Biology subjects

Molleman, F.

Publications and source records attributed to Molleman, F..

6 recordsLinked to original sources

bioRxiv2025

Contrasting mechanisms for using humidity as cue for seasonal polyphenism in two tropical butterflies

Many tropical butterflies show wing pattern plasticity across dry and wet seasons. Dry-season morphs of satyrines (Nymphalidae: Satyrinae) typically are cryptic with small or no eyespots on the ventral wing surface. In contrast, wet-season morphs have large eyespots on their wing margins. These eyespots deflect predator attacks away from vital body parts. Extensive studies have shown that eyespot size is influenced by the temperature experienced during larval development. Temperature-mediated eyespot size plasticity is adaptive in regions where temperature increases with the onset of the wet season. However, many tropical regions lack a reliable temperature-rainfall correlation, and thus, temperature may not always be a reliable predictor of the upcoming adult environment. A potential environmental cue that correlates strongly with seasonality is relative humidity (hereafter, humidity). With the approach of the wet season, humidity increases, and then declines with the onset of the dry season. Here, we tested whether humidity modulates eyespot-size plasticity in two sympatric butterflies that experience similar ecological pressures: Mycalesis mineus and Melanitis leda. We found that humidity directly influenced eyespot size in My. mineus; individuals reared at high humidity developed into adults with larger eyespots than those from low humidity. In contrast, eyespot size in Me. leda showed a weak direct effect of humidity. Instead, humidity modulated eyespot size in Me. leda indirectly through induced changes in the host plant quality. Since the late larval and prepupal stages are temporally closer to the adult environment, selection may favour greater sensitivity to the environmental cue during these stages than during early larval stages. To determine the humidity-sensitive phase, we conducted a switching experiment where humidity was shifted from low to high, and vice versa, at different developmental stages. We demonstrated that, in My. mineus, wandering larval and prepupal stages are sensitive to humidity, whereas the early-feeding larval phases are insensitive. Contrastingly, humidity switching did not influence the eyespot size in Me. leda. This study highlights how two diverging species, evolving under similar ecological pressures, integrate environmental cues in distinct ways to modulate wing pattern plasticity.

evolutionary biology↗

bioRxiv2025

Local adaptations in wing-pattern and life history trait plasticity in a butterfly: humidity as a cue where temperature is unreliable

Many butterflies have wet and dry season morphs with large and small wing eyespots respectively. Eyespot size plasticity is adaptive because the morphs function to avoid predation in their respective season. Eyespot size has been shown to be regulated by rearing temperature in many species. However, temperature is unreliable in some regions because it poorly predicts seasons, and other cues such as humidity may be more reliable. We investigated inter-population differences in cue use for eyespot plasticity in the butterfly Melanitis leda. We reared butterflies from three Indian populations under combinations of temperature and humidity. Butterflies from a population (Vithura) where humidity differentiates seasons but temperature does not, responded only to humidity. Butterflies from a population (Tirunelveli) where seasonality is not distinct, and where temperature and humidity are both unreliable, also responded only to humidity. Butterflies from another population (Coimbatore) where seasonality is not distinct, but where temperature has the highest intra-annual variation, responded only to temperature. This suggests local adaptation in cue use. Life-history traits also differed among populations, with the two populations from more arid regions developing faster and attaining larger body sizes than the one from the humid region. Fast development may be adaptive in dry regions where suitable host plants are available only briefly, while large body size may confer desiccation resistance. We show for the first time that humidity can regulate eyespot size, and that reaction norms vary across populations, fitting to regional climates.

ecology↗

bioRxiv2025

Parasitoids reduce growth rate in oak-feeding caterpillars

O_LIKoinobiont parasitoids have been shown to both reduce and increase the growth rate of caterpillars. However, no comprehensive study has been conducted on all caterpillar hosts of a given plant species. Moreover, most of the existing case studies are on large caterpillars attacking crop plants. This may not be representative of the effect of parasitoids on caterpillar growth on trees. C_LIO_LIWe measured the growth rate of parasitised and non-parasitised spring caterpillars collected from oak trees (Quercus robur & Q. petraea) in France and Poland. C_LIO_LIAcross six species of Lepidoptera, parasitoids reduced caterpillar growth rate on average. C_LIO_LIFurther studies should determine if the reduced growth rate is accompanied by lower consumption rates, so that the plant directly benefits from attracting parasitoids when they are attacked by caterpillars. C_LI

ecology↗

bioRxiv2025

A high-quality draft genome assembly of the Neotropical butterfly, Batesia hypochlora (Nymphalidae: Biblidinae)

We report a long-read high-coverage reference genome assembly of the Neotropical butterfly, Batesia hypochlora (Nymphalidae: Biblidinae). This represents the first reference genome in the Biblidinae subfamily, a clade subject to ongoing studies on seasonal and climate adaptation in the Amazon. We assembled the genome from PacBio HiFi long reads (66X coverage), polished it with Illumina short reads (15X coverage), and annotated it using PacBio IsoSeq RNA data. We observed 15 chromosome-sized scaffolds varying in length from 13.2 Mbp to 37.6 Mbp (median 24.3 Mbp), combining a total genome size of 395.788 Mbp. This assembly is highly contiguous (contig N50 of 25.14 Mbp) and complete (BUSCO completeness score of 98.6% and 0.2% duplication rate). Repeat annotation revealed that the genome consists of about one-third transposable elements. Gene prediction using RNAseq evidence uncovered 19,395 genes, of which 17,400 were assigned to 2,883 orthogroups when including genomes of the fruitfly, silk moth, and three other Nymphalid butterfly species. The high sequencing depth also allowed us to assemble the genomes of the mitochondria and the common endosymbiotic bacterium Wolbachia. The mitochondrial genome was fully assembled (15,540 bp in size) with all expected genes annotated. The Wolbachia genome was fragmented, and we determined that it belongs to the B-supergroup. The high-quality assembly of B. hypochlora can represent the subfamily in further comparative analysis of evolution and provide a key resource for ongoing work to explore reproductive biology and adaptations to seasonality in Amazonian butterflies.

genomics↗

bioRxiv2025

Larger and polymorphic noctuid moths tend to show less inter-annual abundance variation in the canopy of a temperate forest

Inter-annual variation in insect abundance and seasonal phenology can be related to species traits such as body size, larval diet, overwintering stage, and colour variations. We sampled noctuid moths in the canopy of a forest in Western Poland using flight-interception traps during two vegetative seasons. We calculated inter-annual variation for 31 species, and date of peak abundance and length of the flight season for 18 species. We found that for the 23 species for which we had phylogenetic information, larger moths and those with adult colour variation showed less inter-annual abundance variation, which corroborates results of previous studies. We found no indication that phenological traits are associated with the tested species traits. However, species that can feed on the dominant broad-leaved tree in which the traps were placed (Quercus petraea) tended to have a later date of peak abundance than other species. To draw more robust conclusions, future research should encompass a longer time span and a broader range of species. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/643003v2_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@1ed537eorg.highwire.dtl.DTLVardef@494f5org.highwire.dtl.DTLVardef@cf7559org.highwire.dtl.DTLVardef@21495a_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

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↗