Data from: Developmental temperature, not inbreeding, shapes life history and locomotor behaviors in juvenile guppies (Poecilia reticulata)

Inbreeding is thought to play a strong role in shaping life-history traits
and behaviors.  Supporting evidence for this role often comes
from observational studies. Experiments that establish causality and
formally test how environmental factors moderate any effects of inbreeding
remain underutilized. We ran an experiment to test how developmental
temperature and inbreeding influence key life-history traits (growth rate,
size, and age at maturity, survival, sex ratio), and locomotor behaviors
(boldness and habituation) in juvenile guppies (Poecilia reticulata). We
used a controlled breeding design to generate inbred and outbred
individuals that were then reared under a control (26°C) or an elevated
temperature (30°C) until maturity. Developmental temperature strongly
affected life-history traits; both sexes matured earlier at 30°C, but only
males exhibited slower early growth and reduced size at maturity. Female
growth and size at maturity were unaffected. The higher developmental
temperature reduced boldness in both sexes; however, only females
habituated to the novel test environment, but this trend was only
significant for females that developed at 26°C. In contrast, inbreeding
had no significant effects on any of the measured traits, nor did it
significantly interact with temperature. In sum, under our experimental
conditions, developmental temperature is the primary driver of phenotypic
plasticity in guppies, generating sex-specific responses in both life
history traits and behavior, while inbreeding between siblings had no
detectable effects on any of the measured traits, even under thermal
stress. Our findings highlight the key role of temperature in shaping
developmental and behavioral trajectories and reveal that a single
generation of inbreeding may not always affect life history traits, even
under environmental stress.