Welcome to the 'Adventures in Collections' field guide
Are you curious about natural history collections? Then you have come to the right place. Museum collections hold a treasure trove of biodiversity information, and scientists are just now beginning to uncover their evolutionary secrets through specialized techniques. I invite you to explore the ins and outs of museum science with me as I strive to breathe new life into historical specimens during my graduate research.
Here we go!
Here we go!
Defining collections
Natural history
"The direct observation and interpretation of the natural world." – Chris Lay, Curator of the Kenneth S. Norris Center for Natural History, UC Santa Cruz
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Natural history museum
An institution providing natural history exhibits for the public, a home to collections, and a place of research for resident and visiting scientists.
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Museum collection
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An assemblage or archive of objects that are often used for research, exhibition, or education. Collections are traditionally housed in large cabinets off the public floor and organized and maintained by museum curators, staff, and students.
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Specimen
A preserved animal, plant, alga, microbial sample, fossil, mineral, cultural artifact, artwork...
In a natural history collection the possibilities are vast – from mammal skins to pinned insects to frozen tissue samples used for genetic analyses to historical shark tooth weapons from the Gilbert Islands! 
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Photo credit: Drew J, Philipp C, Westneat MW (2013) Shark Tooth Weapons from the 19th Century Reflect Shifting Baselines in Central Pacific Predator Assemblies. PLoS ONE 8(4): e59855. doi:10.1371/journal.pone.0059855
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Why specimens?
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There are an estimated 1 BILLION specimens in North American museum collections alone and 3 BILLION specimens worldwide (iDigBio.org)
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Where did all those specimens come from? Why are they necessary?
Inside collections
Shelf Life – Science Collections For Curious Minds
American Museum of Natural History
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Pickle jars and precious specimens in the Spirit Collection
Natural History Museum London
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How specimens are organized...
Adventures in photographing small mammal skulls
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As part of my graduate research I have begun to investigate morphological variation and pelage color in an African small mammal – the four-toed sengi (Petrodromus tetradactylus).
Sengis are small insectivores endemic to Africa, commonly referred to as 'elephant shrews' due to their long flexible noses and shrew-like appearance. However, sengis are members of the mammalian radiation Afrotheria – an amazing evolutionary lineage that diverged from other mammals approximately 100 million years ago. Other members of Afrotheria include elephants, manatees, hyraxes, aardvarks, golden moles, and tenrecs. There are 19 currently recognized species of sengi including P. tetradactylus, of which there are 10 subspecies. Variations in morphology, coloration, and tail bristles are apparent among P. tetradactylus specimens that were collected across the range, and we can use these specimens to answer some basic but important questions about P. tetradactylus ecology and evolution: 1. Are phenotypic traits correlated with environmental variables (e.g., tree cover, temperature, precipitation)? 2. Do variations in traits coincide with the way subspecies are currently delimited or divided up? How does this compare to genetic variation across the range? 3. Is P. tetradactylus still best described as a single species, or should some subspecies be elevated to full species status? And how will this affect their conservation? |
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So how does one go about quantifying morphological variation in small mammal skulls?
** It is important to recognize from the start that certain types of traits, primarily external traits (e.g., body mass, head-body length, tail length, etc.), change when an animal is prepared as a specimen. These traits are usually recorded at the time of capture and can be used directly for analysis, with caution.
I. Taking skull measurements with calipers:
Measurements can be taken directly with digital calipers. I found this to be a helpful approach when first becoming familiar with the traits I had chosen to focus on. However, it can be difficult to repeat measurements on very small skulls, and care must be taken not to damage them – small mammal bones are indeed small and fragile.
II. Going the geometric morphometrics route with photography:
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Materials checklist:
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Setting things up and getting a decent photo...
More soon!
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Suggested camera settings
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