Biology subjects

Blake, T.

Publications and source records attributed to Blake, T..

4 recordsLinked to original sources

bioRxiv2025

Divergent climate impacts despite similar response to temperature in a widespread aerial insectivore

Climate change is shifting when animals breed1,2, but it is still not clear why some populations keep pace with warming while others fall behind3,4. Differences could arise from variation in sensitivity to temperature3 or constraints on the ability to respond to temperature. Without knowing whether populations differ in sensitivity--or in their ability to act on that sensitivity--we cannot identify which are most at risk. Using 1,555 population-years from 123 populations of tree swallows (Tachycineta bicolor), we show that populations have similar sensitivity to local temperature, advancing breeding by about one day per degree of warming. However, northern populations face tighter time constraints and greater exposure to recent warming. Northern populations have advanced laying dates the most, but still experience stronger selection for earlier breeding, especially in warm years; they have also declined most in breeding abundance. These findings show that vulnerability to climate change can arise not just from different sensitivity to warming, but from when and where populations can respond effectively. By disentangling sensitivity from timing constraints, our results support a general mechanism by which even uniformly responsive species can show uneven impacts of climate change across their ranges.

ecology↗

bioRxiv2023

Long-term changes in the timing of autumn migration in Alaska's boreal songbirds

Alaskas boreal birds face a rapidly changing environment, but we know little about shifts in migratory timing, particularly in autumn. We used quantile regression to quantify long-term changes in autumn capture date in 21 boreal passerines using 22+year datasets from two banding stations in central Alaska. We also quantified differences between sites and explored whether select climate indices during three periods of the annual cycle (breeding, post-fledge, and migration) could predict long-term changes in median capture. Long-term changes in autumn migration were detected in 86% of taxa, 76% of which exhibited advances in capture date ([~]2-3 days/decade), particularly long-distance migrants at one field site. However, site-specific differences unexpectedly highlight the need for caution before extrapolating long-term timing patterns over broad spatial extents. Warmer conditions during the breeding period (using the AO climate index) were associated with advances in autumn capture date in the greatest number of species (9). Collectively, we hypothesize that Alaskas immense size and spatially-variable climate regions impact reproductive timing, often resulting in long-term advances (with warming) and occasionally delays (with cooling). Carry-over effects of reproductive timing may therefore influence the autumn passage of different breeding populations, causing site-specific patterns, such as a species showing long-term advances at one location, but delays at another. Finally, as part of the broader effort to anticipate and reduce declines in boreal migratory birds, our study underscores the conservation value of banding station data in quantifying avian responses to and investigating drivers associated with varied climate indices.

ecology↗

bioRxiv2021

An mRNA SARS-CoV-2 vaccine employing a novel delivery vehicle with a TLR-9 agonist induces neutralizing antibodies and T cell memory

The SARS-CoV-2 pandemic has necessitated the rapid development of prophylactic vaccines. Two mRNA vaccines have been approved for emergency use by the FDA and have demonstrated extraordinary effectiveness. The success of these mRNA vaccines establishes the speed of development and therapeutic potential of mRNA. These authorized vaccines encode full-length versions of the SARS-CoV-2 spike protein. They are formulated with Lipid Nanoparticle (LNP) delivery vehicles that have inherent immunostimulatory properties. Different vaccination strategies and alternative mRNA delivery vehicles would be desirable to ensure flexibility of future generations of SARS-CoV-2 vaccines and the development of mRNA vaccines in general. Here, we report on the development of an alternative mRNA vaccine approach using a delivery vehicle called Charge-Altering Releasable Transporters (CARTs). Using these inherently nonimmunogenic vehicles we can tailor the vaccine immunogenicity by inclusion of co-formulated adjuvants such as oligodeoxynucleotides with CpG motifs (CpG-ODN). Mice vaccinated with the mRNA-CART vaccine developed therapeutically relevant levels of RBD-specific neutralizing antibodies in both the circulation and in the lung bronchial fluids. In addition, vaccination elicited strong and long lasting RBD-specific TH1 T cell responses including CD4+ and CD8+ T cell memory.

immunology↗

bioRxiv2020

On the origin of photoperiod non-responsiveness in barley

In barley, the transition from the vegetative to reproductive phase is complex and under the control of photoperiodic and temperature conditions. One major gene involved is PPD-H1, a PSEUDO-RESPONSE REGULATOR 7 (PRR7) that encodes a component of the circadian clock. Mutation at PPD-H1 resulted in the photoperiod non-responsive ppd-H1 alleles that are beneficial under high latitudinal environments as they allow vegetative growth during the long-day summer conditions whereby higher yields are harvested by farmers. Utilizing a diverse GWAS panel of world-wide origin and a genome-wide gene-based set of 50K SNP markers, a strong association of days to heading with the PPD-H1 gene was detected in multi-location field trials. Re-sequencing of the gene spanning putative causative SNPs, SNP22 (Turner et al. 2005) and SNP48 (Jones et al. 2008), detected recombination between the two, previously reported to be in complete LD. Phenotyping of the recombinants and phylogenetic relationships among haplotypes supported the original conclusion of Turner et al. (2005) that SNP22, present in the CCT domain, is the most likely causative SNP. To infer the origin of non-responsiveness, the PPD-H1 gene was re-sequenced in a geo-referenced collection of 2057 wild and domesticated barleys and compared with the allelic status of the 6000-year-old barley sample from the Yoram cave in the Masada cliff. A monophyletic and post-domestication origin in the Fertile Crescent was found in contrast to the pre-domestication origin proposed by Jones et al. (2008). We show that the photoperiod non-responsiveness originated from Desert type wild barley in the Southern Levant.Competing Interest StatementThe authors have declared no competing interest.View Full Text

plant biology↗