Boyd Deep Canyon Desert Research Center

12 Apr, 08 AM - 29 May, 05 PM

The evolution of mating systems in mammalian taxa has been one of the most active areas of recent zoological research. While mere description of patterns is interesting, the study I propose hopes to go beyond description to look at fundamental causes of the variation we observe today in mammalian mating systems. I propose that infectious disease might be one such fundamental driver of mating system evolution. In particular, diseases that affect the reproductive tract and are passed between individuals during copulation should be particularly important. (The only major change to the current year?s application is the addition of several common Chaetodipus sp. and Neotoma sp. which were found to be abundant last year.) To look at the pattern of disease in the context of mating systems in wild animals, I propose a study that would involve the live capture of several species of small mammals. Live trapping will take place in Riverside County (Palm Desert area) and San Diego County (Borrego Springs area). Traps will be baited with apple/oat mix, and opened at dusk, checked at dawn. Species to be captured include Peromyscus eremicus (100 individuals), P. crinitus(20 individuals), P. maniculatus(50 individuals), Neotoma lepida(20 individuals), Chaetodipus rudinoris(50 individuals), C. spinatus(50 individuals), and C. penicillatus(50 individuals). While in captivity (which will last no more than 15 minutes)all animals will be sedated using isoflurane. Peromyscus and Neotoma will be permanently marked using ear tags (Monel 1005) and screened for bacterial pathogens via genital swabbing (small tipped culture swab). In addition a small sample of tissue will be taken from the distal pinna for genetic analysis. To assess the prevalence of multiple paternity in P. eremicus and Chaetodipus sp. neonatal litters belonging to 10 females (P. eremicus, C. rudinoris, C. formosus) will be collected and euthanized. Typically, juveniles of these species cannot be captured until they begin emerging from the nest, at which point it is extremely difficult to assure that (1) all young in a litter are caught and (2) young from different litters have not begun mixing. Alternatively, in the case that nests cannot be identified, pregnant females may be euthanized. Combined, no more then 10 litters will be collected. Absolute knowledge of maternity for complete litters is critical in determining the frequency of multiple paternity in these species, particularly in the reportedly monogamous P. eremicus. Nest sites for lactating females will be located using live-trapping and fluorescent powder tracking. Once located, adult females will be live-trapped as described above; females will be held in traps for approximately 30 minutes, during which the nest site will be carefully excavated and neonatal young removed. Young will be euthanized immediately via overdose inhalation of Isoflurane. Tissue samples will then be collected for use in genetic analyses. Once young have been removed, the nest site will be restored to its original structure and the adult females will be released at the point of capture. Because females typically have access to multiple nest sites on their territories (although only one site is used to house their current litter), females will have areas in which they can shelter should disruption of the nest containing young cause them to abandon that location. Nest predation is a routine element of the biology of these mice and loss of a litter or nest site does not typically result in mortality of the adult female. A sample size of 10 litters per species is the standardly accepted minimum number that will provide robust information regarding patterns of paternity in these animals. All methods have been approved by the UC Berkeley Animal Care and Use Committee. Using these data, I hope to characterize the vaginal flora; link pathogen load to reproductive success; characterize MHC variability and link it to mate choice and reproductive success; and describe population genetic and demographic patterns; looking for differences at each level between monogamous and promiscuous species. Lastly, any animals found dead or moribund will be collected and transported to UC-Berkeley Museum of Vertebrate Zoology where permanent record will be established and further analysis will be done. Specific to Deep Canyon, I would like to continue to trap in the areas as in previous years, staying sufficiently far from Doug?s trapping grid so as to avoid interruption of his study. P. eremicus nest excavations will not be attempted, as last year?s work has shown that they are usually found in around large boulders, or at depths >1m, and thus inaccessible. In contrast, Chaetodipus nests are relatively shallow and highly accessible. As such, Chaetodipus nests will be excavated in an attempt to prevent sacrificing adult females. In addition, and if time permits, I would like to conduct small scale mammal inventory near the water hole. The mammal community may be substantially different there, as water is readily available. This plan was discussed last summer with Mark, but essentially, I would like to live trap for several nights. No animals will be sacrificed from this area. It would be particularly interesting to determine if P. maniculatus (which is sometimes captured near the station in cooler months) are more common back there.

Visit #12283 @Boyd Deep Canyon Desert Research Center

Approved

Under Project # 6673 | Research

Evaluation of P. eremicus mating system

research_scientist - University of California, Berkeley

Reservation Members(s)

Matthew MacManes Apr 12 - May 29, 2007 (48 days)

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Mayhew housing facilities 1 Apr 12 - May 29, 2007
Lab Space 1 Apr 12 - May 29, 2007