This commentary was adapted from an oral presentation delivered at the 86th Annual Meeting of the American Society of Mammalogists in Amherst, Massachusetts, on 18 June 2006 to recognize receipt of the Joseph Grinnell Award for Excellence in Education. Our continued ability to conduct fieldwork in mammalogy and train the next generation of field mammalogists is threatened by social, institutional, and bureaucratic changes that have accelerated over the past decade. These changes include continued decline in field-based natural history studies in the United States, bureaucratic regulations that are increasing in both number and complexity, increased acceptance of radical animal rights propaganda by our youth, increased fear of nature among United States citizens, and poor understanding of risk in an increasingly risk-averse society. These factors, among others, have made it increasingly difficult to conduct field research in mammalogy, and this commentary shows how these changes influenced the national response to discovery of a new rodent-borne disease, hantavirus pulmonary syndrome (HPS), in 1993. Current guidelines to protect field researchers from HPS may, in fact, be destroying the very enterprise whose practitioners they were designed to protect.

The New World rodent family Heteromyidae shows a marvelous array of ecomorphological types, from bipedal, arid-adapted forms to scansorial, tropical-adapted forms. Although recent studies have resolved most of the phylogenetic relationships among heteromyids at the shallower taxonomic levels, fundamental questions at the deeper taxonomic levels remain unresolved. This study relies on DNA sequence information from 3 relatively slowly evolving mitochondrial genes, cytochrome c oxidase subunit I, 12S, and 16S, to examine basal patterns of phylogenesis in the Heteromyidae. Because slowly evolving mitochondrial genes evolve and coalesce more rapidly than most nuclear genes, they may be superior to nuclear genes for resolving short, basal branches. Our molecular data (2,381 base pairs for the 3-gene data set) affirm the monophyly of the family and resolve the major basal clades in the family. Alternative phylogenetic hypotheses of subfamilial relationships are examined statistically and the Perognathinae and Heteromyinae are found to represent sister clades relative to the Dipodomyinae. The 3 traditional subfamilial groupings are supported; the controversial placement of Microdipodops as a sister clade to Dipodomys in the Dipodomyinae is affirmed, Perognathus and Chaetodipus are distinct sister clades within the Perognathinae, and species of Liomys and Heteromys form the resolved clade Heteromyinae. However, Liomys is found to be paraphyletic relative to Heteromys and, given that this finding corroborates earlier studies, we present a formal taxonomy of Heteromys wherein we place Liomys in synonymy. Semiparametric and parametric methods are used to estimate divergence times from our molecular data and a chronogram of the Heteromyidae, calibrated by the oldest known fossils of Dipodomys and Perognathus, is presented. Our time estimates reveal subfamilial differentiation in the early Miocene (22.3–21.8 million years ago) and pose testable times of divergence for the basal heteromyid nodes. With the basal heteromyid clades resolved and cladogenic events positioned in a time framework, we review the major geological and paleoecological events of the Oligocene and Miocene associated with the early historical biogeography of the family.

One hundred DNA sequences from the mitochondrial cytochrome-b gene of 44 species of deer mice (Peromyscus (sensu stricto), 1 of Habromys, 1 of Isthmomys, 2 of Megadontomys, and the monotypic genera Neotomodon, Osgoodomys, and Podomys were used to develop a molecular phylogeny for Peromyscus. Phylogenetic analyses (maximum parsimony, maximum likelihood, and Bayesian inference) were conducted to evaluate alternative hypotheses concerning taxonomic arrangements (sensu stricto versus sensu lato) of the genus. In all analyses, monophyletic clades were obtained that corresponded to species groups proposed by previous authors; however, relationships among species groups generally were poorly resolved. The concept of the genus Peromyscus based on molecular data differed significantly from the most current taxonomic arrangement. Maximum-likelihood and Bayesian trees depicted strong support for a clade placing Habromys, Megadontomys, Neotomodon, Osgoodomys, and Podomys within Peromyscus. If Habromys, Megadontomys, Neotomodon, Osgoodomys, and Podomys are regarded as genera, then several species groups within Peromyscus (sensu stricto) should be elevated to generic rank. Isthmomys was associated with the genus Reithrodontomys; in turn this clade was sister to Baiomys, indicating a distant relationship of Isthmomys to Peromyscus. A formal taxonomic revision awaits synthesis of additional sequence data from nuclear markers together with inclusion of available allozymic and karyotypic data.

I assessed the systematics of Ammospermophilus leucurus from the islands of Espíritu Santo and San Marcos adjacent to the Baja California peninsula, using sequences of the mitochondrial cytochrome-b (Cytb) gene and morphological analyses from the island and the peninsular samples. For the molecular analysis, the Cytb gene (500 base pairs) was sequenced from individuals from 34 different localities. Maximum-parsimony, maximum-likelihood, and neighbor-joining analyses indicated a phylogenetic break in the central part of the Baja California peninsula. Samples from the islands of Espíritu Santo and San Marcos were grouped with the southern clade with an average of 1.2 substitutions that separated adjacent haplotypes in a network. Two haplotypes occurred on San Marcos Island; one was unique and the other also was present in peninsular samples. The only haplotype found on Espíritu Santo Island also occurred on the peninsula. Both univariate and multivariate morphometric analyses and the pattern of presence–absence of the 3rd upper premolar distinguished samples from Espíritu Santo and the Cape region of the peninsula but not between San Marcos Island and Francisco de la Sierra on the peninsula. Thus, the San Marcos Island ground squirrel could not be distinguished from those of the peninsula and should be recognized as the same subspecies that occupies the adjacent peninsular areas (A. leucurus extimus). In addition, neither molecular nor morphological data supported the recognition of A. insularis (from Espíritu Santo Island) as a distinct species from peninsular samples of A. leucurus, although this taxon showed morphological differentiation in dental characters that still support its recognition as a valid subspecies (A. leucurus insularis).

In 2000, 2002, and 2006 we captured small mammals in the Liangshan Mountains, Mabian Dafengding National Nature Reserve and Meigu Dafengding National Nature Reserve, Sichuan Province, China. Among the collected specimens we identified a new species of the genus Proedromys. Its identifying characteristics are its relatively long tail, broad upper incisors without grooves, comparatively short lower incisors, and features of the molar teeth. The glans penis of the new species also is distinctive, the proximal and distal bacula are bony, whereas the lateral bacula are only slightly ossified. The proximal baculum is flask-shaped, the distal baculum is cap-shaped, and the lateral bacula are stick-shaped. This species is associated with high-elevation spruce–fir forest habitat, an unusual setting for Proedromys across its geographic range.

The 2 cryptic species of multimammate mice that occur widely in South Africa were, for many decades, lumped in a single species Mastomys natalensis sensu lato. This taxon was intensively studied because these rodents play a role in the epidemiology of various zoonoses (notably bubonic plague), serve as important models for biomedical research, and also sometimes cause extensive agricultural damage. The discovery that M. natalensis sensu lato includes 2 cryptic species in southern Africa has complicated interpretation of the results of past research because previous studies may have been based on either M. coucha or M. natalensis, or even on specimens of both species. A previous study aimed at craniometrically distinguishing between these species in South Africa met with some success, but excluded subadult specimens (which constitute a large proportion of museum collections), and cautioned that intraspecific variation might hamper interspecific discrimination. We therefore studied the nature and extent of nongeographic craniological variation using 2 populations of each species. The discriminatory value of a putative diagnostic dental character (presence or absence of t3 cusp on M3) is limited because of considerable variation within and among populations of M. coucha. Sexual dimorphism is negligible in both species, whereas age-related variation is pronounced and involves mainly differences in overall size, as well as some subtle differences in the configuration of the interorbital, postpalatal, and dental regions. Multiple discriminant function analyses aimed at craniometrically distinguishing between the 2 species showed that the inclusion of subadult specimens reduced a posteriori classification accuracy below 95% confidence levels, implying that age-related variation is sufficiently pronounced to obscure interspecific craniometric differences. Future studies aimed at craniometrically distinguishing between these cryptic species will, therefore, have to statistically correct for age-related variation.

A phylogenetic analysis based on partial sequences of 2 mitochondrial genes (cytochrome b and cytochrome c oxidase subunit I) confirmed that Ochotona alpina (Pallas, 1773) and O. turuchanensis Naumov, 1934, are sister taxa to all other Palearctic species of the subgenus Pika. O. hyperborea (Pallas, 1811) contains sufficient genetic heterogeneity to define 2 or 3 races within this species. Examination of genetic data supports the recognition of O. scorodumovi Skalon, 1935, as a distinct species. The proper name of the taxon (either O. scorodumovi Skalon, 1935, or O. mantchurica Thomas, 1909) remains to be established. O. hoffmanni Formozov et al., 1996, is probably the closest relative of O. scorodumovi. These 2 taxa constitute a sister group to O. hyperborea. All the above-mentioned Palearctic taxa constitute the monophyletic alpina–hyperborea group. The pallasi group contains at least 3 taxa: O. (p.) pallasi (Gray, 1867), O. (p.) pricei Thomas, 1911, and O. (p.) argentata Howell, 1928. The taxonomic rank of these 3 taxa requires additional careful investigation. Nearctic pikas O. princeps (Richardson, 1828) and O. collaris (Nelson, 1893) constitute a monophyletic group separate from Palearctic taxa.

We analyzed DNA sequence variation in the cytochrome-b gene and intron 7 of the nuclear fibrinogen, B beta polypeptide gene for 45 specimens of the bat genus Micronycteris, including all currently recognized species except M. sanborni. Phylogenetic analyses of both data sets supported 4 primary lineages within Micronycteris, which we recognize as subgenera: Leuconycteris new subgenus (M. brosseti), Micronycteris Gray (M. megalotis, M. microtis, M. matses, and M. giovanniae), Schizonycteris new subgenus (M. minuta, M. schimdtorum, and M. sanborni), and Xenoctenes Miller (M. hirsuta). Although we provisionally recognize the current alpha taxonomy within Micronycteris, our results did not support monophyly of M. microtis as the name is currently applied. Our results further indicate that cryptic species probably exist within the taxa currently recognized as M. megalotis and M. minuta and possibly M. hirsuta. Additional studies, including thorough geographic sampling and detailed morphological and molecular data sets, are necessary to test our genealogic hypotheses and assess the biodiversity within Micronycteris.

A new species of bat of the genus Miniopterus is described from Madagascar based on a series of specimens taken in the Central Highlands of the island. This new species previously was identified as M. fraterculus, which is widespread in portions of eastern and southern Africa. Comparisons between these 2 taxa were further complicated because M. fraterculus occurs in portions of its range in sympatry with a morphologically similar species, M. natalensis. Based on specimen material and associated tissue samples from near the type localities of M. natalensis and M. fraterculus, as well as access to some of the critical type specimens, morphological and genetic molecular analyses were used to determine that Malagasy specimens previously assigned to M. fraterculus represent a previously unrecognized species of Miniopterus endemic to the island. Given that the habitat used by Miniopterus sp. nov. is not necessarily associated with native forest, that it has a broad distribution across the Central Highlands, and that it has been found in synanthropic situations, this species is not considered a conservation concern.

Several geographically distinct mitochondrial DNA (mtDNA) lineages of the big brown bat (Eptesicus fuscus) have been documented in North America. Individuals from 2 of these lineages, an eastern and a western form, co-occur within maternity colonies in Colorado. The discovery of 2 divergent mtDNA lineages in sympatry prompted a set of questions regarding possible biological differences between haplotypes. We captured big brown bats at maternity roosts in Colorado and recorded data on body size, pelage color, litter size, roosting and overwintering behaviors, and local distributions. Wing biopsies were collected for genetic analysis. The ND2 region of the mtDNA molecule was used to determine lineage of the bats. In addition, nuclear DNA (nDNA) intron 1 of the β-globin gene was used to determine if mtDNA lineages are hybridizing. Eastern and western mtDNA lineages differed by 10.3% sequence divergence and examination of genetic data suggests recent population expansion for both lineages. Differences in distribution occur along the Colorado Front Range, with an increasing proportion of western haplotypes farther south. Results from nDNA analyses demonstrated hybridization between the 2 lineages. Additionally, no outstanding distinctiveness was found between the mtDNA lineages in natural history characters examined. We speculate that historical climate changes separated this species into isolated eastern and western populations, and that secondary contact with subsequent interbreeding was facilitated by European settlement.

We investigated species composition, diversity, and seasonal variation of bat assemblages in the uplifted coral reef tropical forest of Taiwan. We mistnetted 584 bats of 10 species, accounting for one-third of the bat fauna of this island. Miniopterus schreibersii, Hipposideros terasensis, Rhinolophus formosae, and Murina puta were the most frequently caught and abundant species, together accounting for 79% of the relative frequency and 84% of the relative abundance; followed by Rhinolophus monoceros and Myotis taiwanensis. We found no evidence of the presence of Myotis muricola, but added Eptesicus serotinus, Myotis watasei, and Pipistrellus abramus to the list of species recorded from these forests. Both the total and mean numbers of species caught peaked in May–June, whereas the mean capture rates climaxed in July–August. Most species were captured year-round, but M. puta was more abundant in winter and M. taiwanensis was absent during late summer–early winter. The numbers of species present at interior and edge sites were similar, as were species composition and evenness and heterogeneity values. However, capture rates were 2-fold higher at interior than edge sites, in particular for H. terasensis, R. monoceros, and M. taiwanensis and were female-skewed, particularly for M. schreibersii and R. monoceros. The overall similarity in species composition between the forest interior and edge sites, based on assessments of bat captures or bat passes, was nearly 10% higher than the similarity between data of bat captures and bat passes within the forest interior and edge sites, respectively.

We present data on prenatal growth, development, and skeletal ossification for the Angolan free-tailed bat (Mops condylurus), a species distributed throughout sub-Saharan Africa. Specimens were measured for crown–rump length (CRL), greatest length of the skull (GLS), forearm length, mass, and wing area. We cleared and differentially stained specimens for cartilage and bone to quantify pattern of skeletogenesis. Significant regressions for general growth trajectories were generated by plotting CRL and fetal mass against GLS. We quantified growth of the forearm, which showed a positive relationship with growth of the skull. Curiously, wing area was highly positively related to fetal mass, suggesting an ecomorphological relationship of wing loading and flight ability being established early in development in this species. Patterns of ossification in this species were more similar to those of phyllostomid and pteropodid bats than they were to vespertilionid bats, to which M. condylurus is apparently more closely related.

The white-striped free-tailed bat (Tadarida australis) is a common species of insectivorous bat found in mainland Australia. Despite its abundance, very little is known about its roosting ecology. I used radiotelemetry collected during 3 seasons to examine roost fidelity and roosting associations of a summer roosting group. Bats were trapped at a large communal roost in subtropical urban Brisbane, Australia. A total of 132 radiotracking days and nights provided 509 bat-days of data, with each bat being tracked for 26.9 days ± 28.6 SD. Seventeen new roost trees were found, scattered throughout an area of >200 km². Roost cavities were located inside eucalypt trees >83 cm diameter at breast height. Tagged T. australis switched roosts every 10.6 ± 7.9 days on average and spent most of their time in day-roosts with smaller roosting groups despite being 1st caught at the communal roost. I quantified associations between pairs of tagged bats using a pairwise sharing index. The consistent negative values of the pairwise sharing index I calculated indicated that members associated with roost-mates less often than predicted by chance. However, bats typically associated at night at the communal roost, even when they did not occupy it during the day. For every day-visit recorded per bat at the communal roost, each bat visited the same roost twice at night on average. This suggests that nocturnal movements of individuals should be included in assessments of associations between individuals. I postulate that this species employs a fission–fusion pattern based on individual movements to and from 1 communal site. I also argue that the roost network of 1 communal roost and many satellite roosts may be regarded as a single interconnected unit.

Limited information exists on the foraging ecology of the long-legged myotis (Myotis volans), especially with regard to use of available foraging habitats in large, relatively contiguous forested landscapes. During the summers of 2004 and 2005, we radiotagged adult long-legged myotis (n = 70) in north-central Idaho to estimate the size of home ranges and to evaluate use of available foraging habitats. Size of home range and core areas was measured for individuals with ≥31 locations (n = 30) using the adaptive kernel method, and selection among available foraging habitats was evaluated using Euclidean distance analysis. Home-range estimates did not differ among males, pregnant females, and lactating females (P = 0.52). Core-area estimates also did not differ among males, pregnant females, and lactating females (P = 0.62). Second-order habitat analysis, based on vegetation, showed that home ranges of males (P = 0.01), pregnant females (P = 0.001), and lactating females (P = 0.001) all were closest to stands of medium-diameter trees, that is, trees predominantly 12.7–38.0 cm diameter at breast height (dbh), that also contained larger snags typically used as roosts (X̄ = 54.0 cm dbh; n = 100). Second-order habitat analysis, based on slope position, showed that home ranges of males (P = 0.0001), pregnant females (P = 0.001), and lactating females (P = 0.001) were closest to mid-slope positions. Third-order habitat analysis, based on either vegetation or slope position, did not differ from random use for males, pregnant females, and lactating females. More lepidopterans were captured in black-light traps at mid-slope positions than either upper or lower slope positions. Fecal pellets (n = 171) from 62 long-legged myotis revealed a diet primarily composed of Lepidoptera (49.2% volume, 100% frequency) and Coleoptera (31.1% volume, 100% frequency). Examination of our data demonstrates the importance of forest stand structure, topographic position, and abundance of moths in foraging habitat for long-legged myotis.

Reintroduction efforts require knowledge of how many animals are needed for successful establishment. Population viability analysis can be used to predict trajectories of introduced populations and tree squirrels provide an ideal model system to investigate this challenge. Conservation action is needed because more than 80% of species of tree squirrels are of precarious conservation status in some portion of their range. We combined data from closely related species of tree squirrels and used VORTEX to determine how many squirrels are needed to successfully establish populations of 6 species (Sciurus aberti, S. carolinensis, S. niger, S. granatensis, S. vulgaris, and Tamiasciurus hudsonicus). We ran multiple simulations to account for between-patch differences in breeding success (resource availability) and variation between years in different habitats. In the best-case scenarios, populations could be successfully established with fewer than 35 individuals for all species and as few as 15 for a subset of species. Empirical evidence from introductions of tree squirrels supports our simulation results, with 93% of populations of greater than 10 squirrels surviving more than 50 years. With relatively few individuals needed for establishing new squirrel populations, reintroductions are feasible and useful as a buffer for imperiled species.

We augmented food resources to a heteromyid rodent community in the Sonoran Desert of southern California to experimentally ascertain the effect of a resource pulse on rodent abundance, diversity, and home-range dynamics. The same community displayed increased rodent abundance and species diversity in response to the productivity pulse that resulted from the 1997–1998 El Niño Southern Oscillation (ENSO). In marked contrast to the response to the ENSO, our experiment resulted in a decline in rodent diversity because the largest pocket mouse present (Chaetodipus formosus) monopolized the added resources and increased its proportional abundance. In addition, the abundance of adult rodents did not change in response to supplemental resources, even though reproduction, and consequently juvenile abundance, increased greatly. This implies that home-range size and overlap by adult animals remained unchanged despite the greater abundance of food. Among caching species such as pocket mice, this may be an adaptive response to the highly variable and scarce resources of the desert environment. The decline in diversity and lack of change in adult density and home-range dynamics observed with the experimental resource pulse are directly counter to the response of the community to the ENSO resource pulse, and were apparently the result of fine-scale spatial processes. This suggests that the effects of resource pulses are scale-dependent, and that the results of small-scale manipulative experiments may provide limited insight into community responses to large-scale climatic events.

Increasing human impacts on the Kenai Peninsula, Alaska, have raised questions about potential implications for genetic diversity and population structure of local taxa. Black bears (Ursus americanus) occupy most of the Kenai Peninsula and are currently a species of public interest and management focus. In this study, we use 13 nuclear DNA (nDNA) microsatellite loci and sequence data from the mitochondrial DNA (mtDNA) control region to investigate population structure and phylogeographic patterns in black bears on the Kenai and surrounding mainland. We used both aspatial and spatial Bayesian assignment models to evaluate nDNA genetic structure and cluster individuals into genetically distinct groups. Substantial population substructure was detected, indicating restricted gene flow in recent generations as well as signatures of past barriers between the Kenai and mainland. We identified 3 genetically distinct groups that cluster geographically in the Kenai Peninsula, Alaskan mainland, and Prince William Sound areas. Connectivity among genetic groups was moderate, with F_st values ranging from 0.07 to 0.12. Five mtDNA haplotypes were detected, 2 of which were primarily restricted to the Kenai. Our results provide important information about current levels of genetic diversity and connectivity among black bears on the Kenai Peninsula and will provide a baseline for future monitoring.

Female pumas (Puma concolor) give birth in all months of the year with a possible birth pulse in July–September. This pulse is proposed to be timed to provide increased survival probabilities to young born during these months. We tested data on birth dates from 8 different studies for a birth pulse. We also compared survival rates for young born in July–September to those for young born outside of these dates during a 17-year study in Idaho and Utah. The distribution of litters born per month was not uniform, with 41% of births occurring in July–September. Survival rates of young born in July–September were equal to those in other months of the year (0.774 ± 0.006 versus 0.779 ± 0.004). We conclude that there was a propensity for higher numbers of litters to be born in July–September. However, we rejected the hypothesis that young born in July–September had greater survival than young born at other times of the year. We suggest that rather than there being a survival advantage to pumas born in July–September, perhaps there is a survival disadvantage to those born in January–February (4.5% of 484 litters). However, there were insufficient data to test this alternate hypothesis.

Both density-dependent factors and environmental stochasticity can impact the dynamics of free-ranging populations. The pathways through which these factors influence population dynamics can be complex and may be immediate or lagged, and cumulative effects of environmental factors have been reported. We examined the effects of the severity (snow depth and persistence and winter rainfall) of the current and previous winters on the probability that female adult and yearling white-tailed deer (Odocoileus virginianus) would produce a fetus, and that adult females would produce a male fetus. We used logistic regression and Akaike's information criterion to select the best models from a set of 11 a priori candidate models. The severity of the winter 1 year before gestation negatively impacted the probability that both adults and yearlings would produce a fetus. There was no evidence that the probability of yearlings or adults producing a fetus was affected by winter conditions while gestating. Further, there was no evidence that the severity of the winter during which a yearling was gestated affected its probability of producing a fetus as a yearling. As the severity of the winter of gestation increased, the probability of producing a male decreased, consistent with both the Trivers–Willard sex ratio adjustment hypothesis and the extrinsic modification hypothesis. We suggest that both the decreased probability of reproduction after severe winters and the variation in fetal sex ratio may ultimately increase lifetime fitness if they lead to the production of the fittest offspring given the available maternal resources.

The forest buffalo (Syncerus caffer nanus) typically inhabits the dense rain forests of western and central Africa. We recorded the 1st data on the behavior and social interactions of forest buffalo in natural forest clearings that represent crucial places in the rain forest for feeding and social interactions among individuals. Data were collected from a buffalo herd during January 2002–January 2004 in the Bai-Hokou study area (Dzanga-Ndoki National Park, Central African Republic). We analyzed typical behaviors (i.e., grazing, resting or ruminating, and moving) of both the herd and individuals (from 16 to 24 buffalos), as well as the most frequent social interactions. Spatial distribution among buffalos in the herd, related to both distance from forest edge and to the season (wet versus dry seasons), showed that the adult male was commonly closer to the females than to juveniles. Individuals were generally further away from each other when in the vicinity of the forest edge. Moreover, at greater distances from the forest edge, the number of buffalos in the herd increased. During the wet season, the herd was generally smaller and individuals were more spread out within the same clearing. The most common behavior of the male, females, and juveniles was resting or ruminating. Behavioral interactions by adults were mainly addressed to juveniles.

Analysis of the stomach contents of 28 little hairy armadillos (Chaetophractus vellerosus), collected during a 14-month period at Pipinas, Argentina, showed that about 63.6% of the weight of prey items was composed of animal remains, 18% was plant material, and the remaining 18.4% was undetermined organic remains. Insects were the most frequent diet item, followed by plant material, amphibians, reptiles, and lastly birds and mammals in similar proportion. During autumn, plant material was the most abundant item, followed by vertebrates and invertebrates. During winter invertebrates prevailed, followed by a lower percentage of vertebrates and scarce plant remains. Invertebrates also were predominant during spring, whereas plant material and vertebrates composed very low percentages.

Pinnipeds generally swallow prey whole, and most have simple, homodont, nonoccluding cheek teeth. We investigated whether cheek teeth in seals are more variable and weakly integrated than in terrestrial Carnivora. We measured mandibular length and crown length of mandibular postcanines (PCs) in ringed seals (Pusa hispida; n = 912) from the Canadian Arctic, and harp seals (Pagophilus groenlandicus; n = 636) from Newfoundland and Labrador. PC size was uncorrelated or only weakly correlated with adult mandibular length. PC length and mandibular length were strongly bilaterally symmetrical (r ≥ 0.8 between left and right sides). PC size was moderately variable (coefficients of variation [CVs] ∼ 7–10%), and CV varied with position in the toothrow. Adjacent PCs were correlated more strongly in size (to r > 0.8) than PCs more distant from one another. In summary, PC size in ringed and harp seals was slightly more variable than cheek teeth in complex dentitions of fissipeds, and the 2 seals were similar to fissipeds in strong bilateral symmetry in mandibular and PC size, patterned variation along the toothrow, and correlated size between adjacent PCs.

In cetaceans almost all the energy reserves in lipid form are allocated to blubber and are related to basal metabolism and thermal insulation. Our study analyzed the blubber of 57 specimens of franciscana (Pontoporia blainvillei) from the state of Rio Grande do Sul, Brazil. Body fat condition was estimated through blubber weight, girth, and thickness of blubber. Blubber weight increased along with growth, from 2.27 kg in calves to 8.86 kg in mature franciscanas. Blubber weight decreased from 33.91% of total weight in calves to 24.32% in mature franciscanas. A significant difference was found when age classes were compared to each other (P < 0.001) for both males and females, indicating that blubber varied according to growth, independent of sex. Girth showed a good correlation with blubber weight at all 6 locations where it was measured, and thickness of blubber presented a low correlation at all 19 locations where it was measured. Calves face the physiologic problems of low surface to volume ratio, whereas adults expend energy in feeding, reproduction, and taking care of calves.

Molecular genetic techniques have been widely used to evaluate management actions, including the success of species reintroductions. However, conclusions drawn from genetic characterizations must be interpreted in the context of the sampling design and degree of uncertainty underlying genetic parameter estimation and assumptions of analyses performed. For example, failure to correctly identify and sample appropriate groups of individuals for comparative analyses will bias estimates of summary measures of genetic diversity, intersample variance in gene frequency, and derivations of effective population size or degree of reduction or bottlenecks in numerical abundance. We critically evaluate the foundational assumptions underlying the sampling design and analytical methods employed by Swanson and colleagues. Inaccuracies in reporting the founding population history of American marten (Martes americana) in Michigan and high levels of uncertainty underlying estimates of effective population size, bottleneck history, and demographic sustainability suggest that the authors' genetic data are misrepresented.

Reintroduced populations face a genetic bottleneck due to the founding event of the reintroduction. Bringing in additional animals from different locations, or at different times, can restore genetic variation to a reintroduced population and offset the founder event. The reintroduced population of martens in Michigan came from 3 different locations in Ontario and occurred over a 24-year period. The high level of genetic variation found in Michigan's reintroduced marten population could be due to the multiple source locations or the temporal separation of the reintroductions. Based on the genetic variation found in martens, the 3 source locations more likely represent subsamples from a single population and the observed level of genetic variation is due to the temporal separation of the reintroduction events.