Deciding Which

Feral Horse

Populations

Qualify as a

Genetic Resource

By: D. P. Sponenberg

Virginia-Maryland Regional

College of Veterinary Medicine,

VirginiaTech

The third in a series of 13,

Session 1

Background

BLM managers responsible for

feral horses are confronted by

a host of divergent expectations and demands from a

number of constituent groups.

This makes decision-making

for feral horse management

contentious and adversarial at

times. Many factors are

important for feral horse management, including human

societal, environmental, and a

variety of equine factors. One

of these factors is the status

(or not) of a given herd as a

genetic resource.

Only a few feral herds qualify

as genetic resources that are

unique and irreplaceable. The

rationale and mechanism for

designating them as such is

important, because the management for those few herds

should be tailored to accomodate conservation of the

genetic resource as a fundamental goal.

Discussion

Feral horses in the US originate from a wide variety of

breeds and types of horses.

Most populations are influenced by several breeds, each

of which has been common at

some point in the US after

European contact. These composite populations vary from

one to the other, but generally

represent horse types that are

well represented in domesticated, managed horse herds. Such

herds could easily be reconstituted from the resources in

domesticated situations in the

eventuality that the ferals

descending from them become

rare, extinct, or suffer from

inbreeding. Since the domesticated populations of these

breeds are large and readily

accessible there is no need for

programs specifically targeting

the conservation of feral herds,

descended from them, as

genetic resources.

A very few feral populations

remain that descend from types

and breeds now otherwise rare

or extinct, mainly the Colonial

Spanish type. These few populations (Cerbat, Sulphur, Pryor,

Kiger, perhaps others) are

genetic resources of significance

to horse biodiversity and warrant special consideration for

conservation and management

as unique resources. The North

American Colonial Spanish

breed type is otherwise very rare

globally, and only a small reservoir exists in domestication.

The few qualifying feral herds

are therefore an important component of equine biodiversity.

The analysis of candidate

horse populations as to their

status as genetic resources

with a conservation priority

can be straightforward and relatively simple. A first analysis

is simply a visual phenotypic

appraisal by several people

familiar with different types

and breeds of horses, and

specifically with the Colonial

Spanish type. A second, and

usually concurrent, analysis is

the history of the region and the

horses as to foundation types

and introductions. History must

be evaluated carefully, since

neutral observers are rarely the

case and detractors will consistently insist on numerous

recent introductions, while

supporters will favor a pristine

and isolated history. Neither

extreme may be accurate, and the

historical and visual assessments

must therefore go hand-in-hand.

Few populations survive this level

of scrutiny, and can then be

subjected to analysis of bloodtypes or DNA. This last level

is expensive in time and

resources, and need only be

accomplished for candidate

populations that are indeed

likely to be unique genetic

resources.

Conclusion

While breed origin makes some

populations unique, all feral

horses persist in environments

in which natural selection is the

major selection pressure. This

RESOURCE NOTES

NO. 25 DATE 07/19/00

Range

Wild Horse andBurro Program
selection environment is unique

among equine environments,

and its role in shaping the

genetic composition of the

herds is important as a biological process. While it shapes all

populations, its role in shaping

those that are unique by virtue

of founder type is especially

worth consideration since this

phenomenon is an ongoing, if

unplanned, experiment that

cannot be duplicated should

these populations become

extinct.

Contact 

D.Phillip Sponenberg, DVM,

PhD, Professor, Pathology and

Genetics, Virginia-Maryland

Regional College of Veterinary

Medicine, Virginia Tech

Blacksburg, VA 24061

phone 540-231-4805

fax 540-231-7367

e-mail: dpsponen@vt.edu

Range

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