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112-801: The Invasive Species Council (ISC) was incorporated in July 2002, and was formed in response to growing concerns regarding the problem of invasive species in Australia . Founding members include Tim Low , Barry Traill , Kate Blood , and five others. The initial direction of the ISC was to lobby against all invasive species before governments and private industry, and to work with people to achieve outcomes. The ISC makes submissions in its own right or in collaboration with other organisations to governmental inquiries. For example: The ISC highlights potential conflicts of interest, for example in 2015, agriculture taking

224-498: A 1,000 year cold period, potentially reducing human populations to a few tropical refugia. It has been estimated that as few as 15,000 humans survived. In such circumstances genetic drift and founder effects may have been maximised. The greater diversity amongst African genomes may reflect the extent of African refugia during the Toba incident. However, a recent review highlights that the single-source hypothesis of non-African populations

336-733: A ballast tank of a ship traveling from the temperate zone through tropical waters may experience temperature fluctuations as much as 20 °C. Heat challenges during transport may enhance the stress tolerance of species in their non-native range, by selecting for genotypes that will survive a second applied heat stress, such as increased ocean temperature in the founder population. Invasive species often exploit disturbances to an ecosystem ( wildfires , roads , foot trails ) to colonize an area. Large wildfires can sterilize soils, while adding nutrients . Invasive plants that can regenerate from their roots then have an advantage over natives that rely on seeds for propagation. Invasive species can affect

448-554: A cranium from Lantian has been dated to 1.63 mya. Artefacts from Majuangou III and Shangshazui in the Nihewan basin , northern China, have been dated to 1.6–1.7 mya. The archaeological site of Xihoudu ( 西侯渡 ) in Shanxi province is the earliest recorded use of fire by Homo erectus , which is dated 1.27 million years ago. Southeast Asia ( Java ) was reached about 1.7 million years ago ( Meganthropus ). Western Europe

560-595: A few of the traits, and that noninvasive species had these also. Common invasive species traits include fast growth and rapid reproduction , such as vegetative reproduction in plants; association with humans; and prior successful invasions. Domestic cats are effective predators; they have become feral and invasive in places such as the Florida Keys . An introduced species might become invasive if it can outcompete native species for resources. If these species evolved under great competition or predation , then

672-544: A geographically restricted area about 100,000 years ago, the passage through the geographic bottleneck and then with a dramatic growth amongst geographically dispersed populations about 50,000 years ago, beginning first in Africa and thence spreading elsewhere. Climatological and geological evidence suggests evidence for the bottleneck. The explosion of Toba , the largest volcanic eruption of the Quaternary , may have created

784-680: A great decrease in the population size and may constrict genetic variation , the individuals begin to show additive variance as opposed to epistatic variance. This conversion can lead to increased variance in the founding populations, which permits rapid evolution . Selection may then act on the capacity to disperse as well as on physiological tolerance to new stressors in the environment, such as changed temperature and different predators and prey. Rapid adaptive evolution through intraspecific phenotypic plasticity, pre-adaptation and post-introduction evolution lead to offspring that have higher fitness. Critically, plasticity permits changes to better suit

896-470: A habitat in ways advantageous to other species. For example, zebra mussels increase habitat complexity on lake floors, providing crevices in which invertebrates live. This increase in complexity, together with the nutrition provided by the waste products of mussel filter-feeding , increases the density and diversity of benthic invertebrate communities. Introduced species may spread rapidly and unpredictably. When bottlenecks and founder effects cause

1008-703: A limited degree. Populations of modern humans and Neanderthal overlapped in various regions such as the Iberian peninsula and the Middle East. Interbreeding may have contributed Neanderthal genes to palaeolithic and ultimately modern Eurasians and Oceanians. An important difference between Europe and other parts of the inhabited world was the northern latitude. Archaeological evidence suggests humans, whether Neanderthal or Cro-Magnon, reached sites in Arctic Russia by 40,000 years ago. Cro-Magnon are considered

1120-543: A long taproot , or to live on previously uninhabited soil types. For example, barbed goatgrass was introduced to California on serpentine soils , which have low water-retention, low nutrient levels, a high magnesium / calcium ratio, and possible heavy metal toxicity. Plant populations on these soils tend to show low density, but goatgrass can form dense stands on these soils and crowd out native species. Invasive species might alter their environment by releasing chemical compounds, modifying abiotic factors, or affecting

1232-403: A major role in exotic species introduction. High demand for the valuable Chinese mitten crab is one explanation for the possible intentional release of the species in foreign waters. Maritime trade has rapidly affected the way marine organisms are transported within the ocean; new means of species transport include hull fouling and ballast water transport. In fact, Molnar et al. 2008 documented

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1344-590: A merging of populations in East and South Africa . In July 2019, anthropologists reported the discovery of 210,000 year old remains of a H. sapiens and 170,000 year old remains of a H. neanderthalensis in Apidima Cave in southern Greece , more than 150,000 years older than previous H. sapiens finds in Europe. Early modern humans expanded to Western Eurasia and Central, Western and Southern Africa from

1456-465: A more robust or heavily built frame, which suggests that they were physically stronger than modern Homo sapiens . Having lived in Europe for 200,000 years, they would have been better adapted to the cold weather. The anatomically modern humans known as the Cro-Magnons , with widespread trade networks, superior technology and bodies likely better suited to running, would eventually completely displace

1568-674: A new nomenclature system based on biogeography rather than on taxa . By discarding taxonomy, human health , and economic factors, this model focused only on ecological factors. The model evaluated individual populations rather than entire species. It classified each population based on its success in that environment. This model applied equally to indigenous and to introduced species, and did not automatically categorize successful introductions as harmful. The USDA's National Invasive Species Information Center defines invasive species very narrowly. According to Executive Order 13112, " 'Invasive species' means an alien species whose introduction does or

1680-407: A number of years and then experience an explosion in population, a phenomenon known as "the lag effect". Hybrids resulting from invasive species interbreeding with native species can incorporate their genotypes into the gene pool over time through introgression . Similarly, in some instances a small invading population can threaten much larger native populations. For example, Spartina alterniflora

1792-554: A particular pest species could pollute soil and surface water. Encroachment of humans into previously remote ecosystems has exposed exotic diseases such as HIV to the wider population. Introduced birds (e.g. pigeons ), rodents and insects (e.g. mosquito , flea , louse and tsetse fly pests) can serve as vectors and reservoirs of human afflictions. Throughout recorded history, epidemics of human diseases, such as malaria , yellow fever , typhus , and bubonic plague , spread via these vectors. A recent example of an introduced disease

1904-474: A precedence over the wider environment when biosecurity is overseen by agriculture managers. The ISC takes on concerns which are obvious to the public but not on governments' plans, for example in 2016, feral deer, and for example in 2016 petitioning multiple federal and state ministers for action on fire ants . The ISC will then provide background and context to Governments' decisions when they respond. The ISC takes opportunities to build awareness of risks in

2016-418: A result of either a numerical or fitness advantage of the introduced species. Genetic pollution occurs either through introduction or through habitat modification, where previously isolated species are brought into contact with the new genotypes. Invading species have been shown to adapt to their new environments in a remarkably short amount of time. The population size of invading species may remain small for

2128-579: Is Andrew Cox. The first Board President on formation in 2002 was Barry Traill . The President of the Board from 2014 to 2017 is Esther Abram . Invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions , causing ecological, environmental, and/or economic damage. The term can also be used for native species that become harmful to their native environment after human alterations to its food web . Since

2240-673: Is cited by others, for example in work by the University of Technology Sydney on recreational hunting. The ISC operates a science outreach programme focussed on invasive species impacting on the environment. Since 2003 the ISC has presented one or more awards to people who have made a major contribution to protecting Australia's native plants and animals, ecosystems, and people from dangerous new invasive species . The Froggatt Awards are named in honour of Australian entomologist Walter Froggatt . These awards received exceptional national media coverage, and even international coverage, when one

2352-913: Is evidence that Denisovans interbred with Neanderthals in Central Asia where their habitats overlapped. Neanderthal evidence has also been found quite late at 33,000 years ago at the 65th latitude of the Byzovaya site in the Ural Mountains . This is far outside of any otherwise known habitat, during a high ice cover period, and perhaps reflects a refugia of near extinction. Homo sapiens are believed to have emerged in Africa about 300,000 years ago, based in part on thermoluminescence dating of artifacts and remains from Jebel Irhoud , Morocco, published in 2017. The Florisbad Skull from Florisbad, South Africa, dated to about 259,000 years ago, has also been classified as early Homo sapiens . Previously,

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2464-456: Is highly fire-adapted. It spreads rapidly after burning, and increases the frequency and intensity of fires by providing large amounts of dry detritus during the fire season in western North America. Where it is widespread, it has altered the local fire regimen so much that native plants cannot survive the frequent fires, allowing it to become dominant in its introduced range. Ecological facilitation occurs where one species physically modifies

2576-556: Is less consistent with ancient DNA analysis than multiple sources with genetic mixing across Eurasia. The recent expansion of anatomically modern humans reached Europe around 40,000 years ago from Central Asia and the Middle East, as a result of cultural adaption to big game hunting of sub-glacial steppe fauna. Neanderthals were present both in the Middle East and in Europe, and the arriving populations of anatomically modern humans (also known as " Cro-Magnon " or European early modern humans ) interbred with Neanderthal populations to

2688-623: Is likely to cause economic or environmental harm or harm to human health." Typically, an introduced species must survive at low population densities before it becomes invasive in a new location. At low population densities, it can be difficult for the introduced species to reproduce and maintain itself in a new location, so a species might reach a location multiple times before it becomes established. Repeated patterns of human movement, such as ships sailing to and from ports or cars driving up and down highways, offer repeated opportunities for establishment (a high propagule pressure ). In ecosystems ,

2800-600: Is normal, and preserves constellations of genes and genotypes. An example of this is the interbreeding of migrating coyotes with the red wolf , in areas of eastern North Carolina where the red wolf was reintroduced, reducing red wolf numbers. In South Africa's Cape Town region, analysis demonstrated that the restoration of priority source water sub-catchments through the removal of thirsty alien plant invasions (such as Australian acacias, pines and eucalyptus, and Australian black wattle) would generate expected annual water gains of 50 billion liters within 5 years compared to

2912-581: Is now considered invasive in over 60 countries, and has invaded large geographies in several countries prompting aggressive federal efforts at attempting to control it. Primary geomorphological effects of invasive plants are bioconstruction and bioprotection. For example, kudzu ( Pueraria montana ), a vine native to Asia, was widely introduced in the southeastern United States in the early 20th century to control soil erosion . The primary geomorphological effects of invasive animals are bioturbation , bioerosion , and bioconstruction. For example, invasions of

3024-479: Is one of the most problematic invasive plant species in eastern North American forests, where it is highly invasive of the understory , reducing the growth rate of tree seedlings and threatening to modify the forest's tree composition. Native species can be threatened with extinction through the process of genetic pollution . Genetic pollution is unintentional hybridization and introgression , which leads to homogenization or replacement of local genotypes as

3136-570: Is poorly defined and often very subjective. Invasive species may be plants, animals, fungi, and microbes; some include native species that have invaded human habitats such as farms and landscapes. Some broaden the term to include indigenous or "native" species that have colonized natural areas. Some sources name Homo sapiens as an invasive species, but broad appreciation of human learning capacity and their behavioral potential and plasticity may argue against any such fixed categorization. The definition of "native" can be controversial. For example,

3248-903: Is shared by Melanesians , Aboriginal Australians , and smaller scattered groups of people in Southeast Asia, such as the Mamanwa , a Negrito people in the Philippines , suggesting the interbreeding took place in Eastern Asia where the Denisovans lived. Denisovans may have crossed the Wallace Line , with Wallacea serving as their last refugium . Homo erectus had crossed the Lombok gap reaching as far as Flores, but never made it to Australia. During this time sea level

3360-724: Is some evidence that modern humans left Africa at least 125,000 years ago using two different routes: through the Nile Valley , the Sinai Peninsula and the Levant ( Qafzeh Cave : 120,000–100,000 years ago); and a second route through the present-day Bab-el-Mandeb Strait on the Red Sea (at that time, with a much lower sea level and narrower extension), crossing to the Arabian Peninsula and settling in places like

3472-514: Is the main cause of introductions – other than for polar regions . Diseases may be vectored by invasive insects: the Asian citrus psyllid carries the bacterial disease citrus greening . The arrival of invasive propagules to a new site is a function of the site's invasibility. Many invasive species, once they are dominant in the area, become essential to the ecosystem of that area, and their removal could be harmful. Economics plays

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3584-592: Is the spread of the West Nile virus , which killed humans, birds, mammals, and reptiles. The introduced Chinese mitten crabs are carriers of Asian lung fluke . Waterborne disease agents, such as cholera bacteria ( Vibrio cholerae ), and causative agents of harmful algal blooms are often transported via ballast water. Globally, invasive species management and control are substantial economic burdens, with expenditures reaching approximately $ 1.4 trillion annually. The economic impact of invasive alien species alone

3696-524: Is this migration wave that led to the lasting spread of modern humans throughout the world. A small group from a population in East Africa, bearing mitochondrial haplogroup L3 and numbering possibly fewer than 1,000 individuals, crossed the Red Sea strait at Bab-el-Mandeb , to what is now Yemen , after around 75,000 years ago. A recent review has also shown support for the northern route through

3808-697: The 40th parallel ( Xiaochangliang ). Key sites for this early migration out of Africa are Riwat in Pakistan (~2 Ma? ), Ubeidiya in the Levant (1.5 Ma) and Dmanisi in the Caucasus (1.81 ± 0.03 Ma, p =0.05 ). China shows evidence of Homo erectus from 2.12 mya in Gongwangling, in Lantian county. Two Homo erectus incisors have been found near Yuanmou, southern China, and are dated to 1.7 mya, and

3920-489: The Age of Discovery , and accelerating again with international trade . Notably invasive plant species include the kudzu vine, giant hogweed , Japanese knotweed , and yellow starthistle . Notably invasive animals include European rabbits , domestic cats , and carp . Invasive species are the subset of established non-native alien or naturalized species that are a threat to native species and biodiversity. The term "invasive"

4032-522: The Great Lakes via ballast water. These outcompete native organisms for oxygen and food, and can be transported in the small puddle left in a supposedly empty ballast tank. Regulations attempt to mitigate such risks, not always successfully. Climate change is causing an increase in ocean temperature . This in turn will cause range shifts in organisms, which could harm the environment as new species interactions occur. For example, organisms in

4144-685: The Last Glacial Maximum , North Eurasian populations migrated to the Americas about 20,000 years ago . Arctic Canada and Greenland were reached by the Paleo-Eskimo expansion around 4,000 years ago. Finally, Polynesia was populated within the past 2,000 years in the last wave of the Austronesian expansion . The earliest humans developed out of australopithecine ancestors about 3 million years ago, most likely in

4256-620: The Levantine corridor and Horn of Africa to Eurasia . This migration has been proposed as being related to the operation of the Saharan pump , around 1.9 million years ago. Homo erectus dispersed throughout most of the Old World , reaching as far as Southeast Asia . Its distribution is traced by the Oldowan lithic industry, by 1.3 million years ago extending as far north as

4368-620: The Omo remains , excavated between 1967 and 1974 in Omo National Park , Ethiopia , and dated to 200,000 years ago, were long held to be the oldest known fossils of Homo sapiens . In September 2019, scientists reported the computerized determination, based on 260 CT scans , of a virtual skull shape of the last common human ancestor to anatomically modern humans, representative of the earliest modern humans, and suggested that modern humans arose between 260,000 and 350,000 years ago through

4480-766: The Paglicci Cave in Italy, dated to 23,000 and 24,000 years old (Paglicci 52 and 12), identified the mtDNA as Haplogroup N , typical of the latter group. The expansion of modern human population is thought to have begun 45,000 years ago, and it may have taken 15,000–20,000 years for Europe to be colonized. During this time, the Neanderthals were slowly being displaced. Because it took so long for Europe to be occupied, it appears that humans and Neanderthals may have been constantly competing for territory. The Neanderthals had larger brains, and were larger overall, with

4592-412: The Sinai Peninsula and the Levant . Their descendants spread along the coastal route around Arabia and Persia to South Asia before 55,000 years ago. Other research supports a migration out of Africa between about 65,000 and 50,000 years ago. The coastal migration between roughly 70,000 and 50,000 years ago is associated with mitochondrial haplogroups M and N , both derivative of L3. Along

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4704-599: The economic returns from invasive species are far less than the costs they impose. In the Great Lakes region the sea lamprey is an invasive species. In its original habitat, it had co-evolved as a parasite that did not kill its host. However, in the Great Lakes Region, it acts as a predator and can consume up to 40 pounds of fish in its 12–18 month feeding period. Sea lampreys prey on all types of large fish such as lake trout and salmon . The sea lampreys' destructive effects on large fish negatively affect

4816-844: The extinction of species, loss in biodiversity, and loss of ecosystem services , costs from impacts of invasive species would drastically increase. It is often argued that the key to invasive species management is early detection and rapid response. However, early response only helps when the invasive species is not frequently reintroduced into the managed area, and the cost of response is affordable. Weeds reduce yield in agriculture . Many weeds are accidental introductions that accompany imports of commercial seeds and plants. Introduced weeds in pastures compete with native forage plants, threaten young cattle (e.g., leafy spurge, Euphorbia virgata ) or are unpalatable because of thorns and spines (e.g., yellow starthistle ). Forage loss from invasive weeds on pastures amounts to nearly US$ 1 billion in

4928-744: The spatial scale of invasion studies. Small-scale studies tended to show a negative relationship between diversity and invasion, while large-scale studies tended to show the reverse, perhaps a side-effect of invasives' ability to capitalize on increased resource availability and weaker species interactions that are more common when larger samples are considered. However, this pattern does not seem to hold true for invasive vertebrates. Island ecosystems may be more prone to invasion because their species face few strong competitors and predators, and because their distance from colonizing species populations makes them more likely to have "open" niches. For example, native bird populations on Guam have been decimated by

5040-445: The 20th century, invasive species have become serious economic, social, and environmental threats worldwide. Invasion of long-established ecosystems by organisms is a natural phenomenon, but human-facilitated introductions have greatly increased the rate, scale, and geographic range of invasion. For millennia, humans have served as both accidental and deliberate dispersal agents, beginning with their earliest migrations , accelerating in

5152-477: The 958 endangered species under the Endangered Species Act are at risk. The unintentional introduction of forest pest species and plant pathogens can change forest ecology and damage the timber industry . Overall, forest ecosystems in the U.S. are widely invaded by exotic pests, plants, and pathogens. The Asian long-horned beetle ( Anoplophora glabripennis ) was first introduced into

5264-524: The California sea otter ( Enhydra lutris ). Invasive species appear to have specific traits or specific combinations of traits that allow them to outcompete native species . In some cases, the competition is about rates of growth and reproduction. In other cases, species interact with each other more directly. One study found that 86% of invasive species could be identified from such traits alone. Another study found that invasive species often had only

5376-498: The Chinese mitten crab ( Eriocheir sinensis ) have resulted in higher bioturbation and bioerosion rates. A native species can become harmful and effectively invasive to its native environment after human alterations to its food web . This has been the case with the purple sea urchin ( Strongylocentrotus purpuratus ), which has decimated kelp forests along the northern California coast due to overharvesting of its natural predator,

5488-572: The European Russian Arctic from 40,000 years ago. Humans colonised the environment west of the Urals, hunting reindeer especially, but were faced with adaptive challenges; winter temperatures averaged from −20 to −30 °C (−4 to −22 °F) with fuel and shelter scarce. They travelled on foot and relied on hunting highly mobile herds for food. These challenges were overcome through technological innovations: tailored clothing from

5600-471: The Levant and to Europe between 130,000 and 115,000 years ago, and possibly in earlier waves as early as 185,000 years ago. A fragment of a jawbone with eight teeth found at Misliya Cave has been dated to around 185,000 years ago. Layers dating from between 250,000 and 140,000 years ago in the same cave contained tools of the Levallois type which could put the date of the first migration even earlier if

5712-557: The Middle East. Studies show a higher Neanderthal admixture in East Asians than in Europeans. North African groups share a similar excess of derived alleles with Neanderthals as non-African populations, whereas Sub-Saharan African groups are the only modern human populations with no substantial Neanderthal admixture. The Neanderthal-linked haplotype B006 of the dystrophin gene has also been found among nomadic pastoralist groups in

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5824-520: The Neanderthal population. Contemporary Europeans have Neanderthal ancestry , but it seems likely that substantial interbreeding with Neanderthals ceased before 47,000 years ago, i.e. took place before modern humans entered Europe. There is evidence from mitochondrial DNA that modern humans have passed through at least one genetic bottleneck , in which genome diversity was drastically reduced. Henry Harpending has proposed that humans spread from

5936-553: The Neanderthals, whose last refuge was in the Iberian Peninsula . Neanderthals disappeared about 40,000 years ago. From the extent of linkage disequilibrium, it was estimated that the last Neanderthal gene flow into early ancestors of Europeans occurred 47,000–65,000 years BP . In conjunction with archaeological and fossil evidence, interbreeding is thought to have occurred somewhere in Western Eurasia, possibly

6048-533: The Sahel and Horn of Africa, who are associated with northern populations. Consequently, the presence of this B006 haplotype on the northern and northeastern perimeter of Sub-Saharan Africa is attributed to gene flow from a non-African point of origin. " Tianyuan man ", an individual who lived in China c. 40,000 years ago, showed substantial Neanderthal admixture. A 2017 study of the ancient DNA of Tianyuan Man found that

6160-522: The U.S. A decline in pollinator services and loss of fruit production has been caused by honey bees infected by the invasive varroa mite . Introduced rats ( Rattus rattus and R. norvegicus ) have become serious pests on farms, destroying stored grains. The introduction of leaf miner flies ( Agromyzidae ), including the American serpentine leaf miner ( Liriomyza trifolii ), to California has caused losses in California's floriculture industry, as

6272-549: The U.S. in 1996, and was expected to infect and damage millions of acres of hardwood trees. As of 2005 thirty million dollars had been spent in attempts to eradicate this pest and protect millions of trees in the affected regions. The woolly adelgid has inflicted damage on old-growth spruce, fir and hemlock forests and damages the Christmas tree industry. Chestnut blight and Dutch elm disease are plant pathogens with serious impacts. Garlic mustard, Alliaria petiolata ,

6384-591: The alteration in ecosystem functionality (due to homogenization of biota communities), invasive species have resulted in negative effects on human well-being, which includes reduced resource availability, unrestrained spread of human diseases, recreational and educational activities, and tourism. Alien species have caused diseases including human immunodeficiency virus (HIV), monkey pox , and severe acute respiratory syndrome (SARS). Invasive species and accompanying control efforts can have long term public health implications. For instance, pesticides applied to treat

6496-621: The ancestors of Equus ferus (modern horses) evolved in North America and radiated to Eurasia before becoming extinct in North America. Upon being introduced to North America in 1493 by Spanish conquistadors , it is debatable whether the feral horses were native or exotic to the continent of their evolutionary ancestors. While invasive species can be studied within many subfields of biology, most research on invasive organisms has been in ecology and biogeography . Much of

6608-552: The ancestral population shared by East Asians and Native Americans. A 2016 study presented an analysis of the population genetics of the Ainu people of northern Japan as key to the reconstruction of the early peopling of East Asia. The Ainu were found to represent a more basal branch than the modern farming populations of East Asia, suggesting an ancient (pre-Neolithic) connection with northeast Siberians. A 2013 study associated several phenotypical traits associated with Mongoloids with

6720-742: The area of the Kenyan Rift Valley , where the oldest known stone tools have been found. Stone tools recently discovered at the Shangchen site in China and dated to 2.12 million years ago are claimed to be the earliest known evidence of hominins outside Africa, surpassing Dmanisi in Georgia by 300,000 years. Between 2 and less than a million years ago, Homo spread throughout East Africa and to Southern Africa ( Homo ergaster ), but not yet to West Africa. Around 1.8 million years ago, Homo erectus migrated out of Africa via

6832-478: The availability of resources determines the impact of additional species on the ecosystem. Stable ecosystems have a resource equilibrium, which can be changed fundamentally by the arrival of invasive species. When changes such as a forest fire occur, normal ecological succession favors native grasses and forbs . An introduced species that can spread faster than natives can outcompete native species for food, squeezing them out. Nitrogen and phosphorus are often

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6944-706: The beginning of the Upper Paleolithic , gave rise to the major population groups of the Old World and the Americas . Towards the West, Upper Paleolithic populations associated with mitochondrial haplogroup R and its derivatives, spread throughout Asia and Europe, with a back-migration of M1 to North Africa and the Horn of Africa several millennia ago. Presence in Europe is certain after 40,000 years ago, possibly as early as 43,000 years ago, rapidly replacing

7056-467: The behaviour of herbivores , impacting on other species. Some, like Kalanchoe daigremontana , produce allelopathic compounds that inhibit competitors. Others like Stapelia gigantea facilitate the growth of seedlings of other species in arid environments by providing appropriate microclimates and preventing herbivores from eating seedlings. Changes in fire regimens are another form of facilitation. Bromus tectorum , originally from Eurasia,

7168-509: The boundary of the Arctic , by c. 32,000 years ago, when they were being displaced from their earlier habitats by H. sapiens , based on 2011 excavations at the site of Byzovaya in the Urals ( Komi Republic , 65°01′N 57°25′E  /  65.02°N 57.42°E  / 65.02; 57.42 ). Other archaic human species are assumed to have spread throughout Africa by this time, although

7280-507: The business-as-usual scenario (which is important as Cape Town experiences significant water scarcity ). This is the equivalent to one-sixth of the city's current supply needs. These annual gains will double within 30 years. The catchment restoration is significantly more cost-effective then other water augmentation solutions (1/10 the unit cost of alternative options). A water fund has been established, and these exotic species are being eradicated. Invasive species can affect human health. With

7392-542: The claim that modern humans from Africa arrived at southern China about 100,000 years ago ( Zhiren Cave , Zhirendong , Chongzuo City: 100,000 years ago; and the Liujiang hominid ( Liujiang County ): controversially dated at 139,000–111,000 years ago ). Dating results of the Lunadong ( Bubing Basin , Guangxi , southern China ) teeth, which include a right upper second molar and a left lower second molar, indicate that

7504-580: The coast eventually turning northeast to China and finally reaching Japan before turning inland. This is evidenced by the pattern of mitochondrial haplogroups descended from haplogroup M , and in Y-chromosome haplogroup C . Sequencing of one Aboriginal genome from an old hair sample in Western Australia revealed that the individual was descended from people who migrated into East Asia between 62,000 and 75,000 years ago. This supports

7616-511: The densities of native forage plants, declining the habitat-use by wild herbivores and threatening the long-term sustenance of dependent carnivores, including the tiger . Invasive species can change the functions of ecosystems. For example, invasive plants can alter the fire regime (cheatgrass, Bromus tectorum ), nutrient cycling (smooth cordgrass Spartina alterniflora ), and hydrology ( Tamarix ) in native ecosystems. Invasive species that are closely related to rare native species have

7728-436: The expense to monitor, control, manage, and research invasive weed species is approximately AU$ 116.4 million per year, with costs directed solely to central and local government. While in some cases, invasive species may offer economic benefits, such as the potential for commercial forestry from invasive trees, these benefits are generally overshadowed by the substantial costs associated with biological invasions. In most cases,

7840-563: The field lacks any official designation but is commonly referred to as "invasion ecology" or more generally "invasion biology". This lack of standard terminology has arisen due to the interdisciplinary nature of the field which borrows terms from disciplines such as agriculture , zoology , and pathology , as well as due to studies being performed in isolation. In an attempt to avoid the ambiguous, subjective, and pejorative vocabulary that so often accompanies discussion of invasive species even in scientific papers, Colautti and MacIsaac proposed

7952-657: The first anatomically modern humans in Europe. They entered Eurasia by the Zagros Mountains (near present-day Iran and eastern Turkey ) around 50,000 years ago, with one group rapidly settling coastal areas around the Indian Ocean and another migrating north to the steppes of Central Asia . Modern human remains dating to 45,000-47,000 have been found in Germany , while finds of 43,000–45,000 years ago have been discovered in Italy and Britain, as well as in

8064-629: The fishing industry and have helped cause the collapse of the population of some species. Economic costs from invasive species can be separated into direct costs through production loss in agriculture and forestry, and management costs. Estimated damage and control costs of invasive species in the U.S. amount to more than $ 138 billion annually. Economic losses can occur through loss of recreational and tourism revenues. When economic costs of invasions are calculated as production loss and management costs, they are low because they do not consider environmental damage; if monetary values were assigned to

8176-601: The fossil record is sparse. Their presence is assumed based on traces of admixture with modern humans found in the genome of African populations. Homo naledi , discovered in South Africa in 2013 and tentatively dated to about 300,000 years ago, may represent fossil evidence of such an archaic human species. Neanderthals spread across the Near East and Europe, while Denisovans appear to have spread across Central and East Asia and to Southeast Asia and Oceania. There

8288-446: The governments of California and New Zealand have announced more stringent control for vessel hull fouling within their respective jurisdictions. Another vector of non-native aquatic species is ballast water taken up at sea and released in port by transoceanic vessels. Some 10,000 species are transported via ballast water each day. Many of these are harmful. For example, freshwater zebra mussels from Eurasia most likely reached

8400-627: The individual is related to modern Asian and Native American populations. A 2013 study found Neanderthal introgression of 18 genes within the chromosome 3p21.31 region (HYAL region) of East Asians. The introgressive haplotypes were positively selected in only East Asian populations, rising steadily from 45,000 years ago until a sudden increase of growth rate around 5,000 to 3,500 years ago. They occur at very high frequencies among East Asian populations in contrast to other Eurasian populations (e.g. European and South Asian populations). The findings also suggest that this Neanderthal introgression occurred within

8512-489: The individual to its environment. Pre-adaptations and evolution after the introduction reinforce the success of the introduced species. The enemy release hypothesis states that evolution leads to ecological balance in every ecosystem. No single species can occupy a majority of an ecosystem due to the presences of competitors, predators, and diseases. Introduced species moved to a novel habitat can become invasive, with rapid population growth, when these controls do not exist in

8624-533: The inherent nature of many of them having strong weed potential. They will partner with other organisations, for example Paddy Pallin Foundation , an environmental organisation, on weed management, for example Island Conservation , another environmental organisation, on sustaining biodiversity on islands. The ISC also directly undertakes basic science and research, such as in running smooth newt surveys in and around Melbourne . The ISC research and analysis

8736-636: The introductions of the amethyst gem clam and the European green crab . The gem clam was introduced into California's Bodega Harbor from the US East Coast a century ago. On its own, it never displaced native clams ( Nutricola spp.). In the mid-1990s, the introduction of the European green crab resulted in an increase of the amethyst gem at the expense of the native clams. In India, multiple invasive plants have invaded 66% of natural areas, reducing

8848-538: The invaded habitats and bioregions adversely, causing ecological, environmental, or economic damage. The European Union defines "Invasive Alien Species" as those that are outside their natural distribution area, and that threaten biological diversity . Biotic invasion is one of the five top drivers for global biodiversity loss , and is increasing because of tourism and globalization . This may be particularly true in inadequately regulated fresh water systems, though quarantines and ballast water rules have improved

8960-646: The invasive brown tree snake . In New Zealand the first invasive species were the dogs and rats brought by Polynesian settlers around 1300. These and other introductions devastated endemic New Zealand species. The colonization of Madagascar brought similar harm to its ecosystems. Logging has caused harm directly by destroying habitat, and has allowed non-native species such as prickly pear and silver wattle to invade. The water hyacinth forms dense mats on water surfaces, limiting light penetration and hence harming aquatic organisms, and causing substantial management costs. The shrub lantana ( Lantana camara )

9072-492: The larvae of these invasive species feed on ornamental plants. Early human migrations Early human migrations are the earliest migrations and expansions of archaic and modern humans across continents. They are believed to have begun approximately 2 million years ago with the early expansions out of Africa by Homo erectus . This initial migration was followed by other archaic humans including H. heidelbergensis , which lived around 500,000 years ago and

9184-440: The last Neanderthal and the first Homo Sapiens populations of the early Upper Paleolithic. Modern Europeans of today bear no trace of the genomes of the first Homo Sapiens Europeans, but only of those from after the ecological crisis of 38,000 BCE. Modern humans then repopulated Europe from the east after the eruption and the ice age that took place from 38,000 to 36,000 BCE. A mitochondrial DNA sequence of two Cro-Magnons from

9296-567: The latest, with derived forms classified as H. antecessor in Europe around 800,000 years ago and H. heidelbergensis in Africa around 600,000 years ago. H. heidelbergensis in its turn spread across East Africa ( H. rhodesiensis ) and to Eurasia, where it gave rise to Neanderthals and Denisovans . H. heidelbergensis , Neanderthals and Denisovans expanded north beyond the 50th parallel ( Eartham Pit, Boxgrove 500kya, Swanscombe Heritage Park 400kya, Denisova Cave 50 kya). It has been suggested that late Neanderthals may even have reached

9408-443: The limiting factors in these situations. Every species occupies an ecological niche in its native ecosystem; some species fill large and varied roles, while others are highly specialized. Invading species may occupy unused niches, or create new ones. For example, edge effects describe what happens when part of an ecosystem is disturbed, as when land is cleared for agriculture . The boundary between remaining undisturbed habitat and

9520-534: The modern Khoi-San expanded to Southern Africa before 150,000 years ago, possibly as early as before 260,000 years ago, so that by the beginning of the MIS 5 " megadrought ", 130,000 years ago, there were two ancestral population clusters in Africa, bearers of mt-DNA haplogroup L0 in southern Africa, ancestral to the Khoi-San, and bearers of haplogroup L1-6 in central/eastern Africa, ancestral to everyone else. There

9632-611: The molars may be as old as 126,000 years. Since these previous exits from Africa did not leave traces in the results of genetic analyses based on the Y chromosome and on MtDNA, it seems that those modern humans did not survive in large numbers and were assimilated by our major antecessors. An explanation for their extinction (or small genetic imprint) may be the Toba eruption (74,000 years ago), though some argue it scarcely affected human population. The so-called " recent dispersal " of modern humans took place about 70–50,000 years ago. It

9744-635: The new ecosystem. Non-native species have many vectors , but most are associated with human activity. Natural range extensions are common, but humans often carry specimens faster and over greater distances than natural forces. An early human vector occurred when prehistoric humans introduced the Pacific rat ( Rattus exulans ) to Polynesia. Vectors include plants or seeds imported for horticulture . The pet trade moves animals across borders, where they can escape and become invasive. Organisms stow away on transport vehicles. Incidental human assisted transfer

9856-523: The new environment may host fewer able competitors, allowing the invader to proliferate. Ecosystems used to their fullest capacity by native species can be modeled as zero-sum systems, in which any gain for the invader is a loss for the native. However, such unilateral competitive superiority (and extinction of native species with increased populations of the invader) is not the rule. An invasive species might be able to use resources previously unavailable to native species, such as deep water accessed by

9968-528: The newly cleared land itself forms a distinct habitat, creating new winners and losers and possibly hosting species that would not thrive outside the boundary habitat. In 1958, Charles S. Elton claimed that ecosystems with higher species diversity were less subject to invasive species because fewer niches remained unoccupied. Other ecologists later pointed to highly diverse, but heavily invaded ecosystems, arguing that ecosystems with high species diversity were more susceptible to invasion. This debate hinged on

10080-764: The oldest evidence of settlement in Australia, around 40,000 years ago for the oldest human remains, the earliest humans artifacts which are at least 65,000 years old and the extinction of the Australian megafauna by humans between 46,000 and 15,000 years ago argued by Tim Flannery, which is similar to what happened in the Americas. The continued use of Stone Age tools in Australia has been much debated. The population brought to South Asia by coastal migration appears to have remained there for some time, during roughly 60,000 to 50,000 years ago, before spreading further throughout Eurasia. This dispersal of early humans, at

10192-476: The pathways of hundreds of marine invasive species and found that shipping was the dominant mechanism for the transfer of invasive species. Many marine organisms can attach themselves to vessel hulls. Such organisms are easily transported from one body of water to another, and are a significant risk factor for a biological invasion event. Controlling for vessel hull fouling is voluntary and there are no regulations currently in place to manage hull fouling. However,

10304-475: The pelts of fur-bearing animals; construction of shelters with hearths using bones as fuel; and digging "ice cellars" into the permafrost to store meat and bones. However, from recent research it is believed that the ecological crisis resulting from the eruption in c. 38,000 BCE of the super-volcano in the Phlegrean Fields near Naples, which left much of eastern Europe covered in ash, wiped out both

10416-472: The potential to hybridize with the native species. Harmful effects of hybridization have led to a decline and even extinction of native species. For example, hybridization with introduced cordgrass, Spartina alterniflora , threatens the existence of California cordgrass ( Spartina foliosa ) in San Francisco Bay . Invasive species cause competition for native species and because of this 400 of

10528-519: The present-day United Arab Emirates (125,000 years ago) and Oman (106,000 years ago), and possibly reaching the Indian Subcontinent ( Jwalapuram : 75,000 years ago.) Although no human remains have yet been found in these three places, the apparent similarities between the stone tools found at Jebel Faya , those from Jwalapuram and some from Africa suggest that their creators were all modern humans. These findings might give some support to

10640-613: The public mind and creating political interest, for example in 2014, in regard to the importation of dangerous weed seeds going straight through Australian quarantine checks, and again in 2016 embarrassing eBay into temporary action, for example in 2017, in regard to the smooth newt , and that invasive species are possibly a greater threat to native Australian species than habitat loss which is dramatic and assumed to be more important. The ISC will coauthor academic and technical papers with research bodies. For example, in 2010 they collaborated with CSIRO on biofuel sources becoming weeds due to

10752-412: The situation. Invasive species may drive local native species to extinction via competitive exclusion, niche displacement, or hybridisation with related native species. Therefore, besides their economic ramifications, alien invasions may result in extensive changes in the structure, composition and global distribution of the biota at sites of introduction, leading ultimately to the homogenisation of

10864-711: The southern coast of Asia and to Oceania by about 50,000 years ago. Modern humans spread across Europe about 40,000 years ago. Early Eurasian Homo sapiens fossils have been found in Israel and Greece, dated to 194,000–177,000 and 210,000 years old respectively. These fossils seem to represent failed dispersal attempts by early Homo sapiens , who were likely replaced by local Neanderthal populations. The migrating modern human populations are known to have interbred with earlier local populations, so that contemporary human populations are descended in small part (below 10% contribution) from regional varieties of archaic humans. After

10976-562: The spread of biological invasions, mitigate further impacts, and restore affected ecosystems. For example, the damage caused by 79 invasive species between 1906 and 1991 in the United States has been estimated at US$ 120 billion. Similarly, in China , invasive species have been reported to reduce the country's gross domestic product (GDP) by 1.36% per year. The management of biological invasions can be costly. In Australia , for instance,

11088-412: The theory of a single migration into Australia and New Guinea before the arrival of Modern Asians (between 25,000 and 38,000 years ago) and their later migration into North America. This migration is believed to have happened around 50,000 years ago, before Australia and New Guinea were separated by rising sea levels approximately 8,000 years ago. This is supported by a date of 50,000–60,000 years ago for

11200-548: The time of their emergence. While early expansions to Eurasia appear not to have persisted, expansions to Southern and Central Africa resulted in the deepest temporal divergence in living human populations. Early modern human expansion in sub-Saharan Africa appears to have contributed to the end of late Acheulean ( Fauresmith ) industries at about 130,000 years ago, although very late coexistence of archaic and early modern humans, until as late as 12,000 years ago, has been argued for West Africa in particular. The ancestors of

11312-413: The tools can be associated with the modern human jawbone finds. These early migrations do not appear to have led to lasting colonisation and receded by about 80,000 years ago. There is a possibility that this first wave of expansion may have reached China (or even North America ) as early as 125,000 years ago, but would have died out without leaving a trace in the genome of contemporary humans. There

11424-453: The way H. sapiens interbred with Neanderthals and Denisovans, with Denisovan DNA making 0.2% of mainland Asian and Native American DNA. Migrations continued along the Asian coast to Southeast Asia and Oceania, colonising Australia by around 65,000–50,000 years ago. By reaching Australia, H. sapiens for the first time expanded its habitat beyond that of H. erectus . Denisovan ancestry

11536-589: The western Sahelian zone by 130,000 years ago, while tropical West African sites associated with H. sapiens are known only from after 130,000 years ago. Unlike elsewhere in Africa, archaic Middle Stone Age sites appear to persist until very late, down to the Holocene boundary (12,000 years ago), pointing to the possibility of late survival of archaic humans , and late hybridization with H. sapiens in West Africa. Populations of Homo sapiens migrated to

11648-502: The work has been influenced by Charles Elton's 1958 book The Ecology of Invasion by Animals and Plants which creates a generalized picture of biological invasions. Studies remained sparse until the 1990s. This research, largely field observational studies, has disproportionately been concerned with terrestrial plants . The rapid growth of the field has driven a need to standardize the language used to describe invasive species and events. Despite this, little standard terminology exists;

11760-405: The world's fauna and flora and the loss of biodiversity . It is difficult to unequivocally attribute extinctions to a species invasion, though there is for example strong evidence that the extinction of about 90 amphibian species was caused by the chytrid fungus spread by international trade. Multiple successive introductions of different non-native species can worsen the total effect, as with

11872-557: Was a significant back-migration of bearers of L0 towards eastern Africa between 120 and 75 kya. Expansion to Central Africa by the ancestors of the Central African forager populations (African Pygmies) most likely took place before 130,000 years ago, and certainly before 60,000 years ago. The situation in West Africa is difficult to interpret due to a sparsity of fossil evidence. Homo sapiens seems to have reached

11984-672: Was awarded to the Australian Federal Minister for Agriculture and Water Resources , Barnaby Joyce , in part for the Minister's action in regard to pet dogs incorrectly brought to Australia by the actor, Johnny Depp , and his partner, in April 2015. The ISC has a regular publication, the Feral Herald . The ISC is run by a chief executive officer (CEO), and is overseen by a board of directors. The CEO in 2017

12096-416: Was estimated to exceed $ 423 billion annually as of 2019. This cost has exhibited a significant increase, quadrupling every decade since 1970, underscoring the escalating financial implications of these biological invasions. Invasive species contribute to ecological degradation , altering ecosystem functionality and reducing the services ecosystems provide. This necessitates additional expenditures to control

12208-532: Was first populated around 1.2 million years ago ( Atapuerca ). Robert G. Bednarik has suggested that Homo erectus may have built rafts and sailed oceans, a theory that has raised some controversy. One million years after its dispersal, H. erectus was diverging into new species. H. erectus is a chronospecies and was never extinct, so its "late survival" is a matter of taxonomic convention. Late forms of H. erectus are thought to have survived until after about 0.5 million ago to 143,000 years ago at

12320-470: Was introduced in the San Francisco Bay and hybridized with native Spartina foliosa . The higher pollen count and male fitness of the invading species resulted in introgression that threatened the native populations due to lower pollen counts and lower viability of the native species. Reduction in fitness is not always apparent from morphological observations alone. Some degree of gene flow

12432-486: Was much lower and most of Maritime Southeast Asia formed one land mass known as Sunda . Migration continued Southeast on the coastal route to the straits between Sunda and Sahul , the continental land mass of present-day Australia and New Guinea . The gaps on the Weber Line are up to 90 km wide, so the migration to Australia and New Guinea would have required seafaring skills. Migration also continued along

12544-484: Was the likely ancestor of Denisovans and Neanderthals as well as modern humans. Early hominids had likely crossed land bridges that have now sunk. Within Africa, Homo sapiens dispersed around the time of its speciation , roughly 300,000 years ago. The recent African origin paradigm suggests that the anatomically modern humans outside of Africa descend from a population of Homo sapiens migrating from East Africa roughly 70–50,000 years ago and spreading along

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