SURVIVAL OF MANX SHEARWATERS PUFFINUS PUFFINUS

The breeding success of Manx Shearwaters at Skokholm Island, Pembrokeshire, was followed in study burrows, and data on survival of the young were augmented by ringing large numbers as they were about to leave the island and recapturing them in later years.
The weight of the young at fledging and the date at which they leave affect their chances of survival; overall, as many as 30% of the young birds may survive to reach breeding age, which is thought to be normally about 5–6 years. Adult mortality varies between wide limits of about 5 and 20%, but juvenile survival appears to be of about the right order to balance adult losses.
The significance of the one-egg clutch is discussed. At the normal time of laying the female may not be able to obtain sufficient food to form a second egg. A two-egg clutch, laid at a later date, would not produce more surviving young since these would fledge too late in the season to have a good chance of survival.
The advantage of leaving the island at a heavy weight is discussed, and it is concluded that the fat stores laid down give heavy young a greater chance than light young of migrating a long distance without food. It is possible that the young may even reach their winter quarters (off Brazil) without having to feed on passage if they depart with enough stored fat.     

SURVIVAL AND SOURCES OF MORTALITY IN OCELOTS

Abstract: Survival and cause-specific mortality estimates are needed to develop effective conservation strategies for the endangered ocelot (Leopardus pardalis) in the United States. We radiomonitored 80 ocelots (36 F, 44 M) from 1983 to 2002 and analyzed survival and cause-specific mortality rates. Pooled estimates of annual survival rates differed between resident (Ŝ = 0.87) and transient (Ŝ = 0.57) ocelots (P = 0.02); therefore, survival and cause-specific mortality analyses were partitioned for resident and transient ocelots. Sex-specific annual survival was similar between resident ocelots (M = 0.92, F = 0.83, P = 0.16) and transient ocelots (M = 0.53, F = 0.63, P = 0.75). Most mortalities were from human (e.g., ocelot-vehicle collisions; M = 45%) and natural (e.g., animal attack, disease; M = 35%) sources. Transient ocelots had higher natural mortality rates (disease, intraspecific mortality; M = 0.26) than resident ocelots (M = 0.04, P = 0.03). Other sources of mortality did not differ (P ≥ 0.10) between resident or transient ocelots or male and female resident or transient ocelots (P ≥ 0.08). Human population expansion within the Lower Rio Grande Valley of southern Texas, USA, will increase transportation-related problems and decrease the quantity of ocelot habitat, leading to increased ocelot-vehicle collisions and possibly cause more transient behavior, thus significantly lowering ocelot survival. Research and development of ocelot road underpasses should be conducted to mitigate ocelot-vehicle collisions.     

视网膜神经节细胞的纯化和体外存活

我们用特异性抗体Thy1.1结合尼龙筛方法分离和纯化新生大鼠视网膜神经节细胞,比较顶盖提取液对这些纯化细胞的作用。预先以快蓝(fast blue,FB)逆行标记的视网膜细胞悬液,接种在包被了Thy1.1抗体的培养皿上30分钟,冲洗未粘附的细胞,显微镜下计数粘附细胞中FB标记的视网膜神经节细胞纯度的百分比,最高为95%。用孔径15μm尼龙筛方法分离的纯度仅为60±5%。上述两种方法纯化的视网膜神经节细胞,仅在有顶盖提取液存在时,细胞存活并生长活跃,胞体大且有突起伸出。MTT微量比色法测定培养24小时纯化细胞存活的光密度(OD)值,显示以Thy1.1特异性抗体纯化的细胞,其OD值比值(+Te/-Te)是12.3(0.111/0.009);以尼龙筛纯化的OD值比值(+Te/-Te)是6.4(0.102/0.016);未经纯化的OD值比值(+Te/-Te)是3.8(0.095/0.025)。在上述三组中,加Te与无Te细胞生存的OD值比较,相差均非常显著(P<0.01)。结论:在纯化的视网膜神经节细胞的培养中,由于排除了其他细胞所引起的非特异性反应,神经节细胞能够更直接地反映顶盖提取液的生物效应;视网膜神经节细胞纯度越高,其作用越显著。     

昆虫多状态发育的生存分析

针对昆虫种群变态发育过程,本文给出了一个多状态生存函数的模型。使用生存分析的方法对模型进行丁分析。本文还对有关的生存参数如各状态的死亡风险,发育风险,年龄特征死亡率,年龄特征发育率以及状态发育历期等进行了讨论并且给出了它们的极大似然估计值。关于马铃薯块茎蛾数值例子的分析表明所提出的摸型用来描述昆虫种群的发育过程是有效的。本文的结论可以做为组建描述昆虫种群多状发育的年龄一状态特征生命表的理论基础。     

SENSORY SHELF-LIFE ESTIMATION OF ALFAJOR BY SURVIVAL ANALYSIS

Survival analysis methodology was used to estimate the shelf life of alfajor (a chocolate‐coated individually wrapped cake) at 20 and 35C by using results obtained from consumers when asked if they would accept or reject samples with different storage times. Sensory acceptability (measured by consumers), off‐flavor (measured by a trained panel) and moisture content were linearly related to time. These correlations were used to estimate values at the shelf‐life times calculated for 25 and 50% rejection probability. Survival analysis provided the following shelf‐life estimation: 74 days at 20C and 33 days at 35C for a 25% of rejection, 87 days at 20C and 39 days at 35C for a 50% of rejection. An alfajor stored at 20C having an acceptability value below 4.9 (1–9 hedonic scale) and off‐flavor intensity above 5.3 (0–10 scale) would be rejected by 25% of the consumers. Chemical data were not good shelf‐life predictors.     

GENETIC VARIATION AND JUVENILE SURVIVAL IN RED DEER

The survival of red deer (Cervus elaphus L.) calves to two years of age was examined in relation to electrophoretic variation in a population on the Scottish island of Rhum. Survival was analyzed using logistic analysis in which the “phenotypic” factors birth weight, birth date, subdivision of the study area, cohort, and sex, which affect the probability of a calf's survival, were taken into account. All three polymorphic loci examined, Mpi, Idh-2, and Trf (each with two detected alleles) are significantly associated with juvenile survival. At Mpi, there is selection against one allele, f (or an allele at a linked locus), and there are indications that this effect is stronger in females than males. For Idh-2, overall, the heterozygote class survives better than the two homozygotes, which survive equally well. However, again there is a difference between the sexes; female heterozygotes survive much better than homozygotes, whereas male homozygotes survive better than heterozygotes, and the difference in survival is smaller. Furthermore, there is an interaction involving Mpi, Idh-2, and survival in which Mpi^f carriers that are also Idh-2 homozygotes survive very badly compared with other Mpi-Idh-2 combinations, which all survive equally well. For Trf, the heterozygote class survives best, and there is also a difference in survival between the two homozygote classes. Genotype frequencies in the adult population are consistent with the results for calf survival, in that the Mpi^f frequency is lower in succeeding cohorts of surviving adults, whereas no significant gene frequency change is apparent for Idh-2 or Trf.     

MUTATION LOAD AND THE SURVIVAL OF SMALL POPULATIONS

Previous attempts to model the joint action of selection and mutation in finite populations have treated population size as being independent of the mutation load. However, the accumulation of deleterious mutations is expected to cause a gradual reduction in population size. Consequently, in small populations random genetic drift will progressively overpower selection making it easier to fix future mutations. This synergistic interaction, which we refer to as a mutational melt-down, ultimately leads to population extinction. For many conditions, the coefficient of variation of extinction time is less than 0.1, and for species that reproduce by binary fission, the expected extinction time is quite insensitive to population carrying capacity. These results are consistent with observations that many cultures of ciliated protozoans and vertebrate fibroblasts have characteristic extinction times. The model also predicts that clonal lineages are unlikely to survive more than 10⁴ to 10⁵ generations, which is consistent with existing data on parthenogenetic animals. Contrary to the usual view that Muller's ratchet does more damage when selection is weak, we show that the mean extinction time declines as mutations become more deleterious. Although very small sexual populations, such as self-fertilized lines, are subject to mutational meltdowns, recombination effectively eliminates the process when the effective population size exceeds a dozen or so. The concept of the effective mutation load is developed, and several procedures for estimating it are described. It is shown that this load can be reduced substantially when mutational effects are highly variable.     

THE SURVIVAL RATES OF SOME SOUTHERN AFRICAN PASSERINES

Yom-Tov, Y., McCleery, R. & Oatley, T. 1994. The survival rates of some southern African passerines. Ostrich 65:329-332.

Little information is available on survival rates of southern hemisphere passerines, but two recent studies indicate that Australian passerines tend to live longer than their northern hemisphere relatives. The aim of this paper is to provide data on survival of some South African passerines and compare them with Australian data. The survival rates of eleven species (eight genera) of South African passerines were calculated using recapture data provided by the South African Bird Ringing Unit for birds whose retraps occurred more than 12 months after the original ringing. Survival did not depend on either the length of the study or body mass. Mean survival rate was similar to that of 32 species of Australian passerines, which is at least 1,2 greater than that of British passerines.