Geology topics

Joshua D. Miller

Publications and source records attributed to Joshua D. Miller.

4 recordsLinked to original sources

USGS2026

Strengthening ties between the U.S. Geological Survey and Interstate Fisheries Commissions

Fish inhabiting marine coastal and Great Lakes waters of the United States forage, migrate, and reproduce without regard to human-made boundaries. In the mid-20th century, the 32 states along the U.S. coasts and Great Lakes recognized the growing need for coordinated, interjurisdictional fisheries management and formed four interstate or international fisheries commissions through federal legislation. While distinct in their authorities, each commission shares functions to support their regional partners, including coordinating fisheries science and supporting information sharing. The U.S. Geological Survey (USGS) is a federal bureau focused exclusively on science with substantial fisheries research capacity. This empowers USGS to serve as an independent broker of scientific information, which is greatly appreciated by decision-making agencies. The USGS does not maintain broad infrastructure for engaging partners across regions. Therefore, collaboration between the USGS and fisheries commissions ensures that USGS fisheries science helps address the most pressing interjurisdictional management priorities. The USGS has worked with fisheries commissions for decades to a greater or lesser extent in each of the four coastal regions: Atlantic, Pacific, Gulf, and Great Lakes. In 2020, the USGS began efforts to cohesively strengthen these partnerships across the regions. In 2024, leadership from four USGS fisheries science centers and headquarters met with the four fisheries commissions in person for the first time during the American Fisheries Society Annual Meeting. During the gathering, the new Interstate Fisheries Commissions–USGS Partnership developed coordination mechanisms and identified shared science priorities where the USGS capacity best aligns with the science needs of the commissions. Here we describe the history of collaboration between the USGS and fisheries commissions and the emerging interregional partnership.

Fisheries↗

USGS2024

Assessing the risk of climate maladaptation for Canadian polar bears

The Arctic is warming four times faster than the rest of the world, threatening the persistence of many Arctic species. It is uncertain if Arctic wildlife will have sufficient time to adapt to such rapidly warming environments. We used genetic forecasting to measure the risk of maladaptation to warming temperatures and sea ice loss in polar bears ( Ursus maritimus ) sampled across the Canadian Arctic. We found evidence for local adaptation to sea ice conditions and temperature. Forecasting of genome-environment mismatches for predicted climate scenarios suggested that polar bears in the Canadian high Arctic had the greatest risk of becoming maladapted to climate warming. While Canadian high Arctic bears may be the most likely to become maladapted, all polar bears face potentially negative outcomes to climate change. Given the importance of the sea ice habitat to polar bears, we expect that maladaptation to future warming is already widespread across Canada.

Ecology Letters↗

USGS2024

Development of an 8K SNP chip to assess adaptive diversity and hybridization in polar bears

The polar bear ( Ursus maritimus ) is a species particularly vulnerable to the effects of climate change. As the climate warms, polar bears will be forced to move to more suitable habitats which are likely to shrink, adapt to the new conditions, or decline in population size. However, the genomic diversity within and among all 19 subpopulations of polar bears, and therefore their adaptive potential, is currently unknown. In addition, warmer climates are likely to result in more frequent contact between polar bears and grizzly bears ( U. arctos ), with which they can hybridize. Here we describe the development, quality control, and application of the Ursus maritimus V2 SNP chip. This 8 K SNP chip contains loci explicitly selected to assess both RAD-derived and transcriptome-derived loci, as well as SNPs to detect hybridization between species. A total of 7,239 loci (90.3% of those printed) were successfully genotyped, with over 99% genotype concordance for individuals typed in duplicate on this chip, and between individuals typed here and on the Ursus maritimus V1 SNP chip. Using simulations, we demonstrate that the markers have high accuracy and efficiency to detect hybridization and backcrosses between polar bears and grizzly bears. However, empirical analysis of 371 polar bears, 440 grizzly bears, and 8 known hybrids found no novel instances of recent hybridization. The Ursus maritimus V2 SNP chip provides a powerful tool for monitoring the adaptive potential of this species along with assessing population structure, quantitative genomics, and hybridization in polar bears.

Conservation Genetics Resources↗

USGS2023

Late glacial–Younger Dryas climate in interior Alaska as inferred from the isotope values of land snail shells

The isotope values of fossil snail shells can be important archives of climate. Here, we present the first carbon (δ 13 C) and oxygen (δ 18 O) isotope values of snail shells in interior Alaska to explore changes in vegetation and humidity through the late-glacial period. Snail shell δ 13 C values were relatively consistent through the late glacial. However, late-glacial shell δ 13 C values are 2.8‰ higher than those of modern shells. This offset is best explained by the Suess effect and changes in the δ 13 C values of snail diet. Snail shell δ 18 O values varied through the late glacial, which can be partially explained by changes in relative humidity (RH). RH during the snail growing period was modeled based on a published flux balance model. Results suggest a dry period toward the beginning of the Bølling–Allerød (~14 ka) followed by two distinct stages of the Younger Dryas, a wetter stage in the early Younger Dryas from 12.9 to 12.3 ka, and subsequent drier stage in the late Younger Dryas between 12.3 and 11.7 ka. The results show that land snail isotopes in high-latitude regions may be used as a supplementary paleoclimate proxy to help clarify complex climate histories, such as those of interior Alaska during the Younger Dryas.

Alaska↗