Biology subjects

Halali, S.

Publications and source records attributed to Halali, S..

6 recordsLinked to original sources

bioRxiv2026

Evolution of Reproductive Plasticity in a Seasonal Tropical Environment

Seasonality drives the evolution of reproductive plasticity in butterflies. An extreme form is reproductive diapause, where individuals halt reproduction during unfavourable seasons through cascades translating predictive environmental cues into reproductive phenotypes. How diapause evolves from milder forms of plasticity through changes in those cascades is poorly understood. In the tropics seasonality is common, but it is unclear how phylogenetically widespread reproductive diapause is, and exactly how seasonal tropical climates drive reproductive plasticity. Here, we study reproductive plasticity in Amazon butterflies using a multi-year monthly time series of reproductive phenotypes. Sampling 4 subfamilies across Nymphalids, we observe a phylogenetically widespread occurrence of diapause, suggesting repeated evolutionary changes in reproductive plasticity. Detailed analyses of two Catonephele species reveal a shared temperature response, but dry season diapause only in C. acontius. Thus, evolution of diapause combines cue conservation with species-specific divergence of trait plasticity, suggesting gradual and modular evolution of reproductive plasticity.

evolutionary biology↗

bioRxiv2026

Dietary ethanol affects feeding behaviour, flight performance, and mating success in a fruit-feeding butterfly

O_LIThe evolution of fleshy fruits around 124 million years ago introduced a nutritious resource and drove shifts toward fruit-feeding across the animal kingdom, leading to a variety of adaptations for locating and exploiting this resource. Fruits are inherently dynamic, changing in physical, chemical, and biological properties as they progress from development through ripening to decay. C_LIO_LIFruit fermentation produces ethanol, a volatile compound that is simultaneously caloric, intoxicating, and potentially noxious. While the immediate and long-term effects of dietary ethanol are well documented in mammals, and to some extent in insects such as Drosophila, very little is known about its impact on frugivorous butterflies. C_LIO_LIAlthough ethanol can serve as a foraging cue for frugivorous butterflies, its ingestion may impair performance and reduce fitness. Here, we examine how dietary ethanol affects ecologically and reproductively relevant behaviours in the Afrotropical butterfly Bicyclus anynana, a species that feeds on fermenting fruits in the wild. C_LIO_LIWe found that butterflies exposed to ethanol-supplemented diets initiated feeding more rapidly, but also spent less time feeding, and they required more stimuli to sustain flight. Moreover, feeding behaviour differed between males and females and between mated and virgin individuals, while flight performance differed between sexes but was not affected by mating status. C_LIO_LIGiven the involvement of flight in male courtship, we also tested the hypothesis that negative effects of ethanol consumption on flight would impair courtship. We found that males fed on ethanol-supplemented diets--particularly young ones--had reduced mating success and took longer to secure a mating. C_LIO_LITogether, our findings demonstrate that ethanol consumption affects behaviours closely tied to survival and fitness in B. anynana, suggesting that exposure to fermenting resources may impose selective pressures on physiology, behaviour, and reproductive strategies in frugivorous insects. C_LI

animal behavior and cognition↗

bioRxiv2023

Larval growth rate affects wing shape more than eyespot size in the seasonally polyphenic butterfly Melanitis leda

Butterflies often show adaptive phenotypic plasticity where environmental cues during early stages are used to produce a phenotype that maximizes fitness in the environment experienced by adults. Many tropical satyrine butterflies (Nymphalidae: Satyrinae) are seasonally polyphenic and produce distinct wet- and dry-season form adults providing tight environment-phenotype matching in seasonal environments. Dry-season forms, which are expressed in the dry season, can be induced in the laboratory by growing larvae at low temperatures or on poor food quality. Since both these factors also tend to reduce larval growth rate, larval growth rate may be an internal cue that translates the environmental cues into the expression of phenotypes. If this is the case, we predict that slower-growing larvae would be more likely to develop a dry-season phenotype. To test this hypothesis, we measured both larval growth rate and adult phenotype (eyespot size and wing shape) of individuals of the common evening brown butterfly (Melanitis leda), reared at various temperatures and on various host-plant species. We found that among treatments, larvae with lower growth rates (low temperature, particular host plants) were more likely to develop dry-season phenotypes (small eyespots, falcate wing tips), but within treatments, larval growth rate was mainly linked to wing shape, not eyespot size. These relationships tended to be stronger for males than females as males showed a wider range of eyespot sizes and wing shapes. Overall, only plasticity in wing shape appears to be (partly) mediated by larval growth, and in a sex-specific manner.

evolutionary biology↗

bioRxiv2022

Exploring links between climatic predictability and the evolution of within- and transgenerational plasticity

In variable environments, phenotypic plasticity can increase fitness by providing tight environment-phenotype matching. However, adaptive plasticity is expected to evolve only when the future selective environment can be predicted based on the prevailing conditions. That is, the juvenile environment should be predictive of the adult environment (within-generation plasticity) or the parental environment should be predictive of the offspring environment (transgenerational plasticity). Here, we test links between environmental predictability and evolution of adaptive plasticity by combining time series analyses and a common garden experiment using temperature as a stressor in a temperate butterfly (Melitaea cinxia). Time series analyses revealed that across season fluctuations in temperature over 48 years is overall predictable. However, within the growing season, temperature fluctuations showed high heterogeneity across years with low autocorrelations and timing of temperature peaks were asynchronous. Most life-history traits showed strong within-generation plasticity for temperature and traits such as body size and growth rate broke the temperature-size rule. Evidence for transgenerational plasticity, however, was weak and detected for only two traits each in an adaptive and non-adaptive direction. We suggest that low predictability of temperature fluctuations within the growing season likely disfavours the evolution of adaptive transgenerational plasticity but instead favours strong within-generation plasticity.

evolutionary biology↗

bioRxiv2020

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

Global change can trigger shifts in habitat stability and shape the evolution of organismal life-history strategies, with unstable habitats typically favouring a faster pace-of-life. 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 ~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.

evolutionary biology↗

bioRxiv2019

To mate, or not to mate: The evolution of reproductive diapause facilitates insect radiation into African savannahs in the Late Miocene

O_LIMany tropical environments experience cyclical seasonal changes, frequently with pronounced wet and dry seasons, leading to a highly uneven temporal distribution of resources. Short-lived animals inhabiting such environments often show season-specific adaptations to cope with alternating selection pressures.\nC_LIO_LIAfrican Bicyclus butterflies show strong seasonal polyphenism in a suite of phenotypic and life-history traits, and their adults are thought to undergo reproductive diapause associated with the lack of available larval host plants during the dry season.\nC_LIO_LIUsing three years of longitudinal field data for three species in Malawi, dissections demonstrated that one forest species reproduces continuously whereas two savannah species undergo reproductive diapause in the dry season, either with or without pre-diapause mating. Using additional data from field-collected and museum samples, we then documented the same three mating strategies for a further 37 species.\nC_LIO_LIPhylogenetic analyses indicated that the ancestral state was a non-diapausing forest species, and that habitat preference and mating strategy evolved in a correlated fashion.\nC_LIO_LIBicyclus butterflies underwent rapid diversification during the Late Miocene, coinciding with expansions into more open savannah habitat. We conclude that the ability to undergo reproductive diapause was a key trait that facilitated colonization and eventual radiation into savannahs in the Late Miocene.\nC_LI

evolutionary biology↗