Germination ecology of drupelets of the fig (Ficus carica L.)

Abiotic and biotic factors and their effects on germination of fig drupelets were studied. The drupelets germinated between 10^oC and 30^oC.Constant humidity was necessary for germination and frequent drying out of the substrate was unfavourable. Total darkness for the whole duration of the experiments had a slighly negative effect on germination. The fastest germination occurred at constant humidity and an alternating temperature of 20/30^oC with exposure to light for 8 hours (at the higher temperature) and to darkness for 16 hours (at the lower temperature).Natural or artificial removal of drupelets from the syconium guaranteed a high germination percentage, whereas no germination occurred in drupelets left inside the syconium. Hence birds and mammals act as dispersal agents and mediators of germination. As they eat pieces of fig syconium, they free the drupelets from the flesh, eliminating the effect of inhibitors and/or microenvironments with high osmotic pressure inside the syconium. These findings support the hypothesis that germination occurs in autumn or spring depending on the climatic zone in which the species grows.     

Development of Plastids in Pollen and Tapetum of Rye-grass, Lolium perenne L

Proplastids of both tapetal cells and microsporocytes were presentearly in anther development. Tapetal proplastids differentiated—probablyinto elaioplasts—at late microspore stage. The tapetalcytoplasm was completely resorbed by early tricellular pollenstage. Microspore proplastids differentiated into amyloplastsat early bicellular stage, and were present in both vegetativeand generative cells. In the generative cell, the amyloplastswere ephemeral and apparently degenerated within autophagicvacuoles. Plastids were absent from sperm cells. Vegetativecell amyloplasts increased in number apparently by fission suchthat one amyloplast produced one amyloplast and one proplastidper division. Mature pollen grains were estimated to containbetween 550 and 820 amyloplasts with only one starch granuleper plastid. Elaioplasts, amyloplasts, plastid division, plastid differentiation, starch granules, autophagy, Lolium perenne, Poaceae, rye-grass     

Characterization of 59 canine single nucleotide polymorphisms in the Italian wolf (Canis lupus) population

We characterized 59 canine single nucleotide polymorphisms (SNPs) in the endangered Italian wolf (Canis lupus) population, which were discovered by resequencing sequence‐tagged‐site (STS) DNA sequences that are known to contain SNPs in domestic dogs. Dog SNPs were usually found also in wolves. Additional SNPs unique in dogs or wolves were discovered, which is important for detecting hybrids between dogs and wolves. We developed new primer sets and analysed 15 SNPs by Pyrosequencing. The characterized SNPs will provide an important addition to the genetic markers that are currently available for studying wild populations of canids.     

Spatio-temporal population genetics of the Danish pine marten (Martes martes)

A spatio-temporal study of genetic variation in the Danish pine marten ( Martes martes ) populations from the Jutland peninsula and from the island of Sealand was performed using 11 microsatellite markers. Samples obtained from 1892 to 2003 were subdivided into historical (prior to 1970) and recent (from 1970) groups. As compared with the historical samples, there was a significant loss of genetic variation in the recent Jutland population, but not in Sealand. Effective population sizes were estimated using Bayesian-based software (TMVP). Historical effective population sizes were 5897 (90% highest probability density, HPD, limits: 1502–6849) in Jutland and 1300 (90% HPD limits: 224–5929) in Sealand, whereas recent effective population sizes were 14.7 (90% HPD limits: 10.9–23.5) in Jutland and 802 (90% HPD limits: 51.8–5510) in Sealand. Significant genetic differentiation ( F _ST) was found between the two historical samples, between the two recent samples, and between the historical and the recent sample in Jutland; whereas the F _ST value between the historical and the recent sample in Sealand was not significant. The significant genetic differentiation between the historical and the recent samples indicates changes in the genetic compositions over time, and the higher F _ST values between the two recent samples, as compared with the two historical samples, indicates that the populations in Sealand and Jutland have drifted apart within a short time span. No deviation from Hardy–Weinberg equilibrium was found within populations, indicating no further substructuring.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 457–464.     

Development and Ultrastructure of Cucurbita pepo Nectaries of Male Flowers

The development of the nectary of the male flower ofCucurbitapepo L. was studied from 5d before to 2d after anthesis. Thenectary consists of parenchyma that stores starch in the presecretorystages, and epidermis. An hour before nectar secretion begins,the starch is hydrolyzed. The nectar exudes from the stomataand forms a continuous layer on the nectary surface. Duringanthesis the nectar may all be collected by pollinators or someor all of it may remain in the nectary and be successively resorbed.The nectary parenchyma stores material for synthesizing thesugar component of nectar and stores similar material againafter nectar resorption. It is also responsible for nectar productionand secretion. The epidermis is actively involved in the reabsorptionprocess. The resorption of nectar is a phenomenon that allowsthe plant to recover invested energy. Few observations on thisphenomenon have hitherto been published. Amyloplasts; Cucurbita pepo L.; courgette; nectaries; Nectar resorption; plastid; secretion; starch     

The smell of danger: chemical recognition of fish predators by the invasive crayfish Procambarus clarkii

1. Since avoiding predation can compromise animal fitness, prey are expected to respond to different predator species with an intensity appropriate to the level of risk. In fresh waters, the threat of predation is typically assessed by chemical cues, in particular by odours released by either injured/disturbed conspecifics (conspecific alarm odour) or predators (predator odours). Here, we used the most widely distributed crayfish in the world, the invasive North American Procambarus clarkii, to investigate the relative effectiveness of odours emitted by fish predators compared with conspecific alarm odour. We also tested whether P. clarkii is able to discriminate between fish predators of which it has ‘experience’ (either recent, via introduction to the same water body, or old, by sharing a native range), as well as between fish predators that pose low or high risk. 2. The study was carried out on introduced populations of P. clarkii from two sites, characterised by different fish assemblages: the Malewa River (a tributary of Lake Naivasha, Kenya) and Lake Trasimeno (Italy). Laboratory experiments consisted of three sequential phases (‘water’, ‘food’ and ‘smell’ phases) and five treatments. Treatments differed in the odour presented during the smell phase, i.e. no odour (plain water) and odours from either injured conspecifics or three fish species per site. Crayfish from the Malewa River population were confronted with the odours of largemouth bass (Micropterus salmoides), common carp (Cyprinus carpio) and tilapia (Tilapia zillii) (all introduced to Lake Naivasha but absent from the Malewa River), and those from the Lake Trasimeno population with the odours of the introduced largemouth bass and carp and the native chub (Squalius cephalus). Largemouth bass is the only predator that imposes a high risk to crayfish, and it also shares its native range with P. clarkii. We analysed the time spent by crayfish feeding, in locomotion and in adopting a raised or lowered posture. A reduction in the time spent feeding and in locomotion, and an increase in the time spent in the lowered posture were considered to indicate alarm. 3. Crayfish from both populations responded with a more pronounced reduction in feeding to conspecific alarm odour rather than to predator odours. Crayfish from the Malewa River reacted with the same intensity to the odours of the three fish species tested, whereas, in Lake Trasimeno, the odour of largemouth bass was significantly more threatening than the odours of the other two species. 4. Procambarus clarkii seems to perceive a general fish odour that alerts it to possible predation risk without the need of either a direct recent experience or via sharing a common native range. However, where they coexist with fish, crayfish become able to distinguish among species, adapting the intensity of their response to the effective risk. Our results confirm the relatively high learning capacity of P. clarkii reported in previous studies and suggest the existence of mechanisms that make predator recognition particularly efficient in this extraordinarily successful invader.     

A molecular phylogeny of the peacock-pheasants (Galliformes: Polyplectron spp.) indicates loss and reduction of ornamental traits and display behaviours

The South-east Asian pheasant genus Polyplectron is comprised of six or seven species which are characterized by ocelli (ornamental eye-spots) in all but one species, though the sizes and distribution of ocelli vary among species. All Polyplectron species have lateral displays, but species with ocelli also display frontally to females, with feathers held erect and spread to clearly display the ocelli. The two least ornamented Polyplectron species, one of which completely lacks ocelli, have been considered the primitive members of the genus, implying that ocelli are derived. We examined this hypothesis phylogenetically using complete mitochondrial cytochrome b and control region sequences, as well as sequences from intron G in the nuclear ovomucoid gene, and found that the two least ornamented species are in fact the most recently evolved. Thus, the absence and reduction of ocelli and other ornamental traits in Polyplectronare recent losses. The only variable that may correlate with the reduction in ornamentation is habitat, as the two less-ornamented species inhabit montane regions, while the ornamented species inhabit lowland regions. The implications of these findings are discussed in light of models of sexual selection. The phylogeny is not congruent with current geographical distributions, and there is little evidence that Pleistocene sea level changes promoted speciation in this genus. Maximum likelihood and maximum parsimony analyses of cytochrome b sequences suggest that the closest relatives of Polyplectron are probably the peafowl and the argus pheasants.     

Effect of the 1990 die-off in the northern Italian seas on the developmental stability of the striped dolphin Stenella coeruleoalba (Meyen, 1833)

Developmental stability of the community of striped dolphins, Stenella coeruleoalba (Meyen, 1833), that died during the Mediterranean epizootic of 1990 was compared with that of the population prior to and after the epizootic, to assess whether animals that died were the developmentally less stable individuals in the population. Significantly higher levels of fluctuating asymmetry (FA) were found in those individuals that died. Tissue levels of organochlorine pesticide residues and PCBs were determined and the correlation between contaminant concentration and FA was tested. No correlations were found between the contaminant level and FA.     

Variation in nectar–sugar profile of Anchusa and allied genera (Boraginaceae)

The nectar–sugar profile (fructose, glucose and sucrose) of 14 species of Anchusa and five members of the allied genera Anchusella, Cynoglottis, Hormuzakia and Lycopsis (Boraginaceae: tribe Boragineae) was determined. Most of the species examined (c. 74%) produce sucrose‐dominant nectar, whereas the remaining taxa produce sucrose‐rich nectars. Little variation in nectar–sugar composition was found in some species, even when sampling was repeated in different years and/or localities. Average sucrose concentration was 57.75% (coefficient of variation 19.1%). The only floral morphological character that was correlated with the nectar–sugar profile is the length of the corolla tube, as taxa with relatively long floral tubes produce nectar with lower glucose concentrations. The flowering period is also related to sugar composition, as nectar of late‐flowering species contains lower sucrose concentrations. However, small differences in sugar profiles do not reflect phylogenetic relationships based on molecular studies. It would appear that dry habitats and time of flowering are the main determinants of nectar–sugar composition in the genus Anchusa sensu lato. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 616–627.     

Genetic structure of the Danish red deer (Cervus elaphus)

The red deer (Cervus elaphus) population in Denmark became almost extinct in recent historical times due to over‐hunting. The species has subsequently recovered within remote areas, but non‐Danish individuals have been introduced at several localities. To assess genetic structure, past demographic history, and the possibility of a still existing original stock, we analysed 349 specimens from 11 geographically separate areas and from three enclosed areas, genotyping 11 microsatellite loci. Moreover, an 826‐bp fragment of the control region of the mitochondrial DNA was sequenced for 116 recent specimens and seven museum specimens. There was a significant difference in mean expected heterozygosity (H_E) between the three enclosed areas and the 11 unenclosed areas. Significant departures from Hardy–Weinberg equilibrium were observed in the three enclosed areas and in nine of the unenclosed areas. The overall degree of genetic differentiation among all 14 areas was significant (F_ST = 0.09, P < 0.01), primarily because the mean pairwise F_ST for the three enclosed areas was significantly higher than that for the 11 unenclosed areas. A Bayesian clustering procedure detected three genetically distinct populations and indicated reduced gene flow between the enclosed and unenclosed areas. The individuals in the unenclosed areas show genotypic mixture, presumably as a result of gene flow among them. Markov Chain Monte Carlo simulations, based on the genealogical history of the microsatellite alleles, suggest a drastic decline in the effective population size of the enclosed areas some 188–474 years ago. Mitochondrial DNA analysis of the recent specimens showed seven haplotypes. Individuals from the enclosed Jægersborg Dyrehave contain haplotypes that occur all over Denmark and also are found in Western Europe. A close relationship between Scandinavian and Western European red deer is most likely. Only individuals from the unenclosed Lindenborg Estate and the enclosed Tofte Skov did not group with any other Danish individuals. As six of seven museum specimens had haplotypes also found in modern Danish samples, the current population of red deer in Denmark is genetically close to the original Danish red deer. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 688–701.