Importance of Natural Resources

From the Leaf-litter to the Canopy: Unraveling Insect Diversity and Evolution


Good morning, my name is Bonnie
Blaimer, I’m now in my third year as a post-doc here working with Seán
Brady and Ted Schultz in the Entomology Department and the
title of my talk today is “From the Leaf-litter to the Canopy: Unraveling
Insect Diversity and Evolution with Field Surveys and Phylogenomics.” So I study insects because they’re
truly are an invisible majority in all terrestrial ecosystems. About 900,000 to a million species
of insects have been described. This is more than 50% of all
eukaryotic organisms living on earth. But extrapolations actually say that
this number might be a gross estimate so we truly … know very little
still about insect diversity. Unfortunately a lot of this unknown
diversity is already disappearing mainly through habitat destruction
such as in countries that I’ve recently worked in, Madagascar and Myanmar. So as many people here in this room
would agree I see it as part of my mission to sort of preserve
unknown biodiversity before it is lost. So within the insects my favorite
groups are the Hymenoptera which are the ants, bees, and wasps. And most of my research currently focuses
on the ants which account for about 10% of the Hymenoptera. Ants are very successful group. They occur in all terrestrial habitats
from the deserts to the rainforests and within forest habitats we
can usually divide ants up in three distinct layers: the soil,
the leaf litter and the canopy. So I have become especially
interested in the forest canopy as the distinct habitat layer for ants. And this really a still unexplored
habitat and I started to asses and compare arboreal ant diversity
with the leaf litter ant diversity. Most of this field research happens
in Madagascar where I collect arboreal ants while climbing trees and then I take these ants back
to the lab and further look at the diversity and structure
of these communities. So one of the questions that particularly
interests me within this research is whether in the evolution of ants
the canopy habitat or the leaf litter habitat was colonized first by ants. So within a recent project we
actually traced the evolution of arboreal lifestyle in ants using
Madagascar as an example. So we reconstructed this phylogeny
showing us relatedness for about 300 Malagasy ant species and then using models we could then
reconstruct the evolution of his habitat trait. And what we found was that actually
most Malagasy ants have started out living on the ground and then
consecutively colonized the canopy habitats. Now very recently I’ve also had
the opportunity to get involved in investigating insect biodiversity in
yet another very poorly explored region, the Tanintharyi
region in Myanmar. Here I was part of a Smithsonian
team assessing insect diversity in general, so not just
ants or the canopy and here we had the main goal
to inform conservation decisions and habitat monitoring in Myanmar. But also we wanted to preserve
samples and build resources for future research both in our morphological
collection here at NHB and in our genomic tissue libraries in
the biorepository out at MSC. Now moving away from these field
surveys now, I would like to give you a brief inside into the other part of my
research life when I’m not a field biologist. Here I’m actually using phylogenomic
techniques to study insect biodiversity on the molecular level. Phylogenomics can be understood
as genome-wide targeted DNA sequencing for systematic purposes and here we currently target
a group of markers called “ultraconserved elements”
in ants but also in bees. And I just want to here single out
one project that we recently started on the evolution of Carpenter bees. Carpenter bees are large bumblebee-like
bees but can become economically important because they are
wood boring as their name implies. So what’s particularly interesting
about this project is that we’ve been successful in gathering data from
very old specimens that have been sitting in our collection
for up to 120 years. So there is a negative correlation
with age and DNA quality as shown here in the lower graph and with
age and DNA sequence capture rate shown here in the upper graph. But the bottom line, the main point
here, is that we’re still getting a lot of data from these very old specimens. So to me this project is sort of a
perfect example of why our natural history collections are so valuable. For this project we’re able to
entirely rely on our very own NMNH collections for these bees. We have about 200 species lined up
for this project and now we don’t have to go out painstakingly recollect or acquire samples
from other collaborators. So to briefly summarize I’ve shown
you some examples of my projects that aim to preserve biodiversity by
building our natural history collections, both on the specimen and on the
genetic level through field surveys mostly in understudied habitats. And then … also how I use these
novel and the historic museum collections to investigate and study the
history of this biodiversity for example with new
phylogenomic methods. Thank you very much and of course
I haven’t done all this research by myself and here some people
that I like to acknowledge for these projects and
also some funding sources. [ applause ] Given that you’ve shown that DNA
is degrading in the museum specimens through time, do you think that there
is anything that we should do or could do to preserve our traditional
collections better as a genetic resource. Yeah, I mean definitely. First of all I should say,
what I didn’t mention is that these bees were pinned. They
were not in alcohol, stored in ethanol. So if you collect straight into
ethanol that’s great and of course liquid nitrogen would be the top quality but that’s not
really possible in remote field settings, so 95% ethanol would be great. But these were all pinned so they
have just been dried for 125 years. Bonnie, you talk about Carpenter bees
and I’m interested in the controlling their behavior specifically getting
them out of my garage … [ laughter ] but I don’t want to kill them, so
what should we do and what’s, do you have any
recommendations? Um …
[ more laughter ] That’s kind of the wrong question
for me because I’m actually not a bee expert, but an ant expert and I don’t know too much
about pest control in general. Okay, fair enough.
[ laughter continues ] Does anyone have an
answer to that question? Maybe fumigation or
maybe smoking them out. Oh, okay. That’s a good
idea, we’ll try that. Thanks. So, so the work, the DNA work you
did with the, with these specimens, how did you sample the pinned
specimens, did you take a leg or something like that? Ah, yeah, I just took a leg. [ Okay ] … so actually the point that I was
trying to get at is that in our traditional specimens we now know we
have many examples that … there is a significant amounts of DNA
preserved and yet it is degrading on a decadal time scale. And so if we feel that these are
important genetic resources and as stewards of the national collections
I think that there are things we can do in many different parts of our
collections to preserve the DNA. An example in insects would be
or particularly important specimens say for example the types, of many
insects you could just go ahead and take a leg now, photograph it and
put it in liquid nitrogen so that the DNA preservation is … is stopped, you know
the DNA degradation is stopped at this point. Does that make sense? Yeah, that makes sense. That’s
actually, I mean that’s really a good idea. I think ideally if we go on sampling
now, we would have two specimens. One as a voucher that we preserve
for genetic purposes and one as a pinned morphological voucher, right,
but in the case where we just have one single specimen, yeah,
that would be a good idea, I think. Absolutely. Especially for insects, we always
have 6 legs and the 2 sides are the same so we can lose 3 legs
basically and we’ll still have all the morphological characters. Yeah, I mean we clearly, we can
think about how to collect better going forward but for the historical material,
we can think about how to do a better job of preserving
the information content. I was just wondering how the
Carpenter bees were collected to begin with. Whether they were
collected in ethyl acetate or cyanide, maybe that also makes a
difference in regards That’s really hard …
[ … to beetles ]. sorry, I don’t want to
cut off your question. Ah, that’s really hard to say because
they’ve been collected from such a long time ago and they have very
little information on the pin, right, so we don’t know how they
were originally collected. So with some samples that were
very old we get good data from them and some of them of the same
age, we don’t. So there must have been some variation in how
they were collected originally.


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