Reproductive Effort in Squirrels: Ecological, Phylogenetic, Allometric, and Latitudinal patterns

The distinctive features of reproduction in squirrels are the lack of allometric influences on the duration of reproductive investment; the strong allometric influences on offspring mass; and a trade-off between number and size of young, suggesting an important developmental component to reproduction. Lengths of gestation and lactation do not vary with body size but neonatal and weaning mass do. Apparently, the major constraint on reproduction in squirrels is not resources per se (food, calories, minerals, or water) but rather the length of time such resources are available. Squirrels adjust growth rate to fit the timing of resource abundance. Within the familial reproductive pattern, arboreal squirrels invest more into reproduction than do ground squirrels. Flying squirrels (Pteromyini) have a larger temporal investment into reproduction but a smaller energetic investment compared with other squirrels. Ground squirrels do not have a distinct reproductive profile, because marmotine and nonmarmotine ground squirrels differ. Marmotine ground squirrels have a small temporal investment and a large energetic investment on a per litter but not on an annual basis. Nonmarmotine ground squirrels have a reproductive pattern similar to that of tree squirrels, a pattern intermediate between marmotines and flying squirrels. Within this locomotor-ecological framework, reproductive patterns differ among subfamilies. Tribes differ in having few (2-4) versus many (4-8) young, and in the relative allocation of investment into gestation versus lactation. Specific environmental influences on reproduction in squirrels occur at lower taxonomic levels within the framework of a broad reproductive pattern set by earlier radiations into particular locomotor and nest-site niches

Effect of Transatlantic Transport on Reproduction of Agouti and Nonagouti Deer Mice, \u3ci\u3ePeromyscus maniculatus\u3c/i\u3e

In conjunction with establishing colonies of deer mice in the UK, effects of transportation on reproduction in agouti (A) and nonagouti (a) deer mice were assessed. Adults were shipped via ground courier and air freight from Northampton, Massachusetts, USA to Sutton Bonington, Leicestershire, England in February and June. Deer mice were paired upon arrival in Sutton Bonington, whereas matched controls were paired in the original colonies at shipping. To assess reproduction, the following variables were monitored for 110 days for all 96 pairs: number of pairs producing litters, time from pairing to birth, interlitter interval, litter size at birth, and litter size at weaning. Generally, shipping suppressed litter production and delayed its timing, but had less effect on litter size. Overall, 32 of 48 control pairs (67%) produced 69 litters compared with 37 litters from 21 of 48 pairs (44%) after shipping. Pairing-to-first-litter intervals were approximately two oestrous cycles shorter in control animals (39 vs 53 days). Averaged over all litters, litter size was higher in control pairs (4.4 vs 4.0). With respect to genotype, control agouti deer mice were less productive than nonagouti animals, but they reproduced better than nonagoutis after shipping. In control animals, colourmorphs did not differ with respect to litter production or timing, but agouti pairs had smaller litters (first litter: A: 3.1, a: 4.2) and this difference increased at successive litters (third litter A: 3.9, a: 6.0). After shipping, agouti animals produced more litters (A: 22, a: 15), and did so earlier (pairing to birth: A: 47 days, a: 60 days), as well as more frequently (interlitter interval: A: 32 days, a: 51 days). Litter size was also more similar between genotypes after shipping (A: 4.0, a: 4.1). Overall, control agouti animals produced 37% fewer offspring than nonagouti pairs (A: 116 neonates, a: 185 neonates), but after shipping agouti deer mice produced 43% more offspring than nonagouti animals (A: 87 neonates, a: 61 neonates). In sum, transport stress suppressed reproduction for several weeks after shipping and this suppression was exacerbated in nonagouti deer mice

Cabassous chacoensis (Cingulata: Dasypodidae)

Cabassous chacoensis (Chacoan naked-tailed armadillo) is a little-studied, primarily fossorial armadillo endemic to xeric parts of the Gran Chaco in western Paraguay and northern Argentina. C. chacoensis is listed as Near Threatened by the International Union for Conservation of Nature and Natural Resources

Beta-blockers and physical frailty in patients with end-stage liver disease.

AimTo investigate beta-blocker (BB) use in patients with cirrhosis and determine their effects on physical frailty and overall survival.MethodsAdult outpatients with cirrhosis listed for liver transplantation underwent testing of physical frailty using the performance-based Liver Frailty Index, comprised of chair stands, grip strength, and balance testing, as well as self-reported assessments of exhaustion and physical activity. BB use was assessed from medical chart review. Univariable and multivariable logistic regression were performed to determine BB use and their association with measures of physical frailty. Competing risk analyses were performed to determine the effect of BB use on wait-list mortality, as defined by death or delisting for being too sick for transplant.ResultsOf 344 patients, 35% were female, median age was 60, median model for end stage liver disease was 15, and 53% were prescribed a BB. Compared to those not on BB, patients on BB were similar except for percentage female (25% vs 46%; P < 0.001) and BMI (29 vs 28; P = 0.008). With respect to tests of physical frailty, BB use was not associated with increased odds of frailty (by the Liver Frailty Index), exhaustion, or low physical activity. BB use was, however, significantly associated with a decreased adjusted risk of mortality (SHR 0.55; P = 0.005).ConclusionIn patients with cirrhosis awaiting liver transplantation, BB use is not associated with physical frailty. We confirmed the known survival benefits with BB use, and concerns about adverse effects should not deter their utilization when indicated

Allometry of Litter Mass in Bats: Maternal Size, Wing Morphology, and Phylogeny

We examine how litter mass in bats varies with respect to wing loading, an important aerodynamic aspect of flight. From geometric proportions, litter mass should scale to wing loading by an exponent of three. Conversely, analysis of aerodynamic consequences of carrying extra mass suggests that an exponent significantly less than three would be selectively advantageous. Our results show that Megachiroptera and Microchiroptera differ in the relationship between litter mass and wing loading. Litter mass in megachiropterans scales as expected by geometric proportions, whereas litter mass in microchiropterans, as a group, and for individual families, scales as expected if aerodynamic consequences of flight influence litter mass more than size constraints. Thus, selection pressures on reproductive traits appear to differ between the two suborders of bats

Pteronura brasiliensis (Carnivora: Mustelidae)

Pteronura brasiliensis (Zimmermann, 1780), the giant otter, is the largest freshwater otter. Found in South America, it inhabits slow-moving rivers and creeks and feeds predominantly on fish. Extinct in the southern portions of its former range, P. brasiliensis is listed as Endangered by the International Union for Conservation of Nature and Natural Resources. Threats to P. brasiliensis include habitat destruction, illegal hunting, and disease

Peramorphosis, an evolutionary developmental mechanism in neotropical bat skull diversity

Background The neotropical leaf‐nosed bats (Chiroptera, Phyllostomidae) are an ecologically diverse group of mammals with distinctive morphological adaptations associated with specialized modes of feeding. The dramatic skull shape changes between related species result from changes in the craniofacial development process, which brings into focus the nature of the underlying evolutionary developmental processes. Results In this study, we use three‐dimensional geometric morphometrics to describe, quantify, and compare morphological modifications unfolding during evolution and development of phyllostomid bats. We examine how changes in development of the cranium may contribute to the evolution of the bat craniofacial skeleton. Comparisons of ontogenetic trajectories to evolutionary trajectories reveal two separate evolutionary developmental growth processes contributing to modifications in skull morphogenesis: acceleration and hypermorphosis. Conclusion These findings are consistent with a role for peramorphosis, a form of heterochrony, in the evolution of bat dietary specialists

Limits to sustained energy intake XII : is the poor relation between resting metabolic rate and reproductive performance because resting metabolism is not a repeatable trait?

Peer reviewedPublisher PD

Comparative Genomic Characterization of the Multimammate Mouse Mastomys coucha.

Mastomys are the most widespread African rodent and carriers of various diseases such as the plague or Lassa virus. In addition, mastomys have rapidly gained a large number of mammary glands. Here, we generated a genome, variome, and transcriptomes for Mastomys coucha. As mastomys diverged at similar times from mouse and rat, we demonstrate their utility as a comparative genomic tool for these commonly used animal models. Furthermore, we identified over 500 mastomys accelerated regions, often residing near important mammary developmental genes or within their exons leading to protein sequence changes. Functional characterization of a noncoding mastomys accelerated region, located in the HoxD locus, showed enhancer activity in mouse developing mammary glands. Combined, our results provide genomic resources for mastomys and highlight their potential both as a comparative genomic tool and for the identification of mammary gland number determining factors

The influence of wildlife water developments and vegetation on rodent abundance in the Great Basin Desert

Rodent communities have multiple functions including comprising a majority of the mammalian diversity within an ecosystem, providing a significant portion of the available biomass consumed by predators, and contributing to ecosystem services. Despite the importance of rodent communities, few investigations have explored the effects of increasing anthropogenic modifications to the landscape on rodents. Throughout the western United States, the construction of artificial water developments to benefit game species is commonplace. While benefits for certain species have been documented, several researchers recently hypothesized that these developments may cause unintentional negative effects to desert-adapted species and communities. To test this idea, we sampled rodents near to and distant from wildlife water developments over 4 consecutive summers. We employed an asymmetrical before-after-control-impact (BACI) design with sampling over 4 summers to determine if water developments influenced total rodent abundance. We performed an additional exploratory analysis to determine if factors other than free water influenced rodent abundance. We found no evidence that water developments impacted rodent abundance. Rodent abundance was primarily driven by vegetation type and year of sampling. Our findings suggested that water developments on our study area do not represent a significant disturbance to rodent abundance and that rodent abundance was influenced by the vegetative community and temporal factors linked to precipitation and primary plant production. Our findings represent one of the 1st efforts to determine the effects of an anthropogenic activity on the rodent community utilizing a manipulation design