CHARACTERISTICS OF TERRITORIAL AND MATING CALLS IN WILLOW PTARMIGAN LAGOPUS L. LAGOPUS

ABSTRACT

During territorial behaviour and pair formation willow ptarmigan cocks and hens use several different calls. Cocks use mainly a “flight call”, a “ground call” and three different “threat calls”. Hens give similar calls to cocks. It is suggested that the structure of the calls is well adapted to (1) transmit their possible information content over long distances, and (2) make localization easier for birds during the territorial display periods, which take place mainly in poor light at dusk and dawn. We also suggest that the cock and hen calls express different degrees of aggressiveness, and that hen calls, in addition to attracting cocks, function as territorial “keep out” signals to other hens.     

Evolution of the climatic niche in scaly tree ferns (Cyatheaceae,Polypodiopsida)

Although climatic niche conservatism has been assumed by a large number of studies focused on climatic niche evolution, there are examples of climatic niche diversification and adaptation to changing climates. In this article, we reconstruct a climatic niche of scaly tree ferns (Cyatheaceae) using a rigorous analytical procedure which combines climatic niche modelling with reconstruction of continuous characters given a phylogenetic hypothesis. To estimate the limits to climatic niches of species, we used climate envelope modelling and ordination. Ancestral climatic niches of species were reconstructed by maximum likelihood and least‐squares analyses. We observed a trend towards niche conservatism with occasional events of niche transformations in scaly tree ferns. We discuss the implications of our study with respect to the potential and limitations for applications of niche modelling to evolutionary studies. We suggest that future studies of evolution of climatic niches could be considerably improved by employing approaches enabling reconstruction of continuous response to climatic gradients. Further progress may also be achieved by exploring models of character evolution other than the Brownian motion model. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 1–19.     

Fungal infections of the phytoplankton: seasonality, minimal host density, and specificity in a mesotrophic lake

Phytoplankton infections by fungal parasites in the upper, mixed layer of a mesotrophic northern temperate lake were analysed according to the following parameters: host and parasite species, host population density and prevalence of infection, resting spore formation by the parasite, and the lowest host density at which parasites appeared. The phytoplankton taxa recorded included the Cyanobacteria, Dinomastigota, Chrysophyceae, Bacillariophyceae, Chlorophyceae, Cryptophyceae and Haptophyceae, but infection was never found in the last two classes. The parasites belonged almost exclusively to the monocentric Chytridiomycetes. Fungal epidemics occurred at all times of the year. Parasites appeared at population densities as low as about 1 cell ml⁻¹ in some host species, with infection prevalence sometimes exceeding 80%. The proportion of the total phytoplankton biovolume infected by fungi was usually much <1%, but occasionally reached 10%. Parasitism proved to be highly species-specific, with one parasite species usually infecting only one host species. In the case of Zygorhizidium planktonicum , which infected both Asterionella formosa and Synedra acus , there is evidence that two species-specific formae speciales , each infecting only one of these two host species, are present in the lake.     

Mating tactic dependent sperm transfer rates in Panorpa similis (Mecoptera; Panorpidae): a case of female control?

Abstract 1. Male Panorpa scorpionflies offer salivary masses as nuptial gifts during copulation. Previous studies have shown that there is usually a strong correlation between the number or size of salivary masses provided and copulation duration. As a result of constant sperm transfer rates, copulation duration is the most important determinant of male fitness in these species. 2. Differences in copulation durations for gift‐giving and non‐gift‐giving males of the Caucasian scorpionfly Panorpa similis have been shown to be much smaller on average than those observed in other Panorpa species. In this study, we therefore focus on the number of sperm transferred in copulations of P. similis both with and without salivary masses. 3. We find that although the average copulation duration in the presence of nuptial gifts is only twice as long as the average copulation duration without nuptial gifts, gift‐giving males transfer almost 11 times more sperm during copulations than non‐gift‐giving males. This is as a result of substantially higher sperm transfer rates (sperm/minute) in copulations in which nuptial gifts are present. 4. Implications of this finding for the interpretation of the mating system of P. similis and the question of which sex controls sperm transfer rates are discussed.     

Food intake of fruit-feeding butterflies: evidence for adaptive variation in proboscis morphology

Adult butterflies feed from a variety of substrates and have appropriate adaptations. We examined proboscis morphology in a community of fruit-feeding butterflies (Nymphalidae) in a tropical forest in Uganda. These data were supplemented with behavioural observations and measurements of intake rate on natural and artificial substrates. We found no sexual dimorphism in proboscis morphology even though puddling behaviour is usually performed by males. Two main feeding techniques could be distinguished on the basis of behaviour and morphology: the piercing technique, typically found in Charaxinae, and the sweeping technique employed by both Nymphalinae and Satyrinae. These techniques, distinguished in previous studies, are described in more detail and their relative efficiencies are discussed in the context of sexual dimorphism, food-choice and life history evolution.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 86 , 333–343.     

A molecular phylogeny and a revised classification of tribe Lepisoreae (Polypodiaceae) based on an analysis of four plastid DNA regions

Phylogenetic relationships within the palaeotropical tribe Lepisoroideae (Polypodiaceae) were investigated by studying sequence variation of four plastid DNA regions: rbcL, rps4 plus rps4‐trnS IGS, trnL intron plus trnL‐F IGS, rbcL‐atpB IGS plus part of atpB. In total, over 4000 nucleotides were sequenced for 39 species. Seven well‐supported clades were found in the analyses of the combined data set. We provide a new classification of Lepisoroideae by integrating phylogenetic results and known variation of morphological characters. The two small genera Neocheiropteris and Tricholepidium are supported as monophyletic, the genus Paragramma is resurrected and the genera Lepisorus, Neolepisorus, Lemmaphyllum and Lepidomicrosorium are re‐circumscribed. We proposed 14 new combinations, among which Caobangia is treated as a synonym of Lemmaphyllum. A key for identifying the recognized genera is presented. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 28–38.     

Variation in the δ13C of foliage of Pinus sylvestris L. in relation to climate and additions of nitrogen: analysis of a 32-year chronology

We report an analysis of both the long‐ and short‐term drivers of the carbon (C) isotope composition (δ¹³C) values of current year needles of Pinus sylvestris L. linked to changing atmospheric carbon dioxide (CO₂) concentrations (c_a) and climate using data from a uniquely long‐term nitrogen (N) fertilization experiment in the north of Sweden (consisting of three N dosage levels and a control treatment) from 1970 until 2002. N loading produced trees with less negative δ¹³C of foliage, by around 0.45‰ on average, with the difference in δ¹³C between control and N treatments not dependant upon N dosage. The average δ¹³C values decreased at a rate of around 0.03‰ yr⁻¹, even after accounting for the Suess effect (the decrease in the atmospheric CO₂δ¹³C due to anthropogenic emissions of isotopically light CO₂). This decrease is large enough to cause a significant, progressive change in the δ¹³C down through a soil profile. Modelled values of plant intrinsic water use efficiency (WUE_i) and the ratio of leaf internal to external [CO₂] (c_i/c_a) showed that this was the result of c_i increasing in parallel with c_a (while c_i/c_a increased), thus causing little change in WUE_i over the 32 years of study. The residuals from the relationships between year and δ¹³C were used to examine the impact of climate on the interannual variation of C isotope composition of needles. This included the use of a fire hazard index (FHI) model, which integrates climatic factors known to influence plant stomatal conductance and hence δ¹³C. The FHI produced the best fit with δ¹³C values when climate data were averaged over the whole growth season (for control plots) and for July for all the N treatments, explaining ca. 60% of the total interannual variation in δ¹³C. Further, trees from the N treatments appeared more susceptible to air‐humidity‐based climate parameters, as seen from higher correlation coefficients, than were control trees. Thus, our data suggest the possibility of increased susceptibility to drought conditions in ecosystems with moderate to high N deposition rates. Also, there is the possibility that, because there was no apparent change in WUE_i of P. sylvestris in this ecosystem over the last 32 years, the rate of sequestration of C into boreal ecosystems may not increase with c_a, as has been predicted.     

The fine structure of the somatic muscles and their attachment to the cuticle in two species of Pycnogonida

The fine structure of the somatic muscles and their attachment to the cuticle in the pyenogonids Nymphon (Chaetonymphon) macronyx G. O. Sars and Boreonymphon cf. abyssorum (Norman) is described. The muscles possess characteristics which are typical of arthropod slow muscle fibers: relatively long sarcomeres, a mean A-band length of about 6 μm and a ratio of thin to thick contractile filaments of 4:1. The sarcotubular system consists of distinct t-tubules, an irregular SR part and randomly distributed dyads and triads, the muscles are attached to the cuticle by specialized epidermal cells containing microtubules extending from the cuticular to the muscular side. The myoepidermal and epidermal-cuticular junctions are described.     

Phylogenetic Relationships of Five Species of the Amphipod Genus Gammarus

The phylogenetic relationships of five amphipod species of the genus Gummarus: G. oceanicus, G. locusta, G. salinus, G. zaddachi and G. duebeni are presented based on starch gel electrophoresis of 12 enzymes determined by 17 loci. The five species separate into three groups: G. locusta and G. duebeni each represent a distinct group while G. oceanicus, G. salinus and G. zaddachi together form a third group. This grouping results when the number of diagnostic loci, as well as when genetic distance between species pairs, are considered. The results compare well with morphological and, to some extent, ecological data.