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Abstract PremiseShowy mistletoes are obligate hemiparasites of woody plants. Host specificity is therefore a fundamental determinant of mistletoe diversity, persistence, geographic distribution, and abundance. Investigations of host specificity in Australian Loranthaceae have focused mostly on host range (taxon counts), but additional insights into specificity are gained by quantifying mistletoe prevalence on taxa in their host range and by exploring specificity in a phylogenetic context. MethodsWe estimated measures of host specificity to characterize mistletoe–host interactions at a continental scale by using occurrence records in the Atlas of Living Australia. We calculated host taxon richness, mistletoe prevalence, and phylogenetic diversity, and used rarefaction curves to evaluate sampling coverage. ResultsMany mistletoe taxa were represented by few records that listed the host, which often was identified to genus only. Mistletoe genera were recorded on 29 orders and 80 families, and no association was observed between host richness and number of records per genus. Rarefaction curves suggested that additional host orders and families remain to be discovered forAmylotheca,Decaisnina,Dendrophthoe, andMuellerina. Four mistletoe genera were most prevalent on Myrtales, one on Fabales, and one on Laurales. Rosids were most often the recorded hosts (84.3% of all records). We found evidence of significant phylogenetic clustering in host use byAmyema,Amylotheca, andDecasinina. ConclusionsOur results, particularly the high prevalence on rosids, suggest that relationships of mistletoes with rainforest lineages may have been established early in the history of Australian Loranthaceae and that some lineages co‐diversified with their hosts in arid regions. 

Abstract Coloration is a multifaceted trait that serves various functions, including predator defense, thermoregulation, and immune response, among others. We investigated pupal color variation in Chlosyne lacinia pupae, focusing on identifying the cue that influences variation in melanization. Through laboratory experiments, we demonstrated that pupae reared on black backgrounds exhibited significantly higher melanization compared to those on white backgrounds. Additionally, black pupae experienced longer developmental periods, suggesting a trade-off between defense and developmental time. Our findings support crypsis as a likely evolutionary driver for increased melanization in response to substrate color. We discuss potential implications for predator avoidance, immune response, and developmental costs associated with melanization. This study provides insights into the adaptive significance of pupal melanization in response to environmental cues, shedding light on the complex interplay between life history traits in butterflies. 

Abstract Sodium is essential for animals, and its heterogeneous distribution can cause a range of phenomena, from sodium‐seeking behaviours to impacting their performance. Although sodium content in soils and plants is relatively well documented, data for higher trophic levels are limited. Knowledge of the variation in sodium in lower trophic levels could have implications for understanding the behaviour and physiology of species at higher levels.We investigated the variation in tissue sodium concentration between males and females of four butterfly species. Puddling behaviour of Lepidoptera suggests sodium needs of males are generally greater than females, thus, we predicted males would accumulate more sodium than females on a given diet.Larvae were reared on plants (forBattus philenor,Chlosyne laciniaandDanaus plexippus) and an artificial diet (forPieris rapae) under Low Na (no added sodium) and High Na (sodium added) conditions. Among species and sexes, we quantified and compared adult absolute tissue sodium concentrations and bioconcentration factors, which indicate net sodium accumulation or excretion relative to individuals' diets.On average, individuals on low‐sodium diets had higher bioconcentration values across all species. Male butterflies accumulated significantly higher sodium concentrations than females in two sodium treatments forB. philenor, andP. rapaeand only in the High Na treatment forC. lacinia. However, inD. plexippus, individuals accumulate sodium in the High Na treatment, but males and females responded in the same way.Our study revealed sex‐ and species‐specific patterns of butterfly sodium accumulation, which could be linked to variations in behaviour and/or performance. Differences in sodium content across species have implications for variation in predation and trophic‐level interactions, an interesting avenue for future ecological and evolutionary research. 

Abstract As an abundant element in the Earth’s crust, sodium plays an unusual role in food webs. Its availability in terrestrial environments is highly variable, but it is nonessential for most plants, yet essential for animals and most decomposers. Accordingly, sodium requirements are important drivers of various animal behavioural patterns and performance levels. To specifically test whether sodium limitation increases cannibalism in a gregarious lepidopteran herbivore, we hydroponically manipulatedHelianthus annuushost plants' tissue-sodium concentrations. Gregarious larvae of the bordered patch butterfly,Chlosyne lacinia, cannibalized siblings when plant-tissue sodium concentrations were low in two separate experiments. Although cannibalism was almost non-existent when sodium concentrations were high, individual mortality rates were also high. Sodium concentration in host plants can have pronounced effects on herbivore behaviour, individual-level performance, and population demographics, all of which are important for understanding the ecology and evolution of plant-animal interactions across a heterogeneous phytochemical landscape. 

Abstract Urbanisation is occurring globally, leading to dramatic environmental changes that are altering the ecology and evolution of species. In particular, the expansion of human infrastructure and the loss and fragmentation of natural habitats in cities is predicted to increase genetic drift and reduce gene flow by reducing the size and connectivity of populations. Alternatively, the ‘urban facilitation model’ suggests that some species will have greater gene flow into and within cities leading to higher diversity and lower differentiation in urban populations. These alternative hypotheses have not been contrasted across multiple cities. Here, we used the genomic data from the GLobal Urban Evolution project (GLUE), to study the effects of urbanisation on non‐adaptive evolutionary processes of white clover (Trifolium repens) at a global scale. We found that white clover populations presented high genetic diversity and no evidence of reducedN_elinked to urbanisation. On the contrary, we found that urban populations were less likely to experience a recent decrease in effective population size than rural ones. In addition, we found little genetic structure among populations both globally and between urban and rural populations, which showed extensive gene flow between habitats. Interestingly, white clover displayed overall higher gene flow within urban areas than within rural habitats. Our study provides the largest comprehensive test of the demographic effects of urbanisation. Our results contrast with the common perception that heavily altered and fragmented urban environments will reduce the effective population size and genetic diversity of populations and contribute to their isolation. 

We conducted a literature review and added some novel observations of the natural history of the bordered patch butterfly, Chlosyne lacinia (Nymphalidae). Regarding color and patterning, C. lacinia is considered one of the most variable butterflies in the Western Hemisphere, with phenotypic variation occurring in larvae, pupae, and adults. Several studies have been conducted on C. lacinia, partly due to its notable phenotypic variation and status as a pest species of domestic sunflowers (Helianthus annuus). Even so, the origins, development, and maintenance of phenotypic variation remain poorly known. Having the most extensive geographic range of any species in its genus, C. lacinia ranges from Argentina to the mid-latitude midwestern United States. Moreover, C. lacinia displays six distinct adult morphs across its geographic range. Morphologically continuous, relatively geographically narrow gradients between adjacent morphs have given rise to alternative interpretations about subspecies. By providing the first comprehensive maps of adult morphs, including data collected via citizen science in iNaturalist, we provide directions for further research into the species' biology. Realizamos una revisión bibliográfica sobre la historia natural de la mariposa del parche bordeado, Chlosyne lacinia (Nymphalidae) que complementamos con observaciones nuevas. En cuanto al color y el patrón, C. lacinia se considera una de las mariposas más variables del hemisferio occidental, con variación fenotípica en larvas, pupas y adultos. Se han realizado numerosos estudios sobre C. lacinia, principalmente debido a su notable variación fenotípica y a su condición de especie plaga del girasol doméstico (Helianthus annuus). Aun así, el origen, desarrollo y mantenimiento de esta variación fenotípica siguen siendo poco estudiados. Teniendo la distribución geográfica más extensa de todas las especies de su género, C. lacinia se encuentra desde Argentina hasta latitudes medias del medio oeste de Estados Unidos. Además, C. lacinia presenta seis distintos morfos adultos a través de su distribución geográfica. Debido a que morfos geográficamente adyacentes presentan una morfología continua entre ellos, el reconocimiento de las subespecies es controversial. A través de mapas de distribución de cada morfo adulto con datos de iNaturalist, planteamos hipótesis y preguntas para futuras investigaciones sobre la biología de esta especie. 

Host-parasite interactions and host susceptibility are key traits in understanding trophic energy transfer, nutrient movement and general macro-ecoevolutionary dynamics of mistletoe systems and plant-plant interactions. This research investigates host susceptibility and size-dependent interactions of the mistletoe Phoradendron quad- rangulare, a widely distributed species, on Guazuma ulmifolia. We studied the interplay between mistletoe load and host tree size, while also exploring the allometric relationship between host branch size and mistletoe size. A field surveys on 67 trees revealed varying mistletoe loads, with most trees showing no occurrence of P. quadrangulare. Parasitized trees had significantly larger diameters at breast height (DBH) than non-parasitized trees. The susceptibility of host trees to mistletoe parasitism increased with increasing DBH, indicating a positive relationship between host size and mistletoe prevalence. Furthermore, mistletoe stem diameter was found to be influenced by the diameter of the host branch suggesting that larger host trees provide more substrate for larger-sized parasites and surface area for mistletoe colonization, potentially contributing to the parasite’s survival and prevalence. This study also highlights the importance of host size in mistletoe presence and performance and provides insights into the broader eco-evolutionary dynamics and conservation strategies needed to conserve mistletoes, an often-underappreciated keystone taxa. 

Some mistletoe species (Loranthaceae) resemble their host plants to a striking degree. Various mechanisms have been proposed for the developmental origins of novel traits that cause mistletoes to appear similar to their hosts, as well as for the adaptive phenotypic evolution of such traits. Calder (1983) proposed a logically flawed group selectionist seed‐dispersal hypothesis for mistletoes to resemble their hosts. Calder's (1983) hypothesis does not provide a viable potential explanation for mistletoe resemblance to hosts.