I have at last posted my last assignment of 12!  Now I have to start thinking of crop circles... But to be honest, I dont want to think about crop circles... Do we need to figure out everything in life?  Can some things not stay mysteries?  I have no idea what to think about crop circles.  All I can say is that whoever is making them is an artists and I would much rather spend time outdoors than sit in front of my computer and struggle with crop circles...

Lemurs have been isolated on the island of Madagascar for millions of years and thus adaptive radiation of these creatures has been confined to this island. ⁽¹⁾  The fossil record is poor and when exactly the lemurs inhabited Madagascar and when they split from the other prosimian primates would be guesswork, but the fact that Madagascar has been isolated for millions of years, is widely accepted. ⁽¹⁾ The lemurs thus have had a long time to adapt to the different environments of the island and in the absence of other primates and relatively few mammals could fill many ecological niches, the island offered.  According to Patricia Wright (1999, p. 31), “adaptive radiation of lemurs on Madagascar may have been uniquely characterized by selection toward efficiency to cope with the harsh and unpredictable island environment”. ⁽²⁾

They differ from anthropoids (monkeys, apes, humans) in several behavioural features, such as female dominance, targeted female-female aggression, lack of sexual dimorphism, strict seasonal breeding and cathemerality (being active during the day as well as night). ⁽²⁾ There are several suggested hypothesis for these adaptations, the latest being the “energy frugality hypothesis” postulating that the majority of traits are either adaptations to conserve energy or to maximize use of scarce resources. ⁽²⁾

In Africa and Asia other prosimians (bushbabies, pottos, lorises and tarsiers) remained small, solitary and nocturnal, avoiding the diurnal monkeys, to prevent competition.  In Madagascar though, lemurs have a wide variety of lifestyles, varying degrees of social structures and they come in all sorts of sizes.  One feature they still share with all other prosimians though, is their heavy reliance on their sense of smell. ⁽³⁾

Some lemurs have become very small and fill a gap in the absence of squirrels and other prosimians. The smallest living primates today are the grey mouse-lemur (Microcebus murinus) and the rufous mouse-lemur (M. rufus) weighing only between 45-90 grams. ^{(3, 4)}  They are nocturnal and generally solitary when foraging for food. During the day females sometimes group together sleeping in tree holes or nests built of leaves. ^{(3, 4)}  They are also arboreal and their diet consists of fruit, flowers, nectar, insects and spiders. They have acute noses, which they use to detect food as well as keeping in touch with neighbours.  They scent mark twigs by urinating in their cupped hands, wiping it on their feet and then wiping them on a branch, as well as leaving smelly footprints as they move on. ⁽³⁾  Some species of dwarf and mouse-lemurs even hibernate during the winter months, when food is scarce, which is very unusual behaviour for primates. ⁽³⁾

In the genus Phaner there is a small lemur that has adapted to a specialized diet of resinous sap of certain trees. For this diet its adaptations involve teeth, tongue, nails and digestive system. ⁽³⁾

The aye-aye (Daubentonia madagascariensis) must be one of the most unusual lemurs.  They are nocturnal, about the size of a domestic cat and covered in a thick black fur coat with longer white-tipped hairs giving it a shaggy appearance. Their huge ears are capable of picking up faint sound of larvae inside wood.  But it is their long bony third finger that is most remarkable. They move along in trees, tapping along with their fingers on wood and listening until they have found what they have been looking for; grubs!  Their chisel-like teeth then quickly gnaw a hole in the wood and the long middle finger is then used to extract the grub.  They also eat nuts and even eggs, again using their chisel-like teeth to gain access and then using their long finger to extract the content. ^{(3, 5)}

Probably the best known is the ring-tailed lemur (Lemur catta).  They are also about the size of a domestic cat and inhabit the dry southern part of Madagascar.  Their preferred habitat is the gallery forest that fringes major rivers, but they are found in other habitat as well. They are the best adapted to a partly terrestrial lifestyle of all the lemurs, although a lot of time is spent in the trees, where they mostly feed on fruit, but also leaves, seeds and the odd insect.  These lemurs are diurnal and live in sociable societies that are led by females.  Sent marking from glands on their wrists, armpits (males) and genital area (both sexes) is part of their daily routine and serves as territorial boundaries. ⁽³⁾  

Some lemurs make the most of both day and night and space out their activities over a 24-hour period. The brown lemur (Lemur fulvus) is one such specie.  They mostly feed on fruit but also eat leaves. ⁽³⁾

The family Indriidae contains the largest living lemurs, namely the indri (Indri indri). They are possibly the most strictly diurnal and arboreal of all lemurs.  They live in small family groups and feed on leaves, flowers and fruit.  They jump from tree to tree, usually hugging tree trunks, rather than flexible branches due to their weight.  The indri is however famous for its singing.  They use their eerie chorus to mark their territory. ^{(3, 6)}

The sifakas, like the indri are agile jumpers and can jump up to 10 meters.  They are smaller than the indri and usually land upright.  They do cover ground on the floor sometimes, but cannot walk on all fours, but will rather jump, with arms held high. ^{(3, 6)}

Some lemurs have become very specialized in their diet, like the golden bamboo lemur (Hapalemur aureus), the grey bamboo lemur (Hapalemur griseus) and the greater bamboo lemur (Hapalemur simus).  What baffled scientists is that they all can all live together in close proximity eating from the same plants. It was then established that they prefer different parts of the same plant and so prevent competition.  What is further remarkable is that the golden bamboo lemur prefers young bamboo shoots, containing cyanide and highly toxic, but this lemur has managed to overcome that obstacle. ⁽³⁾

Today Madagascar has between 23-52 living species of lemurs (depending on the source one uses). ^{(3, 8)} But many more, especially the larger ones, have already gone extinct and due to continued habitat destruction and fragmentation, all remaining species are at risk. ^{(3, 8)}

References:

1. Martin RD. 2000. Origins, diversity and relationships of lemurs. International Journal of Primatology  21 (6): 1021-1049
2. Wright PC. 1999. Lemur traits and Madagascar ecology: coping with an island environment. American Journal of Physical Anthropology 110 (S29): 31-72
3. Preston-Mafham K. 1991. Madagascar. A Natural History. Pages 141-188, Chapter 7. The Lemurs. Cape Town. Struik Publishers.
4. Wikipedia contributors. Gray Mouse Lemur [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 9, 18:09 UTC [cited 2006 May 4]. Available from: http://en.wikipedia.org/w/index.php?title=Gray_Mouse_Lemur&oldid=47725424
5. Wikipedia contributors. Aye-aye [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 28, 05:04 UTC [cited 2006 May 4]. Available from: http://en.wikipedia.org/w/index.php?title=Aye-aye&oldid=50537743.
6. Wikipedia contributors. Indriidae [Internet]. Wikipedia, The Free Encyclopedia; 2006 Mar 24, 16:02 UTC [cited 2006 May 4]. Available from: http://en.wikipedia.org/w/index.php?title=Indriidae&oldid=45277136.
7. Wikipedia contributors. Golden Bamboo Lemur [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 27, 18:21 UTC [cited 2006 May 4]. Available from: http://en.wikipedia.org/w/index.php?title=Golden_Bamboo_Lemur&oldid=50456767.
8. Wikipedia contributors. Lemur [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 2, 01:41 UTC [cited 2006 May 4]. Available from: http://en.wikipedia.org/w/index.php?title=Lemur&oldid=51141271.

Karen Marais

BCB Hons NISL student

University of the Western Cape

Private Bag X17

Bellville

E-mail  2657211@uwc.ac.za

Web  http://brit-journal.com/karen2006bcbnisl/

Continental drift can be explained through the theory of plate tectonics. If one would cut the earth in half the interior can be roughly divided into the core, the mantle and the crust.  But to understand plate tectonics, one has to understand the relationship of the outermost part of the mantle and crust and how they interact. The outermost part of the earth’s interior is made up of two layers. The lithosphere is made up of the crust and the upper solidified part of the mantle.  This layer floats on the super-hot and liquid part of the mantle called the asthenosphere.  The lithosphere is not a solid connected mass, but it is broken up into tectonic plates that can move relative to one another under the influence of convection currents within the asthenosphere.  The movement of these floating tectonic plates explain the phenomenon of seafloor spreading and continental drift.⁽¹⁾

It is about 180 million years ago that Pangea ⁽²⁾(a super-continent that included all big land masses at that time) split to form the northern super-continent Laurasia ⁽³⁾(today’s Europe, Asia and North America) and the southern super-continent Gondwana (today’s Africa, Madagascar, Antarctica, South America, India, Australia, New Zealand, New Guinea). ⁽⁴⁾ By that time in the animal kingdom, the mammals had arrived, although still overshadowed by the ruling dinosaurs.   

We do not know for sure, if placental mammals evolved from marsupial mammals.  It is more likely that they evolved side by side, but in geographic isolation.  This brings us back to Gondwana.  The super-continent began to break up in the late Jurrasic, with Africa first separating and drifting north, followed by India about 125 million years ago (which eventually collided with Asia and in the process formed the Himalayas) and then New Zealand about 80 million years ago.  South America, Antarctica and Australia stayed connected, although only the tip of South America was connected to Antarctica that linked it to Australia, for another almost 50 million years.⁽⁴⁾

Coming back to the animal kingdom, it is only after the dinosaurs were wiped out less than 80 million years ago, that the mammals diverged to fill the empty ecological niches, left by the now extinct dinosaurs.  From the fossil record, it seems that the placental mammals evolved in the northern hemisphere and the marsupials probably first evolved in the southern hemisphere, most likely in South America. Marsupials could migrate via the land bridge that connected South America to Antarctica and onwards to Australia, and vice versa. But then the three continents separated. First Australia separated and drifted north (45 million years ago) ⁽⁴⁾, then about 30 million years ago Antarctica and South America separated with Antarctica drifting south over the south pole and South America drifting north to eventually connect to North America (about 15 million years ago).⁽⁴⁾

The fact that Australia has been isolated since, explains the huge diversity of marsupials concentrated there.  Without competition of the placental mammals, marsupials diverged to fill all the ecological niches offered by their environment.  South America has the second largest diversity of marsupials, mostly opossums.  Once South and North America became connected the placental mammals from the north started migrating south and they soon out-competed most marsupials.  One very resilient marsupial however made it into North America and still exists there today, the Virginia opossum.

With the fossil records we have today, the correlation in plant species across different continents, geological similarities between continents, the study of tectonic plates and how continents have drifted over time and still do today; scientists have drawn a fairly  complete picture that manages to explain the distribution of placental and marsupial mammals today.  And so the mystery has been solved.

References:

1. Wikipedia contributors. Plate tectonics [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 1, 00:49 UTC [cited 2006 May 1]. Available from: http://en.wikipedia.org/w/index.php?title=Plate_tectonics&oldid=50972274.

2.      Wikipedia contributors. Pangaea [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 1, 02:05 UTC [cited 2006 May 1]. Available from: http://en.wikipedia.org/w/index.php?title=Pangaea&oldid=50981883.

3.      Wikipedia contributors. Laurasia [Internet]. Wikipedia, The Free Encyclopedia; 2006 Mar 19, 12:44 UTC [cited 2006 May 1]. Available from: http://en.wikipedia.org/w/index.php?title=Laurasia&oldid=44497306.

4.      Wikipedia contributors. Gondwana [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 26, 11:03 UTC [cited 2006 May 1]. Available from: http://en.wikipedia.org/w/index.php?title=Gondwana&oldid=50238306.

“One of the earliest birds was a toothy, long-tailed creature the size of a crow, with feathers evolved from scales”. ^{(Reader’s Digest Editors. 1974, p.250)}  This was Archaeopteryx, first discovered in a limestone quarry near Solnhofen, Germany in 1861.  Since then birds have adapted greatly, perfecting their anatomy for flying and their physiology for providing the energy to fly.

Although Archaeopteryx most probably could fly for short distances, its body was heavy and not well adapted for it.  Birds had to greatly reduce their weight to make them able flyers.  Today, birds lost the heavy reptilian tail and they have replaced a heavy jaw and teeth with a light but strong beak.  Many of their bones are hollow and almost paper-thin, but they are reinforced by internal struts for extra strength.  The lower vertebra of their back and the hip girdle are fused together for strength and act as an anchor for the muscles that control their tail feathers.  They all have a keeled breastbone for attachment of the strong pectoral muscles that produce the downstroke in flight.  The small breast muscles raise the wings by a “rope and pulley” attachment at the top of the arm bone. The collar bones are fused (wishbone) to give stability at their shoulders. ^{(1, 2)}

The position of their organs is also optimal for flight, with the lungs being high up in their trunk and the heavier organs like the heart, digestive organs and the pectoral muscles being positioned ventrally.  This arrangement also places the centre of gravity in an ideal position, preventing the bird from flipping over in flight. ⁽²⁾ Even the reproductive organs have been modified by shrinking to a fraction of their functional weight out of breeding season. ⁽¹⁾

Because flight can demand high levels of energy (for the flight muscles can consume huge amounts of oxygen), a bird’s heart is big relative to its body.  Its respiratory system is also unique.  Birds have in addition to their lungs special air sacs that even extend into the bones.  When they inhale, the air flows through the lungs and into the air sacs and when they exhale the air passed back through the lungs, giving the bloodstream another chance to take up still more oxygen and get rid of carbon dioxide.  These special air sacs also function as a cooling system in times of intense exertion. ⁽¹⁾

Birds also need to take in high-calorie foods to provide them with the energy they need.  They mostly eat foods like seeds, insects, fruit, nectar or small mammals and avoid food that is high in bulk and low in calories.  Their metabolism is high, due to their relative high body temperature, which they maintain through their excellent insulating properties of their feathers. Their high metabolism rate can also be seen as a weight-saving advantage, as food is quickly digested and waste products soon excreted. ⁽¹⁾

Ultimately, it is the feather that has made the birds lords of the air. Their feathers can weigh twice as much as their skeleton, but individually they are “as light as a feather”.  Apart from the downy underlayers, feathers have some 600 barbs on either side of the main shaft (quill), which forms the feather’s vanes.  Each barb again has a main stem with about 800 barbules on either side.  The barbules pointing towards the tip of the feather have little hooks, while those pointing to the base have a little ridge at the top onto which the hooks fit.  This forms an almost air tight surface, which is essential for flying. It also has the advantage that a “torn” vane can be re-zipped by being stroked lengthwise several times.  This is what actually happens when birds are preening themselves.  They are repairing their feathers, keeping them in good condition. (Preening also entails waterproofing the feathers by spreading oil from a special oil gland just above their tail.) ⁽¹⁾

A bird’s wing shape differs according to their specific function and thus the bird’s lifestyle.  Large seabirds have long narrow wings, which allow them to glide effortlessly which is very energy efficient.  Soaring birds, like raptors have long broad wings with prominent primary feathers for manoeuvrability and stability in turbulent air. They make use of thermals to conserve energy. Ground feeding birds have short broad wings with arched bones that allow them to take off fast when threatened.  Swept-backed wings that taper to slender tips make swifts very agile for catching flying insects, without having to flap their wings.  A hummingbird has a unique wing structure.  They are able to hover best of all birds and can even fly backwards.  Their “arms” are very short, but their “hands” long with ten long and powerful primary feathers.  Their elbow and wrist joints are rigid, but their shoulder joints are so mobile, that their wings can practically move in any direction, giving them their extraordinary flying abilities.  But it comes at a cost, as it consumes huge amounts of energy. ⁽¹⁾

The birds are the most widely travelled and species rich of all vertebrates.  Through flight they have mastered the air, but it is the uniqueness of their feathers that has given them this edge.

References:

1.      Reader’s Digest Editors. 1974. Animal Families. Marvels and mysteries of animal behaviour. Pages 250-261 in Animals in Action. Hong Kong: Reader’s Digest Association Far East Limited.

2.      Wikipedia contributors. Bird skeleton [Internet]. Wikipedia, The Free Encyclopedia; 2006 Mar 10, 23:12 UTC [cited 2006 Apr 30]. Available from: http://en.wikipedia.org/w/index.php?title=Bird_skeleton&oldid=43210309.

Karen Marais

BCB Hons NISL student

University of the Western Cape

Private Bag X17

Bellville

E-mail  2657211@uwc.ac.za

Web  http://brit-journal.com/karen2006bcbnisl/

I always thought that frogs and toads lay their eggs in water, where they spawn as tadpoles and then metamorphose into frogs (or toads).  This group of amphibians have however developed many different kinds of reproductive strategies, all following the egg-tadpole-frog route, but not all opting for the “safety in numbers” strategy.

The “safety in numbers” strategy is purely where the female frog lays hundreds to thousands of eggs in water, but then abandons them.  These eggs are then very vulnerable to predation, but the success lies in their numbers.  And this strategy has been successful, as many frogs and toads living today, still use this strategy.

Some frogs however have gone a step further.  In moist areas, like the South American rain forests some plants provide literal little ponds, as water is collected in their cup-like structure and it is here were some frogs have chosen a home.  Here they lay their eggs and the little tadpoles have a secure environment to metamorphose into little frogs. 

In Southern Africa there are several frog species that have found terrestrial breeding sites that are safe from predators.  One such frog is the Shovel-nosed frog that digs a tunnel with a chamber in the muddy banks of pans, where the eggs are laid and fertilized (fertilization takes place externally in frogs).  The female then stays with the eggs, which are kept moist by a rubbery mass.  Once the tadpoles hatch, she digs a tunnel to the waters edge, the tadpoles crawl onto the females back and she carries them to the water, where they can the metamorphose into frogs. (Carruthers 2001, p.15)

There are several species of Leaf-folding Frogs, which use the perimeter of pans where grass has been inundated by shallow waters.  Here the eggs are laid and the male then fertilizes them and also folds and glues the grass blade into a leaf-tube.  As the tadpoles hatch, the glues softens, allowing them to drop into the water to complete their development into frogs. (Carruthers 2001, p.17)  Other frogs use trees that hang over water bodies as a nesting site.  The Foam Nest Frog female secretes a fluid, which she churns up with her hind legs into a foam ball.  It is into this foam ball that the eggs are laid and then fertilized.  The outer surface then hardens, but inside the eggs are protected and stay moist.  Once the tadpoles have hatched, they break through the crust and drop into the water. (Carruthers 2001, p.20)

A Caribbean frog, the whistling frog, lays fairly large eggs that are hidden in moist areas beneath organic material.  Here the tadpoles fully metamorphose inside the fluid filled eggs, feeding on the yoke.  The little frogs have a tiny spike on their noses with which they pierce the eggs and then hatch. 

Some frogs have become purely terrestrial as the several species of rain frogs.  They spend most of their time in underground tunnels and only emerge when it rains.  It is then in these underground tunnels that they also breed.  Because the rain frogs are so short legged and round the male cannot mount (amplexus) the female and so she secretes a glue that glues them together. The glued pair the lays and fertilize the eggs in a chamber underground, where the tadpoles remain inside the eggs and feed off the egg yolk until they have metamorphosed into frogs.  (Carruthers 2001, p.23)  So, a strategy away from water has also proven to be successful.

Another amazing adaptation can be observed in the very scarce and localized Ghost Frogs.  The tadpoles of this species metamorphose very slowly, due to the cold water of mountain streams and take up to a year.  The tadpoles however have enormous mouths that span the whole width of their body. In this big mouth they have sixteen rows of teeth, which they use to pull themselves over rocks while eating off the algae.  What makes it remarkable is that this is fast running water.  They have even been observed climbing waterfalls, clinging to the algae covered rock surface with their teeth.  This “fast running water” environment they metamorphose in is unique to ghost frogs. (Carruthers 2001, p.33) 

Some frogs have taken it another step further and have become involved parents.  The midwife toad, which is a misnomer as it is the male that does the caring, wraps the strings of eggs around his hind legs protecting them from predation, until the tadpoles hatch. 

The pipa toad from Brazil has developed a truly amazing strategy of parental care.  These toads are aquatic and as the eggs are laid and fertilized in the water, the male carefully manoeuvres each egg with sort of back-flip onto the females back, where they stick.  Up to a hundred eggs can be stuck to her back.  Her skin then swells, embedding the eggs and eventually covering them completely under her skin.  The eggs hatch in about 3 weeks time, but the tadpoles stay under her skin for another 3 weeks before they emerge from under her skin.

Darwin’s frog from Chile has taken parental caring yet another step further.  The male guards the eggs that have been laid on the forest floor until he sees movement in them.  He then “eats” the eggs, storing up to 12 eggs in his vocal sack.  There they develop through the tadpole stage into fully developed little frogs.  The height of parental care however goes to a tiny little frog living on a remote mountain in West Africa.  The female stores the fertilized eggs inside her extended oviducts.  There they hatch and the tadpoles feed on little white flakes the female secretes internally.  For 9 month she carries her young until the next rainy season, when she “gives birth” to fully developed little frogs.

References:

Carruthers V. 2001. Frogs and Frogging in Southern Africa.  Cape Town: Struik Publishers (Pty) Ltd

The rest of the information was taken from the 6^th episode of the BBC Life on Earth series, by David Attenborough.

What do you do when it is a long week-end, your husband and kids have gone away for the week-end and you have stayed at home because you need to work and what is more you are reliant on the internet, which you can access only from your home.... and then there seems to be a problem with the Universities server as you cannot log on to the site you need to work from??  You get "dik die donder in"!!!! All I can say is damn technology.  I think I should go an live in the bush...

How do insects attract a mate?  Different insects use different strategies and what seems attractive to one group goes unnoticed to another.  But they all serve the same purpose:  to find a mate and complete their life cycle. Here are a few examples of the diversity in attraction methods that have evolved from colour, to smell to sound.

Butterflies and moths are the adult stage of a group of insects called the Lepidoptera. The sole purpose of this stage is to find a suitable mate, sexually reproduce and secure the maximum amount of offspring.  There is no simple distinction between moths and butterflies, but generally moths are mostly nocturnal and their larvae construct intricate cocoons to protect the pupae.  The wondrous colours of most butterflies and some diurnal moths are produced by small scales that cover the wings and body.  “These scales have pigments that produce the white, red, yellow and orange colours with the brighter metallic and iridescent colours being produced by fine grooves and ridges on the scales that diffract light.” ⁽¹⁾  In some species the males have modified scales in the form of long scent hairs that release chemicals to attract females during courtship.⁽¹⁾ This is a species specific communication, where females respond only to the chemicals release by males of their own species. ⁽¹⁾

Wing patterns and colours in butterflies play a role in attracting a mate.  In some species the specific wing patterns allow a mate to recognize a partner of the same species. ⁽²⁾  In others it seems that the brightness of the colours influences the selection of a mate. ⁽³⁾  Some species have ultra-violet reflecting colours which indicate their sex allowing females to recognize a male and males to recognize each other. ⁽⁴⁾ Polarized light for mate recognition is used by some species of butterfly that inhabit deep forests where lighting can be tricky. ⁽⁵⁾ But is not only colour that is used to attract the opposite sex.  Many butterflies perform elaborate courtship displays to attract females.

Moths use pheromones to attract each other.  The sex pheromones are produced and released by the female moths to advertise their readiness to mate. These sex pheromones can be picked up by male moths over very long distances.  They have thus adapted a “smell strategy” compared to the butterflies, who have perfected their “colour strategy”.

Insects in the order Orthoptera use sound as their attraction strategy.  Grasshoppers and locusts produce sounds with special sound producing organs on their hind legs.⁽⁶⁾  They do this by rubbing these special organs on their hind legs against the strong veins of their wings.  Crickets and katydids have specialised sound organs on their wings.⁽⁶⁾ With these organs the katydids produce a sound that sounds like “Katy did, Katy didn’t”, hence its name. ⁽⁷⁾

Cicadas are of the order Hemiptera.  The male cicadas also have specialized sound organs and are the master singers of all insects.  These organs produce the sound through vibrating the membranes with the help of strong muscles.  They have two hollow resonators in their abdomen that amplifies the sound, and some species have the capability of producing sounds exceeding an incredible 106 decibels.⁽⁸⁾

References:

1. Picker M, Griffiths C, Weaving A. 2002. Field Guide to Insects of South Africa. Cape Town: Struik Publishers. Page 314

2. Fordyce, JA, Nice, C.C., Forister, M.L. & Shapiro, A.M. 2002. The significance of wing pattern diversity in the Lycaenidae: mate discrimination by two recently diverged species. J. Evol. Biol. 15: 871–879.

3. Knüttel, H. & Fiedler, K. 2001. Host-plant-derived variation in ultraviolet wing patterns influences mate selection by male butterflies. J. Exp. Biol. 204: 2447–2459.

4. Silberglied R, Taylor O. 1978. Ultraviolet reflection and its behavioral role in the courtship of the sulfur butterflies Colias eurytheme and C. philodice (Lepidoptera, Pieridae). Behavioral Ecology and Sociobiology  3: 203-243

5. Sweeny A, Jiggins C, Johnsen S. 2003. Nature 423: 31

6. Picker M, Griffiths C, Weaving A. 2002. Field Guide to Insects of South Africa. Cape Town: Struik Publishers. Page 74

7. Wikipedia contributors. Katydid [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 27, 02:10 UTC [cited 2006 Apr 27]. Available from: http://en.wikipedia.org/w/index.php?title=Katydid&oldid=50357634.

8. Wikipedia contributors. Cicada [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 27, 12:00 UTC [cited 2006 Apr 27]. Available from: http://en.wikipedia.org/w/index.php?title=Cicada&oldid=50409567.

Terrestrial plants first evolved without flowers.  The first land plants evolved around 400 million years ago and were probably mosses. They used a mechanism of a sexual and an asexual cycle to reproduce.  Then at around 350 million years ago the cycads came along and with them a different reproductive mechanism developed.  They evolved into male and female plants, both producing a huge central cone, which evolved from the previous spores.  The male plants produced huge amounts of pollen which is mostly wind dispersed.  But little insects also started feasting on the nutritious pollen and along with that a strategy developed to attract these creatures that were now helping the process of pollen dispersal.  One species of cycad even today practises a strategy where the temperature in the cone is raised by about 2 degrees when the pollen is ready for distribution.  This attracts weevils, which come to feast on the pollen, get themselves covered in the process and then deliver the pollen to another cycad in search of another meal.  This way of pollen dispersal is a lot more economical than the wind and both the cycads and the weevils are winners ⁽¹⁾.

 It is only about 100 million years ago when the first flowering plants evolved.  This was an advertisement strategy and still is today. Pollen is nutritious and insects long learned to utilise this food source.  Now plants developed more strategies to attract the pollinators and the flowering plants were born.  Water-lilies and magnolias are descendants of some of the oldest plant families that first produced true flowers.  They still reward the little beetles that visit them with little more than the pollen, but this has served to be successful enough for these plants to be around still today. 

Some plants developed an exclusive relationship with just one species of insect. One such example present today is of the pink Orphiump frutescence that is only pollinated by carpenter bees. The flower holds its pollen inside its hollow anthers and the only way the pollen can escape is through a tiny hole at the top of the anther.  The carpenter bee has perfected its technique of extracting the pollen by alighting on an anther and then beating its wings at a certain frequency, just right to make the pollen spout out of the hole at the top.  As only the carpenter bees can buzz at this frequency, they alone can extract the pollen.  They however do not know if a flower has been visited before and so they move from flower to flower, shaking the anthers and in the process pollinating the flowers with the pollen that has collected on their furry bodies ⁽²⁾.

Another such example of a specialized partnership is seen in the twinspurs (Diascia) in South Africa.  There reward is oil which is secreted at the far end of the spurs.  Several species of solitary bees have developed brushes on there forelegs to collect the oil.  For each species of twinspur there is a corresponding species of oil-collecting bee with forelegs that exactly match the length of the spurs ⁽¹⁾. 

Some flowers started producing nectar as a reward to attract insects and some produced scented chemical to attract their pollen couriers and yet another advertisement is colour.  Many even developed “landing strip marks” or nectar guides that help the insects guide their tongues into the flowers to collect their reward and often also parcels of pollen which they then carry to the next flower.

Some plants even mimic others to try and trick a pollinator to visit.  One such example is the cluster disa (Disa ferruginea) on Table Mountain.  It has a bright red colour and closely resembles the red Tritoniopsis triticea  (alongside it also grows), which produces a rich nectar reward.  The disa however produces none, but manages to trick the mountain pride butterfly who repeatedly visits the empty flowers and thereby pollinating it ⁽²⁾.

There are many more examples of how plants and insects have evolved together, adapting together to serve each other.  Some are extremely bizarre, but all serving a purpose of fulfilling a life-cycle, all part of a functional ecosystem and should the one disappear, so will the other...