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Volume 11, Issue 2, 2015
Author Bridget FarhamSource: Quest 11 (2015)More Less
Early modern humans were the first of our species to start moving around the Earth. As a result of these migrations the species spread across the planet - the first alien invaders, you could say. And in many ways our species fulfils most of the criteria for an 'invasive' species - we transferred ourselves (human activity), we moved into completely new habitats, we changed our behaviour to suit those new habitats and we reproduced prolifically. It would appear that we were also instrumental in the extinction of other similar species - the Neanderthals.
Source: Quest 11, pp 5 –7 (2015)More Less
Invasive species are currently regarded as one of the five major causes of biodiversity loss. The other causes are habitat destruction, over-exploitation of species, climate change and pollution. The relative importance of invasive species as a threat varies from place to place, but very few ecosystems anywhere on Earth have been spared the effects of invasive species.
Source: Quest 11, pp 8 –10 (2015)More Less
Some invasive species are more successful and harmful than others. Pinpointing which species deserve the most attention remains a great challenge, especially given the complexity of biological systems. Scientists have devised several classification schemes based on the rate of spread and environmental impacts to figure out which species can be considered the worst invaders. This information can also be used to predict future impacts given scenarios of environmental change, such as global warming and habitat degradation. Among insects, the harlequin ladybird (Harmonia axyridis) is high on the list of successful invaders, with considerable risk to native diversity.
Author Olaf WeylSource: Quest 11, pp 11 –13 (2015)More Less
The Cape Floristic Region of South Africa is a global biodiversity hotspot with an exceptional degree of biodiversity and endemism. Better known for its rich plant communities, the region is also home to 17 fish species which occur nowhere else on earth. Most are restricted to a single river or tributary within a river, which makes them particularly vulnerable to human impacts such as alien fish introductions, habitat destruction, and pollution.
Source: Quest 11, pp 13 –59 (2015)More Less
Iimbovane learner begins her future in science
Grasslands of Lesotho helped to inspire a career in invasion science
Meet molecular systematics laboratory manager Tlou Manyelo
Monitoring invasive species from icy islands to arid lands
Fishing for invasive species
Introducing invasive plants for biofuel: weighing up the pros and cons
From hydrologist to invasion biologist
From forestry to invasion science
From insects to invasion science
A career in invasion science
From mathematics to invasion science
Author Mhairi E. AlexanderSource: Quest 11, pp 14 –16 (2015)More Less
All organisms must eat in order to survive, and for predators this involves killing and eating prey. For the individuals that are involved there are obvious consequences, such as survival or death. However, these relationships also scale up and play a critical role in how populations and communities are structured. Predator-prey relationships are therefore critically important ecological interactions.
Author Mathieu RougetSource: Quest 11, pp 18 –20 (2015)More Less
The South African population increased by 1.3% in 2013 - another 70 000 people added to the population each year if this rate of increase continues. This growing population will need more land for agriculture, settlements, transport and other forms of infrastructure. New roads will be built, crop fields will expand and new residential areas will be planned. Much of this change in land use will affect wild space - natural areas.
Author Brian Van WilgenSource: Quest 11, pp 22 –23 (2015)More Less
Fires are a natural feature of many of South Africa's ecosystems, and they occur regularly in the dry season in fynbos shrublands, grasslands and savannas across the country. Plant species that occur naturally in fire-prone ecosystems are adapted to survive fires, either by re-sprouting after fire, or by germinating from seeds that survive the fire. Not only are plants adapted to survive fires, they also often require fires to complete their life cycles, or to remove competition from other plants. In other words, the vegetation is not only fire-adapted, it is often fire-dependent.
Source: Quest 11, pp 24 –26 (2015)More Less
When most South Africans think about invasive species the first thing that comes to mind is a pine tree or a wattle tree. The idea that grasses can be problematic invasive species probably seems absurd. Yet if we venture beyond our shores we find that this is precisely the case in many other parts of the world. Grasses are among the most abundant and damaging invaders of natural areas in regions such as the Americas, Australasia and Pacific islands like Hawaii.
Source: Quest 11, pp 27 –29 (2015)More Less
Ants dominate most ecosystems, are highly adaptable and can live in a wide range of environments and form 15 - 20% of the biomass of land animals. They play a very important role in the ecosystem, particularly through their symbiotic relationships with other organisms such as other arthropods (e.g. insects and spiders), plants, and fungi. Furthermore, they influence the surrounding vegetation through seed dispersal and various other ecosystem services.
Author Steve JohnsonSource: Quest 11, pp 30 –33 (2015)More Less
In this age of efficient transport across land, sea and air, the Earth has become a global village. Travel and trade between countries has led to the introduction of countless plant and animal species into regions where they had never occurred naturally before. Most of these alien species do not survive outside the pampered confines of human settlements, but some eventually become naturalised and even invasive, and some transform natural ecosystems. This process of invasion begins when alien species become incorporated into the various ecological networks that sustain life. This article discusses pollination networks, the web of interactions between plants and their animal pollinators.
Source: Quest 11, pp 34 –37 (2015)More Less
Many of us share our environment with a number of wild animals, and among the vertebrates, the amphibians (Class: Amphibia) may be the most numerous. In South Africa, amphibians are only represented by frogs (Order: Anura), but worldwide there are two other groups, the tailed salamanders (Order: Caudata), and the limbless caecilians (Order: Gymnophiona). Together, there are more than 7 300 species, with the frogs making up 88%.
Source: Quest 11, pp 38 –41 (2015)More Less
Invasion biology has become an important area of biological research, especially in the light of global climate change. The invasion of alien species is recognised as one of the leading causes of extinction of indigenous animal species, particularly birds. The negative impacts of alien birds could include damage to property and crops, noise and nuisance, and the spread of disease to humans and native species. One example is feral pigeons found in cities. They nest and roost on buildings in large flocks and spread harmful bacteria in their faeces and in some cases parasites from their feathers. Some people also develop an allergy to their feather and scale dust.
Source: Quest 11, pp 42 –43 (2015)More Less
South Africa is globally renowned for its rich diversity of plant and animal life. Among the variety of ecosystems, South Africa has three internationally-recognised biodiversity hotspots: the Maputo-Pondoland Albany, the Fynbos and the Succulent Karoo biomes. For national and international scientists, the country provides many opportunities to study and observe different ecosystems. However, in a country where resources are scarce and science education is a privilege, we as scientists need to take science to the public.
Author Tammy RobinsonSource: Quest 11, pp 44 –45 (2015)More Less
Marine organisms (mainly invertebrates and algae) have been moved around the globe, both intentionally and accidentally, since people first began navigating the seas. As such the mechanisms through which species are introduced (also called vectors) have changed as oceanic transport has developed through time. This has led to different types of species being introduced at different stages through history.
Source: Quest 11, pp 46 –47 (2015)More Less
Invasive species can be managed in many different ways, but of course if we can prevent species being introduced, then there will be no invasions. Prevention can be achieved by banning imports of certain species, or ensuring that ships, cargo and passengers are inspected and cleaned before they arrive. Using laws and regulations in this way does, however, come at a cost to personal freedom.
Source: Quest 11, pp 48 –50 (2015)More Less
People collect non-native species for a range of reasons - some are serious plant or animal collectors, while others just like a variety of plants in their gardens. Cities are by definition places where large numbers of people live in close proximity, and they tend to accumulate a variety of new species in large numbers, and this (large numbers of people, a proportion of who collect a large variety of non-native species in a relatively small area) explains why such species are abundant in cities. The growth in the number and size of cities worldwide has also contributed to the problem and South African cities are no exception.
Risk assessment - a key tool for reducing the incidence and impacts of invasions : feature - science in practiceAuthor Sabrina KumschickSource: Quest 11, pp 52 –53 (2015)More Less
Most alien species are introduced to a new area because they provide some sort of benefit for at least part of society. Mammals, reptiles and birds are often introduced as pets, attractive plants as garden plants, and trees to provide building material. Alien species are also crucial for the survival of humankind, considering that most crops and livestock used worldwide are not native to most parts of the planet where they are grown. However, we need to keep in mind that some alien species are not beneficial to the environment and economy where they are introduced, and in some cases the damage they do is greater than the benefit they were introduced for.
Source: Quest 11, pp 54 –56 (2015)More Less
Humans have moved species to areas outside their native ranges for millennia, and alien species are now common components of most ecosystems. Agriculture, forestry, pet and horticulture trade in most parts of the world are largely based on alien species. Some examples of valuable alien species that have been introduced globally are tomatoes, native to the South American Andes, chickens from Asia, and roses which are native to Asia, Europe, North America and northwest Africa.