Monday, April 5, 2010
Introduced Species
On page 109, Jerry Coyne discusses the issues of introducing certain types of species such as the cane toad that have become pests and invasive species. However, Jerry Coyne also discusses how the European honeybee die off when these bees were introduced in Japan. What is the common relationship, if one, for the reason that certain species are capable of surviving or even taking over a geographic region, while other species fail to survive very long? What similarities create advantages or differences that are insignificant that give certain introduced species the ability to survive compared to others.
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The reason certain species can survive in any environment is the simple fact that the aforementioned species has the adaptations that suit the environment the species has been introduced to and/or the species’ niche has not already been occupied by another species.
ReplyDeleteFor instance, the cane toad when introduced to Hawaii had no competition for its ecological niche. The toads’ main source of food were the beetles growing on the sugarcane. Because there were no organisms in Hawaii before the toad that ate the beetle, the cane toad had no competition for a food source. There were no amphibians in Hawaii before the toad, therefore the metaphorical “job position” was open for the taking.
The toad also had traits that were greatly suited their new environment. Hawaii also has a very humid, warm, and ideal climate for the thermoconforming (ectothermic) amphibian. The fact that these toads are poisonous is another trait that helps the other toads to survive and reproduce in the future. While the one toad is consumed, that toad gives a warning to any other predator by killing its assailant. Now the toads will have greatly reduced amounts of predators because of the fear instilled.
The reason the toads did so well in Hawaii also illustrates the reason the European Honey Bees did not fare well in Japan.
First of all, the bees had to compete for their ecological niche with the native honey bees. This is not to say that the amount of food available was insubstantial for both species to coexist, but the honey bees have a predator. The Japanese hornets are brutal killers that attack the honey bees nest. The native honey bees had already developed an adapted behavior to deal with their predator (roasting them alive = epic!) while the europeans did not.
Simply put, the similarities between introduced species that are successful are as follows. The new species’ ecological niche has not been previously taken and/or their adaptations are suitable to the new environment. Whether this means that the new species outcompetes the native species for a niche because the newcomer is better adapted than the native, or the new species can change into a completely different niche because of traits that suit the environment, all species that survive in a new environment have adaptations that allow that species to survive and reproduce.
Certain species are able to survive and even take over a geographic because they possess some quality in their genetic make up that allows them to have some advantage over the species already living there. Because the new introduced species came from a different region, their DNA always them to survive better and reproduce more than certain animals. The introduced animals may have also evolved and have been a "newer species" to the world. These animals possess some natural selection quality that makes them better suited than other animals.
ReplyDeleteSome advantages that introduced species have is that they know how to survive with other species around similar to the ones already living on the island. For example New Zealand birds are flightless. The island also only had very few reptiles and mammals. When new species were introduced into New Zealand, 11 species of a flightless bird became extinct (Coyne 109). Because the birds in New Zealand never had reason to fly away from predators, their genetic make up didn't allow them to fly. When new predators came to their territory, they didn't have quality to survive and therefore became extinct.
Another reason native species tend to die out fast when introduced species take over is that the introduced species could take over the native species' habitat or their food source. For example the Asian chestnut blight fungus eliminated most of the American chestnut trees in Eastern United States. Many animals lived in those chestnut trees and now had no place to live because their home was destroyed by an introduced specie. As a result some of those animals became extinct including the ten moth specie (http://www.actionbioscience.org/biodiversity/simberloff.html).
Both Brady and Anika have brought up good points and characteristics of invasive species that agree with Coyne's statement: "Evolutionary theory predicts that many animals and plants arriving in new and unoccupied habitats will evolve to thrive there, and will form new species, filling up ecological niches" (Coyne 110). This is accomplished through adaptive behavior and natural selection.
ReplyDeleteTo address the similarities between successful invasive species, let's consider the three things involved in adaptation through natural selection: a variable starting population, heritability, and the variation's effect on reproductive success (118).
The original population must have many different combinations of traits so that in evolutionary time the unnecessary and weak are eliminated and the helpful are replicated and enhanced. Factors that contribute to the possibility of having a variable population are reproductive frequency and clutch size (number of offspring per reproductive episode). If the introduced species is one that reproduces often and with a large clutch size, it is more likely to include variety.
Heritability determines the inheritance of trait. This is necessary simply because if one trait is naturally selected as advantageous, it cannot help the species unless it is copied in the majority of the offspring. Similarly, the third part is almost self explanatory because a species can only survive through increased reprductive success, the reason for all selective advantages.
http://www.anselm.edu/homepage/jpitocch/genbios/ecologybi04.html
Both Brady and Anika have brought up good points and characteristics of invasive species that agree with Coyne's statement: "Evolutionary theory predicts that many animals and plants arriving in new and unoccupied habitats will evolve to thrive there, and will form new species, filling up ecological niches" (Coyne 110). According to Campbell, "there is no single explanation for why a species becomes dominant in a community. One hypothesis suggests that dominant species are competitively superior in exploiting limited resources such as water or nutrients. Another explanation is that dominant species are most successful in avoiding predation or the impact of disease. This latter idea could explain the high biomass attained in some environments by invasive species" (Campbell 1207). Ultimately, though, domination due to the ability to avoid predation or the damage of disease is accomplished through adaptive behavior and natural selection.
ReplyDeleteTo address the similarities between successful invasive species, let's consider the three things involved in adaptation through natural selection: a variable starting population, heritability, and the variation's effect on reproductive success (118).
The original population must have many different combinations of traits so that in evolutionary time the unnecessary and weak are eliminated and the helpful are replicated and enhanced. Factors that contribute to the possibility of having a variable population are reproductive frequency and clutch size (number of offspring per reproductive episode). If the introduced species is one that reproduces often and with a large clutch size, it is more likely to include variety. This requirement relates to the theme continuity and change; mutations and sexual reproduction constantly create new genetic combinations that would provide this variety, and changes in a gene pool that originally held such variation are made through natural selection.
Heritability determines the inheritance of trait. This is necessary simply because if one trait is naturally selected as advantageous, it cannot help the species unless it is copied in the majority of the offspring. Similarly, the third part is almost self explanatory because a species can only survive through increased reprductive success, the reason for all selective advantages.
One example of a successful introduced species is the American bullfrog. Size, ease and quickness of mobility, generalized eating habits, and reproductive capability enhanced the frog's chances of survival. Their aggressive behavior, too, would make them very strong competitors and predators.
http://amphibiaweb.org/declines/IntroSp.html
http://www.anselm.edu/homepage/jpitocch/genbios/ecologybi04.html
The reason certain species can survive in any environment is the simple fact that the aforementioned species has the adaptations that suit the environment the species has been introduced to and/or the species’ niche has not already been occupied by another species.
ReplyDeleteFor instance, Coyne discusses how the cane toad when introduced to Hawaii had no competition for its ecological niche(110). The toads’ main source of food were the beetles growing on the sugarcane. Because there were no organisms in Hawaii before the toad that ate the beetle, the cane toad had no competition for a food source. There were no amphibians in Hawaii before the toad, therefore the metaphorical “job position” was open for the taking.
The toad also had traits that were greatly suited their new environment. Hawaii also has a very humid, warm, and ideal climate for the thermoconforming (ectothermic) amphibian. The fact that these toads are poisonous is another trait that helps the other toads to survive and reproduce in the future. While the one toad is consumed, that toad gives a warning to any other predator by killing its assailant. Now the toads will have greatly reduced amounts of predators because of the fear instilled. http://www.teachersnetwork.org/dcs/critter/canetoad/
The reason the toads did so well in Hawaii also illustrates the reason the European Honey Bees did not fare well in Japan according to Coyne.
First of all, the bees had to compete for their ecological niche with the native honey bees. This is not to say that the amount of food available was insubstantial for both species to coexist, but the honey bees have a predator. The Japanese hornets are brutal killers that attack the honey bees nest. The native honey bees had already developed an adapted behavior to deal with their predator (roasting them alive = epic!) while the europeans did not.
Simply put, the similarities between introduced species that are successful are as follows. The new species’ ecological niche has not been previously taken and/or their adaptations are suitable to the new environment. Whether this means that the new species outcompetes the native species for a niche because the newcomer is better adapted than the native, or the new species can change into a completely different niche because of traits that suit the environment, all species that survive in a new environment have adaptations that allow that species to survive and reproduce.
This prompt relates to the biological theme of interdependence in nature. The whole prompt is about how organisms cooperate with other organisms and the environment. Whether the species work together, compete, or just be parasites to one another(like the tapeworms we discussed in the invertebrates unit), all of the species such as the cane toad or the japanese hornets have to live with one another. How well the species does that defines whether or not the species will survive to reproduce or not. The cane toad had the adaptations to live in its environment while the european honey bee could not find a way to be interdependent with nature.