Populations of Agrostis diluta Kurcz. and Psathyrostachys caespitosa (Sukaczev) Peschkova in Yakutia: dynamics of vitality

In Yakutia, natural floodplain meadows and steppes have long been involved in economic activities. To develop methods of rational use, one needs to constantly consider the state of vegetation, mainly its constituent populations. Our research focuses on studying the dynamics of the vitality of the populations of the Agrostis diluta Kurcz. and steppe Psathyrostachys caespitosa (Sukaczev) Peschkova cereals. These species play an essential role in the composition of vegetation cover. We determined the vitality coefficient IVC. Our study of populations over several years has revealed the dynamic mobility of the vital structure, which is of adaptive significance and ensures the sustainability of populations. We have found that the vital structure of the cereal populations of the meadow Agrostis diluta and the steppe Psathyrostachys caespitosa during long-term studies (2007–2013 and 2007–2016, respectively) is heterogeneous. In unfavorable humidification conditions, we characterize years as depressive. Under favorable conditions of humidification, they quickly turn into thriving plants. In addition to the weather of the vegetation periods, habitat specificity affects the vitality of species populations that differ in ecological and coenotic characteristics. The Q quality index and IVC correspond to each other by year and form a clear descending order during the transition from a thriving to a depressive state. Currently, the vital state of the populations of both species is satisfactory.

Reevaluating Scorpion Ecomorphs using a Naïve Approach

BackgroundEcomorphs create the opportunity to investigate ecological adaptation because they encompass organisms that evolved characteristic morphologies under similar ecological demands. For over 50 years, scorpions have been empirically assigned to ecomorphs based on the characteristic morphologies that rock, sand, vegetation, underground, and surface dwellers assume. This study aims to independently test the existence of scorpion ecomorphs by quantifying the association between their morphology and ecology across 61 species, representing 14 families of the Scorpiones order.ResultsWithout a priori categorization of species into ecomorphs, we identified four groups based on microhabitat descriptors, which reflect how scorpion ecospace is clustered. Moreover, these microhabitat groups, i.e. ecotypes, have significantly divergent morphologies; therefore, they represent ecomorphs. These ecomorphs largely correspond with the ones previously described in the literature. Therefore, we retained the names Lithophilous, Psammophilous, and Pelophilous, and proposed the name Phytophilous for vegetation dwellers. Finally, we sought to map the morphology-ecology association in scorpions. We provide evidence that the morphological regions most tightly associated with ecology are the walking legs and pedipalps. Moreover, the major trend in ecomorphological covariation is that longer walking legs and relatively slender pedipalps (pincers) are associated with sandy microhabitats, while the inverse morphological proportions are associated with rocky microhabitats. ConclusionsScorpion ecomorphs are validated in a naïve approach, from ecological descriptors and whole body anatomy. This places them on a more solid quantitative footing for future studies of ecological adaptation in scorpions. Our results verify some of the previously defined ecomorphotypes and can be used as a starting point to understand the adaptive significance of ecological morphology.

The larval structures and bionomics of Idgia iriomoteana (Coleoptera: Prionoceridae)

The life cycle, bionomics and mature larval structures of the Japanese prionocerid species, Idgia iriomoteana Nakane, 1980 were investigated in captivity. The results showed that I. iriomoteana has the following characteristics: (1) the larval morph is less advanced in terms of miniaturization, and larvae pass seven larval molts before they pupate; (2) the life cycle is univoltine with summer, not winter, dormancy; (3) the first instar larvae are larger than the size of the egg, but foetomorphic larval instar (which is observed in the Melyridae: Malachiinae) is not shown. Based on comparison with melyrid species, the degree of miniaturization, dormancy behaviour, adaptation to the tropical and subtropical climates and the adaptive significance of a large first instar larva are all discussed. This study is the first to report the complete life cycle of a member of the family Prionoceridae.

Anther cones increase pollen release in buzz-pollinated Solanum flowers

The widespread evolution of tube-like anthers releasing pollen from apical pores is associated with buzz pollination, in which bees vibrate flowers to remove pollen. The mechanical connection among anthers in buzz-pollinated species varies from loosely held conformations, to anthers tightly held together with trichomes or bio-adhesives forming a functionally joined conical structure (anther cone). Joined anther cones in buzz-pollinated species have evolved independently across plant families and via different genetic mechanisms, yet their functional significance remains mostly untested. We used experimental manipulations to compare vibrational and functional (pollen release) consequences of joined anther cones in three buzz-pollinated species of Solanum (Solanaceae). We applied bee-like vibrations to focal anthers in flowers with (“joined”) and without (“free”) experimentally created joined anther cones, and characterised vibrations transmitted to other anthers and the amount of pollen released. We found that joined anther architectures cause non-focal anthers to vibrate at higher amplitudes than free architectures. Moreover, in the two species with naturally loosely held anthers, anther fusion increases pollen release, while in the species with a free but naturally compact architecture it does not. We discuss hypotheses for the adaptive significance of the convergent evolution of joined anther cones.

Number and Size of Offspring

Offspring number and size are two of the most variable life-history traits. Among species, much of this variability can be attributed to genetic, developmental, physiological, or structural constraints. Some trait combinations are not possible because of differences associated with a species’ evolutionary history. Substantial variation in propagule number and size can exist among populations of the same species, generating questions concerning the adaptive significance of this variability. The most influential models are those attributed to Lack on clutch size and to Smith and Fretwell on offspring size. Fundamental to both sets of models is a trade-off between offspring number and parental investment per offspring. When offspring survival or fitness continuously varies with offspring size, the fitness of the parent depends on both offspring size and the number of offspring of that size that the parent can produce. If offspring survival is independent of offspring size, parental fitness is maximized when individuals maximize the production of minimally sized propagules.

Horizontal orientation facilitates pollinator attraction and rain avoidance in radially symmetrical flowers

PremiseFloral angle, such as upward, horizontal, and downward orientation are known to evolve under both biotic and abiotic agents to enhance pollination success in zoophilious plants. Adaptive significance of horizontal orientation in radially symmetrical (actinomorphic) flowers under biotic and abiotic selection pressures were largely unknown, although those in bilaterally symmetrical flowers have been well studied.MethodsUsing experimentally angle changed flowers, we examined the effects of flower angle on pollinator behaviors, pollination success and rain avoidance in a population of insect-pollinated Platycodon grandiflorus. We further investigated the frequency and amount of precipitation in the flowering season and pollen damage by water in this species. Main results: Horizontally oriented flowers received more visitations and pollen grains on the stigma in male and/or female phases than downward and/or upward oriented flowers and avoided pollen damage by rainfall compared to upward oriented flowers. The pollen germination experiment showed that approximately 30% of pollen grains burst in distilled water, thus pollen damage by rainfall was potentially serious in P. garndiflorus.ConclusionIn this study, our field experiments revealed that upward flowers cannot avoid damage from rainfall during the flowering period whereas both upward and downward flowers suffered from pollinator limitation in female success. Thus, horizontal flower orientation is suggested to be adaptive in this insect-pollinated actinomorphic species which blooms in the rainy season.

Introduction

Of all the explanations that have been advanced for the persistence of war over time the most compelling is by the Dutch ethologist Nico Tinbergen. His study of animal behavior led him to propose an investigative strategy which raises four questions about war: what are its origins; what are the mechanisms which allow it to flourish; what is its ontogeny, or its historical evolution over time; and how does it function- how does its adaptive significance facilitate its reproductive success? War continues to evolve, to offer new opportunities and options. The question is whether it will escape human control. Thanks to scientists like Tinbergen we have discovered that our intelligence is specific to one species – it’s different from that of other animals and it will be different again from the machine intelligence we are about to create.

Mating behaviour, mate choice and female resistance in the bean flower thrips (Megalurothrips sjostedti)

Many species of thrips (Thysanoptera) in the family Thripidae form mating aggregations, but the adaptive significance of these aggregations and the extent of male and female mate choice is poorly understood. We studied the mating behaviour of the bean flower thrips Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), which forms male aggregations and occurs across sub-Saharan Africa. We tested whether males choose mates by female age or mating status. No-choice mating bioassays with one male and one female were used to simulate the way males usually encounter only one female at a time in aggregations in the field. Virgin females violently resisted mating attempts by males, but we found no compelling evidence to establish whether this was indiscriminate or was screening suitable males. Younger males (1–2 days old) did not discriminate females by age (1–2 or 7–10 days old), but older males (7–10 days old) avoided mating with older females. Any male choice by female mating status (virgin or mated) was weak or absent. The mating behaviour of M. sjostedti shows broad similarities with that of other thrips species that form aggregations, but also shows some distinct and novel differences, which can help our understanding of the adaptive significance of aggregations.