David O. Ribble

Dispersal in a Monogamous Rodent, Peromyscus Californicus

In view of theoretical interest in the relationships between mating systems and dispersal patterns and the paucity of empirical data on dispersal in monogamous mammals, I studied natal dispersal in the monogamous rodent Peromyscus californicus. Genealogical relationships were determined using fluorescent pigment transfer and DNA fingerprinting, and dispersal distances were determined using dispersal fences and intensive trapping. Minimum dispersal distances were greater for females than for males. Philopatric males (those settling within one home—range diameter of their birth site) tended to be from smaller litters than non—philopatric males. Minimum dispersal distances of males were positively associated with natal litter size at weaning, whereas minimum dispersal distances of females were positively associated with number of sisters in the natal litter. These results suggest that intrasexual mate competition drives female dispersal, while resource competition drives male dispersal. Males remain closer t...

Home Ranges and Social Organization of Syntopic Peromyscus boylii and P. truei

Using radiotelemetry, we investigated sizes, spatial distributions, and overlap patterns of home ranges for two syntopic populations of Peromyscus boylii and P. truei . Home ranges were calculated from the minimum convex polygon (MCP) and the fixed-kernel-density estimator of radiolocations from 3 summers in northern New Mexico. During each summer, these Peromyscus exhibited a seasonal cycle in abundance, starting low in early summer and increasing through the summer months. Both estimates of home-range size were correlated significantly, although the fixed-kernel-density estimates were usually larger. Home ranges of male P. truei were larger than those of female P. truei and male and female P. boylii . The disproportionately larger size of ranges of male P. truei was likely due to distribution of female P. truei , which were more dispersed than female P. boylii . The MCP home ranges of male P. boylii also were larger than home ranges of female P. boylii . Both species’ home ranges were related inversely to conspecific density, but only home ranges of P. truei varied inversely with heterospecific density. Females of both species tended to overlap little intrasexually; males had home ranges that overlapped home ranges of multiple females and males. Patterns in home-range size and overlap were consistent with a promiscuous mating system for both species.

A COMPARISON OF HOME RANGES OF TWO SPECIES OF PEROMYSCUS USING TRAPPING AND RADIOTELEMETRY DATA

Abstract We investigated differences between sizes of home ranges using trapping and radiotelemetry data for syntopic Peromyscus boylii and P. truei. Sizes of home ranges were calculated from the minimum convex polygon of trap locations and radiotelemetry locations and compared between individuals. The 2 estimates of home-range size were significantly correlated, although on an average trapping home ranges were significantly smaller than sizes of radiotelemetry home ranges. Home-range sizes from radiotelemetry were inversely correlated with conspecific density, but home-range sizes from trapping were not. Thus, at low density, radiotelemetry home ranges were significantly larger than trapping home ranges, but at high density there was no difference between radiotelemetry and trapping home ranges. These results indicate that radiotelemetry results in larger estimates of home-range size, particularly at lower densities of conspecifics. The largest size estimates of home ranges were from a combination of radiotelemetry and trapping data.

Differences in Ultrasonic Vocalizations between Wild and Laboratory California Mice ( Peromyscus californicus )

Background Ultrasonic vocalizations (USVs) emitted by muroid rodents, including laboratory mice and rats, are used as phenotypic markers in behavioral assays and biomedical research. Interpretation of these USVs depends on understanding the significance of USV production by rodents in the wild. However, there has never been a study of muroid rodent ultrasound function in the wild and comparisons of USVs produced by wild and laboratory rodents are lacking to date. Here, we report the first comparison of wild and captive rodent USVs recorded from the same species, Peromyscus californicus. Methodology and Principal Findings We used standard ultrasound recording techniques to measure USVs from California mice in the laboratory (Peromyscus Genetic Stock Center, SC, USA) and the wild (Hastings Natural History Reserve, CA, USA). To determine which California mouse in the wild was vocalizing, we used a remote sensing method that used a 12-microphone acoustic localization array coupled with automated radio telemetry of all resident Peromyscus californicus in the area of the acoustic localization array. California mice in the laboratory and the wild produced the same types of USV motifs. However, wild California mice produced USVs that were 2–8 kHz higher in median frequency and significantly more variable in frequency than laboratory California mice. Significance The similarity in overall form of USVs from wild and laboratory California mice demonstrates that production of USVs by captive Peromyscus is not an artifact of captivity. Our study validates the widespread use of USVs in laboratory rodents as behavioral indicators but highlights that particular characteristics of laboratory USVs may not reflect natural conditions.

The mating system of northern populations of Peromyscus maniculatus as revealed by radiotelemetry and DNA fingerprinting

We studied the social organization and mating system of Peromyscus maniculatus in the Kananaskis Valley of Alberta by investigating both home range use and mating success. Radiotelemetry indicated ...

Competition models with Allee effects

In this paper, we study a generalized two-species contest-competition model with an Allee effect. We provide a complete analysis of the global dynamics of the system. In particular, we determine all the invariant manifolds, the extinction, the exclusion and the coexistence regions. We use tools from topology and dynamical systems to show that all orbits must converge to one of the equilibrium points of the system. The analysis shows that there are several potential scenarios including competition coexistence, exclusion and extinction.

Hierarchical competition models with Allee effects

We consider a two-species hierarchical competition model with a strong Allee effect. The Allee effect is assumed to be caused by predator saturation. Moreover, we assume that there is a ‘silverback’ species x that gets first choice of the resources and where growth is limited by its own intraspecific competition, while the second ‘inferior’ species y gets whatever is left. Both species x and y are assumed to have the property of strong Allee effect. In this paper we determine the impact of the presence of the Allee effect on the global dynamics of both species.