Dynamic egg color mimicry

Evolutionary hypotheses regarding the function of eggshell phenotypes, from solar protection through mimicry, have implicitly assumed that eggshell appearance remains static throughout the laying and incubation periods. However, recent research demonstrates that egg coloration changes over relatively short, biologically relevant timescales. Here, we provide the first evidence that such changes impact brood parasite–host eggshell color mimicry during the incubation stage. First, we use long‐term data to establish how rapidly the Acrocephalus arundinaceus Linnaeus (great reed warbler) responded to natural parasitic eggs laid by the Cuculus canorus Linnaeus (common cuckoo). Most hosts rejected parasitic eggs just prior to clutch completion, but the host response period extended well into incubation (~10 days after clutch completion). Using reflectance spectrometry and visual modeling, we demonstrate that eggshell coloration in the great reed warbler and its brood parasite, the common cuckoo, changes rapidly, and the extent of eggshell color mimicry shifts dynamically over the host response period. Specifically, 4 days after being laid, the host should notice achromatic color changes to both cuckoo and warbler eggs, while chromatic color changes would be noticeable after 8 days. Furthermore, we demonstrate that the perceived match between host and cuckoo eggshell color worsened over the incubation period. These findings have important implications for parasite–host coevolution dynamics, because host egg discrimination may be aided by disparate temporal color changes in host and parasite eggs.     

太原黄耆(豆科)花器官及胚珠发育研究

太原黄耆是新近发表的物种,分布于中国陕西和山西。该实验利用扫描电子显微镜对太原黄耆的花器官发生和发育过程进行观察研究。结果显示:(1)太原黄耆的各轮花器官都是从远轴端向近轴端单向连续发生,在不同轮之间存在花器官重叠发生的现象。(2)在花的发育过程中,出现2种共同原基,即初级共同原基和次级共同原基,由初级共同原基发育成对萼雄蕊原基和次级共同原基,再由次级共同原基发育成花瓣原基和对瓣雄蕊原基。(3)雄蕊管近轴端基部开口是在进化过程中产生的特殊结构,是一种对传粉者的适应机制,从而有利于传粉活动的进行。(4)胚珠为倒生胚珠,具有2层珠被,认为倒生胚珠是内外2层珠被共同作用的结果。     

Functional specialization of one copy of glutamine phosphoribosyl pyrophosphate amidotransferase in ureide production from symbiotically fixed nitrogen in Phaseolus vulgaris

Purines are essential molecules formed in a highly regulated pathway in all organisms. In tropical legumes, the nitrogen fixed in the nodules is used to generate ureides through the oxidation of de novo synthesized purines. Glutamine phosphoribosyl pyrophosphate amidotransferase (PRAT) catalyses the first committed step of de novo purine synthesis. In Phaseolus vulgaris there are three genes coding for PRAT. The three full‐length sequences, which are intron‐less genes, were cloned, and their expression levels were determined under conditions that affect the synthesis of purines. One of the three genes, PvPRAT3, is highly expressed in nodules and protein amount and enzymatic activity in these tissues correlate with nitrogen fixation activity. Inhibition of PvPRAT3 gene expression by RNAi‐silencing and subsequent metabolomic analysis of the transformed roots shows that PvPRAT3 is essential for the synthesis of ureides in P. vulgaris nodules.     

Genetic Analysis of Group Composition and Breeding System in a Wild Common Marmoset (Callithrix jacchus) Population

We established pedigree relations in three wild common marmoset social groups for which observational data were available, together with genotypes of some individuals from neighboring groups. Relatedness of 40 individuals were based on 11 microsatellite loci amplified from nDNA obtained noninvasively from plucked hair. The wild marmosets were only half as variable as a captive population characterized previously: 2–6 alleles/locus; H_O = 0.41 and H_E = 0.35. Parentage exclusion probabilities were 61.8% for an offspring and one alleged parent and 90.7% for an offspring with one confirmed and one alleged parent. Each group (n = 5–14 individuals) had two breeding females and 2 adult males. Within each group the infants and reproductively inactive adults were closely related to at least the breeding females; the latter were related to each other as closely as mother/infant pairs or sisters. Relatedness of adult males was lower, indicating recent intergroup dispersal. Genetic data confirm Callithrix jacchus live in relatively stable extended family groups of closely related individuals. Matings occurred preferentially among the least related adults and most infants were fathered by the dominant male. The genetic data are consistent with polygynmonandry as are the field observations. Callithrix have variable mating systems, ranging from monogamy to polyandry to polygyny within social groups plus extragroup copulations; our data provide no evidence for polyandry and are inconclusive with respect to extragroup paternity. Nevertheless, noninvasive multilocus genotyping methods will resolve these questions when longer-term studies of entire populations are undertaken.     

Discovery of an ancient lineage of Cyprinus carpio from Lake Biwa, central Japan, based on mtDNA sequence data, with reference to possible multiple origins of koi

MtDNA sequence data ( c . 2100 bp of complete D‐loop + cytochrome b gene regions) showed a principal phylogenetic split within common carp Cyprinus carpio between the Lake Biwa wild form ( n  = 3) and 'Eurasian' wild ( n  = 18) and domesticated ( n  = 35) forms. This supports the idea of the ancient origin of the Lake Biwa wild form, as well as the East Asian origin of wild common carp, previously proposed on the basis of fossil data. In addition, a possible multiple origin of koi carp was indicated by the polyphyletic distribution of five mtDNA haplotypes of koi carp within the 'Eurasian' clade.     

Reproductive cycle and growth of Phyllopteryx taeniolatus

In this study, 36 males, 33 females and 15 juveniles of the common or weedy seadragon Phyllopteryx taeniolatus , a syngnathid fish endemic to the waters of southern Australia, were identified using visual implant fluorescent elastomer tags and pattern of appendages and their reproductive cycle and growth was studied from May 2001 to June 2002. Brooding males were present for a period of >6 months, from June–July to early‐January. The percentage of males that were pregnant in the studied areas peaked in November–December, near the end of the breeding season. Two pregnancies were reported for some males. Ten recruits were identified from November to June. Growth rates for young‐of‐the‐year, young of the previous year, males and females were measured. The von Bertalanffy growth constant K was estimated at 0·098 month⁻¹.     

Resistance of Common Bean (Phaseolus vulgaris) to Bacterial Wilt Caused by Curtobacterium flaccumfaciens pv. flaccumfaciens

Bacterial wilt caused by Curtobacterium flaccumfaciens pv. flaccumfaciens is an important new disease of common bean (Phaseolus vulgaris) in western Canada. Both yellow and orange variants of the pathogen were found in the region. A controlled environment study was conducted to assess 124 common bean cultivars and lines from eight market classes for resistance to the yellow and orange variants of the pathogen, using the hilum injury/seed inoculation method. Results of the screening tests showed significant (P < 0.05) differences in resistance to bacterial wilt among the cultivars or lines. The great northern line L02E317, the great northern cultivar Resolute and pinto lines L02B662 and 999S‐2A, were highly resistant to both variants of the pathogen, with disease severity indices of 0 on a rating scale of 0 (no wilt symptoms) to 5 (dead seedling). Resistant cultivars or lines were found among black, great northern, pink, pinto, small red and Flor de Mayo bean market classes. The study concludes that new bacterial wilt‐resistant germplasm exists among Canadian bean cultivars and lines, and constitutes a valuable resource for breeding common beans for resistance to both yellow and orange variants of C. flaccumfaciens pv. flaccumfaciens.     

The ingestion of bacteria in suspension by the common carp Cyprinus carpio L.

Groups of large (65 -75 g) and small (8-17 g) common carp ( Cyprinus carpio L.) fingerlings were exposed to the bacterium Chromobacterium violaceurn in order to establish whether they could detect and ingest unattached bacteria. Small fish exposed to both bacteria and to cell-free bacterial extracts showed a significant increase in opercular beat rates, thus demonstrating that they are able to detect the presence of unattached bacteria in suspension. Examination of carp gut contents showed that the proportion of small fish ingesting bacteria increased with exposure time although no significant relationship was observed among larger fish. Significant, positive correlations between numbers of viable bacteria isolated from the intestinal tracts and concentration in the environment were observed. Possible mechanisms of bacterial ingestion are discussed.     

Host selection and utilisation of Sonchus oleraceus (Asteraceae) by Helicoverpa armigera (Lepidoptera: Noctuidae): A genetic analysis

The cotton bollworm (Helicoverpa armigera) prefers the common sowthistle (Sonchus oleraceus L.) to cotton (Gossypium hirsutum L.), sorghum (Sorghum bicolor L.) and maize (Zea mays L.) for oviposition in the field in Australia. Using the common sowthistle and cotton as host plants, we carried out this study to evaluate genetic variation in both oviposition preference and larval growth and genetic correlation between maternal preference and larval performance. There was a significant genetic component of phenotypic variation in both characters, and the heritability of oviposition preference was estimated as 0.602. Helicoverpa armigera larvae survived slightly better and grew significantly faster on common sowthistle than on cotton, but genetic correlation between maternal preference and larval growth performance was not detectable. Instead, larval growth performance on the two hosts changed with families, which renders the interaction between family and host plant significant. As a result, the genetic correlation between mean values of larval growth across the two host species was not different from zero. These results are discussed in the context of the relationship between H. armigera and the common sowthistle and the polyphagous behaviour of this insect in general.