Search

A lack of genetic diversity in cultivated black raspberry ( Rubus occidentalis L.) germplasm has been widely recognized as a major factor limiting progress towards breeding improved cultivars. Despite this, little effort has been made since the early twentieth century to systematically collect and evaluate wild black raspberry for germplasm improvement. In recent years, there has been renewed interest in black raspberry breeding to replace existing cultivars that lack durability and disease resistance. We planted seedlings from 109 wild black raspberry populations, representing 24 US states and two Canadian provinces, in the field in replicated trial plots in Corvallis, Oregon (USA), to evaluate their performance. These populations showed wide variation in morphology, architecture, fruiting season, vigor, and apparent field tolerance to Verticillium wilt. For nearly every trait examined, wild black raspberry germplasm exhibited a range of variation beyond existing cultivars, and showed great potential for use in future breeding. While most populations were fairly uniform phenotypically, segregation for fruit gloss and possible tolerance to Verticillium wilt was noted in a few, indicating the possibility of simple inheritance of these traits. A few populations with unusual morphology, such as spinelessness or flower abnormalities, were identified, as were populations that flowered on first year canes and produced fall fruit. Populations from the southern edge of the range appear to be particularly well adapted to western Oregon, with vigorous upright growth, strong canes, and some with a low incidence of Verticillium wilt. This germplasm will be of great value to breeders interested in developing improved black raspberry cultivars. [ABSTRACT FROM AUTHOR]

Breeding progress in black raspberry ( Rubus occidentalis L.) has been limited by a lack of genetic diversity in elite germplasm. Black raspberry cultivars have been noted for showing very few phenotypic differences and seedlings from crosses between cultivars for a lack of segregation for important traits. Despite these challenges, little molecular work has been done to explore genetic diversity and relationships in wild and cultivated black raspberry germplasm. Microsatellite, or simple sequence repeat (SSR), markers are highly polymorphic codominant markers useful for studying genetic diversity, population genetics, genetic fingerprinting and other applications. We examined genetic diversity in 148 wild and cultivated black raspberry accessions using 21 polymorphic SSR markers. Black raspberry cultivars clustered tightly and showed higher than expected heterozygosity while that of wild accessions was low. Relationships between wild black raspberry accessions were poorly resolved and regional clusters were mostly absent from our analysis. Our results indicated that wild black raspberry germplasm is a relatively untapped resource available for future breeding. [ABSTRACT FROM AUTHOR]

The distribution area and the timing of migration of many bird species have recently changed, presumably due to climatic factors. In our study, we estimated the effect of climate change on migration phenology and biometrics of two sister Sylvia species: the medium-distance migrant Blackcap ( Sylvia atricapilla) and the long-distance migrant Garden Warbler ( Sylvia borin). We used the data of 52,440 Blackcaps and 6,943 Garden Warblers caught and ringed at the Ócsa Bird Ringing Station (47°15′N, 19°15′E) in Hungary between 1984 and 2008. The age and in case of Blackcaps the sex groups were handled separately. The timing of the spring migration of Garden Warblers shifted earlier, whereas it did not change in Blackcaps during the study period. We presume-in accordance with other observations concerning Blackcaps in West-Europe-that it probably has changed earlier than the 1980s. The timing of autumn migration shifted about 2 weeks later in all age and sex groups of Blackcaps. We found significant correlation in the timing of autumn migration of sex groups, the sign of the differences between the timing of males and females changed. Juvenile Garden Warblers shifted their autumn migration 13 days later, but adults did not. Mean body mass decreased while mean wing length increased suggesting a change in the composition of the trans-migrant population. We hypothesise that due to climate change the breeding range of these species expanded northwards, producing an increased ratio of long-winged northern individuals in the trans-migrant populations. [ABSTRACT FROM AUTHOR]

Blackcaps Sylvia atricapilla reject artificial cuckoo eggs, and their eggs vary little in appearance within clutches, whereas among clutches eggs vary considerably. Low variation within clutches facilitates discrimination of parasitic eggs, whereas high variation among clutches makes it harder for the cuckoo to mimic the eggs of a certain host species. These traits have most probably evolved as counteradaptations against brood parasitism by the common cuckoo Cuculus canorus, even though blackcaps are not regularly parasitised today. In this study, we investigated how fine-tuned the rejection of parasitic eggs is in this species by introducing three types of eggs into their nests: a real non-mimetic egg the approximate size of a cuckoo egg, an artificial mimetic egg the size of a cuckoo egg and a real conspecific egg. As the rejection frequency of both mimetic and non-mimetic artificial cuckoo eggs has been shown to be high in previous studies, the variation in rejection behaviour between individuals is low, indicating that most individuals within the population are able to reject parasitic eggs. Thus, we predict that (1) the intraclutch variation in egg appearance should be generally low in all individuals, and that (2) regarding conspecific eggs, rejection decisions should be highly dependent on the degree of mimicry between parasitic and host eggs. We found support for these predictions, which indicates that due to their highly sophisticated countermeasures against brood parasitism, blackcaps can probably be regarded as current winners of the arms race with the common cuckoo. Furthermore, the high and consistent rejection frequency of cuckoo eggs found throughout Europe for this species supports the spatial habitat structure hypothesis, which claims that woodland-nesting species breeding near trees, like blackcaps, presumably experienced a high level of parasitism throughout their range in the past and, therefore, their rejection behaviour, once evolved, spread rapidly to all populations. [ABSTRACT FROM AUTHOR]

Copyright of Journal fuer Ornithologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Female hand-raised blackcaps ( Sylvia atricapilla) held in constant conditions (except for simulated seasonal changes in photoperiod) showed significantly more, and significantly longer, autumnal migratory activity as well as significantly later initiation of spring migratory activity than males from the same population (including siblings) held under identical conditions. [ABSTRACT FROM AUTHOR]

Crossbreeding experiments with blackcaps from a nonmigratory population (of the Cape Verde Islands) and a migratory population (from southern Germany) demonstrated that the urge to migrate as well as orientation behavior can be transmitted rapidly into a nonmigratory bird population and thus have a substantial genetic basis. [ABSTRACT FROM AUTHOR]

It has been argued that the body mass levels achieved by birds are determined by the trade-off between risks of starvation and predation.Birds have also been found to reduce body mass in response to an increased predation risk. During migration, the need of extra fuel for flights is obvious and crucial. In this study, migratory blackcaps (Sylvia atricapilla) were subject to an experimental stopover situation where the predation risk was manipulated by exposure to a stuffed predator. Blackcaps that perceived an imminent risk of predation increased their food intake and fuel deposition rate during the first periodof stopover compared with a control group. The pattern of night activity indicates that birds that were exposed to the predator also chose to leave earlier than birds in the control group. Since there was no cover present at the stopover site, birds might have perceived the risk of predation as higher regardless of whether they were foraging or not. Under such circumstances it has been predicted that birds should increase their foraging activity. The findings in this study clearly indicate that birds are able to adjust their stopover behaviour to perceived predation risk. [ABSTRACT FROM AUTHOR]