CONTRASTING PATTERNS OF PHENOTYPIC PLASTICITY IN REPRODUCTIVE TRAITS IN TWO GREAT TIT (PARUS MAJOR) POPULATIONS

Phenotypic plasticity is an important mechanism via which populations can respond to changing environmental conditions, but we know very little about how natural populations vary with respect to plasticity. Here we use random‐regression animal models to understand the multivariate phenotypic and genetic patterns of plasticity variation in two key life‐history traits, laying date and clutch size, using data from long‐term studies of great tits in The Netherlands (Hoge Veluwe [HV]) and UK (Wytham Woods [WW]). We show that, while population‐level responses of laying date and clutch size to temperature were similar in the two populations, between‐individual variation in plasticity differed markedly. Both populations showed significant variation in phenotypic plasticity (IxE) for laying date, but IxE was significantly higher in HV than in WW. There were no significant genotype‐by‐environment interactions (GxE) for laying date, yet differences in GxE were marginally nonsignificant between HV and WW. For clutch size, we only found significant IxE and GxE in WW but no significant difference between populations. From a multivariate perspective, plasticity in laying date was not correlated with plasticity in clutch size in either population. Our results suggest that generalizations about the form and cause of any response to changing environmental conditions across populations may be difficult.     

大山雀和褐头山雀种间关系研究

在地理分布重叠地区的大山雀Parus major和褐头山雀Parus montanus栖息地海拔高度不同。大山雀栖于海拔2,370米以下,集中于次生杨桦林和老年人工杨树林;褐头山雀栖于海拔2,300米以上,集中于混交林和山杨栎林。它们的栖息地有一定重叠,但重叠值较低。重叠地带觅食生态位的四维中,树种选择一维有所不同,其余三维生态位重叠值均较大。两个种营养生态位有一定重叠,食物大小的重叠值更大。在进化发展过程中,两种山雀间完全的生态分离没有发生。     

FACTORS GOVERNING FEEDING RATE, FOOD REQUIREMENT AND BROOD SIZE OF NESTLING GREAT TITS PARUS MAJOR

SUMMARY Observations were made on feeding rates and food-consumption of nestling Great Tits Parus major mainly in Larch plantations at lake Yamanaka, Japan. Feeding frequencies were recorded by an automatic recorder. There were marked differences between early and late broods; the feeding frequencies were twice as great in early than in late broods of the same size. No clear tendency was observed in the variations of feeding frequencies in relation to brood size. There was, however, a clear inverse relationship between the frequencies and the average size of food brought to the nests. The males' share in terms of feeding frequencies is described. These figures, however, did not follow the males' contribution in terms of weight of food, which was nearly always higher than the females'. It is pointed out that feeding frequencies are far too variable to be used as a true index of food consumption by nestlings, and are not reliable. Attempts were made to measure the weight of food; the method is described. The average weight of food brought by males was lighter in early than in later broods. The total weight of food was estimated. The trend of daily food consumption per chick was similar to that of the chick's growth curve. It was found that up to about the tenth day of the nestling period daily food-intake per chick increased linearly as body weight increased. At some nests, rate of defaecation was observed. This was at first low, but it increased steeply on the third day, with a steady increase thereafter. By comparing the rates of food intake, faeces output, and weight increment of a chick, it was found that only 20–30% of digested matter (the difference between food-intake and faeces-output was used up daily (for body temperature regulation various external effort, etc.). The factors responsible for this high efficiency of growth in nestlings are discussed. There was a clear inverse relationship between the total weight of food brought per chick per day and the brood size. This is largely because the heat-loss is greater in small than in large broods, so that a chick from a small brood in fact needs more energy to maintain its body temperature after a certain age than one from a large brood. This is discussed in detail. Factors which caused variations in size of food are discussed in relation to feeding frequencies. It is pointed out that, because of the inverse relationship between energy requirement by each chick and brood size, the total food requirement by a brood as a whole did not vary directly in proportion to the brood size. An estimation showed that a b/3 still required about 75% of the total food required by a b/8. A smaller brood is less advantageous than expected to parents feeding nestlings when they encounter adverse conditions, e.g. food shortage in the habitat, or a lack of help by their mates, etc. On the other hand, it is suggested that once they have left the nest, the food-demand by a brood of fledglings the parents have to feed, so that, in the fledging period, in times of food shortage it would certainly be advantageous to have fewer young. It is suggested that, although fledglings may consume three to four times as much food as nestlings, the parents, in providing this food, would not work proportionately harder, since the parents' efficiency of providing food could be higher in feeding the fledglings, which always follow the parents as they are hunting, than in feeding the nestlings to which food has to be brought. On this basis, the adaptive significance of the length of the nestling period in nidicolous species is discussed in relation to clutch size, brood size and food requirement.     

THE FOOD AND FEEDING HABITS OF GOLDENEYE BUCEPHALA CLANGULA IN GREAT BRITAIN

The food and feeding habits of Goldeneye Bucephala clangula are described, based on the analyses of 51 stomach contents and a brief review of the literature. The type of food taken depends on the type of habitat being used, the availability and size of the food items and on the methods of feeding—though animal material largely predominates.
In estuarine and coastal areas, small crustaceans and in particular Carcinus maenas figured highly in the diet, with some molluscs and small fish. In two brackish-water feeding birds, seeds formed the bulk of the food, some caddis-fly larvae also being taken. In freshwater feeding birds insects predominated, particularly Trichoptera larvae, chironomid larvae and the adults of Corixa spp. Some crustaceans ( Asellus, Gammarus ) and small molluscs were taken and occasionally small fish. A small amount of plant material was taken in the form of seeds, mainly Potamogeton spp.
The relation between Goldeneye and fishing interests is briefly discussed and it is concluded that fish normally form a small part of the diet and it is unlikely that any serious depredation of fish stocks is common.     

AN EXPERIMENTAL STUDY OF VARIATION IN THE PHACELIA SERICEA COMPLEX

Gillett , Georce W. (Michigan State U., East Lansing.) An experimental study of variation in the Phacelia sericea complex. Amer. Jour. Bot. 48(1): 1–7. Illus. 1961.—The Phacelia sericea complex consists of 2 diploid (n = 11), intergrading species, P. idahoensis and P. sericea. The experimental culture of several races of this complex demonstrated that differences in pubescence, leaf shape, and flower shape persist in plants grown in a common environment. Experimental interspecific F₁ hybrids demonstrated high fertility; portrayed intermediate expressions of pubescence, leaf shape, and flower shape; and were found to be, in many cases, indistinguishable from many wild intermediates. A study of herbarium specimens revealed numerous intergrades in which pubescence, leaf shape, and flower shape are highly variable, though loosely correlated. The evidence obtained from herbarium specimens, greenhouse cultures, field investigations, chromosome studies, and experimental hybridizations suggests a hybrid origin for the wild intermediates, recognized as Phacelia sericea (Graham) A. Gray subsp. ciliosa (Rydb.) Gillett.     

大兴安岭曲壳类硅藻分类研究

对大兴安岭曲壳类硅藻进行了分类学研究,结合国际通用的分类系统对Karayevia RoundBukhtiyarova(卡氏藻属)、Lemnicola RoundBasson(附萍藻属)、Planothidium RoundBukhtiyarova(平面藻属)和Psammothidium BukhtiyarovaRound(沙生藻属)4个属的分类特征进行了描述,对在大兴安岭地区观察到的曲壳类硅藻12个分类单位进行了详细的形态学描述,并给出了他们的生境分布特点。研究观察到中国新记录3个分类单位:Achnanthes tumescens SherwoodLowe(膨胀曲壳藻)、Planothidium lanceolatoide(Sovereign)Lange-Bertalot(近披针形平面藻)、Psammothidium rossii(Hustedt)BukhtiyarovaRound(罗斯沙生藻)。     

AN EXPERIMENTAL STUDY OF PATERNITY AND TAIL ORNAMENTATION IN THE BARN SWALLOW (HIRUNDO RUSTICA)

Previous studies of the socially monogamous barn swallow (Hirundo rustica) have shown that males that most frequently engage in extrapair copulations and whose partners are least involved in copulations with extrapair males are those with long tail ornaments. In this study, through the use of three highly polymorphic microsatellite markers, we analyze the relationships between length of tail ornaments of male barn swallows and proportion of nestlings fathered in own broods, number of offspring fathered in broods of other pairs, and total number of offspring fathered, using both a correlational and an experimental approach. Consistent with our predictions, we show that males with either naturally long or experimentally elongated tails have higher paternity (proportion of biological offspring in own broods), and they produce more biological offspring during the whole breeding season than males with naturally short or experimentally shortened tails. Males with naturally long tails also had more offspring in extrapair broods than short-tailed males, but the effect of tail manipulation on the number of offspring fathered in extrapair broods, although being in the predicted direction, was not statistically significant. Cuckolded males that did not fertilize extrapair females had smaller postmanipulation tail length than cuckolders. We conclude that there is a causal, positive relationship between male tail length and paternity. Since female barn swallows have extensive control over copulation partners and heritability of tail length is high, this study shows that female choice is a component of selection for larger male ornaments. Benefits from extrapair fertilizations to females may arise because they acquire “good” genes for sexual attractiveness or high viability for their offspring.