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The Desert Tortoise Council Newsletter

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The Desert Tortoise Council Newsletter THE DESERT TORTOISE COUNCIL NEWSLETTER WINTER 2009-OUR 34th YEAR Our Goal: To assure the continued survival of viable populations of the desert tortoise throughout its range INSIDE THIS NEWSLETTER… MASSIVE HEAD-STARTING OF MASSIVE HEAD-STARTING OF THE THE MOJAVE DESERT TORTOISE MOJAVE DESERT TORTOISE ...................... 1 BOARD OF DIRECTORS............................... 4 A Desert Tortoise Council Position Paper FROM THE EDITOR....................................... 4 ANNOUNCEMENTS....................................... 4 Populations of the Mojave Desert Tortoise DESERT TORTOISE COUNCIL 2010 (Gopherus agassizii) have declined significantly SYPOSIUM INFORMATION........................... 4 over recent decades due largely to human activities, NEWS ............................................................. 6 including unauthorized collection of animals as RELATED MEETINGS ................................. 12 pets, human-subsidized predation, overgrazing by INVOLVEMENT OPPORTUNITY ................. 14 domestic livestock, off-road vehicle impacts to SCHOLARSHIPS / AWARDS ...................... 14 tortoise habitat, the introduction of disease, habitat DESERT TORTOISE COUNCIL fragmentation by highways, and urbanization. The MEMBERSHIP.............................................. 16 conservation and recovery of these populations is, therefore, of the utmost importance, and this goal is stipulated in the Desert Tortoise (Mojave Population) Recovery Plan (1994). Proposals and actions to address this decline and ensure the survival of the species must be founded on the best available science, conform to Federal and State law regarding protected species, and not further endanger the Mojave Desert Tortoise. Reducing existing threats to the tortoise from human activities is central to the survival of viable, native populations. One strategy for increasing desert tortoise populations is head-starting, whereby eggs and hatchlings are protected and then released at an age when the animals are less vulnerable. There are Photo Credit: Irene Alexakos pilot head-starting programs at Edwards Air Force Taken at Military Corps Air Ground Combat Center Base, Fort Irwin National Training Center, and the Marine Corps Air Ground Combat Center in www.deserttortoise.org Twentynine Palms. In a variation on this strategy, Juvik, Nagy and Kiester state that genetic studies the proposal by James Juvik, Kenneth Nagy and suggest “a relatively uniform genotype over most of Ross Kiester (2009) is to collect eggs from the the California Mojave.” We are concerned that captive desert tortoise held by thousands of private “relatively uniform” is irrelevant. A single base pair owners in Southern California, rear the hatchings to substitution can be adaptive. The assessment of “predator-resistant” size, and then release these genetic variation they cite was based on the tortoises by the thousands into the Mojave Desert. mitochondrial genome only and not nuclear genes. The initial goal is to collect and incubate 1,000 eggs Evidence is mounting that localized mitochondrial from some 200 captive tortoise pairs. This massive discordances reflect selection on the mitochondrial head-starting proposal raises a number of concerns genome itself via mito-nuclear discordance. Such for the Desert Tortoise Council. evidence also implies selection on the corresponding nuclear genes. Juvik, Nagy and A desert tortoise restoration program on the scale Kiester note that Murphy et al. (2007) proposed by this project must rest on the best “hypothesized that these genetic differences may be available science, yet there are scientific issues that adaptive.” This is untrue. A scientific hypothesis remain to be addressed by the proponents. The cannot contain “may”, rather it tests whether a authors assert that they will “break the cycle of specific null hypothesis can be rejected or not; a disease transmission…associated with captive null hypothesis can never be proven to be true and tortoises…and provide healthy animals for hypothesis testing involves “either/or” decision reintroduction.” However, the work on Gopher making, not hedging. Many recent studies Tortoises in Florida and Desert Tortoises in demonstrate that selection occurs in functional California cited by Juvik, Nagy and Kiester only genes that have clear adaptive value, such as those “appears to confirm that maternal tortoise disease involved in sensing the environment. Rather than transmission does not occur in ova” (italics added). forming and scientifically testing a hypothesis of There must be certainty that all eggs are disease local adaptability, Juvik, Nagy and Kiester free, and not just for the Mycoplasma that we know explicitly assume that tortoises can (rapidly) adapt of. In addition, there must be irrefutable evidence to anthropogenic effects. Evidence suggests that the captive-bred tortoises will survive once otherwise. Adaptability is a function of generation released. To date, there are insufficient data to time and many species with far shorter generation conclude that current head-starting programs are times than Mojave Desert Tortoises are unable to successful. These trial projects simply have not adapt and are going extinct. Juvik, Nagy and Kiester operated long enough to determine their degree of cite no literature demonstrating adaptation in either success. Habitat matters on this issue since the mitochondrial or nuclear genomes, and none of the places referenced by the proponents as examples more modern in vitro experimentation where this type of intervention appeared to work in demonstrating adaptive selection to variables such the past are quite different habitats. Those locations as salinity and temperature. They have not tested are not as arid as the Mojave Desert where there is whether the genetic structuring in the Mojave less annual forage, particularly during drought Desert Tortoise corresponds to adaptive gene periods. A massive head-starting program, complexes, or not. Their assumption is not science. furthermore, might simply increase food shortages for both native and released tortoises. While screening to ensure that captive tortoises contributing eggs are of Mojave rather than Sonoran Releasing captive tortoises without sufficient stock or hybrids, the goal of the massive head- scientific evidence that they will survive would be starting proposal “…is to create populations with unethical. high genetic variability to provide the greatest opportunity for evolutionary response to change.” The Desert Tortoise Council is concerned with the In pursuing this goal, the proponents reject the implications of the proposed intervention for the argument that reintroduced populations should genetic composition of the Mojave Desert Tortoise. genetically match wild populations due to www.deserttortoise.org demonstrated genetic differentiations within the Tortoise Council believes it would be imperative to Mojave Desert Tortoise (Murphy et al. 2007). ascertain where these tortoises could be placed While genetic variability may or may not contribute before the head-start process began. Since they are to greater adaptability, the proposed intervention captive bred and of unknown origin, they should not contradicts the fundamental strategy of the Desert be released in designated critical habitat. Areas Tortoise (Mojave Population) Recovery Plan (1994) outside of critical habitat are mostly military lands, to protect evolutionarily significant population privately-owned lands, open off-road vehicle areas, units. The six “recovery units” in the Recovery Plan lands slated for the construction of solar energy were identified with data on genetic variability, facilities, or lands adjacent to urban and urban/rural morphology, and behavior patterns of populations areas within the West Mojave Desert. Such lands as well as ecosystem types. Consistency with the clearly would not be conducive to the survival of genetic specifications of the Recovery Plan must be head-started tortoises. a consideration in the preparation of the State of California “Propagation Permit” that would be A fundamental aspect of the massive head-starting required. It is illegal in California to privately breed proposal is that it would simply return animals to tortoises in captivity without a permit. The genetic areas where the situation that lead to their previous composition of the Mojave Desert Tortoise must decline or extirpation has not been eliminated or also be a consideration in the preparation of the substantially reduced. The proponents state that Environmental Impact Report that would be massive head-starting “…can potentially swamp necessary because of the scale of the proposed some decline factors…” and they cite the captive project and in the Environmental Impact Statement breeding program of the Nene Goose (Branta that would be required for releasing numerous sandvicensis) as evidence (Juvik et al. 2009) Yet the tortoises on Federal land. analogy is faulty because only the eggs and young of the Nene Goose were threatened, and it was only The Desert Tortoise Council is concerned that alien predators that led to the bird’s near extinction. massive head-starting could further endanger wild It is sustained anthropogenic transformations of the populations of the Mojave Desert Tortoise. The environment that are the cause of the decline in proposed project might train more ravens, coyotes populations of the Mojave Desert Tortoise, and and dogs to pursue this State- and Federally- subsidized predators are only one of those protected
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