breed conservation - discover
Post on 20-Jan-2016
28 Views
Preview:
DESCRIPTION
TRANSCRIPT
breed conservation - discover
D. PHILLIP SPONENBERG, DVM, PHD
VIRGINIA-MARYLAND REGIONALCOLLEGE OF VETERINARY MEDICINE
VIRGINIA TECH, BLACKSBURG, VA
AND - THE AMERICAN LIVESTOCKBREEDS CONSERVANCY
steps in conservation
ALBC uses these steps in conservationdiscover (encounter and define)secure the populationsustain for the long term
all three steps are needed to assure success in the survival of breeds
discover
The first step is to discover these rare breeds and populations
the USA has a good informal network with an interest in the conservation of these resources
discover
this network usually indicates the existence of a population that is a candidate for conservation
usually this network commits “errors of inclusion” rather than “errors of exclusion” which helps to alert conservationists
misses relatively few breeds from consideration
always better to commit “errors of inclusion” because this indicates that the network is unlikely to ignore a population that truly merits conservation
discover
part of the “discover” step is defining breeds and populations
define
define
ALBC uses this definition of “breed”a group of animals with a phenotype that is distinct and recognizable, and that produces this type after being mated within the population
this definition is based in genetics, and establishes the breeds as genetic resources
implies a certain level of genetic uniformity and predictability
this definition of breeds ignores populations with high levels of variability, even if some of these do have cultural importance
goal is the conservation of genetic resources that can be predictable as they serve agriculture
define
classes of breeds
local – landrace – adapted- rustic
standardized
industrial
feral
classes of breeds
each class of breeds needs its own appropriate strategy for effective conservation
industrial
little or nothing possible for their conservationimpossible to duplicate the physical and
selection environment in which these animals live
high risk that some will go extinct
standardized breeds have breed associations for their breeders
standardized breeds are usually well definedconservation of these is easier than the othersimportant to maintain a high level of genetic
variation
standardized breed
few are important to conserveisolated for long times with distinct foundation
and physical type
feral breeds
landrace
usually well adapted
usually poor documentation (history, production)
poor recognition as a true breed in most places
productive potential is poorly documented
ome do have high production potential and are important to conserve and develop
ost are adapted and resistant
landrace
landrace
they do need to be “genetic resources” in the strict sense
need a level of genetic variation that does not prevent prediction of performance
landrace
these need to be defined carefullyimportant to decide which animals to include and
which to excludein many cases need to rescue a breed or a
bloodline without losing characteristics
landrace
need to develop strategies for long term maintenance
landrace
three steps for effective conservation
Discover/ encounter/ definesecuresustain
Final success depends on all three steps
for landraces it is necessary to decide if the population is truly a breed in the genetic sense
“breed” in this sense is a group of animals that are similar by origin and type, and that reproduce that type after mating within the group
discover
To decide if a population is a breed depends on investigations
phenotype (measured or visual inspection)historygenetic data (bloodtypes, DNA fingerprints)
landrace
investigation - history
ideal is long term isolation from other breeds
isolation comes from geography or owner practices
history
some cases will have high levels of isolation
many cases will have doubtful histories, or even more than one version of history
the history and the external phenotype usually agree
investigation - phenotype
in the US few people experienced in zootechnology
rare to measure animals to define breeds
measurements are always more accurate but are not possible in all cases
feral animals, or very extensive systems, present challenges to phenotypic evaluation – especially if measurements are needed
phenotype
look at the animals and compare them to other breeds in the area, looking for evidence of crossbreeding or mixtures with other breeds
this method, even though not exact, works very well in practice
history and phenotype usually agree
most populations either have the uniformity expected of a true breed, or are very variable from crossbreeding
steps one and two
traits such as color or presence/absence of horns are usually not very important
landraces usually vary more in these traits than do standardized or industrial breeds
this variation doesn’t prevent use of these breeds
conservation should include this variability
steps one and two
step three
genetic investigations are more expensive than those for history or phenotype
usually genetic investigations after the other twoafter eliminate populations obviously crossbredinclude only those that are more uniform
genetic data
genetic data are usually for relative frequencies of alleles
can be analyzed different ways to reveal relationships of populations
branching tree of breed relationships
points out breed groups
this type of “tree”also reveals the relative groupings aswell as the distance ofeach population from the others
complicated, butindicates individualanimals, and howdifferent they are if the population is split twoways, three, four, or fivereveals fundamentalpoints of division
genetic results provide background for deciding appropriate strategies for conservation
can reveal a mixed or uniform population
can indicate animals to include or exclude
step three
DNA results can indicate relationships between breeds, and which are most distinct or distant from others
step three
some individual animals are very important for genetic variation for the future of the breed
step three
Pineywoods cattle
from southeast USAadapted to a humid subtropical environmentiberian origin
Pineywoods
herds isolated from one another for a centuryone breed or many?all of the cattle are more like one another than
any other breedall of the herds have low numbers.logical to include them all in a single breed to
assure their effective conservation
Pineywoods
BOUNDS
SEAL
GARNER
LADNERHICKMAN
DIAMOND
DEDEAUX
CONWAY
O’NEAL
PALMER
VICE
AGRICOLA
BEACH
BROADUS
BAYLIS
CARTER
CLARK
BARNES
ROBINSON
GRIFFEN
HOLT
POPPLE
ALBANY
EZELL
KNAPP
bloodlines
Pineywoods
each breeder thinks his cattle the most pure of all
need to replace that attitude with more inclusion
Pineywoods
philosophy that works for this breed is to include all of the typical cattle from this region under a single registry and association
cattle are inspected to exclude the herds that have evidence of influence from zebu, Devon, Angus, or Hereford
Pineywoods
these cattle vary more than standardized breedsimportant to include this variation
dwarves and polled (hornless) cattle
Pineywoods
another breed is closely related: Florida Crackertwo breeds were separated due to decisions
based on regionalism of the breedersDNA results indicate these two breeds have been
separated for more than a centurysome distinctions have arisen
Pineywoods
effective to separate the two breeds to conserve
Pineywoods
in the beginning the association encountered resistance from traditional breeders
would not register cattlechange to free registrations worked to increase
the numbers of breeders registering cattle
Colonial Spanish Horses
similar to the Pineywoods cattle breedmany herdseach isolated for centuries
one breed or many?
Strains of the breed
some herds have fewer than 30 horsesimpossible to maintain these in isolation for the
long term, without inbreeding
Colonial Spanish Horses
Colonial Spanish Horses
total population is likely under 3,000 horses
all of these horses are very similar to one another
very distinct from other horses in the USA
logical to group them together for conservation
Colonial Spanish Horses
equinos c
Colonial Spanish Horses
Co
goal is to save the various bloodlines in several herds
also to blend these into a composite mixture
top related