The Effects of Fragmentation on the Population Genetics
of Black-tailed Prairie Dogs (LT61)
(Genetic structure of a metapopulation of black-tailed prairie dogs (pdf)
Lisa Savage, E212 Anatomy Zoology, Deparment of Biology, Colorado State University, Fort Collins, CO 80523
970-491-2058 lsavage@lamar.colostate.edu
Mike Antolin
970-491-1911 Antolin@lamar.colostate.edu
Objective: The objectives of this study are: 1) to establish levels of genetic heterogeneity within and among black-tailed prairie dog populations along gradients of colony size and isolation, 2) to make comparisons between the levels of genetic heterogeneity in regions with and without the sylvatic plague, and 3) to delineate the relationship between the factors of genetic variability, the degree of isolation of a given colony, colony size, and extinction risk in prairie dog metapopulations.
Methods: We plan to live-trap black-tailed prairie dogs along a gradient of isolation in two regions: Southwestern South Dakota, where there is no historic evidence of plague epizootics, and Northern Colorado, where plague has been regularly documented. We will record sex and body mass of all trapped individuals. A tissue sample will be collected from each individual for genetic analysis, and the animals will be released following this procedure. Genetic variability within and among populations will be measured using microsatellite (simple sequence repetitive DNA) loci markers, and MHC (major histocompatibility complex) markers. Cluster analysis of data from the genetic markers will reveal patterns of relatedness among populations and be used to evaluate the how isolation and the sylvatic plague effects the genetic population structure of black-tailed prairie dogs. Sampling and tissue collection We will bait the prairie dogs using progold sweet chop horse feed. They will be captured with Tomahawk wire-cage live traps (24 x 6 x 6), weighed, sexed, checked for reproductive status and ear-tagged. All animals will be dusted with flea-powder after capture, and all personnel will wear gloves and long-sleeved shirts while handling animals. A tail clip tissue sample will be collected from each individual for genetic analysis using the following procedures: a. Captured prairie dogs will be handled by a field technician using a canvas cone. The field technician will wear leather work-gloves covered with latex gloves to both prevent injury of the technician and to prevent transmission of diseases between dogs. b. The hair on the distal portion of the tail will be trimmed. c. The tail will be sprayed with Hibiclens (4% chlorhexidine gluconate), an antibacterial spray. d. The tail will be wiped down using gauze and rubbing alcohol, to remove dirt and oils. e. The tail will wiped with sterile gauze. f. A ring block will be administered by subcutaneous injection approximately 2 cm proximal to the amputation site. Block reagents will consist of a 75:25 mixture of 0.75% bupivacaine/2% lidocaine and epinephrine 1:400,000. This will result in 2.8mg/ml bupivicaine and 2.5 mg/ml lidocaine. For prairie dogs weighing less than 500g, we will administer 0.2 ml of this solution for a total dose of 0.56 mg bupivicaine and 0.5 mg lidocaine. For prairie dogs between 500g and 750g we will use 0.3 ml, for a dose of 0.84 mg bupivicaine and 0.75 mg lidocaine. For prairie dogs above 750g we will use 0.4 ml, for a dose of 1.12 mg/ml bupivicaine and 1 mg lidocaine. All doses will be well within the 1-2 mg/kg safe dose range, and should be well tolerated while providing complete analgesia at the amputation site. g. A small mammal touniquet will be applied just proximal of the amputation site. h. One cm of distal portion of tail will be amputated with a guillotine-type nail trimmer. This style of nail trimmer will be used for amputation because its crushing action provides hemostasis. i. The tissue sample will be placed in a microcentrifuge tube containing an isotonic saline buffer (1X SSC:0.15 M NaCl, 15 mM sodium citrate, 1 mM EDTA) and stored at -80oC until the DNA can be extracted. j. The amputation site will be wound-clipped with 9 mm Clay-Adams stainless steel clips. This method of skin-margin apposition is fast, secure, provides good hemostasis, and is well-tolerated in long-term placement applications. k. Vetbond surgical glue will be applied to the amputation site to aid in holding the wound shut. l. The amputation site will be sprayed with a tetracycline antibiotic spray that dries immediately. m. The animal will be ear tagged for individual identification using Monel #1005-1 small mammal tags and applicator. The tags hold a six-digit sequence, and are 5/16” long when closed and 9/64” wide. n. The tourniquet will be removed and the animal will be released into its burrow. o. Hair and nail trimmers will be wiped down with ethyl alcohol and gauze, then soaked in 95%EtOH and burned to sterilize them. We will sample using a preconditioning protocol recommended by Doug Sargent, a wildlife biologist at Buffalo Gap National Grasslands. Each colony will be pre-baited for three days, in which the traps are set upside down, with the doors open and bait inside the traps to allow the prairie dogs to become familiar with the traps and bait. On the fourth day, we will set the traps twice, once before dawn and once in the afternoon, avoiding trapping in the middle of the day. We will check the traps every few hours, so that the prairie dogs will not remain in the traps for more than 1-2 hours.
Study Area: This research will be conducted on the Shortgrass Steppe Long-Term Ecological Research Area which includes the Central Plains Experimental Range and the Pawnee National Grasslands. The vegetation on the SGS-LTER is characterized as short grass prairie, with blue gramma (Bouteloua gracilis) making up 60-80% of the plant cover. Prairie dogs generally are found in swales and broad drainages where bunchgrasses and annual forbs dominate. We will be sampling between 10 to 12 colonies, 6 of which are on the CPER, and up to 6 of which are found on the Pawnee National Grasslands.
01/31/2008