For unlimited access to Homework Help, a Homework+ subscription is required.
Read the information on exotix and invasive species and answer this question;
writing assignment : Maximum 1 page answer is needed for the below question
Question:Should the government work to prevent the introduction of exotix species to Canada??
From Freeman et al. 2019. Biological Sciences.
Global trade and global travel have vastly increased the rate of exchange of plants, animals, fungi, and microorganisms around the world. A nonnative species that is introduced into a new area is called an exotic species. Exotic species do not necessarily pose problems, and they can even be beneficial in some circumstances. But some exotic species pose a direct threat to native species by eating them, competing with them, causing disease, or other types of interactions. For example, a lethal fungus is spreading from Asia in the exotic salamander pet trade, endangering native salamanders worldwide. Exotic species can also pose indirect threats by changing the local biotic or abiotic resources.
If an exotic species is introduced to a new area, grows to large population size, and disrupts species native to the area, it is called an invasive species. For example, Burmese pythons were set free by pet owners into the Florida Everglades and are now dramatically affecting native wildlife there. Argentine ants have dispersed around the world in food shipments and are forming supercolonies that outcompete native ants. The round goby, a small benthic fish from Eastern Europe first detected in Ontario rivers in 1990, has since spread to all five Great Lakes. The round goby competes for food and spawning habitat with native fishes and is thought to be responsible for the local extinction of native sculpin species from areas of Lake Michigan.
The impact of invasive species can also be beneficial. McMaster University biologist James Quinn and his colleagues investigated the diet of double-crested cormorant chicks in Lake Ontario to determine whether the parent birds were taking advantage of the newly abundant round goby to feed their young. They found that the round goby was the second most frequent fish species eaten by cormorant chicks, suggesting that piscivorous birds are changing their diet to feed on this invasive fish.
Genetic analysis carried out by Tony Einfeldt, a researcher at the University of New Brunswick, suggests that Hediste diversicolor, an abundant polychaete worm in the Bay of Fundy, is an invasive species that originated in France. H. diversicolor is an important prey item for birds and fish in the mud flats in the Bay of Fundy. The polychaete is a poor swimmer with low dispersal ability and could not have made its own way to Canadian waters. The polychaetes live in mud, so they would not end up in ballast water taken in by ships to balance the mass of their cargo. Einfeldt suggests that these species were likely carried to Canada in the early 1600s by ships used by early European explorers such as Samuel de Champlain and Henry Hudson. Prior to 1880, ships lacked ballast tanks, and sailors loaded ships with intertidal material, including rocks, sticks, and mud, as âdry ballastâ. Hediste diversicolor likely arrived in the Bay of Fundy in this intertidal mud. The worms form burrows and bring water currents through their burrows as they feed. As a result, H. diversicolor acts as an ecosystem engineer, altering nutrient flow and restructuring the muddy intertidal where it lives. The invasive polychaete is also a major food source for millions of birds and fish in the Bay of Fundy and plays a key role in the ecology of the area. âThe reason that many of these birds and fish come to our mud flats is to feed on these prey. There are so many of them,â says Einfeldt. âThe idea that so much of what our ecosystem runs on came from our history â it's very exciting.â
Modified from Breining. 2009. A New View on Exotic Species. Yale Environment 360
When biologist Mark Davis talks about invasive species, he eventually comes to LTL, his shorthand for Learn to Love them. Invasive species are here to stay, says Davis, so get used to them, and forget about ripping out the fast-spreading plant purple loosestrife on a large scale or throwing Asian carp on the bank to die. If newcomers are only changing the ecosystem but ânot causing significant harm,â then âaltering oneâs perspective is certainly much less costly than any other sort of management program.â
Davis claims that assuming that invasive species are inherently bad, that ecosystem integrity can be measured by the number of alien species, or even that newly arrived species are functionally different from longtime residents, simply isnât supported by science. Many introduced species have proven valuable and useful, including crops (from apples to wheat), horticultural plants (hostas and Norway maples), and game species (ring-necked pheasants and brown trout). He holds firm to that position, while conceding that some newcomers can be terribly destructive.
âSome invasive species are causing problems,â admits Davis, who says he supports control programs where damage is great and controls stand a chance of success. One highly destructive invasive species causing great economic harm, for which Davis supports eradication programs, is the emerald ash borer, a beetleârecently introduced into eastern Canada from Asiaâthat typically kills 99% of ash trees in affected areas.
Today, biologists continue to wage a war on alien species that have taken root by accident or design. Zebra mussels, Dutch elm disease, purple loosestrife, Eurasian water milfoil, American bullfrogs, gypsy mothsâCanada is beset by exotic species invading native forests, spreading across prairies, and clogging streams and lakes. Davis takes issue with some conventional views of exotic species.
Because native species evolved in a specific ecosystem and exotics didnât, natives are better suited to their environment. In fact, says Davis, a scientist who didnât know the history of individual organisms would have difficulty in distinguishing natives from non-natives. The Galapagos Islandsâa world heritage site of biodiversityâprovide just such an example. For years, conservationists fretted over invasive weeds overrunning the islands. Because the weeds were out of control, conservationists assumed they were non-natives, recently introduced by humans. Research showed, however, that the plants were native and had been present since prehistoric times.
Diverse communities of native species resist invasions by alien species. While carefully controlled experiments on small plots have confirmed this idea, studies in natural forests and grasslands show the opposite, says Davis. Natural disturbances, such as disease or fire, and fluctuations in resources in diverse communities offer plenty of footholds for invaders.
Pristine ecosystems are highly evolved and well-ordered. Again, ecologists have little evidence for this, Davis says. Ragtag assemblages of exotics and natives quickly adapt and perform about as well. âIf you view [nature] as a continually changing tumult, the introduction of new species isnât necessarily looked at as a huge threat.â He cites the example of regeneration of forests in Puerto Rico, where non-native species are facilitating the re-establishment of native species.
The spread of invasive species threatens to drive natives extinct. Rarely happens, Davis says, except on islands, in lakes, or in other insular environments. Usually itâs the oppositeâthe appearance of exotics increases species richness, he maintains. Throughout Canada, local ecosystems have roughly 20 percent more plant species than they once did because of the addition for foreign species.
Exotics signify a âdegradedâ ecosystem. âThere isnât such a thing as a healthy ecosystem or a sick ecosystem,â Davis says. âEcosystems have no goal or purpose. Theyâre just the species and the physical and chemical processes taking place.â
In some cases, invasions of invasive species do threaten native species with extinction. Chestnut blight, caused by an introduced fungus, swept across southern Ontario in the 1950s and virtually exterminated the native chestnut tree. Ecologist Dan Simberloff says, âWe know it caused total global extinction of at least seven species of moths that were host-specific only on North American chestnuts.â
Even if exotics donât drive native species to extinction, they can completely transform ecosystems. âThere are some biotic communities that have entirely disappeared because of invasive species,â says Simberloff. âThere are others that have drastically changed over large areas.â For example, Eurasian cheat grass now dominates millions of hectares of Western range, displacing native bunch grasses and reducing the value of the range for livestock.
James Carlton, Pew Fellow in Marine Conservation, contends that biologists can distinguish natives from exotics. âWe can easily distinguish natives from many (not all!) non-natives many times in many ways, based very much on how they function in an ecosystem. Native species are often finely tuned physiologically to the environment, whereas nonnative species may possess a repertoire of adaptations that clearly do not match the environment.â
Conservation biologist Dov Sax became positive about the impact of invasive species as an undergraduate at the University of California, Berkeley. A professor leading a field trip described the Bay Areaâs abandoned plantations of Australian eucalyptus trees as a âbiological desert.â Says Sax, âThere was all kinds of stuff growing in there. I found there were really a similar number of species in both [native oak and eucalyptus] woodland types. Exotics werenât always doing the awful things people thought they were doing.â Land managers canât begin to control the thousands of exotics that reach native ecosystems through globalized trade and travel. âConservation biology in the past has been built around the idea of preventing change,â says Sax, âbut itâs impossible to do.â
In a matter of decades, researchers believe, animals and plants are adapting to life in a warmer world. Some species will be unable to change quickly enough and will go extinct, but others will evolve, as natural selection enables them to carry on in an altered environment. With global warming pushing some animals and plants to the brink of extinction, conservation biologists are now saying that the only way to save some species may be to move them. The future landscape will be home to ânovel ecosystems,â never-before-seen agglomerations of species, of which exotics will be a key â and often valued component, Sax and others say. âIf we lump them into this category of all being evil or awful in some way,â he says, âwe may blind ourselves to those situations where theyâre actually providing a benefit either for humans or for biological conservation.â For example, a recent study of two nonnative wetland plants, suggests they provide waterfowl habitat, biomass production, and nitrogen retention that equals that of native species. Davis feels we should focus instead on disease organisms, agricultural pests, and other threats and says, âItâs important to distinguish harm from change.â
What exactly was Hooker's response to Darwin's, Origin of Species? Thank you for your help. I need help deciphering what his opinions truly were.
Hooker, J. D. 1859. [Review of] On the origin of species. Gardeners' Chronicle (31 December): 1052. Part 1.
From the above expressions it will be inferred that we have risen from the perusal of Mr. DARWIN'S book much impressed with its importance, and have moreover found it to be so dependent on the phenomena of horticultural operations, for its facts and results, and so full of experiments that may be repeated and discussed by intelligent gardeners, and of ideas that may sooner fructify in their minds than in those of any other class of naturalists, that we shall be doing them (and we hope also science) a service by dwelling in some detail upon its contents. Thus much we may premise, that it is a book teeming with deep thoughts on numberless simple and complex phenomena of life; that its premises in almost all cases appear to be correct; that its reasoning is apparently close and sound, its style clear, and we need hardly add its subject and manner equally attractive and agreeable; it is also a perfectly ingenuous book, bold in expressions as in thought where the author adduces what he considers clear evidence in his favour, frank in the statement of objections to the hypotheses or conclusions founded on its facts and reasonings; and uniformly courteous to antagonistic doctrines. In fine, whatever may be thought of Mr. DARWIN'S ultimate conclusions, it cannot be denied that it would be difficult in the whole range of the literature of science to find a book so exclusively devoted to the development of theoretical inquiries, which at the same time is throughout so full of conscientious care, so fair in argument, and so considerate in tone. . . . Hitherto most [naturalists] have, as we have already observed, contented themselves with the hypothesis that they were independently created, and the minority have clung to the only other explanation hitherto conceived, that they have all been created by variation from a single first-created living organism, or a few such. Now it must be borne in mind that both these views are mere hypotheses in a scientific point of view; neither has any inherent or prescriptive right to a preference in the mind of the impartial inquirer; but the most superficial observation will show that the hypothesis of original creations is incapable of absolute proof, except the operation be witnessed by credible naturalists, and can only be supported by facts that are either not conclusive against the opposite doctrine, or may be regarded as equally favourable to it; and this hypothesis is hence placed at a disadvantage in comparison with that of the creation of species by variation, which takes its stand on the familiar fact that species do depart from the likeness of their progenitors, both in a wild and domestic state. On the other hand the hypothesis of creation by variation labours under the disadvantage of being founded upon a series of phenomena, the action of each of which individually, as explained by Mr. DARWIN, would appear to prevent the possibility of species retaining their characters for any length of time, and it therefore appears at first sight opposed to the undisputed fact, that many hundreds of animals and plants have transmitted their characters unchanged (or nearly so) through countless generations, and covered, even within the historic period, many square miles of country each with millions of its exact counterpart. To explain this anomaly and to raise this hypothesis of creations by variation to the rank of a scientific theory, is the object of Mr. DARWIN'S book, and to do this he has endeavoured to invent and prove such an intelligible rationale of the operation of variation, as will account for many species having been developed from a few in strict adaptation to existing conditions, and to show good cause how these apparently fleeting changelings may by the operation of natural laws be so far fixed as to reconcile both the naturalist and the common observer to the idea, that what in all his experience are immutable forms of life may have once worn another guise. The hypothesis itself is a very old one; it was, as all the world knows, strongly advocated by LAMARCK, and later still by the author of the "Vestiges of the Natural History of the Creation," but neither of these authors were able to suggest even a plausible method according to which Nature might have proceeded in producing suitable varieties, getting rid of intermediate forms, and giving a temporary stability to such as are recognised as species by all observers. Mr. DARWIN has been more successful, though whether completely so or not the future alone can show. We shall proceed to examine his method in another article.
Case Study
Skolnikland is in Eastern Africa, with a population of 30 million people. The country has a plains region, a hill region, and a region with high mountains. It has a number of ecosystems. The plains are dry for much of the year, there is some rainforest, and the rest of the country includes both hills and mountains. There are two seasons of heavy rainfall.
The citizens come from several ethnic groups that tend to live in their own regions and speak different languages. The ethnic groups largely follow one of three different religions. The large cities are mixed ethnically. One ethnic group is economically and socially very dominant. The people from this group live in the capital and most of the large cities. The national language is the language of this dominant ethnic group.
According to World Bank criteria, Skolnikland is among the poorest countries in the world. The economy has been growing at about 4% per year on average over the last decade, but the economy had very slow economic growth in the decades prior to that. The richest 10% of the population controls 80% of the national income.
About 80% of the people live in rural areas and 20% in urban areas. The number of people living in urban areas has been growing recently at an increasing pace. Most people earn their livelihood in agriculture but there is an increasing garment manufacturing industry in the two largest cities. There are also a number of mining industries. In addition, other export industries are beginning to grow, mostly focused on the export of commodities to China.
The total fertility rate is about 4.5 but it has been declining slowly over the last two decades, from over 6. There is an almost equal number of men and women in the population. Infant mortality is about 90 per 1,000 live births. Maternal mortality is about 500 per 100,000 live births. Thirty-five percent of the children are underweight for age.
The adult literacy rate is about 40%. The educational enrollment rate, especially for girls at the primary and secondary levels, has been growing slowly, but steadily. Most recently, this rate has been growing at an increasing pace and about 75% of the girls now attend school regularly, although many of them are of very low quality.
Only about 50% of citizens have access to safe water. Only about 30% have access to sanitary disposal of human waste.
HIV prevalence is 7% of the adult population. The number of new HIV cases annually has begun to plateau. About half of the people eligible for treatment for HIV are on treatment. Malaria is rampant in the plains.
Investments in the road system have been growing at a solid pace in the last decade and the use of private automobiles has begun recently to increase more rapidly.
Skolnikland has a pluralistic health system that is made up of public and private institutions, publicly financed providers, licensed private providers, unlicensed medical practitioners, and traditional healers. There is no health insurance, except for some free services for the poor in the few publicly financed hospitals, which the better off people do not attend. The health system is not very effective or efficient and is generally of low quality. The HIV, TB, and malaria programs are not effective or efficient and they are just beginning to adopt paradigms for services that follow global best practices.
QUESTION 11
If you were interested in investing in maternal and child health using a results-based financing scheme, which program is the most appropriate?
A. Invest in training more skilled birth attendants in a village.
B. A plan to give the local clinic in the village a grant after the clinic demonstrates that its efforts have led after two years to lower under-5 child mortality.
C.Provide all pregnant women in the village with a full course of antenatal vitamins.
QUESTION 12
In Skolnikland today, approximately what proportion of the burden of disease, measured in DALYs, is likely to be Group I-related?
A. 45%
B. 35%
C. 60%
QUESTION 13
In Skolnikland, life expectancy fell in the 1990s, which can be attributed to:
A. Malaria
B. HIV
C. Pneumonia
QUESTION 14
In Skolnikland, the cost for treating severe diarrhea in young children is $18 for community-based care and $20 for clinic-based care. The cure rate for community-based care is 60%. The cure rate for clinic-based care is 90%. Which approach is the most cost-effective?
A. Community-based care
B. Clinic-based care
C. They are equally cost-effective
QUESTION 15
In Skolnikland, what are likely to be three of the five leading causes of death of under-5 children, besides perinatal causes?
A. TB, diarrhea, pneumonia
B. Malaria, diarrhea, measles
C. Diarrhea, malaria, pneumonia
