Biodiversity

Wednesday, May 03, 2006

MEERKATS AND PRAIRIE DOGS

The meerkat or suricate (Suricata suricatta, Family Herpestidae) is one of Southern Africa’s best loved little mammals. They are social mammals that live together in underground burrows in a tight knit community usually called a gang, mob or band. They have a highly organized structure to their gang, with an alpha pair taking the leading role.(1) The alpha female is however not always the only breeding female in the group. If there is more than one breeding female, the births are synchronized, which makes caring for the young easier. (2)

They are said to have an altruistic lifestyle, looking out for each other. There is always a sentry or two on guard, while the others are out foraging for food, just playing or sunning them. (1) The sentry will stand up on its hind legs, often on top of a termite mound, keeping a constant watch for raptors and other predators. If danger is spotted, the sentry will give a warning bark and the others will run for cover to the closest entrance to their burrow. They are believed to have different barks for different messages, not only warning the rest of the mob if there is danger, but also letting them know that it is safe to continue foraging. (1, 2) Each individual is however also vigilant when out foraging for food. They will stand upright every few seconds to scan for danger and if satisfied continue their frantic digging for insects or reptiles. (2) If they are attacked, they will often gang up and try to intimidate the attacker by fluffing up their fur and with gaping mouths launch themselves as a unit at the attacker. (2)

The young are protected by babysitters, often young females, who without having her own babies will lactate and feed them, while the others are out foraging for food with the rest of the gang. (1,2) Once the young are big enough to venture outside, the babysitters will keep a close eye and stay close to an entrance. If danger is imminent and they do not make it to the burrow, they will even protect the young with their life by lying on top of them. (1)

They scent mark their territory frequently as neighbouring groups are hostile towards each other. Violent skirmishes between two groups can occur which intriguingly may be followed by a swapping of allegiances after the fight. This leads to new genes being added to the gene pool. (2) Mutual grooming serves to strengthen bonds and is part of their daily routine. Sometimes members of a group are separated for days and then grooming plays a big part in the welcoming rituals. (1)

Another Southern African mammal that lives together in a warren is the Cape ground squirrel (Xerus inauris, Family Sciuridae). Groups of up to 30 individuals are usually led by an alpha female. Only one mature breeding male is tolerated among the group of females. (3) They are vigilant and communicate constantly with each other through different calls, while out foraging for bulbs, roots, grass and the odd termite. (3) Their safety strategy is in their numbers and their constant communication. A very interesting reaction to an approaching snake has been recorded, where “the squirrel closest to the intruding snake will imitate the snake’s crawling motion by bringing its tail to the side of its body in a sweeping motion.”(3, page 128) This can thwart the attack as the snake gets so unnerved, that it moves away. (3) They also make use of the ‘babysitting system’ like the suricates and show similar social behaviour.

Some mole-rats are also social mammals, with the Damara mole-rat (Cryptomys damarensis, Family Bathyergidae) being the most social of all. (4) They live together in extensive colonies, reaching numbers that can exceed 40 individuals. (4) Because they live in a very arid part of Southern Africa, their biology is hugely affected by rainfall. The colony only has one breeding pair, with the rest being offspring that translate into a co-operative workforce. Many of the offspring never found their own colony and live a life of socially induced infertility, but this is their mean to survival as during the brief periods of rainfall, extensive digging must takes place to improve their burrow and to find enough food to store for the dry months ahead. (4) They eat bulbs, corms and tubers, many being toxic to other mammals. Their strategy to protect them from predators is living underground. Their nest site and food store can be as deep as two meters under the ground. (4)

Prairie dogs (Cynomis sp., Family Sciuridae) in the United States can be seen as the equivalent to the Southern African meerkat. They are also sociable mammals, living together in burrows. They can live together in much greater numbers than the meerkats and these big communities are called prairie dog towns. These towns once could stretch over a hundred square kilometres, but today, due to habitat loss their numbers have been much reduced. (5, 6)

The prairie dogs live together as a family unit of one male with a few females and their offspring. Many such family units live side by side, each respecting their neighbours’ territory and so forming a town. Once a burrow becomes too crowded, it is the parents that depart, establishing a new burrow at the edge of the town. The presence of neighbours is useful as the first to detect a predator will emit a sharp bark and the message is quickly conveyed from family to family alerting the whole town. They are also said to have sentries that keep a look out while the others are grazing. (6) Like meerkats they partake in mutual grooming and have a greeting ritual of “kissing”. (6) They also have a variety of calls that they use to communicate. (6)

The few examples of burrowing mammals I have mentioned have found safety in a tight knit social group, all with their own intricate rituals and a certain order in their respective communal societies.


Reference:
1. Wikipedia contributors. Meerkat [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 28, 11:27 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Meerkat&oldid=50567374.
2. Hes L and Mills G. 1997. The Complete Book of Southern African Mammals. Pages 208-209 in Suricates by DW MacDonald. Cape Town. Struik.
3. Hes L and Mills G. 1997. The Complete Book of Southern African Mammals. Pages 128-129 in Cape Ground Squirrel by A Knight . Cape Town. Struik.
4. Hes L and Mills G. 1997. The Complete Book of Southern African Mammals. Page 123 in Damara Mole-Rat by J Jarvis. Cape Town. Struik.
5. Wikipedia contributors. Prairie dog [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 2, 04:07 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Prairie_dog&oldid=51159074.
6. Reader’s Digest Editors. 1974. Animal Families. Marvels and mysteries of animal behaviour. Pages 141 and 151 in Animals in Action. Hong Kong: Reader’s Digest Association Far East Limited.

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/

CHEERS AND ALL THE BEST

Dear everyone

I felt it appropriate to inform you, after chatting with our Honours course co-ordinator and Dr. Knight, that I have moved my elective module of Biodiversity to next year to balance my work load.

I trust you will all have a super time with this module this year and wish you all the very best results, especially Karen and Vincent.

Cheers for now...

David

David Vaughan
Senior aquarist, Quarantine
Two Oceans Aquarium
Cape Town, South Africa
(021) 418 38 23
dvaughan@aquarium.co.za
davidvaughan.b-logging.com

THE STRUCTURE AND SIGNIFICANCE OF DNA TO LIFE.

Deoxy Ribonucleic acid (DNA) is a nucleic acid usually in double helix strand( two coiled strands of molecules) containing the genetic instructions specifying the biological development of all cellular forms of life, and most viruses.1 All forms of life have got DNA be it single celled animals(prokaryotes) or multicellular organisms(eukaryotes). For eukaryotes like plants, animal and fungi have most of their DNA found in the nucleus of the cell as compared to the prokaryotes like bacteria that have their DNA in the cytoplasm as they don’t have a distinct nucleus membrane.1

To be able to understand why it is the basis of life we first look at what it is and how it functions to form the basis of life. DNA has two strands shaped like a twisted ladder or a zip and is composed of building blocks called nucleotides consisting of deoxyribose sugar, a phosphate group and any of the four nitrogen bases (nucleobases) Thymine (T), Adenosine (A), Guanine (G) and Cytosine (C). The bases are arranged in an order, such that each base pairs up with another predetermined base to form any of the these A+T, T+A, C+G and G+C forming hydrogen bonds.1 DNA divides into two strands during a process called replication which is more like unzipping giving rise to two strands and with the help of an enzyme the correct bases are matched up to ensue the same form as the original DNA. Only that this time we have two and not one like in the beginning now we’ve got an extra DNA, This process is called replication. In case an error occur during the process of replication it’s known as mutation leading to the wrong information being encoded and will continue being passed on like that.

The DNA contains this hereditary information and also can be changed (transcribed) into RNA which is then partly converted into proteins. This gives us one of the functions of DNA that they are core in the synthesis of proteins. Proteins are essential as they help in body repair and are the building blocks in muscle and are responsible for growth. Therefore it serves as the source of any protein to be formed

DNA is also involved in the passing of hereditary material in life. The hereditary material is stored in genes (which are hereditary units). The genes are encoded in DNA and RNA (ribonucleic acid) and therefore contain the heredity information encoded in them. Therefore for succession to take place DNA is involved and it’s the one transferred from one individual to the other. The traits (characteristics) that define a particular group are passed on from one individual to their offspring through the genes contained in the DNA. They are inherited from the parent or parents depending on whether it’s there’s sexual or asexual reproduction.

It’s argued that in the beginning before there was any life DNA was first formed after Hydrogen, carbon monoxide, ammonia and methane were sparked by ultra violet rays from the lightning.

For life to be there DNA has to be involved to maintain it in terms of protein synthesis and to pass it on in the form of genes.

Reference:

1. Wikipedia contributors. DNA [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 1, 23:16 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=DNA&oldid=51121850

2. Wikipedia contributors. Gene [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 25, 14:09 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Gene&oldid=50087668

ANTEATING MAMMALS, MARSUPIALS AND MONOTREMES

There are quite a number of mammals that have adapted to eating ants or termites. I will look at each family separately and discuss the adaptations each has made for their special diet.

The order Xenarthra includes the anteaters, sloths and armadillos. (They were previously grouped in the order Edentata along with the pangolins and the aardvark, but since they are not related, they have now been placed in separate orders.) There are four species of anteaters in the family Myrmecophagidae, namely the Silky Anteater (Cyclopes didactylus), the Giant Anteater (Myrmecophaga tridactyla), the Northern Tamandua (Tamandua mexicana) and the Southern Tamandua (Tamandua tetradactyla).(1)

The Silky Anteater is the smallest of all anteaters, only 360-450 millimeters long and weighing less that 500 grams. It lives in lowland rainforests of South America, almost exclusively in trees. Like all anteaters it has a tubular mouth, although not nearly as long as the others. It has a long sticky tongue, with many tiny hooks on and sticky saliva. It flicks its tongue in and out quickly eating mainly tree dwelling ants and termites that get “trapped” on its sticky tongue. They do not have teeth, but rather strong stomach muscles, that contract tightly to help digest its food. They also have two long claws on each front paw, which they use for climbing and defense and a long prehensile tail that aids them in climbing. (2)

The Giant Anteater is the largest of its kind. It inhabits many different habitats from grassland to rainforest in Central and South America. They can reach a length of over two meters and can weigh up to 60 kilograms. They have an exceptionally long nose and tubular mouth, with and even longer sticky tongue, which they use to extract termites out of their nests. They use their long sharp claws and strong forelimbs to break open termite mounds, to get to their food. They do not have any teeth, but again their stomach is adapted to digest its food through strong contractions, aided by little stones they occasionally take in. They also have unusual articulations in the vertebra of their lower back, which provide support when they use their forelegs for digging. They also use there strong claws for defense, by standing on their hind legs, using their tail as a counter-balance and slashing out, even killing predators this way. (3, 4)

The tamanduas are smaller and have an even larger range in habitat. They also climb trees and have a prehensile tail that aids them in climbing and acts as a counter-balance on the ground in much the same way as the Giant Anteater. Their nose is not as long as their giant cousins, but they too have the adapted sticky tongue, that they flick out eating mostly ants and termites. Sometimes they raid bees’ nests eating the larvae and honey. They too have long, strong claws and powerful forelimbs as well as the special joints in their backs that aid them when using their front legs for digging and breaking open termite mounds. (4)

The order Pholidota contains the pangolins or scaly anteaters. There are eight species between Africa and Asia. They all have large plate-like scales, which fit over each other like tiles on a roof. If threatened they roll themselves into a tight ball, their razor sharp scales acting as their defense. They too have a relative long sensitive nose and a very long sticky tongue. There forelimbs are powerful but their claws are so long that they have to walk on their hind legs, using their long tail to balance. But this frees them to use their strong forelimbs to dig and break open termite mounds, much in the same way the American anteaters to. They also hang from branches in trees and use their claws to break away the bark to get to ants nests. They are mainly nocturnal and use their acute sense of smell to find their prey. (5)

The aardvark is of the order Tubulidentata. As the order suggests they do have teeth, but these are unusual. The aardvark is only found in Africa. They are nocturnal, sleeping during the day in excavated termite mounds. They exclusively feed on ants and termites and again have a suitable long sticky tongue. Their head is elongated with a tubular mouth adapted for its habit of eating ants and termites. The nose is a round disk, hence the name aardvark. They have powerful front legs used for digging and a very keen sense of smell to find food. They do not have claws, but rather flattened shovel-like nails. (6)

The numbat ( Myrmecobius fasciatus ) is the only marsupial that almost exclusively feeds on termites. It does not have the powerful forelimbs and long claws of the other anteaters, but it does have a sticky tongue, a degenerate jaw with dysfunctional teeth, a pointed nose and an acute sense of smell. Because it cannot break open the termite mounds, it has to synchronize its feeding time with the activities of the termites. It is thus diurnal and uses its sense of smell to locate the termites’ underground galleries leading to their feeding grounds. These are shallow and the numbat is able to reach them easily, even without having long specialized claws. (7)

The echidnas fall in the order Monotremata. The Short-beaked Echidna (Tachyglossus aculeatus) is an ant and termite eater and has all the adaptations for its specialized diet. A long snout and tubular mouth, toothless jaw, long sticky tongue and powerful limbs with long claws for digging. They have coarse hairs and spines and roll up into a spiny ball to protect themselves. (8)


References:

1. Wikipedia contributors. Xenarthra [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 25, 13:28 UTC [cited 2006 May 2]. Available from: http://en.wikipedia.org/w/index.php?title=Xenarthra&oldid=50082389.
2. Wikipedia contributors. Silky Anteater [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 12, 14:53 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Silky_Anteater&oldid=48121629.
3. Wikipedia contributors. Giant Anteater [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 23, 14:22 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Giant_Anteater&oldid=49755422.
BBC editors. Anteaters[Internet]. BBC, Scinece & Nature – Wildfacts; [cited 2006 May 3]. Available from: http://www.bbc.co.uk/nature/wildfacts/factfiles/679.shtml
5. Wikipedia contributors. Pangolin [Internet]. Wikipedia, The Free Encyclopedia; 2006 Apr 18, 15:53 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Pangolin&oldid=49016676.
Wikipedia contributors. Aardvark [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 2, 17:54 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Aardvark&oldid=51233429.
7. Wikipedia contributors. Numbat [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 2, 11:03 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Numbat&oldid=51192390.
8. Wikipedia contributors. Echidna [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 1, 17:41 UTC [cited 2006 May 3]. Available from: http://en.wikipedia.org/w/index.php?title=Echidna&oldid=51072093.

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/