Direct vs. indirect competition model, Biology

Assignment Help:

Pikas (component 1), also known as "rock rabbits" or "coneys", are small relatives of rabbits belonging to the genus Ochotona. The 30 species in this genus are confined to high altitudes in Asia, North America, and parts of eastern Europe, where they live in alpine tundra environments. Although most species live in crevices on rocky mountainsides, a few burrowing species are found in open steppe landscapes. One of the latter species is the plateau (or black-lipped) pika (O. curzoniae), which lives on the Tibetan Plateau in the People's Republic of China. In this area, pikas are believed to act as a "keystone species" (one whose presence or absence exerts a disproportionate effect on community diversity).

Pikas feed mostly on grasses (component 2) and to a much lesser extent on other plants (component 3). Similarly to prairie dogs in the American west, pika make burrows that are the primary homes of a variety of small birds and lizards, create soil disturbance (e.g., aeration, mixing) that increases plant species diversity, are the main or major prey species for most of the predatory animals in the area, and engage in other activities (e.g., fertilizing soil with their waste products and burying food stores of seeds that may sprout later on) that increase the growth of other plants and overall ecological productivity.

Lizards (component 4), including: Ching Hai toadhead agamas (Phrynocephalus vlangalii) and multi-ocellated racerunners (Eremias multiocellata) live in pika burrows, but do not benefit (or hinder) the pikas.

Passarine birds (component 5), including: Hume's ground jay (Pseudopodoces humilis), Isabelline wheatears (Oenanthe isabellina), and several species of snowfinches (Pyrgilauda spp.) use the burrows constructed by the pikas for nesting. They likewise also do not benefit or hinder the pikas. They avoid pika burrows that are already occupied by lizards (and lizards avoid burrows once they are occupied by birds).

Small predatory birds (component 6), including: upland buzzards (Buteo hemilasius), black kites (Milvus migrans), and little owls (Athene noctua), and small predatory mammals (component 7) such as steppe polecats (Mustela eversmanni), mountain weasels (M. altaica), Tibetan sand and red foxes (Vulpes ferrilata, V. vulpes), and Pallas's cat (Otocolobus manul) all rely heavily on pikas for food.

Raptors (component 8), including: saker falcons (Falco cherrug), goshawks (Accipiter gentiles), and golden eagles (Aquila chrysaetos), depend upon pikas as a major food source. They also feed on passerine birds and small predatory birds.

Domestic livestock (component 9) including sheep, horses, and yaks are maintained by humans for meat and milk, and also serve as work animals. They graze on grass and other plants. Their feeding activities and trampling the on the soil increases the amount of barren ground, which is good for pikas.

Large carnivores (component 10), including, wolves (Canis lupus), and snow leopards (Uncia uncia) feed on pikas and the young of domestic livestock. They also feed on small predatory mammals or their young.            

Brown bears (component 11) occasionally feed on pikas. More importantly, however, they feed on a wide variety of plants (but not on grasses).

Humans (component 12) in the area depend on their domestic livestock for meat and milk. Their livestock benefit from human protection. Humans shoot golden eagles (even though these have been shown not to eat livestock), snow leopards and wolves (which do prey upon their livestock or their young). Humans hunt brown bears for their skins and some of their other body parts (i.e., claws, bones, and gall bladders that make their way to Chinese cities, where they are sold on the black market for "medicinal" purposes), but they do not eat them. They also poison pikas, believing both that they compete with their livestock for food and that their holes injure livestock that step in them.

1.   Click on the "Prediction" button. You will then be able to simulate the effects of an increase in each species by clicking on its highlighted number at the top of the matrix. What happens to the pika (i.e., does this species increase, decrease, or remain the same) when each of the following: passerine birds, smaller carnivores, larger carnivores, livestock, and humans both increase and decrease? Explain what you think is happening to produce these changes.

2.  What happens to all other species when the pika both increase and decrease (i.e., which species' populations increase, decrease, or remain the same)? Explain what you think is happening to produce these changes.

3.  Which model (direct vs. indirect competition) seems to be more realistic? How could your models better address this question? Explain and give examples.


Related Discussions:- Direct vs. indirect competition model

What is reduction, What is reduction? The most commonly understood defi...

What is reduction? The most commonly understood definition of reduction is the removal of oxygen or addition of hydrogen ions. However, chemically, reduction can be defined as

Determine the symptoms of cholera, Determine the Symptoms of Cholera  A...

Determine the Symptoms of Cholera  An infective dose of around one million organisms should be ingested to cause illness. The bacteria adhere to the small intestine wall, where

Biota of lakes, Biota of Lakes Lakes exhibit life zones. So far you h...

Biota of Lakes Lakes exhibit life zones. So far you have been reading about the vertical zonation of lakes. The lakes can be divided into horizontal zones as well. This divis

What is diatoms, What is Diatoms? Bacillariophyta are commonly known as ...

What is Diatoms? Bacillariophyta are commonly known as diatoms because of their unique structure. These unicellular photosynthetic organisms are composed of two overlapping glas

What is active site, What is Active site Active site : The site on  ...

What is Active site Active site : The site on  the surface of an enzyme to which  substrate or substrates bind.

Explain human cells that produce proteins for exportation, What are some ex...

What are some examples of human cells that produce proteins for exportation? Which cytoplasmic organelle is expected to be well-developed and abundant in those cells? Specializ

From which floral structure do fruits come, From which floral structure do ...

From which floral structure do fruits come? Fruits are customized ovaries of the flowers.

Tumours of kidney - wilm''s tomour, Tumours of kidney - Wilm's Tomour ...

Tumours of kidney - Wilm's Tomour So  far you have learnt about the disorders in glomerular dysfunctioning, now you will learn about the tumours in kidney the wilm's  tumour.

Explain about the brownian ratchets and molecular motors, Explain about the...

Explain about the Brownian ratchets and molecular motors ? How work is carried out by molecules within biological cells is essential to understanding how cells function. A clue

Characteristic feature of respiration, Characteristic Feature of Respiratio...

Characteristic Feature of Respiration From our opinion we may say that the characteristic feature of respiration is the intake of oxygen and the output of the carbon dioxide.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd