Biology subjects

Cannon, C. H.

Publications and source records attributed to Cannon, C. H..

5 recordsLinked to original sources

bioRxiv2022

Virtually the same? Evaluating the effectiveness of remote undergraduate research experiences

In-person undergraduate research experiences (UREs) promote students integration into careers in life science research. In 2020, the COVID-19 pandemic prompted institutions hosting summer URE programs to offer them remotely, raising questions about whether undergraduates who participate in remote research can experience scientific integration. To address this, we investigated indicators of scientific integration for students who participated in remote life science URE programs in summer 2020. We found that these students experienced gains in their scientific self-efficacy and scientific identity similar to results reported for in-person UREs. We also found that these students perceived high benefits and low costs of doing research at the outset of their programs, and their perceptions did not change despite the remote circumstances. Yet, their perceptions differed by program, indicating that programs differentially affected students perceptions of the costs of doing research. Finally, we observed that students with prior research experience made greater gains in self-efficacy and identity, as well as in their perceptions of the alignment of their values with those of the scientific community, in comparison to students with no prior research experience. This finding suggests that additional programming may be needed for undergraduates with no prior experience to benefit from remote research.

scientific communication and education↗

bioRxiv2021

Old and ancient trees are life history lottery winners and act as evolutionary buffers against long-term environmental change

Trees can live many centuries with sustained fecundity and death is largely stochastic. We use a neutral stochastic model to examine the demographic patterns that emerge over time, across a range of population sizes and empirically observed mortality rates. A small proportion of trees ([~]1% at 1.5% mortality) are life-history lottery winners, achieving ages >10-20x median age. Maximum age increases with bigger populations and lower mortality rates. One quarter of trees ([~]24%) achieve ages that are 3-4 times greater than median age. Three age classes (Mature, Old, and Ancient) contribute unique historical diversity across complex environmental cycles. Ancient trees are an emergent property of forests that requires many centuries to generate. They rradically change generation time variance and population fitness, bridging infrequent environmental cycles. These life-history lottery winners are vital to future forest dynamics and invaluable data about environmental history and individual longevity. Old-growth forests contain trees that cannot be replaced through restoration or regeneration in the near future. They simply must be protected to preserve their unique diversity.

plant biology↗

bioRxiv2021

"How do we do this at a distance?!" A descriptive study of remote undergraduate research programs during COVID-19

The COVID-19 pandemic shut down undergraduate research programs across the U.S. Twenty-three sites offered remote undergraduate research programs in the life sciences during summer 2020. Given the unprecedented offering of remote research experiences, we carried out a study to describe and evaluate these programs. Using structured templates, we documented how programs were designed and implemented, including who participated. Through focus groups and surveys, we identified programmatic strengths and shortcomings as well as recommendations for improvements from the perspectives of participating students. Strengths included the quality of mentorship, opportunities for learning and professional development, and development of a sense of community. Weaknesses included limited cohort building, challenges with insufficient structure, and issues with technology. Although all programs had one or more activities related to diversity, equity, inclusion, and justice, these topics were largely absent from student reports even though programs coincided with a peak in national consciousness about racial inequities and structural racism. Our results provide evidence for designing remote REUs that are experienced favorably by students. Our results also indicate that remote REUs are sufficiently positive to further investigate their affordances and constraints, including the potential to scale up offerings, with minimal concern about disenfranchising students.

scientific communication and education↗

bioRxiv2019

Conserved DNA polymorphisms distinguish species in the eastern North American white oak syngameon: Insights from an 80-SNP oak DNA genotyping toolkit

The eastern North American white oaks, a complex of approximately 16 potentially interbreeding species, have become a classic model for studying the genetic nature of species in a syngameon. Genetic work over the past two decades has demonstrated the reality of oak species, but gene flow between sympatric oaks raises the question of whether there are conserved regions of the genome that define oak species. Does gene flow homogenize the entire genome? Do the regions of the genome that distinguish a species in one part of its range differ from the regions that distinguish it in other parts of its range, where it grows in sympatry with different species? Or are there regions of the genome that are relatively conserved across species ranges? In this study, we revisit seven species of the eastern North American white oak syngameon using a set of 80 SNPs selected in a previous study because they show differences among, and consistency within, the species. We test the hypothesis that there exist segments of the genome that do not become homogenized by repeated introgression, but retain distinct alleles characteristic of each species. We undertake a rangewide sampling to investigate whether SNPs that appeared to be fixed based on a relatively small sample in our previous work are fixed or nearly fixed across the range of the species. Each of the seven species remains genetically distinct across its range, given our diagnostic set of markers, with relatively few individuals exhibiting admixture of multiple species. SNPs map back to all 12 Quercus linkage groups (chromosomes) and are separated from each other by an average of 7.47 million base pairs ({+/-} 8.74 million bp, s.d.), but are significantly clustered relative to a random null distribution, suggesting that our SNP toolkit reflects genome-wide patterns of divergence while potentially being concentrated in regions of the genome that reflect a higher-than-average history of among-species divergence. This application of a DNA toolkit designed for the simple problem of identifying species in the field has an important implication: the eastern North American white oak syngameon is composed of entities that most taxonomists would consider \"good species,\" and species in the syngameon retain their genetic cohesion because characteristic portions of the genome do not become homogenized despite a history of introgression.

evolutionary biology↗

bioRxiv2017

Novel insights into karyotype evolution and whole genome duplications in legumes

Legumes (family Fabaceae) are globally important crops due to their nitrogen fixing ability. Papilionoideae, the best-studied subfamily, have undergone a Whole Genome Duplication (WGD) around 59 million years ago. Recent study found varying WGD ages in subfamilies Mimosoideae and Caesalpinioideae and proposed multiple occurrences of WGD across the family based on gene duplication patterns. Despite that, the genome evolution of legume ancestor into modern legumes after the WGD is not well-understood. We aimed to study genome evolution at the subfamily level using gene-based linkage maps for Acacia auriculiformis and A. mangium (Mimosoideae) and we discovered evidence for a WGD event in Acacia. In additional to synonymous substitution rate (Ks) analysis, we used ancestral karyotype prediction to further corroborate this WGD and elucidate underlying mechanisms of karyotype evolution in Fabaceae. Using publicly available transcriptome resources from 25 species across the family Fabaceae and 2 species from order Fabales, we found that the variations in WGD ages highly correlate (R=0.8606, p-value<0.00001) with the divergence age of Vitis vinifera as an outgroup. If the variation of Ks is corrected, the age of WGDs of the family Fabaceae should be the same and therefore, parsimony would favour a single WGD near the base of Fabaceae over multiple independent WGDs across Fabaceae. In addition, we demonstrated that genome comparison of Papilionoideae with other subfamily provide important insights in understanding genome evolution in legumes.

evolutionary biology↗