Erki Õunap

Systematic position of Lythriini revised: transferred from Larentiinae to Sterrhinae (Lepidoptera, Geometridae)

The tribe Lythriini is a small group of diurnally active geometrid moths consisting of a single Palaearctic genus Lythria with five species. The systematic placement of Lythriini has remained controversial: though traditionally it has been placed into the subfamily Larentiinae, a number of morphological characters link this tribe with the subfamily Sterrhinae. A molecular phylogenetic study was conducted to verify the systematic position of Lythriini, using sequences of both mitochondrial and nuclear genes: elongation factor 1α (EF‐1α), wingless (wgl), 28S rRNA expansion segment D2 (28S D2), cytochrome oxidase subunit 1 (COI) and NADH dehydrogenase subunit 1 (ND1) (a total of 3784 bp). Phylogenetic analysis reliably demonstrated that Lythriini belong to the subfamily Sterrhinae. Therefore, we propose to remove tribe Lythriini from Larentiinae and unite it with Sterrhinae. Moreover, our analysis supports the monophyly of both Sterrhinae and Larentiinae. However, although both morphological data and interspecific genetic distances insinuated that Lythria cruentaria and L. sanguinaria are sister species, the latter formed a clade of sister taxa together with L. purpuraria.

Degree of specialization is related to body size in herbivorous insects: a phylogenetic confirmation

Numerous studies have suggested a general relationship between the degree of host specialization and body size in herbivorous animals. In insects, smaller species are usually shown to be more specialized than larger‐bodied ones. Various hypotheses have attempted to explain this pattern but rigorous proof of the body size–diet breadth relationship has been lacking, primarily because the scarceness of reliable phylogenetic information has precluded formal comparative analyses. Explicitly using phylogenetic information for a group of herbivores (geometrid moths) and their host plant range, we perform a comparative analysis to study the body size–diet breadth relationship. Considering several alternative measures of body size and diet breadth, our results convincingly demonstrate without previous methodological issues—a first for any taxon—a positive association between these traits, which has implications for evaluating various central aspects of the evolutionary ecology of herbivorous insects. We additionally demonstrate how the methods used in this study can be applied in assessing hypotheses to explain the body size–diet breadth relationship. By analyzing the relationship in tree‐feeders alone and finding that the positive relationship remains, the result suggests that the body size–diet breadth relationship is not solely driven by the type of host plant that species feed on.

Lycaena dispar on its northern distribution limit: an expansive generalist

The aim of this study was to evaluate host plant and habitat preferences of Lycaena dispar, an oligophagous butterfly species endangered in some parts of its European range. In laboratory trials, the females of Estonian populations accepted various species of Rumex as oviposition substrates. Growth performance of the larvae did not differ between the hosts offered (only R. acetosa proved to be unsuitable). In the field, extensive use of the two most common host species – R. crispus and R. obtusifolius – by the Estonian populations of L. dispar was confirmed. Unlike in the laboratory, larval performance in the field was better on R. obtusifolius than R. crispus. A likely explanation is the more ephemeral character of the aboveground parts of R. crispus plants: these tend to wilt before the larvae of L. dispar have reached the stage adapted to hibernation. A countrywide analysis of landscape occupancy revealed a positive association of the occurrence of L. dispar with ditches and human settlement. We conclude that moderate anthropogenic pressure maintains suitable habitats for L. dispar through creating favourable conditions for R. obtusifolius, the primary host of the butterfly in the region. Due to its generalism in both host and habitat use, L. dispar is not in the need of active conservation measures on the current northern limit of its distribution. The favourable status of the species in Estonia is corroborated by its recent range expansion which parallels similar trends elsewhere in Eastern Europe.

Phylogeny of the subfamily Larentiinae (Lepidoptera: Geometridae): integrating molecular data and traditional classifications: Phylogeny of Larentiinae

Larentiinae are the second largest subfamily of Geometridae, with more than 6200 described species. Despite recent advances in molecular systematics of geometrid moths, phylogenetic relationships between the numerous subgroups of Larentiinae are poorly known. In this study we present the most comprehensive attempt to date to resolve the phylogeny of Larentiinae, having sampled at least one species from all currently recognized 23 tribes. Fragments of one mitochondrial (COI) and eight nuclear (EF‐1α, WGL, GAPDH, RPS5, IDH, MDH, CAD and 28S) genes were sequenced, for a total of 6939 bp. Maximum likelihood and Bayesian analyses resulted in identical well‐resolved phylogenetic trees, which had maximum or near‐maximum support values at most nodes. Almost all conventionally recognized tribes represented by more than one genus were found to be monophyletic. Close to the root of Larentiinae, six tribes branch off the main lineage one after another, with Dyspteridini being sister to all other members of the subfamily. The rest of larentiines are divided into two very diverse lineages, comprising eight and at least ten tribes, respectively. There were just three findings incongruent with the conventional tribal subdivision of the subfamily. First, the genera Collix Guenée and Anticollix Prout formed a separate, previously unrecognized but well‐supported clade at the tribe level. Second, the Palaearctic genus Pelurga Hübner was placed apart from Larentia Treitschke and Mesoleuca Hübner, which were the other members of Larentiini in this analysis. Third, Cataclysmini appeared together with genera belonging to Xanthorhoini, leaving the latter paraphyletic. The Neotropic genus Oligopleura Herrich‐Schäffer is shown to belong to the tribe Euphyiini (comb.n.) according to both molecular data and male genital morphology. The results and the tribal classification of Larentiinae are discussed with reference to the principal publications since the end of the 19th Century. We conclude that the current tribal classification of Larentiinae is not controversial from the phylogenetic point of view and that its increasing complexity has merely reflected the accumulation of information, mainly through different methods of biosystematic study having become available for researchers. Our results indicate that diurnal lifestyle, accompanied by conspicuous coloration, has evolved independently in several subgroups of Larentiinae.

An ordination of life‐histories using morphological proxies: capital vs income breeding in insects

Predictive classifications of life histories are essential for evolutionary ecology. While attempts to apply a single approach to all organisms may be overambitious, recent advances suggest that more narrow ordination schemes can be useful. However, these schemes mostly lack easily observable proxies of the position of a species on respective axes. It has been proposed that, in insects, the degree of capital (vs. income) breeding, reflecting the importance of adult feeding for reproduction, correlates with various ecological traits at the level of among-species comparison. We sought to prove these ideas via rigorous phylogenetic comparative analyses. We used experimentally derived life-history data for 57 species of European Geometridae (Lepidoptera), and an original phylogenetic reconstruction. The degree of capital breeding was estimated based on morphological proxies, including relative abdomen size of females. Applying Brownian-motion-based comparative analyses (with an original update to include error estimates), we demonstrated the associations between the degree of capital breeding and larval diet breadth, sexual size dimorphism, and reproductive season. Ornstein-Uhlenbeck model based phylogenetic analysis suggested a causal relationship between the degree of capital breeding and diet breadth. Our study indicates that the gradation from capital to income breeding is an informative axis to ordinate life-history strategies in flying insects which are affected by the fecundity vs. mobility trade off, with the availability of easy to record proxies contributing to its predictive power in practical contexts.

A comparative perspective on longevity: the effect of body size dominates over ecology in moths

Both physiologically and ecologically based explanations have been proposed to account for among‐species differences in lifespan, but they remain poorly tested. Phylogenetically explicit comparative analyses are still scarce and those that exist are biased towards homoeothermic vertebrates. Insect studies can significantly contribute as lifespan can feasibly be measured in a high number of species, and the selective forces that have shaped it may differ largely between species and from those acting on larger animals. We recorded adult lifespan in 98 species of geometrid moths. Phylogenetic comparative analyses were applied to study variation in species‐specific values of lifespan and to reveal its ecological and life‐history correlates. Among‐species and between‐gender differences in lifespan were found to be notably limited; there was also no evidence of phylogenetic signal in this trait. Larger moth species were found to live longer, with this result supporting a physiological rather than ecological explanation of this relationship. Species‐specific lifespan values could not be explained by traits such as reproductive season and larval diet breadth, strengthening the evidence for the dominance of physiological determinants of longevity over ecological ones.

Management affects the pollinator abundance but not the reproductive success of butterfly orchids

Management of semi-natural grasslands should be based on the requirements of plants as well as their pollinators since conditions beneficial for plants are not necessarily beneficial for their pollinators and vice versa. The factors affecting the reproductive success (fruit set) of Platanthera bifolia and Platanthera chlorantha and their pollinators in agricultural landscape and woodlands were studied. In the years 2014–2016, we observed and caught moths during the flowering period of Platanthera species (late June–mid July) in four pure P. bifolia, five pure P. chlorantha and nine mixed populations under management or no management in Estonia. We determined pollinator species richness, pollinator abundance, fruit set and visibility of Platanthera plants in each population. We found that pollinator assemblages of P. bifolia and P. chlorantha did not differ between managed and unmanaged sites. Pollinator abundance had an effect on the fruit set of P. bifolia but not on that of P. chlorantha. Presence or absence of management, visibility of plants and rarefied pollinator species richness did not affect the fruit set of either plant species. Pollinator abundance was significantly higher in unmanaged populations of both plant species but rarefied pollinator species richness was higher only in unmanaged populations of P. chlorantha. Based on our findings the recommendations for management of semi-natural grasslands are to promote larger landscape diversity for the benefit of moth abundance by leaving unmanaged patches in different parts of a grassland in different years and rotational and post-fruiting management for higher reproductive success of orchids.

Day-flying moths are smaller: evidence for ecological costs of being large

Research on evolutionary forces determining optimal body sizes has primarily relied on experimental evaluation of respective selective pressures. Accounting for among‐species variation through application of phylogenetic comparative methods is a complementary although little used approach. It enables the direct association of body size values with particular environments. Using phylogenetically explicit comparative analyses, we show that small body size is associated with diurnal (rather than nocturnal) activity of adults among temperate species of the moth family Geometridae. The association of an exclusively adult trait with species‐specific body size suggests that optimal body sizes are at least partly determined by the costs being a large adult, as opposed to the more frequently considered costs of attaining large size. It appears likely that size‐selective predation by insectivorous birds is the primary factor responsible for selection against large body size in day‐flying moths.

Epirrita pulchraria (Taylor, 1907) transferred to Malacodea , with notes on the phylogeny and ecology of the tribe Operophterini (Lepidoptera: Geometridae: Larentiinae)

The Nearctic Epirrita pulchraria (Taylor, 1907) was revealed as a sister taxon of the Palaearctic Malacodea regelaria Tengström,1869 in a molecular phylogenetic analysis of the tribe Operophterini. DNA sequence variation in one mitochondrial (COI) and eight nuclear (28S, EF-1α, WGL, GAPDH, RPS5, IDH, MDH, CAD) gene fragments was used in the analysis. Bayesian inference resulted in a well-resolved phylogenetic hypothesis. According to the recovered phylogeny a new combination is proposed: Rachela pulchraria Taylor, 1907 is transferred from Epirrita Hübner, 1808 to Malacodea Tengström, 1869 as Malacodea pulchraria (Taylor, 1907) comb. nov. Larvae of both M. pulchraria and M. regelaria feed on coniferous trees, which distinguishes them from other members of the tribe. Close relatedness of M. pulchraria and M. regelaria is also supported by our study of male genital morphology. Ambiguous phylogenetic affinities of Epirrita viridipurpurescens (Prout, 1937) are discussed.