Stiver, K. A. | Search bioRxiv

bioRxiv2025

Warm waters undermine cryptic female choice

Reproduction is often more thermally sensitive than survival. Thus, understanding the thermal sensitivity of reproductive interactions is crucial given global warming. However, it is unknown how temperature influences female control over fertilization after mating (i.e., cryptic female choice). We tested how temperatures relevant to current conditions and climate change projections influence cryptic female choice in a marine fish, Symphodus ocellatus. Under typical conditions, females bias fertilization dynamics to favor dominant males. We find that warmer temperatures decrease female influence on sperm velocity and reduce the expected paternity of dominant males. Our results demonstrate that temperatures relevant to climate change can shift the balance between mate choice and male-male competition. Thus, climate change may influence sexual selection, leading to evolutionary changes in reproductive traits.

evolutionary biology↗

bioRxiv2021

Morpholino-mediated knockdown of the brain mineralocorticoid receptor affects glucocorticoid signaling and neuroplasticity in wild ocellated wrasse (Symphodus ocellatus)

Uncovering the genetic, physiological, and developmental mechanisms underlying phenotypic variation is necessary for understanding how genetic and genomic variation shape phenotypic variation and for discovering possible targets of selection. Although the neural and endocrine mechanisms underlying social behavior are evolutionarily ancient, we lack an understanding of the proximate causes and evolutionary consequences of variation in these mechanisms. Here, we examine in the natural environment the behavioral, neuromolecular, and fitness consequences of a morpholino-mediated knockdown of the mineralocorticoid receptor (MR) in the brain of nesting males of the ocellated wrasse, Symphodus ocellatus, a species with male alternative reproductive tactics. Even though MR knockdown did not significantly change male behavior directly, this experimental manipulation strongly altered glucocorticoid signaling and neuroplasticity in the preoptic area, the putative hippocampus homolog, and the putative basolateral amygdala homolog. We also found that individual variation in stress axis gene expression and neuroplasticity is strongly associated with variation in male behavior and fitness-related traits. The brain region-specific effects of MR knockdown on phenotypic integration in the wild reported here suggest specific neuroendocrine and neuroplasticity pathways that may be targets of selection.

animal behavior and cognition↗