吉林白城地区草原栗斑腹(巫鸟)窝卵数、营巢成功率和繁殖成功率的研究

对分布于吉林白城地区草原生境中栗斑腹巫鸟的窝卵数、营巢成功率和繁殖成功率的初步研究结果表明 ,繁殖期栗斑腹巫鸟种群的平均窝卵数为 5 .0 9± 0 .5 8枚 /巢 ;窝卵数与产卵期、出巢数与产卵期、窝卵数与卵大小之间呈负相关 ,产卵期与孵化率之间存在极显著的负相关关系 ,巢外径与窝卵数之间存在显著的正相关关系 ,巢的其余指标均与窝卵数呈正相关 ;平均孵化期为 12± 0 .4 9d ,孵化率为 36 .3% ,繁殖成功率为 11.11% ;7日龄以上的雏鸟群体大小为 2 .5 6± 1.5 3只 ,栗斑腹巫鸟的雏鸟存活率为 2 7.6 9% .     

Philopatry, kin clusters, and genetic relatedness in a population of woodrats (Neotoma macrotis)

Studies of highly kin-structured mammal societies have revealedthe importance of natal philopatry in determining the distributionof genetic variation within populations. In comparison, therelationship between philopatry and genetic diversity withinpopulations of moderately kin-structured societies has receivedrelatively little attention. Previous studies of Neotoma macrotishave suggested that females form distinct kin clusters. Eachkin cluster overlaps spatially with the home range(s) of oneor more males that are not related to each other or to the femaleswith which they are spatially associated. To examine interactionsbetween philopatry and genetic structure in this apparentlymoderately kin-structured species, we characterized spatialand genetic relationships among individually marked femalesin a population of N. macrotis from central coastal California.Our field studies revealed that, contrary to expectation, femalesin this population were not strongly philopatric and spatiallyclustered females were not characterized by high levels of geneticrelatedness. Nevertheless, genetic structure was evident withinthe study population; spatial and genetic distances among femaleswere significantly correlated, suggesting that dispersal patternsinfluenced genetic structure even in the absence of marked femalephilopatry. Because females with overlapping spatial distributionswere not typically closely related to one another, opportunitiesfor the evolution of kin-selected social behavior (e.g., cooperativecare of young) appear to be limited in this population.     

Syntaxin 1A modulates the sexual maturity rate and progeny egg size related to phase changes in locusts

The migratory locust (Locusta migratoria) exhibits clear phenotypic plasticity depending on its population density. Previous studies have explored the molecular mechanisms of body colour, behavior, immunity, and metabolism between high population density gregarious (G) and low population density solitarious (S) locusts. However, the molecular mechanisms underlying differences in reproductive traits remain unknown. G locusts reach sexual maturation much faster and lay larger eggs compared with S locusts. The traits of G locusts decreased significantly with isolation, whereas those of S locusts increased with crowding. Analysis of gene expression in female adults indicated that syntaxin 1A (Syx1A) was expressed significantly higher in G locusts than in S locusts. After silencing Syx1A expression in G locusts by RNA interference (RNAi), their sexual maturity rate and progeny egg size changed towards those of S locusts. Similarly, increment in the traits of S locusts with crowding was blocked by Syx1A interference. Changes in the traits were also confirmed by decrease in the level of vitellogenin, which is regulated by Syx1A. In conclusion, plasticity of the sexual maturity rate and progeny egg size of G and S locusts, which is beneficial for locusts to adapt to environmental changes, is regulated by Syx1A.     

Higher investment in flight morphology does not trade off with fecundity estimates in a poleward range‐expanding damselfly

1. Evolutionary increases in dispersal‐related traits are frequently documented during range expansions. Investment in flight‐related traits is energetically costly and a trade‐off with fecundity may be expected during range expansion. 2. However, in contrast to wing‐dimorphic species, this trade‐off is not general in wing‐monomorphic species. In the absence of a dispersal‐‐fecundity trade‐off, an increased investment in clutch size at the expansion front is expected possibly at a cost of reduced offspring size. 3. The study evaluated investment in female flight morphology and fecundity‐related traits (clutch size, hatchling size) and potential trade‐offs among these traits in replicated populations of the poleward range‐expanding damselfly Coenagrion scitulum. 4. Females at the expansion front had a higher relative thorax length, indicating an increased investment in flight; this can be explained by spatial sorting of dispersal ability or in situ natural selection at the expansion front. Edge females produced larger hatchlings, however, this pattern was totally driven by the population‐specific thermal larval regimes and could not be attributed to the range expansion per se. By contrast, clutch sizes did not differ between core and edge populations. There was no signal of a dispersal–fecundity trade‐off either for a trade‐off between clutch size and hatchling size. 5. These results indicate that evolution of a higher dispersal ability at the expansion front of C. scitulum does not trade off with investment in fecundity, hence a dispersal–fecundity trade‐off is unlikely to slow down range expansion of this species.     

Estimates of relatedness and inbreeding in goose strains from DNA fingerprints

The purpose of this study was to determine if DNA fingerprints (DFPs) could be used to estimate relatedness and inbreeding of strains of geese and to compare three methods of calculating relatedness indices. Strains included a control and selected strain from each of the Chinese and Synthetic (Chinese, Hungarian and Pilgrim) breeds. DFP patterns for each strain were based on individual DNA samples from six females, or on pooled DNA from 15 females different from those used for individual samples. Three relatedness indices were used, namely, genetic distance, modified Rogers distance and band sharing. All relatedness indices showed a closer relationship of strains within than between breeds. Correlation coefficients among relatedness indices were higher based on pooled DNA (r ≥|0·97|) than those based on individual DNA (r ≥|0·741). Inbreeding estimates were higher for selected compared with control strains. It appears that the use of DFPs to estimate relatedness, regardless of index used, and inbreeding can be valuable for studying geese where there is a limited breeding history.     

Larval distributions of the ectoparasitoid wasp Eurytoma robusta relative to the host tephritid gall fly Urophora cardui

Parasitism may explain the patchy distributions of host populations. The present paper is a study of larval distributions of the parasitoid Eurytoma robusta in galls of the tephritid gall fly Urophora cardui. It focuses on E. robusta's choice of U. cardui gall and whether this changes relative to the rate of parasitism. Oviposition patterns were inferred by direct counts of larvae in galls and genetically, for both species, using indirect relatedness estimates between gall‐members. Furthermore, rates of parasitism in four populations were monitored for 4 years. The modal distribution of E. robusta larvae per gall was one and independent of the level of parasitism. The mean number of E. robusta per gall did not differ from Poisson distributions at different parasitism rates. We were not able to demonstrate a parasitoid preference for gall size. In contrast, parasitoids may have a negative effect on gall growth. Relatedness estimates showed that E. robusta gall members were often unrelated, whereas U. cardui were siblings. Thus, larval distributions of E. robusta suggest that oviposition behaviour is generally constrained and density independent. In four populations monitored over 4 years, parasitism was initially high (up to 70%), but suddenly declined with no apparent effect on fly (gall) abundance.     

Facultative polygyny in the plant-ant Petalomyrmex phylax (Hymenoptera: Formicinae): sociogenetic and ecological determinants of queen number

In polygynous ants it has been proposed that the coexistence of several queens in a colony evolved as a response to ecological, social and genetic parameters. We present demographic, histological and genetic data showing that the plant-ant Petalomyrmex phylax is facultatively and secondarily polygynous. Polygyny is functional, lowers the reproductive output per queen, and is a kin-selected trait as new queens accepted in polygynous colonies are highly related females that never left their natal colony. The degree of polygyny varies according to a geographical gradient. Northern colonies can be strongly polygynous, while at the southern edge of the species' distribution, colonies are almost exclusively monogynous. However, ecological studies of the host-plant populations revealed that this cline could not be explained by variations in the degree of nest site limitation. We discuss selective costs and benefits associated with these social structures, and propose that this cline may result from historical processes such as selection of a more dispersive strategy along a colonization front.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 86 , 133–151.     

Variation in parent–offspring kinship in socially monogamous systems with extra‐pair reproduction and inbreeding

Female extra‐pair reproduction in socially monogamous systems is predicted to cause cuckolded socially‐paired males to conditionally reduce paternal care, causing selection against extra‐pair reproduction and underlying polyandry. However, existing models and empirical studies have not explicitly considered that cuckolded males might be related to their socially‐paired female and/or to her extra‐pair mate, and therefore be related to extra‐pair offspring that they did not sire but could rear. Selection against paternal care, and hence against extra‐pair reproduction, might then be weakened. We derive metrics that quantify allele‐sharing between within‐pair and extra‐pair offspring and their mother and her socially‐paired male in terms of coefficients of kinship and inbreeding. We use song sparrow (Melospiza melodia) paternity and pedigree data to quantify these metrics, and thereby quantify the joint effects of extra‐pair reproduction and inbreeding on a brood's total allelic value to its socially‐paired parents. Cuckolded male song sparrows were almost always detectably related to extra‐pair offspring they reared. Consequently, although brood allelic value decreased substantially following female extra‐pair reproduction, this decrease was reduced by within‐pair and extra‐pair reproduction among relatives. Such complex variation in kinship within nuclear families should be incorporated into models considering coevolutionary dynamics of extra‐pair reproduction, parental care, and inbreeding.