32. May, R.M. 1978. The dynamics and diversity of insect faunas. Pages 188–204
in L.A. Mound and N. Waloff, eds., Diversity of insect faunas. Royal Entomological
Society of London Symposium 9. Blackwell Scientific, Oxford.
Blog Author: Ben Clinch
Blurb Author: Allen H. Hurlbert
-Associate Professor, University of North Carolina at Chapel Hill
-B.A., Amherst College
-Ph.D., University of New Mexico
-Research interests in macroecology, avian richness and community structure, phenological mismatch between birds and bugs, eco-evolutionary models of diversification.
-“In the Hurlbert Lab we ask questions about the structure of ecological communities, and the processes that are responsible for determining the patterns of diversity, composition, turnover and relative abundance both within local assemblages and across the globe. Our work spans vertebrate, invertebrate, and plant communities, and we use a variety of approaches from manipulative experiments to modeling to working with global scale datasets.”
Paper Author: Robert M. May
-B.S., University of Sydney, Chemical Engineering and Theoretical Physics
-Ph.D., Theoretical Physics
-Appointed Knight Bachelor, 1996
-Companion of the Order of Australia, 1998
-Order of Merit, 2002
-Tons of other awards on Wikipedia
-Early in career, developed interests in animal population dynamics and the relationship between complexity and stability in natural communites.
Main Question: Why are so many of all species insects?
-Background:Insects account for around 50-60% of currently denumerated species, close to 90% of terrestrial animal species. It’s been debated that the relative diversity of insects is attributed to their small size, allowing them to carve out smaller niches.
-Assumptions:Competitive exclusion principle- that make their livings in identical ways cannot coexist. In the Preston-MacArthur-Wilson species-area relation: (1) assuming a particular distribution of species relative abundance, which gives a relationship between total number of individuals and number of species (2) assuming that total number is linearly proportional to area.
Methods:
-Two parts. 1- review different dynamical and evolutionary factors that influence species diversity, determine how that factor favors insects. 2- determine empirical relationship between species number and their size.
-Review various meta-data surrounding the species-size relationship
Results:
-Invertebrate genomes are 15% heterozygous, 5% for vertebrates
-Insects show no differences from vertebrates in the Dyar-Hutchinson rule
-British Coleoptera and terrestrial mammals share a similar species-size graph shape
-Fig. 12.7- crude figure that depicts species number of all terrestrial animals, classified by length
Conclusions:
-Insect size allows them higher intrinsic population growth, r. Thus, they can escape predators by adopting a ‘fugitive’ style
-The ‘switching’ style of predation allows for the coexistence of similar species
-Species-size relation only observes statistical generalities, not ecological aspects of species’ size
-Most of the factors in part 1 were found to not favor insects’ relative diversity. May thinks that most of the reason for insects’ relative diversity comes down to their small size, allowing them to subdivide an environment more finely.
-Unclear whether there are systematic differences in sizes between tropical and temperate insects
-Fig. 12.7 shows a right skewed stair-step graph for the species-size relationship for all terrestrial animals. May asserts that it is a tentative figure due to its crude approximations, and should be pursued further.
Comments/Questions:
-I wished he had included figures to illustrate some of the ideas he threw out there in the first part.
-Funny he referred to large mammals and birds as ‘aesthetically appealing’
-If I didn’t know the implications of the paper I would’ve called it anti-climactic, but it’s pretty impressive that May provided the first representation of the right-skewed richness-size relationship that we looked at in previous papers.
I agree with Ben, some figures and even some more detail would have helped make the first part of the paper more clear. I think that first part is a good review of broad themes in biodiversity, but I´m not sure the evidence is strong enough to rule out all those potential explanations.For example, in the food web section, there is no mention of the relation of insects and Angiosperms and the effect this could have on diversification.
ReplyDeleteThe first part of the paper gave me the feeling that he is trying to summarize and review the theories related to the topic. So maybe that's why he thinks figures are not necessary...? I'm having a hard time understanding 1.4: Food Web Structure. Hoping the discussion will help clear things up.
ReplyDeleteI never thought about the reasons for insect diversity in the sense of predation. A lot of animals prey on them which can trigger competition in survival methods and increase the rate of speciation and diversification. I think insects are fascinating because they are not like many other organisms due to their size, short generations and high dispersal ability.
ReplyDeleteI enjoyed this paper because it is the author's thought process put on paper. May goes over what was known at the time about many different relationships, and gives many ideas for future research. He also includes some nuggets of humor ("I did this more for entertainment than from any sense of conviction", heehee). Although this paper doesn't answer any questions, I agree with the author that being left without answers isn't necessarily a bad thing. The body size trend he highlights - that most species in any category (beetle, bird, mammal) are towards the smaller side of intermediate body size - isn't particularly surprising.
ReplyDeleteIt would be very interesting to see insect parameters compared with plant characters and ecology. Insects are also one of the main indicators for ecological changes, habitat type, climate change, vector ecology and many more. Understanding the complete categorized relative species diversity is crucial to conservation and ecological research. Especially, insects play a general role in disease ecology. The insect body size correlation is a true macroecological pattern defines their geographical distribution. This is an interesting paper.
ReplyDeleteOne main interesting point to me is that between 1978 and 2006, the amount of insect species globally is still estimated. I also appreciate the author's being upfront about some aspects of figures or size bins being crude partitions and of no direct answer from these results.
ReplyDeleteI enjoy the focus of this paper. Instead of asking "why so many?", they dive deeper and ask "why so many more kinds?". It shows how a small change can spark a world of curiosity. This paper points back to a lot of things pointed out in previous reads, such as animal size to range. It also backs up things that just "make sense" when you think about it, but isn't thought of often, such as bugs have such short life spans that their mortality rates are very high. The graphs do a great jobs of supporting the data finds and when the author explains errors on the project, some good points are brought up that never initially struck me as problematic. Overall good read! I really liked how simple this one was to read. It felt more like an overly talkative friend than a science paper.
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