Parasites and Monarchs

[Stanley A. Gorodenski]

Paul,
Let us make it clear that you are talking about something else. I am 
talking about the paper, Ecology Letters. 8: 290-300, but you are 
talking about something outside this paper at the URL you gave. Again, 
the paper itself does not contain "inappropriate alarmist type 
propaganda", as you put it. _Maybe_ the Release you quote does, but not 
the paper.
Stan

Paul Cherubini wrote:

>Stanley A. Gorodenski wrote:
>
>  
>
>>I am in the process of reading this paper now. At this time 
>>I do not see it as political propaganda in the least. What I 
>>see is good science that draws upon results of research on 
>>other taxa and puts the interpretation of their results in that 
>>context.
>>    
>>
>
>Stan, here is another write up of the same study
>http://news.emory.edu/Releases/monarch1109713157.html
>
>I would tend to agree with Ron Gatrelle this write up contains 
>inappropriate alarmist type propaganda rather than just science. 
>
>Using tethered monarchs in a lab, the authors measured the flight 
>endurance of lab reared monarchs that were infected with variable
>levels of a protozoan parasite. They found highly infected 
>monarchs flew somewhat slower, for shorter periods, etc. This 
>is fairly interesting (though not real interesting since they 
>apparently didn't flight test wild caught monarchs) and fairly good 
>science as far as it went. But then the authors decided to launch 
>into unjustified, alarmist monarch migration extinction propaganda 
>with these statements:
>
>"monarch migration in eastern North America is threatened by
>several environment factors such as habitat loss at wintering sites,
>climate warming trends and an increase of tropical milkweed 
>species in milder climates."
>
>"The results of our study add one more reason to protect monarch
>migration east of the Rockies. If this migration collapses due to
>climate warming, habitat loss, pesticide use or other reasons, we
>probably won't lose monarchs as a species, but we'd be left with
>remnant, nonmigratory populations that are heavily infected with
>parasites, which could have several negative effects, from higher
>mortality rates, smaller body sizes and deformities, to more virulent
>strains of the parasite," Altizer says."
>
>Why, in my opinion, is this propaganda? Several reasons:
>
>1. As Ron Gatrelle pointed out "climate change is neutral,
>its functions work just as much against a disease  / parasite / plant /
>animal etc. as it can for it." Ditto in regards to the authors' claim
>of an "increase of tropical milkweed species in milder climates."
>An increase in the abundance of tropical milkweed could have
>neutral, positive or negative impacts on the abundance of migrant
>monarchs.  In fact, back in 1961, Dr. Lincoln Brower hypothesized
>winter monarchs in Florida bred on tropical milkweed then
>migrated north in the spring and repopulated the entire eastern USA 
>with monarchs.
>
>2. The authors state "habitat loss at wintering sites" as if the loss
>was an established fact when to the contrary we know every
>mountain in Mexico that contained overwintering sites
>30 years ago still has them today and in similar quantities.
>
>3. The authors state "If this migration collapses due to climate
>warming, habitat loss, pesticide use or other reasons" as if 
>there was a solid body of evidence to support the notion that 
>small, incremental changes in climate, habitat loss or pesticide 
>use could cause a catastrophic collapse of the migration 
>phenomenon.
>
>To the contrary, we know the monarch migration has been
>robust for the past 125 years despite massive human caused
>changes in the vegetation of the upper Midwest, Great Lakes 
>States and New England (where monarchs breed in the summer)
>during that time period.
>
>4. The authors state "if this migration collapses we'd be left with
>remnant, nonmigratory populations that are heavily infected with
>parasites, which could have several negative effects, from higher
>mortality rates, smaller body sizes and deformities, to more virulent
>strains of the parasite,"  as if there was a solid body of evidence 
>to support the notion that non-migratory monarch populations
>are uniformly small, unhealthy and riddled with deformities, etc.
>
>To the contrary, there are dozens and dozens of  island populations 
>of monarchs in the tropics that have survived since the mid-late 
>1800's with no reports of extinctions that I am aware of.
>
>Paul Cherubini
>
>
>  
>


 
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