Variation in phenology of hibernation and reproduction in the endangered New Mexico meadow jumping mouse (Zapus hudsonius luteus)

Evolutionary constraint and innovation across hundreds of placental mammals

Zoonomia is the largest comparative genomics resource for mammals produced to date. By aligning genomes for 240 species, we identify bases that, when mutated, are likely to affect fitness and alter disease risk. At least 332 million bases (~10.7%) in the human genome are unusually conserved across species (evolutionarily constrained) relative to neutrally evolving repeats, and 4552 ultraconserved elements are nearly perfectly conserved. Of 101 million significantly constrained single bases, 80% are outside protein-coding exons and half have no functional annotations in the Encyclopedia of DNA Elements (ENCODE) resource. Changes in genes and regulatory elements are associated with exceptional mammalian traits, such as hibernation, that could inform therapeutic development. Earth's vast and imperiled biodiversity offers distinctive power for identifying genetic variants that affect genome function and organismal phenotypes.

Courtship behavior of the meadow jumping mouse (Zapus hudsonius)

We describe the first recorded observations of courtship behavior of the meadow jumping mouse (Zapus hudsonius) made in wild-caught and captive-reared animals. Male meadow jumping mice performed a series of courtship behaviors upon approach to the female, including rapid fanning of the muzzle with the forelimbs, self-grooming, muzzle fanning, retreat, and eventual mounting attempts. During courtship, female jumping mice may retreat, ignore the courting male, or bat at the male with forelimbs until the male retreats. Active rejection of courting males by the female is suggestive of female mate choice in this species.

Reproductive phenology and seasonal mass dynamics of black-tailed prairie dogs (Cynomys ludovicianus) at their northern range limit

Intraspecific variation is common and can be substantial in species occupying large geographic ranges. For example, populations at a poleward range limit can be exposed to more severe and variable weather, resulting in more punctuated growing seasons and, consequently, large fluctuations in body mass and additional constraints on reproductive phenology. We monitored variation in these traits in a hibernating population of black-tailed prairie dogs (Cynomys ludovicianus (Ord, 1815)) at their northern range limit across four growing seasons. Overall, individual body mass was highly dynamic both within and across growing seasons, and was correlated with sex, the presence of drought, and reproductive effort. This population experienced between-year variation in the timing of reproduction that was associated with weather variation. The influence of weather was particularly evident in 1 year during which a summer–autumn drought was followed by a severe and prolonged winter. This combination led to high overwinter mortality, substantially delayed emergences from hibernation, lower body masses at emergence from hibernation, and complete reproductive failure the following spring. Our results help to emphasize the influence of environmental conditions on levels of phenotypic variation at a species’ northern range limit, which may ultimately contribute to population viability and success.

Landscape Scale and Microhabitat of the Endangered New Mexico Meadow Jumping Mouse in the White Mountains, Arizona

The New Mexico meadow jumping mouse Zapus hudsonius luteus was listed as endangered under the U.S. Endangered Species Act in 2014, with critical habitat designated in 2016. Despite these recent conservation actions, there is a paucity of published information regarding its habitat associations. The taxon is a riparian obligate that occurs along both low-elevation rivers and high-elevation headwater streams in several disjunct areas of the American Southwest. Habitat information from one region might not apply to others. The distribution and habitat preferences of the New Mexico meadow jumping mouse in the White Mountains in eastern Arizona are poorly known. Objectives of this study were to 1) identify and resurvey historical locations in the White Mountains, 2) survey for new populations in areas with potentially suitable habitat in the White Mountains, and 3) use quantitative data to evaluate habitat associations at the landscape and microhabitat scales and to compare habitat at sites where I captured or did not capture the New Mexico meadow jumping mouse. I found 123 historical records of the New Mexico meadow jumping mouse from 21 locations in the White Mountains, indicating a formerly broad distribution. I conducted field surveys and collected habitat data at 35 sites (14 historical, 21 new) and caught 37 (39 total captures) New Mexico meadow jumping mice at 12 sites, including 6 of 12 historical locations surveyed. The overall capture rate was 0.36%, with an average capture rate at sites where it was present of 1.28% (range = 0.25–2.5%). All historical sites where I caught the New Mexico meadow jumping mouse were in the drainage of the Black River. The six new sites included the first records for Nutrioso Creek and Corduroy Creek and confirmed persistence of the taxon in the East Fork Little Colorado River, San Francisco River, and Blue River watersheds. Habitat used by the New Mexico meadow jumping mouse in the White Mountains was similar to that reported for other montane populations, characterized by tall, dense herbaceous vegetation composed primarily of forbs and sedges on saturated soil in close proximity to flowing water. However, there was significantly more cover provided by alders Alnus spp. at capture sites at both the stream reach and microhabitat scales. All sites where I captured the New Mexico meadow jumping mouse had no authorized livestock grazing, and the taxon was more likely to occur at sites where there were no signs of unauthorized livestock grazing. Further, there was a significant positive relationship between alder cover and time since an area was excluded from livestock grazing. The widespread exclusion of livestock from riparian areas in the White Mountains may have contributed to the higher rate of population persistence of the New Mexico meadow jumping mice in the White Mountains compared with the Jemez and Sacramento mountains, New Mexico. Although the overall persistence rate in the White Mountains (47%) was higher than other populations, the population is at risk of further losses due to small, isolated occupied areas and ongoing threats.