READING PASSAGE 2

Read the text and answer questions 14-26.

Australian parrots and their adaptation to habitat change

A. Parrots are found across the tropic and in all southern hemisphere continents except Antarctica, but nowhere do the display such a richness of diversity and form as in Australia. One-sixth of the world’s 345 parrot species are found there, and Australia has long been renowned for the number and variety of its parrots.

B. In the 16th century, the German cartographer Mercator made a world map that included a place, somewhere near present-day Australia, that he named Terra Psittacorum – the Land of Parrots – and the first European settlers in Australia often referred to the country as Parrot Land. In 1865, the celebrated British naturalist and wildlife artist John Gould said: 'No group of birds gives Australia so tropical and benign an air as the numerous species of this great family by which it is tenanted.'

C. Parrots are descendants of an ancient line. Due to their great diversity, and since most species inhabit Africa, Australia and South America, it seems almost certain that parrots originated millions of years ago on the ancient southern continent of Gondwana, before it broke up into the separate southern hemisphere continents we know today. Much of Gondwana comprised vast rainforests intersected by huge slow-flowing rivers and expansive lakes, but by eight million years ago, great changes were underway. The center of the continent of Australia had begun to dry out, and the rainforests that once covered it gradually contracted to the continental margins, where, to a limited extent, they still exist today.

D. The creatures that remained in those shrinking rainforests had to adapt to the drier conditions or face extinction. Reacting to these desperate circumstances, the parrot family, typically found in jungles in other parts of the world, has populated some of Australia’s harshest environments. The parrots spread from ancestral forests through eucalypt woodlands to colonies the central deserts of Australia, and as a consequence they diversified into a wide range of species with adaptations that reflect the many changes animals and plants had to make to survive in these areas.

E. These evolutionary pressures helped mould keratin, the substance from which breaks are made into a range of tools capable of gathering the new food types favored by various species of parrot. The size of a parrot’s short, blunt beak and the length of that beak’s do curved upper section are related to the type of food each species eats. Some have comparatively long beaks that are perfect for extracting seeds from fruit; others have broader and stronger beaks that are designed for cracking hard seeds.

F. Differently shaped beaks are not the only adaptations that have been made during the developing relationship between parrots and their food plants. Like all of Australia’s many honey eating birds, the rainbow-coloured lorikeets and the flowers on which they feed have long co­evolved with features such as the shape and colour of the flowers adapted to the bird’s particular needs, and physical a example, red is the most I attractive colour to birds, and thus flowers which depend on birds for pollination are more often red, and lorikeets’ to gues have bristles which help them to collect as much pollen as possible.

G. Today, most of Australia’s parrots inhabit woodland and open forest, and their numbers decline towards both deserts and wetter areas. The majority are nomadic to some degree, moving around to take advantage of feeding and breeding places. Two of the dry country parrots, the pink and grey galah and the pink, white and yellow corella have expanded their ranges in recent years. They are among the species that have adapted well to the changes brought about by European settlement forest telling created grasslands where galahs and corellas thrive.

H. But other parrot species did not fare so well when their environments were altered. The clearing of large areas of rainforest is probably responsible for the disappearance of the double-eyed fig parrot, and numbers of ground parrots declined when a great part of their habitat was destroyed by the draining of coastal swamps. Even some parrot species that benefited from forest clearing at first are now comforted by a shortage of nesting sites due to further man-made changes.

I. New conditions also sometimes favour an incoming species over one that originally inhabited the area. For example, after farmers cleared large areas of forest on Kangaroo Island off the coast of South Australia, the island was colonised by galahs. They were soon going down holes and destroying black cockatoo eggs in order to take the hole for their own use. Their success precipitated a partial collapse in the black cockatoo population when the later lost the struggle for scarce nesting hollows.

J. There may be no final answer to ensuring an equitable balance between parrot species. Nest box programmers help ease the shortage of nesting sites in some places, but there are not enough, they are expensive and they are not an adequate substitute by large, old trees, such as the habitat they represent and nectar, pollen and seeds they provide. Competition between parrots for nest sites is a result of the changes we humans have made to the Earth. We are the most widespread and dangerous competitors that parrots have ever had to face, but we also have the knowledge and skill to maintain the wonderfully rich diversity of Australia’s parrots. All we need is the wild to do so.

READING PASSAGE 3

Read the text and answer questions 27-40.

Yawning

How and why we yawn still presents problems for researchers in an area which has only recently been opened up to study.

When Robert R Provine began studying yawning in the 1960s, it was difficult for him to convince research students of the merits of ‘yawning science’. Although it may appear quirky to some, Provine’s decision to study yawning was a logical extension of his research in developmental neuroscience.

The verb ‘to yawn’ is derived from the Old English ganien or ginian, meaning to gape or open wide. But in addition to gaping jaws, yawning has significant features that are easy to observe and analyse. Provine ‘collected’ yawns to study by using a variation of the contagion response. He asked people to ‘think about yawning’ and, once they began to yawn to depress a button and that would record from the start of the yawn to the exhalation at its end.

Provine’s early discoveries can be summanized as follows: the yawn is highly stereotyped but not invariant in its duration and form. It is an excellent example of the instinctive ‘fixed action pattern’ of classical animal-behavior study, or ethology. It is not a reflex (short-duration, rapid, proportional response to a simple stimulus), but, once started, a yawn progresses with the inevitability of a sneeze. The standard yawn runs its course over about six seconds on average, but its duration can range from about three seconds to much longer than the average. There are no half-yawns: this is an example of the typical intensity of fixed action patterns and a reason why you cannot stifle yawns. Just like a cough, yawns can come in bouts with a highly variable inter-yawn interval, which is generally about 68 seconds but rarely more than 70. There is no relation between yawn frequency and duration: producers of short or long yawns do not compensate by yawning more or less often. Furthermore, Provine’s hypotheses about the form and function of yawning can be tested by three informative yawn variants which can be used to look at the roles of the nose, the mouth and the jaws.

i)The closed nose yawn

Subjects are asked to pinch their nose closed when they feel themselves start to yawn. Most subjects report being able to perform perfectly normal closed nose yawns. This indicates that the inhalation at the onset of a yawn, and the exhalation at its end, need not involve the nostrils – the mouth provides a sufficient airway.

ii)The clenched teeth yawn

Subjects are asked to clench their teeth when they feel themselves start to yawn but allow themselves to inhale normally through their open lips and clenched teeth. This variant gives one the sensation of being stuck midyawn. This shows that gaping of the jaws is an essential component of the fixed action pattern of the yawn, and unless it is accomplished, the program (or pattern) will not run to completion. The yawn is also shown to be more than a deep breath, because, unlike normal breathing, inhalation and exhalation cannot be performed so well through the clenched teeth as through the nose.

iii)The nose yawn

This variant tests the adequacy of the nasal airway to sustain a yawn. Unlike normal breathing, which can be performed equally well through mouth or nose, yawning is impossible via nasal inhalation alone. As with the clenched teeth yawn, the nose yawn provides the unfulfilling sensation of being stuck in mid-yawn. Exhalation, on the other hand, can be accomplished equally well through nose or mouth. Through thin methodology, Provine demonstrated that inhalation through the oral airway and the gaping of jaws are necessary for normal yawns. The motor program for yawning will not run to completion without feedback that these parts of the program have been accomplished.

But yawning is a powerful, generalized movement that involves much more than airway maneuvres and jaw-gaping. When yawning you also stretch your facial muscles, tilt your head back, narrow or close your eyes, produce tears, salivate, open the Eustachian tubes of your middle ear and perform many other, yet unspecified, cardiovascular and respiratory acts. Perhaps the yawn shares components with other behaviour. For example, in the yawn a kind of ‘slow sneeze or is the sneeze a ‘fast yawn’? Both share common respiratory and other features including jaw gaping, eye closing and head tilting.

Yawning and stretching share properties and may be performed together as parts of a global motor complex. Studies by J.I.P deVries et al. in the early 1980s, charting movement in the developing foet US using ultrasound, observed a link between yawning and stretching. The most extraordinary demonstration of the yawn-stretch linkage occurs in many people paralyzed on one side of their body because of brain damage caused by a stroke, the prominent British neurologist Sir Francis Walshe noted in 1923 that when these people yawn, they are startled and mystified to observe that their otherwise paralyzed arm rises and flexes automatically in what neurologists term an ‘associated response’. Yawning apparently activates undamaged, unconsciously controlled connections between the brain and the motor system, causing the paralyzed limb to move. It is not known whether the associated response is a positive prognosis for recovery, nor whether yawning is therapeutic for prevention of muscular deterioration.

Provine speculated that, in general, yawning may have many functions, and selecting a single function from the available options may be an unrealistic goal. Yawning appears to be associated with a change of behavioral state, switching from one activity to another. Yawning is also a reminder that ancient and unconscious behavior linking us to the animal world lurks beneath the veneer of culture, rationality and language.