href="http://gogreen-now.blogspot.com/2011/04/ecosystems-overview.html" target="_blank" title="http://gogreen-now.blogspot.com/2011/04/ecosystems-overview.html">ecosystems</a> found throughout the islands. Argyroxiphium sandwicense, for example, is endemic to the island of Maui and grows at high elevations from 6,890 to 9,843 feet (2,100 - 3,000 meters) on the dry, alpine slopes of the volcano Haleakala. This species has succulent leaves covered with silver hairs. It is thought that the hairs lessen the pace of evaporative moisture loss and protect the leaves from the sun. In contrast, species of the genus Dubautia that grow in wet, shady <a href="http://gogreen-now.blogspot.com/2011/04/forests.html" target="_blank" title="Forests">forests</a> have large leaves that lack hairs. Despite their "customized" physiologies, the silverswords that have evolved in Hawaii are all closely related to one another, so much so that any two can hybridize. Studies of the silverswords have provided what geneticist Michael Purugganan called a "genetic snapshot of plant evolution". Adaptive radiation is one window into how new plant structures arise.

[News] Adaptive Radiation

In adaptive radiation, numerous species evolve from a common ancestor introduced into an environment with diverse ecological niches. The pro...

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[News] African Agriculture

<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/10/cacti-and-succulents.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="African Agriculture" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsae7ar8Rm71udlu6RItaw5mrI_V3Fh1XZwvkrW6ILo0k2rd4ZkI3Nf6LywDIFiDWT71QKnXF9gUxBu5vKbHb5WCm7PMlfCYlz13iEjK5ACzFNq0Ia89YP_63sWX1JoaxHqOaaQkCqcPs/s1600/african-agriculture-1.jpg" title="African Agriculture" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">African Agriculture</td></tr></tbody></table> Soil and climatic conditions throughout Africa determine not only agricultural practices, such as which crops can be grown, but also whether plant life is capable of sustaining livestock on the land and enabling fishing of the <a href="http://watersome.blogspot.com/2011/11/shipping-on-oceans.html" rel="nofollow" target="_blank">oceans</a>. Rainfall—the dominant influence on agricultural output—varies greatly among Africa’s fifty-six countries. Without <a href="http://gogreen-now.blogspot.com/2011/03/irrigation.html" target="_blank">irrigation</a>, agriculture requires a reliable annual rainfall of more than 30 inches (75 centimeters). Portions of Africa have serious problems from lack of rainfall, such as increasing desertification and periods of drought. Food output has declined, with per capita food production 10 percent less in the 1990’s than it was in the 1980’s. In most African countries, however, more than 50 percent, and often 80 percent, of the <a href="http://be-eco-friendly.blogspot.com/2010/10/population.html" target="_blank">population</a> works in agriculture, mostly subsistence agriculture. Large portions of the continent, such as Mali and the Sudan, have the potential of becoming granaries to much of the continent and producing considerable food exports. <a name="more"></a><table align="center" border="0"><tbody><tr> <td align="center"><a href="http://www.amazon.com/gp/product/1138849332/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=1138849332&linkCode=as2&tag=natureplant-20&linkId=5F7R54ZRKZNCETI3" rel="nofollow"><img border="0" src="http://ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=1138849332&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="http://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=as2&o=1&a=1138849332" style="border: none !important; margin: 0px !important;" width="1" /><a href="http://www.amazon.com/gp/product/0896292045/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=0896292045&linkCode=as2&tag=natureplant-20&linkId=LQ4J3W5OXWJ5SBJX" rel="nofollow"><img border="0" src="http://ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0896292045&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=natureplant-20" /></a><img alt="" border="0" height="1" src="http://ir-na.amazon-adsystem.com/e/ir?t=natureplant-20&l=as2&o=1&a=0896292045" style="border: none !important; margin: 0px !important;" width="1" /></td> </tr></tbody></table> Traditional African Agriculture Traditionally, agriculture in Africa has been subsistence farming in small plots. It has been labor-intensive, relying upon family members. New land for farming was obtained by the <a href="http://be-eco-friendly.blogspot.com/2011/04/slash-and-burn-agriculture.html" rel="nofollow" target="_blank">slash-and-burn</a> method (shifting cultivation). The trees in a forested area would be cut down and burned where they fell. The ashes from the burned trees fertilized the soil. Bothmen andwomenworked at such farming. Slash-and-burn agriculture is common not only in Africa but also in tropical areas around the world. In areas of heavy rainfall, the rainswash out the <a href="http://gogreen-now.blogspot.com/2011/03/nutrients.html" target="_blank">nutrients</a> from soil and burned trees in a period of two to three years. The crops grown depend upon the region. In the very dry, yet habitable, parts of Africa—such as the Sudano-Sahelian region that stretches from Senegal and Mali in the west of Africa to the Sudan in the east—a key subsistence crop is green millet, a grain. Ground into a type of flour, it can be made into a bread-like substance. In moister areas, traditional crops are root and tuber crops, such as yams and cassava. Cassava has an outer surface or skin that is <a href="http://gogreen-now.blogspot.com/2011/02/poisonous-and-noxious-plants.html" target="_blank">poisonous</a>, but it can be treated to remove the poison. The tuber then can be ground and used tomake a bread-like substance.Other important traditional crops are rice and corn, which were introduced by Europeans when they came to Africa. Animal husbandry, or seminomadic herding, is another form of traditional agriculture. Problems that have arisen with this type of agriculture are the availability of water and grass or hay for cattle. Regions that are very moist, such as the Gulf of Guinea, which has rain forest, are not good for cattle because of the tsetse fly, which carries diseases such as sleeping sickness. Crops <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/10/c4-and-cam-photosynthesis.html" imageanchor="1" style="margin-left: 1em; margin-right: 1em;" target="_blank"><img alt="Rice field in Africa" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIq_JLnYe8xmjc3-in1cd06_NaPOoTg14U4atYGTSYhyphenhyphenC0LVeRm5CJqnalOyJBIF1VRUUsFvNCetSn8u6mbPgImt1xhOFTGwo-fpOI0mvAahLtUpeJv7ZYF4wH_m73r2awRM14lkh7ofdD/s1600/rice-africa.jpg" title="Rice field in Africa" width="470" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Rice field in Africa</td></tr></tbody></table> The most widely grown crop is <a href="http://gogreen-now.blogspot.com/2011/01/rice.html" target="_blank">rice</a>, which is grown on more than one-third of the irrigated crop area in Africa. Cultivated mostly in wetlands and valley bottoms, rice is the most common crop in the humid areas of the Gulf of Guinea and Eastern Africa. It is also grown on the plateaus of Madagascar. In the northern and southern regions, rice represents only a small portion of the total crops under water management. <a href="http://gogreen-now.blogspot.com/2010/12/wheat.html" target="_blank">Wheat</a> and corn are cultivated and irrigated, mostly in Egypt, Morocco, South Africa, Sudan, and Somalia. Vegetables, including root and tuber crops, are present in all regions and almost every country. Vegetables are grown on about 8 percent of the cultivated areas under water management. In Algeria, Mauritania, Kenya, Burundi, and <a href="http://historysome.blogspot.com/2012/02/rwandaburundi-conflict.html" rel="nofollow" target="_blank">Rwanda</a>, they are the most widespread crops under water management. Arboriculture (growing of fruit trees), which represents 5 percent of the total irrigated crops, is concentrated in the northern region and consists mostly of citrus fruits. Commercial <a href="http://gogreen-now.blogspot.com/2011/04/fruit-crops.html" target="_blank">crops</a> (for cash and export) are grown mostly in the Sudan and in the countries of the southern region and consist mostly of cotton and oilseeds. Other commercial crops in Africa are sugarcane, coffee, cocoa, oil and date palm, bananas, tobacco, and cut flowers. Sugarcane is grown in all countries except in the northern region. The other commercial crops are concentrated in a few countries. North Africa <table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody><tr><td style="text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/10/calvin-cycle.html" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;" target="_blank"><img alt="olives in african market" border="0" src="https://3.bp.blogspot.com/-Geyj3AOpHJ8/TvlnPtXf36I/AAAAAAAAC3s/1Zi0crKBiik/s1600/african-agriculture-3.jpg" title="olives in african market" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">olives in african market</td></tr></tbody></table>In Morocco, Algeria, Tunisia, Libya, and Egypt, the region’s agricultural resources are limited by its dry climate. Its <a href="http://marketingatoz.blogspot.com/2011/04/products.html" rel="nofollow" target="_blank">products</a> are those typical of the Mediterranean, steppe, and desert regions: wheat, barley, olives, grapes, citrus fruits, some vegetables, dates, sheep, and goats. Agriculture employs less than 20 percent of the working population in Libya and as much as 55 percent in Egypt. From about the middle of the twentieth century, North Africa’s production failed to keep pace with its population <a href="http://gogreen-now.blogspot.com/2011/03/growth-habits.html" target="_blank">growth</a> and remained susceptible to large annual fluctuations. Cropland occupies about 33 percent of Tunisia but less than 3 percent of Algeria, Egypt, and <a href="http://earlyworldhistory.blogspot.com/2012/03/libya.html" rel="nofollow" target="_blank">Libya</a>. Some export crops, such as citrus fruits, tobacco, and cotton, have suffered from strong international competition. The northern region is not a major contributor to the continent’s fish catch. <a href="http://historysome.blogspot.com/2012/08/morocco.html" rel="nofollow" target="_blank">Morocco</a>, however, with its cool, plankton-rich Atlantic waters and access to the Mediterranean Sea, is one of the world’s largest fish producers. Sudano-Sahelian Region This region comprises Mauritania, the western Sahara, Senegal, Gambia, Mali, Burkina-Faso, Niger, Chad, and the Sudan. Because of the region’s extreme dryness, mostly subsistence farming and seminomadic herding are practiced. Millet is the primary crop. In the late twentieth century, this region was devastated by long droughts that caused famine and starvation. Mali and the Sudan have the Niger and Nile Rivers flowing through them. These great rivers provide plenty of water for irrigation of fields. During the rainy season in Mali—typically June through September—the Niger River widens into a great, extensive floodplain. This area is good for the growing of rice. Similarly, in the Sudan the Blue and White Niles meet at Khartoum to form the Nile River. Gulf of Guinea <div class="separator" style="clear: both; text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/10/carbohydrates.html" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;" target="_blank"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv8fQ669wjf5schEdiOGw7_R97t58-1LT6UlTDRXinYBMUSFfVKpr1tMU42hzxOL1QDyYpLhVjnae0lKuPhePzyuPp70hYu1tWayrWwmNykS407_x-r4leSfmEbxbyEPuQkTCpHOa7D1M/s1600/african-agriculture-4.jpg" /></a></div>This region comprises Guinea-Bissau, Cape Verde, Guinea, Liberia, Sierra Leone, Côte d’Ivoire, <a href="http://historysome.blogspot.com/2012/01/togo.html" rel="nofollow" target="_blank">Togo</a>, Ghana, Benin, and Nigeria. With the exception of Nigeria, agriculture there is dominated by rice cultivation. The percentage of total land area that is under cultivation ranges from 60 percent in Liberia to just 9 percent in Sierra Leone. The total cultivable area of Ghana is 39,000 square miles (100,000 square kilometers), or 42 percent of its total land area. Only 4.8 percent of the total land area was under cultivation at the end of the twentieth century. Much of the cultivation is subsistence farming of yams and other crops. Ghana’s efforts in agriculture have been hampered by droughts. Additional problems are that organic matter has been leached out of the soils by heavy rainfall and that increasing <a href="http://be-eco-friendly.blogspot.com/2010/01/deforestation-effects.html" rel="nofollow" target="_blank">deforestation</a> has led to additional erosion. This is the situation in much of the Gulf of Guinea and the central regions. About half of Nigeria’s available land is under cultivation. Increasing rainfall from the semiarid north to the tropically forested south allows for great crop diversity. Principal food crops are <a href="http://gogreen-now.blogspot.com/2011/05/corn.html" target="_blank">corn</a>, millet, yams, sorghum, cassava, rice, potatoes, and vegetables. Nigeria was the world’s fourth-largest exporter of cocoa beans in 1990-1991, accounting for about 7.1 percent of world trade in this commodity. However, Nigeria’s share of the world cocoa market has been substantially reduced because of aging trees, low prices, black pod disease, smuggling, and labor shortages. Central Region This region comprises the Central African Republic, Cameroon, Congo-Brazzaville, Congo-Kinshasa, Gabon, Equatorial Guinea, Burundi, Rwanda, and São Tomé and Príncipe. Cameroon has 14.7 million acres of arable land. In 1997, 55,000 tons of rice were produced, but the country imported 124,000 tons in 1995. In the central region, the percentage of arable land ranges from 0.4 percent for the Congo-Brazzaville to 47 percent for Rwanda. Cassava is harvested in Congo-Brazzaville, Congo-Kinshasa, Equatorial Guinea, and Gabon. Corn is harvested in Congo-Brazzaville, Congo-Kinshasa, and Burundi. In Rwanda, 17 percent of the harvested land is used to grow sweet potatoes. Agriculture is not important in the economy of São Tomé and Príncipe. Eastern Region <div class="separator" style="clear: both; text-align: center;"><a href="http://gogreen-now.blogspot.com/2011/10/carbon-cycle.html" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;" target="_blank"><img border="0" src="https://4.bp.blogspot.com/-2ptzzgN4gPM/TvlpZOuFDrI/AAAAAAAAC4E/wlWZgqIiSYo/s1600/african-agriculture-5.jpg" /></a></div>This region comprises Eritrea, Djibouti, Ethiopia, Somalia, Kenya, Uganda, and Tanzania. Agriculture employs about 80 percent of the labor force in Uganda and <a href="http://historyworldsome.blogspot.com/2013/12/ethiopiaabyssinia.html" rel="nofollow" target="_blank">Ethiopia</a>. Approximately 2.5 million small farms dominate agriculture in both countries. About 84 percent of Uganda’s land is suitable for agriculture—a high percentage compared to the majority of African countries, such as Ethiopia with only 12 percent. Food crops account for about 74 percent of agricultural production. Only one-third is marketed; the rest is for home consumption. In four years out of five, the minimum needed rainfall may be expected in 78 percent of Uganda but in only 15 percent of Kenya. Somalia and Ethiopia receive almost none of the needed minimum. Tanzania has almost four million farms. Traditional export crops include coffee, cotton, cashew nuts, tobacco, and tea. Major staple foods (corn, rice, and wheat) are exported in times of surplus. Tanzania’s climatic growing conditions are favorable for the production of a wide range of fruits, vegetables, and flowers. Drought-resistant crops (sorghum, millet, and cassava) and other substaples such as onions, Irish potatoes, sweet potatoes, bananas, and plantains are also produced. Areas that have 20-30 inches (50-75 centimeters) of rainfall per year rely on a mixture of agriculture and livestock herding. Regions with a smaller annual rainfall or a long dry season can support only drought-resistant crops such as sorghum, millet, and cassava. Over large areas of eastern Africa, rainfall is inadequate for crop cultivation. The whole of Somalia and 70 percent of Kenya receive less than 20 inches (50 centimeters) of rain four years out of five. In these areas, the only feasible use of land is for raising livestock. Agriculture is not an important factor in the economies of Eritrea and Djibouti. Southern Region This region comprises Angola, Namibia, Zambia, <a href="http://epicworldhistory.blogspot.com/2012/07/zimbabwe.html" rel="nofollow" target="_blank">Zimbabwe</a>, Malawi, Mozambique, Botswana, Lesotho, Swaziland, and South Africa. The arable percentage of the total land area ranges from 14 percent in Malawi to just 1 percent in Namibia. With the exception of Mozambique, where cassava predominates, corn is the major crop in the countries in this region. About 13 percent of South Africa’s land area can be used for crop production. Rainfall varies across the country, and varied climatic zones and terrains enable the production of almost any kind of crop. The largest area of farmland is planted with corn, followed by wheat, then oats, sugarcane, and sunflowers. The nation is well known for the high quality of its fruits, such as apples and citrus. Agriculture is the predominant economic activity in Zimbabwe, accounting for 40 percent of total export earnings—about 22 percent of the total economy—and employing more than 60 percent of the country’s labor force. The main export crops are tobacco, cotton, and oilseeds. Zimbabwe is usually self-sufficient in food production. Its main food crops are corn, soybeans, oilseeds, fruits and vegetables, and sugar. Mozambique’s agriculture has been badly hindered by civil war. However, the country has considerable potential for irrigation due to the Zambezi and Limpopo Rivers. The irrigation potential is estimated to be 7.5 million acres. In the 1990’s, only 110,000 acres were irrigated, growing rice, sugarcane, corn, and citrus. Agriculture and livestock production employ about 62 percent of Botswana’s labor force. Most of the country has semidesert conditions with erratic rainfall and poor soil conditions, making it more suitable to grazing than to crop production. The principal food crops are sorghum and corn. Namibia’s cultivated area is only 506,000 acres—only 0.8 percent of the cultivable area. Agriculture makes up approximately 10 percent of the economy but employs more than 80 percent of the population. The major irrigated crops are corn, wheat, and cotton. Indian Ocean Islands <div class="separator" style="clear: both; text-align: center;"><a href="http://be-eco-friendly.blogspot.com/2010/01/fact-about-recycle.html" imageanchor="1" rel="nofollow" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;" target="blank"><img border="0" src="https://2.bp.blogspot.com/-tkViGN3TkWo/TvlqFrEd0GI/AAAAAAAAC4Q/82WkOFKigRk/s1600/african-agriculture-6.jpg" /></a></div>This region comprises Madagascar, Mauritius, the Comoros, and the Seychelles. During the 1990’s an estimated 8.7 million people lived in the rural areas, 65 percent of whom lived at the subsistence level. Only 5.2 percent of Madagascar’s total land area (7.4 million acres) was under cultivation. Of the total land area, 50.7 percent supported livestock production, while 16 percent (1.2 million acres) of the land under cultivation was irrigated. Cassava, planted almost everywhere on the island, is grown as well as corn and sweet potatoes, with smaller quantities of cotton, bananas, and cloves. The fisheries sector, especially the export of shrimp, has been the most rapidly growing area of the agricultural economy in the Indian Ocean Islands region. Mauritius has 30,000 acres of sugarcane plantations that have had one of the highest sugarcane and sugar yields in the world. The Seychelles have a total land area of only 72 squaremiles (187 square kilometers), of which only 3,000 acres are cultivated. This 3 percent of the land area accounts for only 4 percent of the island nation’s economy. The Comoros’ agriculture is heavily weighted toward rice, the staple food of the populace.

[News] African Agriculture

African Agriculture Soil and climatic conditions throughout Africa determine not only agricultural practices, such as which crops can be gro...

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