Timing is key: Why do sex differences in phenology exist?
Many plants and animals adjust their behavior, physiology, or morphology to match seasonal changes in the environment (phenology). The timing of these seasonal events, like flowering, migration, hibernation, and breeding, can vary geographically, and even between males and females at the same location. A literature review found examples of sex differences in phenology and examine how and why they occur. This is important because climate change could affect seasonality in males and females differently, impacting the future of populations.
Researchers focused on 4 different “big questions” or approaches to understand how and why animals behave the way they do (Tinbergen’s 4 questions). They asked why it is advantageous for species to exhibit sex differences in seasonal timing and found evidence that this might arise from competition for territories and mates, or from differences in how the natural environment selects for timing in males and females. They asked whether sex differences in seasonal timing change over development and what physiological mechanisms in the “timing circuits” in the brain might cause them.
While there are a growing number of studies that describe mechanisms that regulate seasonal timing, very little is known about differences between males and females. Researchers also asked whether there are phylogenetic patterns in sex differences. Since very little is known about phylogenetic variation in seasonality, ideas about how new genomic approaches could make advances in this field. Very little research has explicitly addressed sex differences in seasonal timing and that understanding how and why these differences occur is important for predicting the response of species to climate change.
Males and females can differ in the time that they exhibit important seasonal events like breeding, migration, and hibernation. Phenological differences could arise from sexual and natural selection, and the interaction between these forces. The mechanisms behind sex differences in seasonality are not well-understood.