Scientific Biological Collection

DISCLAIMER: Opinion Piece, not a peer reviewed paper.

Quote from Save The Frogs facebook page:

I am told there are over 200,000 dead frogs in Colombian museums, and that at least that many frogs were exported to museums in other countries. I hope the days of mass collections are over.

This saddens me. Not that there are 400K dead frogs from Columbia, but that the person who runs that organization, a Ph.D. in biological sciences, does not understand the value of scientific collection.

I tried to reason with him and he just does not get it. The guy has a doctorate, how does he get a doctorate and not grok this? Seriously.

First of all, while the total number may be huge, it is very rare for more than 50 specimens to be collected from a single site, and usually it is more in the order of 20 or so. When large numbers (like 50) are collected, a good many of them are juveniles or tadpoles that would never have reached sexual maturity and been recruited into the adult population. So immediate impact on the population is very minimal, and the long term impact probably isn’t even measurable.

However there is great value in collection of specimens. Collection of specimens allows scientists to better understand the natural history of the species. What the frog eats, typical weight of the frog, pattern variations in the species, common diseases the species had at the time of collection, and ratio of male to female. Many of those things simply can not accurately determined without specimen collection.

Specimen collection for scientific purposes simply does not contribute to the decline of a species. Sure, if someone went up to my Cascades Frog spot that I know about and collected 30 adult specimens, it probably would do it in. That spot however is only vulnerable to extinction from specimen collection because it is already headed for extinction and probably will be extinct within a decade anyway. Populations that can not withstand scientific collection are doomed as it is without help. That’s just the unfortunate reality. If that population was healthy, there would be at least 500 adults living there (probably 50 right now) as well as large numbers in neighboring habitats (probably 0 right now).

Declines are caused by (in no particular order) over-harvesting for food (where thousands are collected yearly), alterations of the watershed (natural or human-caused), introduction of species that out-compete them (natural or human-caused), diseases they are not resilient too, pesticides, and general habitat degradation. Collecting a series for scientific study really has no impact on their decline.

One of the most basic fundamental concepts of biology is survival of the fittest. Survival of the fittest only works when species over-produce. Basically, more young are produced than are needed to replace the adults in a population when the adults die. Unless the species has just arrived in an area, there almost always are far more young produced than the habitat can support. This is especially true with frogs, most frogs are prey species, producing hundreds or even thousands of offspring per breeding adult female per year.

Many of the offspring are consumed by predators. That’s part of the natural cycle, circle of life stuff. Many disperse. Dispersal is where they move from the population they were born in and look for a new place to live. This is how genes flow between populations. A small number of the offspring grow up to join the adult population. The biological term for that is recruitment.

When specimens are collected for scientific study, adults that were collected from a population allow more room for offspring to join the adult population. If a population can not withstand scientific collection then it also can not withstand a drought or a particularly cold winter.

With the Mountain Yellow-legged Frog complex, there are some lakes in the Sierra’s where a particularly bad winter results in every single adult member of the population dying over winter, leaving only tadpoles as survivors. In Contra Costa County during particularly dry winters, I have found desiccated adult California Red-legged Frogs under logs where they were over-wintering, got too dry, and died.

Evolution designed these species to be able to withstand far greater death rates than what happens with scientific collection. Scientific collection simply does not cause or contribute to the extinction of a population.

There are however many advantages not only to scientific collection, but taking a decent sized series (20 to 30 or even more) during that collection.

First of all, a lot can be determined about the natural history of the species. Typical size and weight, stomach contents, sexual dimorphism characteristics, and even what diseases the species lives with.

If specimens of Species A show evidence of a disease in specimens collected in the 90s that is not present in specimens collected in the 70s then we know the disease probably was not present in the 70s and may be a contributing factor to a decline in Species A. Changes in stomach contents can indicate that something is out of whack resulting in dietary change. For example, the introduction of sport fish may alter the availability of some insect prey. The frog may have to travel further from the water to find food, increasing its exposure to predation and contributing to decline.

But there’s another benefit as well.

The Vegas Valley Leopard Frog (Lithobates [=Rana] fisheri) was thought to have gone extinct in 1942. At one point it was abundant in the Las Vegas Valley but another species, (Homo sapiens) thought it would be a fantastically bright idea to build a water thirsty metropolis in the middle of a fricken desert. We capped the natural springs in the Vegas Valley resulting in the extinction of the frog.

Numerous specimens though had been collected for scientific study, including 10 specimens from Tule Springs on January 13, 1942 that were the last recorded specimens of this species.

If science had not collected a single specimen, the frogs in the Vegas Valley would have still gone extinct. Capping the natural springs is what caused the demise of this once extremely common frog. Scientific collection however did allow us to study the frog even after it was extinct, which led to the discovery that a population of frogs in Arizona is the same species. We would never know if it were not for scientific collection, and now the possibility exists that we can restore habitat in the Vegas Valley and possibly re-introduce the frog.

For many years, many scientists though the Vegas Valley Leopard Frog was possibly a subspecies of the Relict Leopard Frog (Lithobates [=Rana] onca), see Stebbins 1985 for example. But we now know that is not the case, and were it not for the scientific collection that took place when this species was still in the Vegas Valley, the lack of data to examine may still have us in the dark.

The Oregon Spotted Frog (Rana pretiosa) and the Columbian Spotted Frog (Rana luteiventris), until somewhat recently it was believed they were the same species. However examination of museum specimens played a large role in determining that in fact they are two distinct species, and knowing that they are two distinct species allowed us to understand that one member of that complex, the Oregon Spotted Frog, is in serious trouble and in desperate need of recovery.

Scientific collection does not contribute to declines and in fact aids in conservation.

I don’t understand how this is a concept that escapes someone with a Ph.D. in biology. I really don’t.

I like the work that savethefrogs.com does, I really do, but they need to address real issues, not non-existent issues.

Alice Out.