Brett Roper column mug

Brett Roper

There are many ways in which groups of animals are defined. The most widespread is the concept of species. The term “species” is Latin for kind or appearance. A common definition for species, used by scientist and the public alike, comes from Ernst Mayr. He stated that “species are groups of interbreeding natural populations that are reproductively isolated from other such groups.”

Why should hunters or anglers care what they call a group of similar animals? The simplest reason is that it is the basis for most state set harvest limits and seasons. The presence of species also provides the motivation behind bucket lists of fish and wildlife you would like to pursue in your lifetime. Hopefully, part of being an outdoor enthusiast involves a natural curiosity to learn more about a species’ history and habitats. For example I find it curious that there are four spots in the big game record books for two species; brown/grizzly bear and mule/black-tailed deer.

These two bears have the same scientific name, Ursus arctos. Historically the record books separated these bears using an imaginary line that was 75 miles inland from the Alaskan coast. The rational for using distance from the ocean was it implied that because brown bears had greater access to food resources such as salmon, they were bigger. In this case the potential difference in the animal’s sizes, even though they were not geographically isolated, drove these animals being separated in the record book.

Mule deer and black-tailed deer are both Odocoileus hemionus. The processes that lead to the separation of these groups of animals were the presence of glaciers that kept these animals from interbreeding for several millennia. Boone and Crocket’s record book splits the two groups using a line that is approximately 200 miles inland from the Pacific Ocean. They continue to use this geographic line even though there are now genetic tests that can determine if an animal is a black-tailed deer, a mule deer or a hybrid.

With distributions similar to mule and black-tailed deer, dusky and sooty grouse used to be considered a single species — the blue grouse. They are reproductively isolated as sooty grouse are found in the Cascade Mountain Range while dusky grouse occurs in the Rocky Mountains. Since these deer and grouse naturally reproduce and are isolated from one another, you would think they would be treated same. That they are not shows the inconsistency of the scientist, not science. Charles Darwin foresaw these issues when he wrote “Hence, in determining whether a form should be ranked as a species or a variety, the opinion of naturalists having sound judgement and wide experience seems the only guide to follow.”

The concept of species is even more difficult to understand when applied to fish — especially trout. The simplest example is the Idaho record books have a category for rainbow trout and steelhead, even though they are the same species. The only difference is steelhead make a trip to the ocean — they’re anadromous — while the rainbow trout do not. To make this even more confusing, in the Great Lakes they have introduced steelhead, but they migrate to lakes — they’re adfluvial — rather than to the ocean.

Cutthroat are interesting in that there are a 14 recognized subspecies. If you catch a cutthroat trout in the Logan River it is a Bonneville, in Northern Idaho they’re westslope and near the Oregon coast they’re coastal. Based on genetic data, however, the number of justifiable cutthroat subspecies — or species — likely exceeds twenty. This should not be surprising given the variation in the geologic history of watersheds across the west.

This is made even more confusing given the long history of stocking cutthroat trout subspecies outside their native range. The failure to recognize where fish were stocked has had costly consequences to recovery efforts made for greenback cutthroat trout as some fish thought to be this subspecies were not.

So with all this confusion, what’s in a name? I think there is a lot. As the rationale behind naming species has changed through time and with taxa, it should reminded us that groups of animals are shaped by the landscape in which they are found. Additionally many important aspects of a species, such as size and color, can change from place to place. Knowing this provides an incentive to protect local groups of animal even if they aren’t species.

{span style=”font-family: tahoma, arial, helvetica, sans-serif;”}{span style=”font-size: 12px;”}Brett Roper is a fisheries biologist for the Forest Service. When not working or with his family you are likely to run into him anywhere — as long as it is outdoors. He can be contacted at roperguth@gmail.com.{/span}{/span}

Brett Roper is a fisheries biologist for the Forest Service. When not working or with his family you are likely to run into him anywhere — as long as it is outdoors. He can be contacted at roperguth@gmail.com.