Wednesday, April 18, 2007

Hanski and Niemela 1990

Hanski I, Niemelä J. 1990. Elevational distributions of dung and carrion beetles in northern Sulawesi. In: Knight WJ, Holloway JD, editors. Insects and the Rain Forests of South East Asia (Wallacea). p 145-152.

This paper is really interesting to me because I work on carrion beetles in Asia and this paper is specific to my work. In this paper, the authors attempt to document the elevational distributions for all dung and carrion beetles in northern Sulawesi (Indonesia). It was hoped that this would give insight into the processes which are important in structuring dung and carrion beetle communities in tropical forests. They state that carrion beetles are a good animal to use for transect studies because their numbers can be accurately estimated in a short period of time. They compared their transect study in Sulawesi to one previously conducted in Borneo.

Hankski and Niemila found:

1) beetle diversity was higher in Sulawesi than Borneo (apparently because of higher availability of resources-I would have to question this).

2) species richness (# of species) was the same in the two localities -but more montane species were found in Sulawesi (they state that this is probably because Sulawesi has more montane forests than Borneo).

3) no distinct elevational species assemblages were found in Sulawesi

Interestingly, they state, "detailed observations however indicated mutually exclusive ranges in Nicrophorus (two species)...". However, they then contradict themselves by stating further in the paper that, "two species [N. charon and N. distinctus] were found together at one site at 1450 m on Gn. Muajat and therefore their distributions are touching or slightly overlapping". I have also found this evidence where N. distinctus and N. charon occured at the same place at one of my sites. Unfortunately, I was not able to study the elevational ranges of these two species due to the 'problems' I encountered in Dongi Dongi and Rano Rano. In Dongi Dongi, the problem was local people conducting illegal logging and making sure no one (especially white foreigners who look like they could tell the government) was snooping around in the area. The problem in Rano Rano was that it was a 6 hour hike to get to the top and we didn't bring enough food to stay longer than 1 day.

Another interesting quip is "most dung and carrion beetles in SE Asia are attracted, to a varying degree, to both dung and carrion" (Hanski 1988). I wonder if the nepalensis group (Nicrophorus) is attracted to dung as well?

"In SE Asia, only one species occurs in one region: podagricus: Borneo; insularis: Java [also occurs on Sumatra and Bali]; nepalensis: northern Philippines [and mainland Asia], apo: Mindanao; heurni: New Guinea; insignis: Flores."

"As a rule Nicrophorus in SE Asia are restricted to montane forests, but in Solomon Islands and Sulawesi, one species occurs only in the lowlands while the other one is restricted to montane forests". I found that this is not entirely true for species on Sulawesi. Although N. charon is restricted to the highlands, N. distinctus is not restricted to the lowlands.

"Sumatra has two allopatric montane Nicrophorus species". This would be N. insularis and N. hersheli. Nicrophorus hersheli is one of the two species for which I desperately need fresh tissue sample from. It is interesting that the authors state that the two species are allopatric. What barriers on the large island of Sumatra could have caused this allopatry, if it is not one of elevational distribution (and looking at locality data I don't believe it is). I know Sumatra has had a history of partial and full submergence due to sea levels rising and falling in glacial periods, perhaps this had something to due with their ranges?

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