Deserts can be hot or cold, but they are always dry. Around 1/5 of the Earth’s surface is covered in deserts. Deserts most commonly occur when there are unpredictable patterns of rainfall in an area, and the area usually has less than 30 cm of rain per year. In reaction to the extreme heat or the extreme cold, plants and animals make many adaptations. Plants have water-storing leaves or stems that reduce water loss and improve salt tolerance. Many animals learn to survive and get a lot of their moisture from these plants.
Deserts can also be fragile. There is a lot of slow-growing vegetation, and interference from vehicles disrupts the environment. Some tracts of vehicles from the past can still be seen in some areas today.
Sunday, October 24, 2010
The Giant Panda (Ailuropoda melanoleuca) is one of the worlds most loved and most endangered species. The pandas live in 6 regions in southwest China, in the Sichuan, Gansu and Shaanzi provinces. They are found in dense bamboo and coniferous mountains in China. The mountains are covered in heavy rains with torrential rains and a mist all year around.
The panda is in the bear family. The panda is known for its bear like shape and its large, distinctive black patches or spots around the eyes, over the ears, and across its round body. The panda has limited enemies. The panda bear is a herbivore, and its diet consists largely of bamboo. They help to distribute bamboo seeds over areas. As the number of pandas decrease, the amount of bamboo decreases without pandas to distribute bamboo seeds.
Pandas are becoming extinct because people are disrupting their territory and demolishing their natural habitat. This causes pandas to loose their habitat and food supply. Poachers also aid in their extinction.
Friday, October 22, 2010
The human race is a very diverse species according to the number of races, yet homo sapiens have not undergone the process of speciation. Since all males and females can reproduce together despite their race, it has been theorized that all of the human race can be traced back to a common ancestor most commonly called Mitochondrial Eve. She is believed to have a medium brown complexion, dark hair, and strong features resembling the Native American female. Mitochondrial Eve is suspected to have been in the region of East Africa. The theory states that as groups began to radiate off form the original group with Mitochondrial Eve, these different groups became isolated from each other . As they became isolated, the genetic make up of the groups began to change according to the areas that they were located and the ecological niches that the different groups developed.
These are two examples of two African tribes the Maasai and Igbo. The Maasai tribe is a semi-nomadic tribe found around Kenya and Northern Tanzania. Their niche is in hunting and gathering, so because of the niche the people are taller and more slender in order to hunt cattle and other animals. The Igbo tribe is found in Nigeria. The people are of medium stature with skin that is of darker pigment due to the excessive amount of sun. Their niche is in agriculture, therefore they are not as tall as some tribes like the Maasai.Even more groups became more isolated as a result of radiation. Hawaiian people had to become accustomed to dealing with tropical climates. They have more of a complexion somewhat resembling that of the Native Americans and Mitochondrial Eve. Hawaiian people have more melanin production because of more exposure to the sun. They also lived off the land like many other of the isolated groups and had to be adapt in hunting and learning the land. The Alaskan Inuit had little exposure to the sun and developed a vary fair complexion with darker hair. They had to become accustomed to living in freezing temperatures and fishing and hunting whatever game that could be captured because of the rough terrain.
Hawaiian Alaskan Inuit
As groups began to radiate further than the continent of Africa, many more features and niches began to change. Take for instance the individuals that migrated to America, specifically the Native Americans. They encountered a climate much less intimidating than that of Africa, so there skin produced less melanin. To adapt to the terrain though the Native American developed distinct predominant features to withstand the environment and acquired more height. They attained a living from hunting, gathering, and learning how to use the land. Now, look at a group that radiated to Korea. Even less melanin was produced because the people had to deal with more of a humid climate with heavy rains. The people were of an average height, and there niche evolved over thousands of years to be geared towards industrialization.