Seasonal environments drive convergent evolution of a faster pace‐of‐life in tropical butterflies

Abstract

New ecological niches that may arise due to climate change can trigger diversification, but their colonisation often requires adaptations in a suite of life-history traits. We test this hypothesis in species-rich Mycalesina butterflies that have undergone parallel radiations in Africa, Asia, and Madagascar. First, our ancestral state reconstruction of habitat preference, using c. 85% of extant species, revealed that early forest-linked lineages began to invade seasonal savannahs during the late Miocene-Pliocene. Second, rearing replicate pairs of forest and savannah species from the African and Malagasy radiation in a common garden experiment, and utilising published data from the Asian radiation, demonstrated that savannah species consistently develop faster, have smaller bodies, higher fecundity with an earlier investment in reproduction, and reduced longevity, compared to forest species across all three radiations. We argue that time-constraints for reproduction favoured the evolution of a faster pace-of-life in savannah species that facilitated their persistence in seasonal habitats.

phytools 2.0: An updated R ecosystem for phylogenetic comparative methods (and other things)

“…To try out our polymorphic trait evolution model, let's use an excellent, recently-published dataset from Halali et al (2020) consisting of a phylogenetic tree containing 287 Mycalesina butterfly species and data for butterfly habitat use. Halali et al (2020) coded habitat as a polymorphic trait in which, for example, a species using both "forest" and forest "fringe" habitat would be coded as "forest+fringe".…”

“…To try out our polymorphic trait evolution model, let's use an excellent, recently-published dataset from Halali et al (2020) consisting of a phylogenetic tree containing 287 Mycalesina butterfly species and data for butterfly habitat use. Halali et al (2020) coded habitat as a polymorphic trait in which, for example, a species using both "forest" and forest "fringe" habitat would be coded as "forest+fringe". In this case, our polymorphic trait evolution model will assume that to evolve from forest specialization to fringe specialization, a species must first (at least transiently) evolve through the polymorphic condition of using both habitats at once.…”

“…The Halali et al (2020) dataset and tree now come packaged with the phytools library, so both can be loaded using the data function, just as we've seen already for other datasets of this article.…”

Leafminer attack accelerates the development of soil‐dwelling conspecific pupae via plant‐mediated changes in belowground volatiles

“…Developmental time is an important component of insect fitness, the latter defined as the total number of offspring produced by an individual during its lifetime that survive to join the mating population of the next generation (Thompson et al ., 2011 ). Fast life‐history strategies including high growth rates and fecundity, at the cost of reduced longevity, allow the rapid increase in insect population sizes in seasonal habitats (Halali et al ., 2021 ). Faster pupal development may therefore increase L .…”

“…However, it should be noted that a rapid development might entail physiological and ecological trade‐offs as well. For instance, faster developmental times in insects can result in reduced adult biomass (Halali et al ., 2021 ), which in some cases correlates with lower reproductive performance and fecundity (Awmack & Leather, 2002 ). In addition, an increased growth rate might potentiate intraspecific competition for the resources, which can negatively affect insect population growth (Agrawal, 2004 ).…”