Mass Extinction the Earth\'s Biodiversity

Mass Extinction

The Earth's Biodiversity

Mass extinctions are definitely not common; however, if the earth's biodiversity is threatened at a similar rate to pass mass extinctions (such as the one that destroyed the dinosaurs -- except for the birds), there are a number of probable losers, according to McKinney and Lockwood (1999), and one need only look at a list of threatened species. "However," they note, "this almost certainly underestimates the true number of losers as many (probably most) species are in decline but their abundance is not yet low enough to warrant current listing" (1999).

Many of the "global losers" will include threatened birds such as parrots and pheasants and threatened mammals such as apes and rhinoceroses. There will be "local losers" like the babbler bird of the Sumatran forest; parrots of the Brazilian forest; birds in urban areas of the United States; frogs in the Amazon forest; insects of the Boreal forest; and salamanders in the forests of Maine to name a few (McKinney & Lockwood 1999).

In the article entitled "Biologists say planet is undergoing mass species extinction," Daily Galaxy (2009) reports that, "for over 300 million years frogs, salamanders, newts and toads were hardy enough to precede and outlive the dinosaurs up until the present time," but now, within twenty years, many amphibians are becoming extinct. "Scientists are alarmed at how one seemingly robust species of amphibians will suddenly disappear within a few months" (2009).

We can never regain the lost biodiversity, but scientists claim that we can at least work to prevent a "worldwide bio collapse" (Daily Galaxy 2009), but they would all require that immediate action be initiated. Experts say that at least half of the world's present species will be entirely gone by the end of the century and many biologists say that we are right in the middle of an anthropogenic (i.e., caused by humans) mass extinction (2009). It is has been noted by scientists that it takes approximately 10 million years before biological diversity can even begin to get near what it existed before it died off. Over 10,000 scientists in the World Conservation Union have come up with data showing that "51% of known reptiles, 62% of known insects, and 73% of known flowering plants are in danger along with many mammals, birds and amphibians" (2009).

McKinney and Lockwood (1999) came up with a list of traits that influence whether species are "winners" or "losers" in a human-dominated world. Traits promoting range expansion were: selected traits (small size, high fecundity); high variability; widespread; rapid dispersal; generalist (eurytopy); and human commensalism. Some of the traits promoting extinction were: selected traits (large sixe, low fecundity); low variability; rare; slow dispersal; specialist (stenotopy); and poorly adapted to human activities (1999).