Troy L. Best

Ecological Separation of Three Genera of Pocket Gophers (Geomyidae)

A study of the ecology and distribution of Geomys bursarius jugossicularis Hooper, Thomomys bottae cultellus Kelson, and Pappogeomys castanops Baird was conducted in northeastern New Mexico. Comparisons of body size, soils utilized, burrow characteristics, distinguishing surface features, and winter activity revealed each species to be ecologically separate. Altitude and soils are discussed as factors influencing the geographical separation of the species, although soil appears to be the primary limiting factor. Based on the observed distribution and range of soils inhabited, the most limited distribution and the broadest range of soil types is found for the largest species P. castonops, followed by T. bottae and then G. bursarius.

Interspecific Morphologic Variation in Kangaroo Rats (Dipodomys): Degree of Concordance with Genic Variation

Schnell, G. D. (Department of Zoology and Stovall Museum, University of Oklahoma, Norman, Oklahoma 73019), T. L. Best (Natural Sciences Research Institute, Natural History Museum, Eastern New Mexico University, Portales, New Mexico 88130), and M. L. Kennedy (Department of Biology, Memphis State University, Memphis, Tennessee 38152) 1978. Interspecific morphologic variation in kangaroo rats (Dipodomys): degree of concordance with genic variation. Syst. Zool. 27:34-48.-The 24 forms of kangaroo rats (Dipodomys) that have been recognized as species by one or more recent authors were studied using phenetic techniques. A total of 41 morphometric characters (4 skin, 16 skull, and 21 post-cranial) were measured for up to 10 males and 10 females of each species. The standardized average measurements were analyzed and then measurements were divided by principal component I projections based on unstandardized data to reduce the influence of overall size. Phenograms and three-dimensional principal component models were produced and the results compared with the findings of previous authors, including those from allozyme analyses. Several species pairs and groups involving a few species were stable throughout our studies and consistent with groups identified in phylogenetic, specialization, or other classificatory schemes. These include: compactus and ordii; elephantinus and venustus; agilis, paralius, peninsularis, and antiquarius; nitratoides and merriami; and ornatus and phillipsii. However, marked morphologic gaps (other than those based on size) are not present between many of the species groups and attempts to place species into such groups in classifications probably result in an indication of distinctness that goes beyond what is found in nature. In terms of interspecific comparisons, there was no association between phenetic groups based on morphologic data and those constructed using allozyme findings. When comparisons were made among previous classifications and our results, the allozyme data produced the most divergent classifications. Overall, the associations between our morphologic results and previous classifications were relatively weak, reflecting by and large the variance in arrangements of species groups, rather than major differences within groups. Given the relative indistinctness of morphologic groups, it seems unlikely that any one classification can accurately represent interspecific phenetic, cladistic, and/or phylogenetic affinities within the genus. [Phenetics, taxonomic congruence, Dipodomys, kangaroo rats, morphometrics, allozymes.] Significant effort has been expended by a number of investigators studying evolutionary mechanisms to determine the extent of genic variation in local populations, among populations, and among closely related species (see Lewontin, 1974, and Powell, 1975, for general reviews; Selander and Johnson, 1973, summarized data for vertebrates). Workers have attempted to investigate and elucidate a fundamental aspect of evolutionary theory-that race formation and eventually speciation occur by the conversion of genetic variation within populations to variation among populations (Lewontin, 1967). Prakash (1969) emphasized that to understand the speciation process we not only should have a knowledge of genetic differences between closely related species (or populations within a species), but also of the correlation between genic differences and differences based on other characteristics, such as those describing various aspects of morphology, ecological preference, and behavior. Relatively few studies have quantitatively compared interspecific differences in morphology against between species allozyme differences. Sokal (1973) indicated that allozyme variation is an unreliable indicator of classical morphologic (phenetic) variation, citing Sneath and

Age-Related Variation in Skulls of the Puma (Puma concolor)

Measurements of skulls were used to determine if growth continues throughout the lifetime of a puma ( Puma concolor ) and if growth patterns differ between sexes. The dataset included 1,201 adult pumas and consisted of 14 cranial and 5 mandibular measurements. Ages (estimated by the amount of staining and wear of teeth) of specimens examined during our study suggested that few pumas live past ca. 9 years of age in the wild (16 of 609 adult males and 35 of 592 adult females). For both sexes, all of the characters showing no significant variation among age groups were those related to measurements of dentition, indicating that teeth reach their full-grown size by ca. 2 years of age. Growth of the cranium of pumas continues throughout most of the animals life; males continue to grow to 7–9 years of age, and females continue to grow to 5–6 years of age.

SUMMER FORAGING RANGE OF MEXICAN FREE-TAILED BATS (TADARIDA BRASILIENSIS MEXICANA) FROM CARLSBAD CAVERN, NEW MEXICO

Abstract We determined the foraging range of Mexican free-tailed bats (Tadarida brasiliensis mexicana) that spend summer in Carlsbad Cavern, Carlsbad Caverns National Park, New Mexico. We captured bats at varying distances and directions from the cavern and attached a radiotransmitter to each. During daylight hours, we entered Carlsbad Cavern to determine if bats with radiotransmitters were present in the maternity roost. The distribution of localities where captured bats returned to Carlsbad Cavern indicated a nightly foraging range of at least 56 km from Carlsbad Cavern. Our data indicated that the colony eventually dispersed in every direction after leaving the cavern each evening and foraged in a space nearly 4,000 km3. This study was the first to document use of water sources on property of Carlsbad Caverns and Guadalupe Mountains national parks, the Lincoln National Forest, and other sites in southeastern New Mexico and western Texas by members of the colony of T. b. mexicana that reside in Carlsbad Cavern.

Variation in Diet of the Gray Bat (Myotis grisescens)

During spring and summer 1991, a total of 1,476 fresh fecal pellets of gray bats, Myotis grisescens , was collected at Blowing Wind Cave, Jackson Co., Alabama. Fourteen orders of Insecta, unidentified Insecta, an unknown organism (possibly Insecta), two orders of Arachnida, and hair from gray bats were recovered; in decreasing order, the most common taxa were Lepidoptera, Diptera, and Coleoptera. Food categories exhibited significant variation among sampling sessions, nights within sampling sessions, and hours within sampling sessions. When quantity of each food category in fecal pellets was compared with quantity of potential prey available for consumption, there was no statistically significant correlation. There was significant variation in diet over time, but bats did not select prey in proportion to availability.

Variation in Kangaroo Rats (Genus Dipodomys) of the Heermanni Group in Baja California, Mexico

Variation in skin and skeletal measurements of kangaroo rats (genus Dipodomys) was evaluated using 265 specimens from 11 localities in Baja California, Mexico. Cluster analyses were utilized to verify field identification at the two localities where D. gravipes and D. agilis were sympatric and to examine each of the other nine collecting sites for possible sympatric forms. Sexual dimorphism occurred in two external, three skull, and nine postcranial measurements. Males were significantly larger than females in all of these characteristics. Significant interOTU variation occurred in 41 of the 42 characters analyzed. Using correlation analyses the 19 least correlated characters were selected from the original 42. Dipodomys gravipes was readily separable from the other taxa. The data indicate that there are only two species of kangaroo rats ( D. agilis and D. gravipes ) of the heermanni group in Baja California.

Bacular Variation in Kangaroo Rats (Genus Dipodomys)

Bacular variation in 20 species (397 specimens) of Dipodomys was analyzed. No definite trend was apparent in the relationship between body size and bacular size. Comparisons based on three bacular measurements yielded phenetic classifications that showed marked similarities to the interspecific groupings of several previous investigators, although differences exist as well. Our resulting classifications differ significantly from those obtained using morphologic or genic information, but are similar to that suggested from karyotypic data. Significant age variation was evident in D. ordii in shape and size, with elongation occurring and essentially all growth taking place at the proximal end. INTRODUCTION Kangaroo rats (genus Dipod-omys) occupy arid and semiarid regions of western North America from southern Canada through most of Mexico (Hall and Kelson, 1959). Some species have been studied extensively by classical taxonomic methods (Hall and Dale, 1939; Setzer, 1949; Lidicker, 1960a; Lackey, 1967; Genoways and Jones, 1971) and several classifications have been proposed (Grinnell, 1921, 1922; Wood, 1935; Burt, 1936; Setzer, 1949; Lidicker, 1960a; Jchnson and Selander, 1971; Stock, 1974), but numerous problems regarding species limits and other aspects of relationships within the genus remain unresolved. Bacula of adult kangaroo rats differ from other related heteromyids -Perognathus, Liomys and Microdipodops-in being more robust and generally larger. Geomyid bacula are similar in size and appearance, but are heavier and more rounded at the tip. Adult Dipodomys bacula have large, hollow, bulbous bases (Lidicker, 1960b), with species differing in the size of the bulbous base, length of the baculum, curvature of the shaft, and degree of upturn of the tip. There are scattered descriptions of the bacula of some Dipodomys species (Boulware, 1943; Blair, 1954; Lackey, 1967; Genoways and Jones, 1971). However, only Burt (1936, 1960) and Lidicker (1960b) have made systematic comparisons of bacula for more than two or three species. At the time of their comparisons, information was available on only about one-half of the Dipodomys species and for many there were only small samples. The purpose of our study is to use the

Effects of Environment on Phenotypic Variation and Sexual Dimorphism in Dipodomys simulans (Rodentia: Heteromyidae)

The magnitude of sexual dimorphism in size among populations of some small mammals living in different habitats may be a reflection of the degree of habitat partitioning between sexes or nutritional quality of available food. We tested these hypotheses by quantifying between-sex differences in size in populations of the Dulzura kangaroo rat ( Dipodomys simulons ) from several macrohabitat types at regional and local geographic scales. On a regional scale, our results indicated a significant shift in morphology of males and females along a north-south latitudinal gradient. Large kangaroo rats inhabited warm and arid southernmost latitudes, whereas small animals inhabited relatively cool and moist regions to the north. This morphologic gradient represented an increase in size with less seasonal variation in precipitation and temperature. This pattern was clearly counter to Bergmanns rule, but consistent with the hypothesis that temporal variation in availability of food may be an important factor leading to geographic variation in size. External and cranial measures of size dimorphism were not correlated significantly with any major geographic factor, and only cranial measures were associated significantly with variation in climate. At a local level, kangaroo rats living in different vegetation communities within the same latitudinal zone also exhibited significant sexual dimorphism in size; however, macrohabitat heterogeneity appeared to affect males and females equally. Both sexes were larger in Sierran Montane Conifer Forest and Californian Chaparral macrohabitats. Smaller animals occupied Californian Grassland and Coastal-scrub, and Vizcaino vegetation communities. This pattern of variation was observed in all three-way comparisons and suggests the possibility of habitat-mediated phenotypic responses. Finally, only one of eight comparisons involving kangaroo rats living in adjacent plant communities showed a significant two-way interaction between dimorphism and macrohabitat type. Our results, therefore, did not provide strong evidence to substantiate the hypotheses that the magnitude of dimorphism among populations of D. simulans living in different macrohabitats is a reflection of the degree of partitioning between sexes or nutritional quality of available food.

Demographic features and habitat preferences of southern pygmy mice (Baiomys musculus) in Colima, Mexico

In Colima, Mexico, we conducted 8-night mark-recapture grid studies of southern pygmy mice (Baiomys mus- culus (Merriam, 1892)) in January 2003-2007 in dry deciduous and tropical moist forests. For 40 000 trap-nights, 436 indi- viduals were captured 764 times (comprising 18.6% of small mammals). The male:female ratio was 1:1.37, 82.9% were adults, 51.4% of females were pregnant or lactating, and coastal animals, on average, were heavier than those inland. Fe- males moved farther than males. Baiomys was on 17 of 25 grids (densities 1.82-106.24 individuals/ha). Moon illumination did not affect capture or recapture probabilities, but trap-night did (overall, probability increased 1.66%/night). Grids with Baiomys had less bare ground and a more open canopy. Capture sites had more grass, less dead wood and bare ground, a more open and lower canopy, and greater distance to trees. Logistic regression indicated coastal capture sites had more forbs, grasses, and woody plants, and thicker vegetation at 1 m height with trees being relatively distant. Variables differed somewhat for northern sites, and the equation for all grids included 10 of 14 environmental variables. Baiomys frequented edge of an unimproved road traversing one grid. Baiomys musculus, widespread in Colima, exhibited preference for habi- tats with relatively dense ground cover and at least a partially open canopy.

Vegetative Characteristics of Active and Abandoned Leks of Lesser Prairie-Chickens (Tympanuchus pallidicinctus) in Southeastern New Mexico

Abstract Populations of lesser prairie-chickens (Tympanuchus pallidicinctus) have declined sharply across the range of the species, including southeastern New Mexico. Several possible causes for this decline have been suggested, including overgrazing by livestock. To test this hypothesis, vegetative composition of active and abandoned leks of lesser prairie-chickens and the pastures in which they were located was measured using the line-point sampling method. Vegetative composition of active leks and the pastures in which they were located was significantly different from those of abandoned leks and surrounding pastures in all 3 years of the study. Active leks and surrounding pastures had significantly more bluestem (Andropogon) and less dropseed (Sporobolus) than did abandoned leks and surrounding pastures. Abandoned leks were closer to honey mesquites (Prosopis glandulosa) >60 cm in height than were active leks. Results are symptomatic of overgrazing, which is detrimental to populations of lesser prairie-chickens.