Welcome

The Smith­son­ian Con­ser­va­tion Biol­ogy Insti­tute (SCBI) has been a leader in black-​footed fer­ret con­ser­va­tion since a small pop­u­la­tion of this soli­tary, noc­tur­nal car­ni­vore was dis­cov­ered in 1981. SCBI received off­spring from the species’ sur­viv­ing 18 indi­vid­u­als and was the first insti­tu­tion to breed black-​footed fer­rets out­side of Wyoming. Faced with a genetic bot­tle­neck, SCBI sci­en­tists mit­i­gated threats to the sur­vival of the species by using semen that had been cry­op­re­served for 10 to 20 years to arti­fi­cially insem­i­nate live female ferrets.

The SCBI team, includ­ing David Wildt, Paul Mari­nari and JoGayle Howard, as well as part­ners from U.S. Fish and Wildlife Ser­vice (USFWS), Lin­coln Park Zoo, Louisville Zoo­log­i­cal Gar­den, Cheyenne Moun­tain Zoo, Phoenix Zoo and Toronto Zoo, found they could meet the need to increase the num­ber of black-​footed fer­rets born in human care while enhanc­ing genetic diver­sity within the species. The results of their work was pub­lished on 13 August in the jour­nal Ani­mal Conservation.

“Our study is the first to pro­vide empir­i­cal evi­dence that arti­fi­cial insem­i­na­tion with long-​stored sper­ma­to­zoa is not only pos­si­ble but also ben­e­fi­cial to the genetic diver­sity of an endan­gered species,” added Wildt.

The black-​footed fer­ret (Mustela nigripes) is listed as Endan­gered accord­ing the IUCN Red List of Threat­ened Species™. USFWS devel­oped and over­sees the Black-​Footed Fer­ret Recov­ery Pro­gram. The Asso­ci­a­tion of Zoos and Aquar­i­ums’ Species Sur­vival Plan man­ages the black-​footed fer­ret breed­ing pro­gram at ex situ facil­i­ties, such as zoos and breed­ing cen­tres, with a breed­ing pop­u­la­tion com­posed of about 300 ani­mals. For this study, all the males were man­aged either at SCBI or at the USFWS National Black-​Footed Fer­ret Con­ser­va­tion Cen­ter. Sci­en­tists col­lected semen sam­ples from adult black-​footed fer­rets that ranged in age from 1 to 6 years old. All females were solely man­aged at SCBI.

Ini­tially, sci­en­tists used fresh semen to arti­fi­cially insem­i­nate females who failed to nat­u­rally mate with males, result­ing in 135 kits. With just a few founders to rebuild an entire species, early man­agers of the black-​footed fer­ret recov­ery pro­gram knew that genetic diver­sity would be lost. Loss of genetic vari­a­tion can lead to increased sperm mal­for­ma­tion and lower suc­cess of preg­nancy over time. Researchers, led by black-​footed fer­ret Repro­duc­tion Advi­sor Rachel San­tymire of the Lin­coln Park Zoo, rou­tinely col­lected and pre­served black-​footed fer­ret semen for later use as part of stan­dard oper­at­ing procedures.

SCBI main­tains the only genome resource bank for black-​footed fer­rets that pre­serves frozen semen from genet­i­cally valu­able males, thereby extend­ing their repro­duc­tive life. Zoo sci­en­tists use this semen for arti­fi­cial insem­i­na­tion (AI) to main­tain and enhance genetic diver­sity by infus­ing under-​represented genes into the pop­u­la­tion at strate­gic times.

SCBI was the first insti­tu­tion to develop a suc­cess­ful laparo­scopic AI tech­nique for black-​footed fer­rets. Female fer­rets are induced ovu­la­tors, which means that mat­ing causes the ovary to release its eggs. SCBI researchers devel­oped a hor­mone treat­ment that arti­fi­cially causes ovu­la­tion to occur. Sci­en­tists then deposited the male’s fresh or frozen-​thawed sperm directly into the female’s uterus. Ani­mal care staff closely mon­i­tored poten­tially preg­nant females by tak­ing weight mea­sure­ments and remotely mon­i­tor­ing the nest boxes via closed-​circuit cameras.

Dur­ing the 2008 breed­ing sea­son, SCBI sci­en­tists used semen sam­ples from four male black-​footed fer­ret donors that had been frozen for 10 years. Black-​footed fer­ret Pop­u­la­tion Advi­sor Colleen Lynch of River­banks Zoo and Gar­den con­ducted pop­u­la­tion genetic analy­sis to select pair­ings of deceased sperm donors with liv­ing females based on sev­eral genetic met­rics, includ­ing mean kin­ship of the par­ents and inbreed­ing coef­fi­cients of poten­tial off­spring to max­i­mize the genetic ben­e­fit of suc­cess­ful pair­ings. Two became preg­nant and gave birth to two kits. In the years that fol­lowed, sub­se­quent AIs incor­po­rated semen that had been cry­op­re­served up to 20 years, also result­ing in suc­cess­ful preg­nan­cies. Six of the eight kits pro­duced 32 off­spring and grand off­spring by nat­ural mat­ing. More sig­nif­i­cantly, researchers found that incor­po­rat­ing these indi­vid­u­als into the pop­u­la­tion enhanced over­all genetic diver­sity and low­ered mea­sures of inbreed­ing over time.

Black footed fer­ret kits sum­mer 2015:

“Our find­ings show how impor­tant it is to bank sperm and other bio­ma­te­ri­als from rare and endan­gered ani­mal species over time,” said Paul Mari­nari, senior cura­tor at SCBI. “These ‘snap­shots’ of bio­di­ver­sity could be invalu­able to future ani­mal con­ser­va­tion efforts, which is why we must make every effort to col­lect, store and study these mate­ri­als now.”

(Source: Smith­son­ian National Zoo­log­i­cal Park press release, 13.08.2015)