Burrowing Bettong Classification Essay

Are We Using Invasive Species? (Kyrgyzstan)

December 20, 2013 by Amadeus DeKastle & filed under Biodiversity, General


The rabbit has been an invasive species all across the globe for over 2000 years, but is
most commonly known as a pest in Australia. Image courtesy of J.J. Harrison (creative commons)

In agriculture we often have to ask ourselves a very serious question. Are we planting invasive species? This question deals with some incredibly important scenarios. Over the past few centuries humans have unintentionally done some pretty serious damage by introducing a new plant, animal, or fungus in a new area. Before we can answer the question though, we need to learn more about what an invasive species is, and what makes it that way. Lets look at a few examples taken from the website of Invasive Species Specialist Group.(1)

Oryctolagus cuniculus (English Rabbit): Originally domesticated in the year 600 in French monasteries, the rabbit was introduced to Australia in 1788 as a food source for the new colonists. The rabbit population grew rapidly, and in 1920 the population had soared to over 10 billion. This invasive pest is a problem because in such high numbers they completely destroy native vegetative lands. Not only does this endanger the survival of native plants, but it also leaves little or no food for native herbivorous mammals such as the Bilby or the Burrowing Bettong.(2)

Opuntia stricta (Common Prickly Pear): The native range of Optunia stricata is the Eastern coastline of North, Central, and South America, in all tropical and subtropical areas. It was intentionally introduced to Australia with the first colonists in order to create two-meter high hedges that cattle would not pass through. This species of cactus very rapidly got out of hand and took over the rangeland intended for cattle, rendering it a dangerous wasteland. Only with the introduction of a moth that is known to feed on the cactus in its native habitat was the population growth able to be curbed.(1)

Acridotheres tristis (Indian Myna): The Indian Myna is a bird that was originally confined to Central and Southern Asia, most specifically India. In India the Myna is considered to be an important animal for pest control for farmers. However, outside of its native habitat the Myna itself becomes the pest. Mynas compete with native species for food, nesting sites, and other resources. In Hawaii they are know to destroy the eggs of other native birds. The Myna also is a carrier of many viruses that can infect humans.(1)

Achatina fulica (Giant African Snail): Originally found on the Eastern coastline of Africa from Mozambique North to Somalia, the Giant African Snail has been unintentionally introduced to tropical and subtropical countries around the world. This snail is a crop pest, destroys native vegetation, alters ecosystems, and carries diseases. Efforts to curb population growth have not been successful.(1)

Why are these organisms invasive?

So, why are some organisms such terrible pests in an introduced region, but sometimes have limited populations in their native ranges? It all has to do with the ecosystem as a whole. When an organism is introduced into another ecosystem, whether intentionally or not, it tries to carry on doing the exact same thing it did in its original ecosystem: obtain nutrition, grow, and reproduce. The potential food sources, the physical environment, possible predators, weather variations, and other things about the new area may be quite different. These factors:

  1. can cause the organism to become extant (extinct in a certain region) in its introduced ecosystem,
  2. could provide no advantage or disadvantage at all to the organism, or
  3. could provide a more suitable habitat where the organism will thrive.

This last option is what happens in the case of an invasive species. Often, there is no control for the new organism (predators or pests) and the organism becomes a better competitor than other similar species in its new habitat because of this. The population begins to grow quickly, and native species start to get pushed out as a result.

Invasive agriculture?

Now, lets look at some agriculturally significant plants and animals that have been introduced around the world. As you read this section, ask yourself, have these plants out-competed the native species? Do they grow in areas that were once inhabited by different organisms? Does this make them “invasive”?

Triticum sp. (Wheat): Originally cultivated in the Middle Eastern area now comprising Syria, Jordan, and Turkey, wheat has become the most planted crop in the world. It wasn’t till 1602 that wheat was grown in the new world!

Oryza sativa (Rice): Rice is the second most grown crop in the world. Rice has its origins in South East Asia near the border of China and India.

Zea mays (Corn): First cultivated by Pre-Colombian Natives in Mexico, corn is now one of the most widely distributed agricultural plants in the world.

Solanum tuberosum (Potatoes): Potatoes are the 4th most important food crop in the world — originally farmed by the Inca Indians in the Andes Mountains in Peru. Over five centuries ago, potatoes were brought back to the old world where most civilized cultures initially felt that potatoes were morally wrong to eat since they had been the food of pagans in the New World. Eventually, following many campaigns by monarchs to encourage the eating of potatoes, it is now an essential part of the diet in many of the world’s cultures.

Gossypium sp. (Cotton): Most historians suggest that cotton originated in India. It has become a very important crop for textile industries.

Solanum lycopersicum (Tomato): First grown by the native Aztec people in Central America, the tomato was brought to Spain as early as 1493. At one point it was even considered a poison in England! The tomato did not make it to Asia until about 1825.

Cucumis sativus (Cucumber): Originally from Nepal, where it has been cultivated for about 3000 years, the cucumber spread to Europe through the Middle East. By the reign of Emperor Tiberius (42 BC-37 AD) the cucumber had become a staple food and was even grown in primitive greenhouses. Emperor Tiberius was known to eat these every day, summer and winter.

Apis mellifera (European Honeybee): Based on genetic research, all seven different species of honeybees are originally from South East Asia, more specifically from the Philippines. The honeybee only made it to the New World (North, Central, and South America) with the arrival of European colonists.

Bos premigenius (Cattle): The first evidence of domestic cattle are thought to be either in the area now known as Iraq or in Egypt. Cattle were domesticated from a wild animal called an Auroch.

Then use natives instead!

So what does this mean? Should we eschew the use of these plants and animals outside of their original habitats based on the evidence that they have displaced millions and millions of hectares of native species and surely been the cause of the extinction of many plants and animals? Well, some people might take the position of saying yes. Let’s take a look at what it would mean if we were only able to use native organisms for our daily needs. As an example I have used the nation (and surrounding connected ecosystems) of Kyrgyzstan, as this is where I live. Actually, Kyrgyzstan has enough native species to keep you pretty healthy, but in other locations you would have a much harder time just keeping your belly full.

Natives


Malus Sieversii is the ancestor of our domestic apple.
Image courtesy of Lukasz Szczurowski (creative commons)

Malus domestica (Apple): Apple trees are originally from Central Asia and we can still find the original species, Malus Sieversii, in Kyrgyzstan. Malus Sieversii is, however, quite endangered, with less than 1000 trees left in the wild in Kyrgyzstan.

Juglans sp. (Walnut): The town of Arslanbob, Kyrgyzstan has the largest wild fruit and nut forest in the world, dominated by wild walnut trees. These nuts are generally smaller than domestic varieties and are usually considered to be more bitter.

Prunus cerasifera (Plum): Wild plums can be found in a few remote pockets in Kyrgyzstan, but the domesticated plum has nearly pushed this wild ancestor to extinction.

Prunus avium (Cherry): The wild cherry shares the same fate as the wild plum and is also at risk.

Mentha sp. (Mint): Wild Asian mint grows everywhere in the country but is not as useful as domesticated varieties of mint.

Allium cepa (Onion): There are many different species of wild onion in Kyrgyzstan, but few of them produce large enough tubers to make them viable for eating. In addition to that, most wild onion species in Kyrgyzstan grow in very specific elevation zones, which are often above 2000 meters.

Cannabis sp. (Hemp): Used in ancient China and the Central Asian region as a source for fibre to produce paper, clothing, and rope, it has also been used for thousands of years as a medicinal plant.

This list is by no means comprehensive, as there are many more native plants in Kyrgyzstan that are the ancestors to our modern day varieties. These wild ancestors are genetically important resources as they often exhibit tolerance to diseases, temperature fluctuations, limited water availability, and predators. However, the reason these wild varieties are not our “garden varieties” is because they generally do not taste as good.

The answer is control

So, are we planting invasive species? Most often the answer could be construed as yes. If left to its own devices, could wheat become an invasive species? Absolutely. Cattle? Definitely, and in many places cattle has become exactly that. Any organism has the potential to become an invasive species given the correct set of variables that allows it to have perfect growing conditions with no predators. But, this is where we come in. Do you water your garden? Pull up the weeds? Pick the fruits? Fence your animals? This is called control. Without control, many of the plants and animals we use could potentially become invasive. Control is what keeps this from happening. Of course you should be wise in what you plant. If a certain plant is already known to be quite invasive, even in its home habitat, it might be best to avoid using this species. The air potato comes to mind as an example.

Should our worries about causing ecological ruin on our planet stop us from planting new and exciting varieties of purple potatoes, or trying to see if the North American Pawpaw tree will grow in Europe, or maybe an American Persimmon in Kyrgyzstan? I should think not. If we impose limits on ourselves to despise all species that are non-native to our area, then in reality we need to backtrack and remove a lot of non-native plants from our agricultural playbook that we have become dependent on. To do this would be extremely unreasonable, if not impossible.

So next time you plant an apple tree on your farm, just remember, you aren’t in Kyrgyzstan anymore and technically this tree is a non-native with the potential to become invasive. But, as practitioners of Permaculture, we must be willing to pioneer new varieties of a plant, try new species that may have the potential to grow in a different continent, or bring in a new breed of animal that could be beneficial to our system. However, if you choose to do this, it is up to you to take responsibility for your actions. Be wise in what you plant or use. Do the research to see if there is the potential for things to get out of hand. But don’t forget that you’ve already been planting non-natives since day one!

Sources:

  1. http://www.issg.org/worst100_species.html
  2. http://www.abc.net.au/science/articles/2009/04/08/2538860.htm

Further Reading:

Related

Popular

The boodie (Bettongia lesueur), also known as the burrowing bettong, is a small marsupial. Its population is an example of the effects of introduced animals on Australian fauna and ecosystems. Once the most common macropodiformmammal on the whole continent, the boodie now only lives on off-lying islands and in a newly introduced population on the mainland at Shark Bay.[3] This animal, first collected during an 1817 French expedition of the west coast, was named after Charles Lesueur, an artist and naturalist who accompanied a previous French expedition. B. lesueur is known by many common names, including the tungoo, Lesueur’s rat-kangaroo, and the short-nosed rat-kangaroo.[4]

Contents

Taxonomy[edit]

The boodie belongs to the family Potoroidae, which includes the rat-kangaroos, potoroos, and other bettongs. Four species make up the genus Bettongia. Also, three subspecies of Bettongia lesueur exist: B. l. graii, the extinct mainland subspecies; B. l. nova, an undescribed species on Barrow and Brodie Island; and B. l. lesueur.[5]

Etymology[edit]

Its common name is from the Nyungar language - burdi.[6]

Paleontology[edit]

In the late Oligocene, fossils of paleopotoroines and potoroines (potoroid ancestors) appeared. During the Oligocene, ice buildup on Antarctica resulted in less rainfall on Australia. Rainforests declined, replaced by more arid-tolerant leathery leaf woodlands and reed swamps. This climate shift may have favored a radiation of terrestrialmarsupials, including potoroid ancestors.[7] Fossils of the Potoroidae family appear from the mid-Miocene to Recent sediments.[8]Subfossil records of the burrowing bettong have been found in West Victoria, western New South Wales, and South Australia.[9]

Morphology[edit]

The boodie is a small, rat-like marsupial with short, rounded ears and a lightly haired, thick tail. This animal has a pointed rostrum and beady black eyes, hind limbs longer than the forelimbs, and large hind feet. This bettong is yellow-gray above and light gray below. Its short, dense fur feels soft and woolly. The animal bears a faint hip stripe and a distinctive white tail tip. This tail is weakly prehensile and used to carry nest material.[9][10] About the size of a wild rabbit, this little marsupial weighs an average of 1.5 kg.[4] Head and body length is an average of 40 cm.[9] Little to no sexual dimorphism seems to exist. However, morphology varies among subspecies and between islands.[11]

In general, a potoroid skull can be separated from a macropodid skull by the presence of well-developed upper canines and large plagiaulacoid (bladelike) premolars. Also unlike macropodids, the squamosal bone widely contacts the frontal. B. lesueur skulls are short and broad with large palatal vacuities, inflated auditory bullae, and short, broad nasals. The mandible is relatively short and deep compared to other relatives. The dental formula for all the modern potoroines is I 3/1 C 1/0 PM 1/1 M 4/4. Molars are bunodont and quadrate, and the premolars have 9-11 fine, vertical ridges. Young bettongs have two molars which are replaced by one adult premolar; this event is a good indication of maturity. The postcranial skeleton of all potoroids has seven cervical, 13 thoracic, six lumbar, two sacral, and 22 caudal vertebrae, with 13 pairs of ribs.[8]

Reproduction[edit]

If conditions are good, the boodie seems to mate throughout the year, probably using a polygynousmating system. Males do not seem to have dominance hierarchies; rather, they defend females against other males. Some females seem to establish associations with other females; whether these contribute to increased reproductive success is unknown.[3][8]Gestation lasts 21 days, with only one young per litter. Like other marsupial newborns, the newborn is altricial. About four months elapse until weaning.[4] After young leave the pouch, they take six to seven months to mature sexually.[11] Females mate the day after giving birth, and the fertilized egg arrests development until the young is weaned. This is an example of facultative embryonic diapause. In captivity, females are able to bear three young per year.[4]

Ecology[edit]

The boodie once lived in a range of dry subtropical and tropicalhabitats, from open eucalyptus and acacia woodlands to aridspinifex grasslands. In its current range on the islands, it seems to prefer open Triodia (spinifex) and dune habitats, but will burrow anywhere except places with rocky substrate.[11] The burrowing bettong eats a variety of foods, such as seeds, fruits, flowers, tubers, roots, succulent leaves, grasses, fungi, termites, and marine refuse. It will also raid vegetable gardens. Current populations fluctuate, building up during the years with average or good rainfall and crashing during drought years.[4][5] These marsupials are known to live at least three years in the wild.[11]

After colonization of Australia, its predators were mainly the introduced red fox and cats.[4] Some natural predators on the islands include the wedge-tailed eagle and sea eagles; on Barrow Island, monitor lizards appear to be a significant predator.[11] Before its extinction on the mainland, the boodie served a very important function in the Australian grassland ecosystem. As it foraged, it mixed organic matter into the soil, spreading fungi and seeds. This mixing also increased water absorption into the soil and reduced the combustible material under trees, decreasing the likelihood of fire. These actions helped maintain the balance of trees, shrubs, and grasses. The loss of small, ground-foraging animals after European settlement contributed to widespread soil deterioration.[12] Also, B. lesueur may have helped to thin woody weeds on rangeland by browsing shrubs growing after fires.[13]

Behavior and physiological attributes[edit]

B. lesueur is very vocal, communicating through grunts, hisses, and squeals.[9] It shelters in underground burrows, the only macropodiform to do so.[3] Burrows vary from simple tunnels to complex networks with multiple entrances and deep, interconnecting tunnels. These elaborate burrows, or warrens, have been seen having from four to 94 entrances.[9] Warrens are communal, housing an average of 20-40 bettongs. Bettongs appear to switch warrens from time to time, though each has one or two preferred warrens. During the day in the warrens, they form groups of one male and one or many females; males never share warrens with other males. Some of the female-female groups seem to be mother-daughter associations. However, individuals seem to forage alone, showing none of the day-range group associations.[3][11]

The boodie is nocturnal, sheltering during the day in burrows and foraging widely at night for food.[4]Locomotion is mainly with the hind legs. The forelimbs are used for support when the boodie is stationary.[9] This bettong exhibits a slow gait and fast gait. The fast gait (or bipedal hop) is characteristic of the macropodiforms and uses only the hind limbs, with the forelimbs held close to the body and tail acting as a counterbalance. The slow gait (or quadrupedal crawl) is used during foraging and other unstressed times.[8] Nighttime movement is usually fairly limited, averaging less than 200 m. However, researchers have measured this marsupial traveling 2.2 km searching for food. One individual tracked on Barrow Island traveled 5 km.[11]B. lesueur uses scent to locate food, which it digs up with the claws on its strong forelimbs.[5] The boodie will even climb into low shrubs to find food.[4] Demonstrating little interspecific interactions, bettongs are apparently undisturbed by run-ins with other non-predators.

Bettong digestive systems are characterized by a very large sacciform fore stomach, a tubiform fore stomach with limited sacculation, and a small hind stomach. The hind gut has a well-developed, simple cecum. Like many macropodiforms, bettongs have fore gut fermentation. Daily water intake is only about 3% of its body weight. B. lesueur seems to have renal adaptations to conserve water, which is important in its arid and semiarid habitats.[8]

Conservation[edit]

Researchers have proposed many possible causes for the boodie's decline on mainland Australia, which began once Australia was colonized. Nineteenth-century colonists killed boodies, considering them a destructive garden pest. As ranches spread over the grasslands, livestock grazing reduced vegetation cover, shrinking their habitat. Also, introduced species such as foxes, cats, and rabbits took a severe toll on the boodie, especially on islands. Rabbits competed with them for food and shelter, and the foxes and cats became their major predators. The theory that rabbits compete with boodies for food has been disputed in a study done in 2002 [14] although further investigation is needed. Finally, the Indigenous Australians maintained certain fire regimes, and when these ceased, the habitat probably changed.[4] By the 1960s, all the boodies on the mainland were extinct.[5]

Once present in all mainland states except Queensland, the boodie survived on three remnant populations on small offshore islands. These islands include Bernier and Dorre Islands in Shark Bay and Barrow Island off the northwest coast of Western Australia. The marsupial was listed on the 2006 IUCN Red List as Vulnerable due to acute restriction of its area of occupancy to less than 100 km². In 2008, however, due to successful conservation efforts both by government agencies and the private sector, boodies have been listed on the 2008 IUCN Red List as Near Threatened, as its range and population have increased, and are still increasing. Newly established populations included Herrison Prong on mainland Shark Bay by the DEC, as well as Faure Island, Scotia Sanctuary, and Yookamurra Sanctuary, which were established by the Australian Wildlife Conservancy.

References[edit]

  1. ^Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M, eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. p. 57. OCLC 62265494. ISBN 0-801-88221-4. 
  2. ^Richards, J., Morris, K. & Burbidge, A. (2008). Bettongia lesueur. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 December 2008. Database entry includes justification for why this species is listed as near threatened
  3. ^ abcdSander, U., Short, J., & Turner, B. (1997). "Social organisation and warren use of the burrowing bettong Bettongia lesueur (Macropodoidea: Potoroidae)". Wildlife Research24 (2): 143–157. doi:10.1071/WR96021. 
  4. ^ abcdefghi"The burrowing bettong (Bettongia lesueur)". Heirisson Prong Threatened Species Project. 2005-09-25. Retrieved 2006-12-08. 
  5. ^ abcdMassicot, P. (2006-06-02). "Burrowing Bettong". Animal Info. Retrieved 2006-12-08.

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