Science and Wild Buffalo:Science and Wild Buffalo:

A Tool for Advocacy A Tool for Advocacy or an Excuse for Destruction?or an Excuse for Destruction?

Chris KlattBuffalo Allies of Bozeman

19 October 2008

Science Embedded in Cultural Context• Science is a problem-solving tool, a method of

creating models of how the world works with given observations. Everyone is a scientist!

• Observations are colored by values – what are the important phenomena to pay attention to?

• Observations influence the hypotheses put forth: science will operate within the context of the premises that state the “problem.”

• Important insights into the processes of biological organisms can be misleadingly represented as simple systems.

Misapplied Science

from Nott and Gliddon 1868

Craniometry research

Misapplied Science Towards Buffalo

What are the observations?How are these observations a reflection of the values held by society?

Is there a way in which we can dismantle these destructive management policies using the same

science, but with different values?

Hypotheses put forth as management objectives:

-The carrying capacity of the Park is less than 4000 buffalo.

- Vaccinating buffalo in addition to slaughtering seropositive animals will reduce the transmission of brucellosis from buffalo to cattle.

An Alternative Approach for Advocacy

If we can temporarily put aside the reasons why the IBMP partners will not tolerate more than 4000 animals that must stay in the park, what do we know about the current population structure and genetic diversity of the herds? How do these management policies impact the ecology and behavior of these animals?

Population GeneticsPopulation Genetics• Generally, evolutionary theory posits that selection reduces Generally, evolutionary theory posits that selection reduces

genetic diversity of population, and the only way to increase the genetic diversity of population, and the only way to increase the diversity is 1) wait for mutations to accumulate, or 2) have diversity is 1) wait for mutations to accumulate, or 2) have alleles introduced from outside the population via immigration.alleles introduced from outside the population via immigration.

• Nearly all mutations are deleterious, or will decrease fitness. Nearly all mutations are deleterious, or will decrease fitness. These must be purged from the genome via recombination, or These must be purged from the genome via recombination, or sex.sex.

• In small populations, diversity in a population can also decrease In small populations, diversity in a population can also decrease due to random chance, a process known as genetic drift.due to random chance, a process known as genetic drift.

• What happens if a population cannot maintain enough genetic What happens if a population cannot maintain enough genetic diversity?diversity?

Population Genetics• If there isn’t a large enough pool of different alleles (or

differences at a particular location in the genome) to swap with during sex, a small population will begin to see the fixation of deleterious alleles.

• An organism can handle a certain amount of deleterious alleles, or “mutational load”, because its genome has two copies of a particular allele.

• However, inbreeding increases the number of alleles that are homozygous – an evolutionary dead end.

• One way to determine the genetic structure of a population is to estimate the population’s heterozygosity.

Population Genetics

• Previous work in population genetics is misapplied to support current IBMP policy, as the management objectives dictate that lethal removal actions are only curbed once the entire park population falls below 2300, where the “population” supposedly will have a threshold limit of heterozygosity.

• This policy also assumes that the animals removed from the population are removed RANDOMLY.Is the removal random? Which animals are likely to

be targeted in this approach?

Subpopulation Structure

• Substantial evidence for subpopulations – separate breeding groups, determined by genetic markers and telemetry.

• Subpopulation structures need to be accounted for to determine if the current practice of non-random selective slaughter is having a significant bottleneck effect.

Geography and Subpopulation Structure

Subpopulation Structure

“1,084 bison were removed from YNP in the winter of 1996 – 97, representing a 31.5% decrease in total population size. …While the Northern herd suffered a loss of approximately 83.9% (726/825), the Central herd was reduced by only around 13.9% (358/2,571).”Natalie Halbert, PhD Dissertation, University of Texas 2003

Of the 1678 buffalo captured wandering out of the northern boundary of the park, 1286 were killed and 110 were sent to quarantine. It is not yet known what effect this has had on the population structure within the park.

Not Everyone In the Park Agrees…

“It is our job to protect the viability of this population. We take that seriously. We are not taking any actions that will have a serious ongoing negative impact on this population.”Al Nash, YNP Media Spokesman, quoted in CNN story, April 29th 2008

“At present, the greatest vulnerability to the genetic health of Yellowstone bison would be a near-term, large-scale removal of bison from the northern range.”Rick Wallen, YNP Wildlife Biologist, IBMP meeting notes Oct 6th 2008

Conservation Genetics

• Of the approximately 300,000 buffalo in North America today, only the herds in Yellowstone, Wind Cave, and Grand Teton National Parks are considered to be “genetically pure.” These genetic arguments would have to underlie a strategy utilizing the Endangered Species Act.

• Much importance is placed on conserving bison that don’t have evidence of cattle genes, yet these bison have lower levels of genetic diversity and heterozygosity than cattle do (contributed by bottlenecks, habitat fragmentation, and management).

But when it all comes down to it…

Genetic Reductionism?

What makes a wild buffalo wild? Is it merely a genome?