RT Journal Article
SR Electronic
T1 Seasonal plasticity in morphology and metabolism differs between migratory North American and resident Costa Rican monarch butterflies
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.06.17.495480
DO 10.1101/2022.06.17.495480
A1 Ayşe Tenger-Trolander
A1 Cole R. Julick
A1 Wei Lu
A1 Delbert André Green
A1 Kristi L. Montooth
A1 Marcus R. Kronforst
YR 2022
UL http://biorxiv.org/content/early/2022/06/18/2022.06.17.495480.abstract
AB Environmental heterogeneity in temperate latitudes is expected to maintain seasonally plastic life-history strategies that include the tuning of morphologies and metabolism that support overwintering. For species that have expanded their ranges into tropical latitudes, it is unclear the extent to which the capacity for plasticity will be maintained or will erode with disuse. The migratory generations of the North American (NA) monarch butterfly Danaus plexippus lead distinctly different lives from their summer generation NA parents and their tropical descendants living in Costa Rica (CR). NA migratory monarchs postpone reproduction, travel thousands of kilometers south to overwinter in Mexico, and subsist on little food for months. Whether recently dispersed populations of monarchs such as those in Costa Rica, which are no longer subject to selection imposed by migration, retain ancestral seasonal plasticity is unclear. To investigate differences in seasonal plasticity, we reared NA and CR monarchs in summer and autumn in Illinois, USA, and measured seasonal reaction norms for aspects of morphology and metabolism related to flight. NA monarchs were seasonally plastic in forewing and thorax size, increasing wing area and thorax to body mass ratio in autumn. While CR monarchs increased thorax mass in autumn, they did not increase the area of the forewing. NA monarchs maintained similar resting and maximal flight metabolic rates across seasons. However, CR monarchs had elevated metabolic rates in autumn. Our findings suggest that the recent expansion of monarchs into habitats that support year-round breeding may be accompanied by (1) the loss of some aspects of morphological plasticity as well as (2) the underlying physiological mechanisms that maintain metabolic homeostasis in the face of temperature heterogeneity.Competing Interest StatementThe authors have declared no competing interest.