Mutualism between Thisbe irenea butterflies and ants, and the role of ant ecology in the evolution of larval-ant associations

A facultative mutualism between the riodinid butterfly Thisbe irenea and the ponerine ant Ectatomma ruidum is described from Panama. Ants protect larvae against attacks of predatory wasps, but not against tachinid parasitoids. Several potential sources of ecological variation affecting the larval survival of Thisbe irenea are noted. A preliminary means of testing the ability of larvae to appease ants is described that may be applied to all butterfly-ant systems. Observations and literature records indicate that ant taxa which tend butterfly larvae are the same taxa that tend extrafloral nectaries and Homoptera. A general hypothesis for the evolution of myrmecophily among butterflies suggests that ant taxa which utilize secretions in their diet are major selective agents for the evolution of the larval ant-organs, and hence, ant-larval mutualisms. This idea is extended to suggest how appeasement of predaceous ant taxa through the use of larval ant-organs can influence an ant-larval relationship, eventually leading to mutualism.     

Linking species assemblages to environmental change: Moving beyond the specialist-generalist dichotomy

Environmental changes due to land use developments, climate change and nitrogen deposition have profound influences on species assemblages. Investigating the dynamics in species composition as a function of underlying traits may increase our understanding of ecosystem functioning and provide a basis for effective conservation strategies. Here, I use a broad array of species traits for butterflies to identify four main components of associated traits. These reflect the spatial use of the landscape, abiotic vulnerability, developmental rate and phenology, and food specialisation, respectively. The first three trait components each contribute to determine Red List status, but only the developmental rate and phenology component is related to recent population trends. I argue that the latter component reflects the environmental impact of nutrient availability and microclimate, as affected by nitrogen deposition. This perspective sheds a new light on ongoing changes in community composition. Thus, a multidimensional view of trait associations allows us to move beyond the simplistic specialist–generalist dichotomy, renew our view on species-specific studies and help in setting new priorities for conservation.     

Agri-environment schemes and butterflies: the utilisation of two metre arable field margins

The utilisation of two metre field margins by butterflies was studied at three farms in Essex, south east England between 1997 and 2000. The aim of the study was to establish whether field margins, as set up and managed under Countryside Stewardship Scheme guidelines, were beneficial to common farmland butterflies. Thirteen two metre margins (total length 4478 m) and three sections with no margin (total length 656 m) were monitored over the 4 year period using the transect method. Significantly more Maniola jurtina, Thymelicus sylvestris and Thymelicus lineola were seen on the two metre margins than on the control sections, but there was a significant reduction in abundance of Thymelicus sylvestris, Thymelicus lineola and Ochlodes venata on the margins over the 4 year study period. Only the abundance of Pyronia tithonus increased significantly on the two metre margins over that period.     

Core and satellite butterfly species on Elba island (Tuscan Archipelago, Italy). A study on persistence based on 120 years of collection data

Records for butterflies on Elba island in the last 120 years have been summarized and examined. I assessed species occurrence for six periods of twenty years by bibliographic, museum and field data. For five periods data appear complete and species assemblage highly concordant. Nonetheless, a certain evolution of Elba butterflies seems to be occurring. Moreover, I assessed the regression between frequency at sources and frequency on islands among species living on Italian islets and used the residuals as a tendency to be less or more common on islands compared to mainland. By a successive regression, I verified that these residuals are actually related to the number of periods each species has been recorded on Elba. Interestingly, the number of record periods is not correlated with species appearance. I concluded that there is a large core of persistent species and a few species that are occasionally reported on Elba. Such satellite species represent butterflies that are less likely to occupy island biotas and may represent endangered populations.     

关于中国蝶类的几点修正与回顾（鳞翅目：锤角亚目）

关于中国蝶类的几点修正与回顾（鳞翅目：锤角亚目）村山修一（日本大阪府高市城南町４丁目２３—２１）关键词蝶类，修正，中国本文修正了一些最近描述的种的学名，并发表了作者用日文描述的种的英文译文。列出了同物异名。英文译文涉及以下种类：Ｅｕｔｈａｌｌ’ａｎｉ...     

Out-of-Africa again: A phylogenetic hypothesis of the genus Charaxes (Lepidoptera: Nymphalidae) based on five gene regions

Despite the long popularity of Charaxes among collectors and researchers, their evolutionary history is largely unknown. The current and accepted species groupings and relationships within the genus are based exclusively on adult morphology and life histories. Here, we examine the monophyly and evolutionary affinities of the species-groups within the genus Charaxes and explore how they relate to members of their closest genera (Euxanthe, Polyura and Palla) using 4167 bp of sequence data from five (1 mitochondrial and 4 nuclear) gene regions. Within the proposed phylogenetic framework, we estimate ages of divergence within the genus and also reconstruct their historical biogeography. We included representatives of all known species-groups in Africa and Asia, all known species of Euxanthe and Palla and two exemplar species of Polyura. We found the genus Charaxes to be a paraphyletic group with regard to the genera Polyura and Euxanthe, contrary to the earlier assumption of monophyly. We found that 13 out of 16 morphologically defined species-groups with more than one species were strongly supported monophyletic clades. Charaxes nichetes is the sister group to all the other Charaxes. Polyura grouped with the Zoolina and Pleione species-groups as a well-supported clade, and Euxanthe grouped with the Lycurgus species-group. Our results indicated that the common ancestor of Charaxes diverged from the common ancestor of Palla in the mid Eocene (45 million years ago) in (Central) Africa and began diversifying to its extant members 15 million years later. Most of the major diversifications within the genus occurred between the late Oligocene and Miocene when the global climates were putatively undergoing drastic fluctuations. A considerable number of extant species diverged from sister species during the Pliocene. A dispersal–vicariance analysis suggests that many dispersal rather than vicariance events resulted in the distribution of the extant species. The genus Polyura and the Indo-Australian Charaxes are most likely the results of three independent colonizations of Asia by African Charaxes in the Miocene. We synonymize the genera Polyura (syn. nov.) and Euxanthe (syn. nov.) with Charaxes, with the currently circumscribed Charaxes subdivided into five subgenera to reflect its phylogeny.     

Sequential evolution of Euphilotes (Lycaenidae: Scolitantidini) on their plant host Eriogonum (Polygonaceae: Eriogonoideae)

The relationship between the butterfly genus Euphilotes and their host plant genus Eriogonum in western North America is suggested to be one of sequential evolution rather than coevolution. Eriogonum, a genus of nearly 250 species, probably had a Miocene origin, but has had its modern distribution significantly influenced by recent Pleistocene glaciation. The evolution of Euphilotes, as a distinct genus of four sibling species, apparently postdates the establishment and recent proliferation of Eriogonum. Successful speciation in Euphilotes has been accomplished mainly through modifications in genitalia of those butterflies using a single species of Eriogonum. The subsequent proliferation of Euphilotes subspecies has been the result of host switching coupled with geographic isolation onto individual species of Eriogonum acting as restricted biogeographic islands. In the first instance, direct evolutionary competition for a limited resource (one species of Eriogonum) leads to partitioning of that resource by the butterflies whose entire life cycle is associated with that plant species. In the second instance, host switching and isolation have permitted establishment of minor subspecies without significant interaction with other subspecies of the same species. In instances where interspecific subspecies competition exists, resource partitioning, coupled with more pronounced genetic isolation, seem to have occurred resulting in more readily distinct subspecies. We speculate that the success of subspeciation in Euphilotes is dependent upon the numeric size and geographic extent of the host species. Euphilotes subspecies on plants of restricted distributions are themselves seemingly limited in their evolutionary potential as the most dynamic evolution of Euphilotes subspecies is that associated with widespread and variable Eriogonum species. In all instances, the tempo and mode of evolution in Euphilotes appears to be sequential as it follows and is seemingly dependent upon what has already occurred in Eriogonum.     

A typology of indicators of biodiversity change as a tool to make better indicators

Indicators of biodiversity change are of growing political relevance. To be effective, they need to meet a number of scientific requirements, some of which are not easy to fulfil. Here we use a simple typology of biodiversity indicators according to the following two requirements: (1) indicators should reflect changes in biodiversity in general rather than the ups and downs of particular species and species groups, and (2) indicators should be linked to environmental drivers. We apply this typology to existing indicators developed for the Dutch Environmental Data Compendium and describe how the typology may guide the development of indicators of biodiversity change. We conclude that more conceptual and statistical work is needed to make better biodiversity indicators.     

Diuresis and its hormonal control in butterflies

The sudden weight loss after eclosion in the butterflies Acraea horta, Danaus chrysippus and Papilio demodocus is largely due to diuresis. The potassium concentration of the haemolymph is approximately halved as a result, and extensive diuresis leads to increases in sodium concentration and total osmolarity. The isolated Malpighian tubules of all three species are stimulated to fast rates of fluid secretion by cyclic AMP and by homogenates of the brains and corpora cardiaca. The tubules of Papilio lose their sensitivity to stimulation after the first day of adult life, and ingestion of a large volume of artificial nectar by this butterfly does not cause diuresis.     

Habitat reduction and patterns of species loss

This paper uses data of The Distribution Atlas of Polish Butterflies to simulate the effect of four different types of area loss (aggregated, fractal, random, and nested) on species diversity and species–area relationships (SARs). We found that power function and logarithmic SAR models overestimated species loss in the case of aggregated, fractal, and random patterns of area reduction. Instead, the modification of the power function by Plotkin et al. (Proc. Natl. Acad. Sci. USA 97 (2000b) 10850) (S=S₀A^ze^−kA) with k being a shape-adjusting parameter worked better and gave sufficient predictions of species loss. The net effects of the aggregated, fractal, and random types of area loss on species diversity were very similar with an aggregated pattern of area loss leading to slightly higher rates of species loss than both other processes. We conclude that SARs might be useful tools for biodiversity forecasting if they are constructed in a case-specific manner. The use of standard models instead might be misleading.