Exploring genetic and environmental constraints on life-history trait expression in wild North American red squirrels (Tamiasciurus hudsonicus)
Bibliographic record
Abstract
Life-history trade-offs can occur when constraints on one trait or another limits phenotypic expression. These constraints or limits can be evolutionarily important factors like inherited genetic influences, ecologically important aspects of the environment like resource abundance, and/or physiological factors like the capacity to dissipate endogenous body heat. My thesis took an integrated approach to exploring some of the evolutionary, ecological, and physiological facets that impact wild small mammals in Canada’s northern Boreal forest, and how these facets intersect to influence phenotypic expression. It is also one of a few studies to test the links between phenotypic expression and genetic effects using multivariate response models in a wild setting, as well as to quantify how heritable proportions of phenotypic expression can change across an environmental gradient of food availability. In chapter 3, I found that the heritable fraction of phenotypic variance changes as resource availability changes, increasing during mast years for all three life-history traits compared to other years. Also, that variation in red squirrel life-history trait expression is strongly influenced by the resource environment, and evolution of these three life-history traits for red squirrels of the northern boreal forest may not be constrained by underlying genetic architecture. In chapter 4, I found that red squirrels show consistent phenotypic expression of parturition date regardless of resource environment, but also that there are little genetic constraints on the expression of juvenile growth rate and litter size. On top of this, due to an integrated approach, I tested how the resource environment affects phenotypic expression, and how environmental pressures compound (e.g., the combined effects of changes in resource abundance and ambient temperature), with reproductive phenology, elucidating new avenues of selection pressures. Chapter 5 suggests that due to the lack of direct effect of food during mast years on juvenile growth that there is an inherent effect of mast crops that allows for or spurs the expression of a compensatory allocation strategy by adult female red squirrels to their offspring. While chapter 6 suggests that increasing ambient temperatures, brought about by climate change, in conjunction with delays in parturition date may constrain red squirrel reproduction, potentially constraining the sustainability of their population. As our environments continues to change, with shifting phenologies (both with respect to food production and reproduction) and increasing summer ambient temperatures accelerated at high latitudes, it is imperative that we understand how these changes could constrain reproduction for wildlife and affect their capacity to respond to anthropogenic changes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".