Buffalo, zebras, wildebeests, topi,

Buffalo, zebras, wildebeests, topi, and Thomson’s gazelles live in huge groups that together make up some 90 percent of the total weight of mammals living on the Serengeti Plain of East Africa. They are all herbivores (plant-eating animals), and they all appear to be living on the same diet of grasses, herbs, and small bushes. This appearance, however, is illusory. When biologist Richard Bell and his colleagues analyzed the stomach contents of four of the five species (they did not study buffalo), they found that each species was living on a different part of the vegetation. The different vegetational parts differ in their food qualities: lower down, there are succulent, nutritious leaves; higher up are the harder stems. There are also sparsely distributed, highly nutritious fruits, and Bell found that only the Thomson’s gazelles eat much of these. The other three species differ in the proportion of lower leaves and higher stems that they eat: zebras eat the most stem matter, wildebeests eat the most leaves, and topi are intermediate.
How are we to understand their different feeding preferences? The answer lies in two associated differences among the species, in their digestive systems and body sizes. According to their digestive systems, these herbivores can be divided into two categories: the nonruminants (such as the zebra, which has a digestive system like a horse) and the ruminants (such as the wildebeest, topi, and gazelle, which are like the cow). Nonruminants cannot extract much energy from the hard parts of a plant; however, this is more than made up for by the fast speed at which food passes through their guts. Thus, when there is only a short supply of poor-quality food, the wildebeest, topi, and gazelle enjoy an advantage. They are ruminants and have a special structure (the rumen) in their stomachs, which contains microorganisms that can break down the hard parts of plants. Food passes only slowly through the ruminant’s gut because ruminating—digesting the hard parts—takes time. The ruminant continually regurgitates food from its stomach back to its mouth to chew it up further (that is what a cow is doing when “chewing cud”). Only when it has been chewed up and digested almost to a liquid can the food pass through the rumen and on through the gut. Larger particles cannot pass through until they have been chewed down to size. Therefore, when food is in short supply, a ruminant can last longer than a nonruminant because it can derive more energy out of the same food. The difference can partially explain the eating habits of the Serengeti herbivores. The zebra chooses areas where there is more low-quality food. It migrates first to unexploited areas and chomps the abundant low-quality stems before moving on. It is a fast-in/fast-out feeder, relying on a high output of incompletely digested food. By the time the wildebeests (and other ruminants) arrive, the grazing and trampling of the zebras will have worn the vegetation down. As the ruminants then set to work, they eat down to the lower, leafier parts of the vegetation. All of this fits in with the differences in stomach contents with which we began.
The other part of the explanation is body size. Larger animals require more food than smaller animals, but smaller animals have a higher metabolic rate. Smaller animals can therefore live where there is less food, provided that such food is of high energy content. That is why the smallest of the herbivores, Thomson’s gazelle, lives on fruit that is very nutritious but too thin on the ground to support a larger animal. By contrast, the large zebra lives on the masses of low-quality stem material.
The differences in feeding preferences lead, in turn, to differences in migratory habits. The wildebeests follow, in their migration, the pattern of local rainfall. The other species do likewise. But when a new area is fueled by rain, the mammals migrate toward it in a set order to exploit it. The larger, less fastidious feeders, the zebras, move in first; the choosier, smaller wildebeests come later; and the smallest species of all, Thomson’s gazelle, arrives last. The later species all depend on the preparations of the earlier one, for the actions of the zebra alter the vegetation to suit the stomachs of the wildebeest, topi, and gazelle.
Paragraph 1: Buffalo, zebras, wildebeests, topi, and Thomson’s gazelles live in huge groups that together make up some 90 percent of the total weight of mammals living on the Serengeti Plain of East Africa. They are all herbivores (plant-eating animals), and they all appear to be living on the same diet of grasses, herbs, and small bushes. This appearance, however, is illusory. When biologist Richard Bell and his colleagues analyzed the stomach contents of four of the five species (they did not study buffalo), they found that each species was living on a different part of the vegetation. The different vegetational parts differ in their food qualities: lower dow

Kết quả (Việt) 1:

Trâu, ngựa vằn, wildebeests, topi và Thomson của gazelles sống trong các nhóm lớn với nhau tạo nên một số 90 phần trăm của tổng trọng lượng của động vật có vú sống trên đồi đồng bằng đông châu Phi. Họ là tất cả động vật ăn cỏ (động vật ăn thực vật), và tất cả đều xuất hiện để sống cùng một chế độ ăn uống của cỏ, các loại thảo mộc và bụi cây nhỏ. Điều này xuất hiện, Tuy nhiên, là không thực hiện. Nhà sinh vật học Richard Bell và các đồng nghiệp của ông phân tích nội dung của dạ dày của bốn trong số năm loài (họ đã không học buffalo), họ nhận thấy rằng mỗi loài sống trên một phần khác nhau của các thảm thực vật. Các bộ phận khác nhau của vegetational khác nhau của chất lượng thực phẩm: thấp xuống, không có lá mọng nước, dinh dưỡng; cao lên là khó khăn hơn thân cây. Cũng có loại trái cây thưa thớt phân bố, rất bổ dưỡng, và Bell tìm thấy rằng chỉ của Thomson gazelles ăn nhiều các. Ba loài khác nhau ở tỷ lệ thấp hơn lá và thân cây cao hơn mà họ ăn: ngựa vằn ăn hầu hết các vấn đề gốc, wildebeests ăn hầu hết lá, và topi là trung gian. How are we to understand their different feeding preferences? The answer lies in two associated differences among the species, in their digestive systems and body sizes. According to their digestive systems, these herbivores can be divided into two categories: the nonruminants (such as the zebra, which has a digestive system like a horse) and the ruminants (such as the wildebeest, topi, and gazelle, which are like the cow). Nonruminants cannot extract much energy from the hard parts of a plant; however, this is more than made up for by the fast speed at which food passes through their guts. Thus, when there is only a short supply of poor-quality food, the wildebeest, topi, and gazelle enjoy an advantage. They are ruminants and have a special structure (the rumen) in their stomachs, which contains microorganisms that can break down the hard parts of plants. Food passes only slowly through the ruminant’s gut because ruminating—digesting the hard parts—takes time. The ruminant continually regurgitates food from its stomach back to its mouth to chew it up further (that is what a cow is doing when “chewing cud”). Only when it has been chewed up and digested almost to a liquid can the food pass through the rumen and on through the gut. Larger particles cannot pass through until they have been chewed down to size. Therefore, when food is in short supply, a ruminant can last longer than a nonruminant because it can derive more energy out of the same food. The difference can partially explain the eating habits of the Serengeti herbivores. The zebra chooses areas where there is more low-quality food. It migrates first to unexploited areas and chomps the abundant low-quality stems before moving on. It is a fast-in/fast-out feeder, relying on a high output of incompletely digested food. By the time the wildebeests (and other ruminants) arrive, the grazing and trampling of the zebras will have worn the vegetation down. As the ruminants then set to work, they eat down to the lower, leafier parts of the vegetation. All of this fits in with the differences in stomach contents with which we began. Một phần còn lại của những lời giải thích là kích thước cơ thể. Loài động vật lớn đòi hỏi các thực phẩm nhiều hơn động vật nhỏ hơn, nhưng các động vật nhỏ hơn có một tỷ lệ trao đổi chất cao. Động vật nhỏ có thể do đó sống nơi có thức ăn ít hơn, miễn là thực phẩm năng lượng cao nội dung. Đó là lý do tại sao cuộc sống nhỏ nhất của động vật ăn cỏ, Thomson's gazelle, trái cây là rất bổ dưỡng nhưng quá mỏng trên mặt đất để hỗ trợ các động vật lớn hơn. Ngược lại, ngựa vằn lớn sống trên khối lượng của vật liệu gốc chất lượng thấp. Sự khác biệt về sở thích ăn chì, lần lượt, với sự khác biệt trong thói quen di cư. Các wildebeests làm theo, di chuyển của họ, các mô hình của lượng mưa cục bộ. Các loài khác làm như vậy. Nhưng khi một khu vực mới thúc đẩy bởi mưa, các động vật có vú di chuyển về hướng là nó thiết lập để khai thác nó. Lớn hơn, ít ăn khó tính, ngựa vằn, di chuyển đầu tiên; wildebeests choosier, nhỏ đi sau đó; và loài nhỏ nhất của tất cả, Thomson's gazelle, đến cuối. Các loài sau này tất cả phụ thuộc vào việc chuẩn bị của một trước đó, cho hành động của các ngựa vằn làm thay đổi các thảm thực vật cho phù hợp với dạ dày wildebeest, topi và gazelle. Paragraph 1: Buffalo, zebras, wildebeests, topi, and Thomson’s gazelles live in huge groups that together make up some 90 percent of the total weight of mammals living on the Serengeti Plain of East Africa. They are all herbivores (plant-eating animals), and they all appear to be living on the same diet of grasses, herbs, and small bushes. This appearance, however, is illusory. When biologist Richard Bell and his colleagues analyzed the stomach contents of four of the five species (they did not study buffalo), they found that each species was living on a different part of the vegetation. The different vegetational parts differ in their food qualities: lower dow