Why Have Collections?
Why collect specimens and not just take pictures? While photographs hold a great deal of information about animals, they provide only a glimpse of what is gained by preserving a whole specimen. Museums strive to safeguard as much information about each individual specimen as possible -- which includes taking photographs.
Historically, specimens were preserved primarily as dried skins, skulls and skeletons, or in formalin and stored in ethanol. However, many of the ways of describing diversity were not even imagined when the museum started in 1908. For this reason, we now try to preserve much more of the animal whenever we collect a specimen. This includes soft tissues for studies of DNA and proteins, as well as anatomical parts, parasites, and stomach contents.
Besides documenting presence, we use the collections to describe diversity at many different levels. Having specimens in hand allows researchers to compare the morphology, stomach contents, stable isotopes (a chemical view of diet and geographic origin), parasite levels and molecular differences, among many other disciplines of science. Few of these kinds of studies are possible with live animals.
Implicit in the documentation of diversity is the correct identification of species. Some species are quite obvious, but even in California we are still documenting species well outside their commonly recognized range. And certain groups, like shrews, are very difficult to identify without close examination of their skulls and molecular sequences. Likewise, some animals hybridize in nature and one tool might suggest an animal is one species, whereas another tool might suggest it belongs to another! Holding the specimens allows us to recheck identifications later. This is the concept of the voucher specimen. The voucher documents an animal at a specific place and time, thus allowing researchers to re-examine the specimen if results from a study lead to questions about its identification. This would not be possible if the animal were released.
A striking finding from the last few years is that there is much more diversity in some animals than expected. Much of this diversity is easily overlooked, and is ascertained only by sequencing of DNA or looking at small bones or phalli. The result is that new species are being discovered, not just in less-studied areas such as the tropics but also in places like California. Take, for example, the 20 species of slender salamander (genus Batrachoseps) illustrated in the 2003 Peterson field guide to western reptiles and amphibians, compared to one in the 1985 edition! These discoveries would have been overlooked if we only had photographs.
Another important reason for collections is that they allow researchers to assess how populations, species, or communities of animals have changed over time. Some of our collections have excellent historical series from certain areas, and thus are very good representatives of past communities. We can revisit those areas to see if the same species still exist in the same places, take photographs to document changes in habitat, and compare historical and current information on morphology, genetics, and diet, among other traits. By making new collections, we can compare modern with historical records and set a baseline for future studies, the kinds of which may be unknown to us today.To read more on the Value of Natural History Museums, we have a Zotero Library of articles for sharing.