The Geometric Clutch hypothesis is based on the premise that transverse forces (t-forces) acting on the outer doublets of the eukaryotic axoneme coordinate the action of the dynein motors to produce flagellar and ciliary beating. T-forces result from tension and compression on the outer doublets when a bend is present on the flagellum or cilium. The t-force acts to pry the doublets apart in an ...

breeding biology of the great cormorants phalacrocorax carbo sinensis is assessed in thesouthern coasts of the caspian sea, iran during the years 2008-2010. about 84 nests located on 63 trees wereexamined. nests were built on large trees located in abbas abad marsh, gilan province. initially, eggs werefound on first week of april and egg laying continued until the last week of may. clutch size ...

Increasing demands on comfort, performance, and fuel efficiency in vehicles lead to more complex transmission solutions. One such solution is the Automated Manual Transmission (AMT). It works just like an ordinary manual transmission but the clutch and gear selection are computer controlled. In this way high efficiency can be accomplished with increased comfort and performance. To be able to co...

Many life-history traits are expressed interactively in life, but to a varying extent on different occasions. Changes in trait expression can be accounted for by differences in the quality of the environment ('environmental constraint' hypothesis) or by strategic adjustments, if the relative contribution of the trait to fitness varies with time ('strategic allocation' hypothesis). In birds, egg...

At Belmont, Lower Hutt, a population of starlings which nested in 500 nest boxes on 1500 ha of pasture land was studied from 1970 to 1979. In total, 750 breeding females and 60 males were individually banded, and of 4006 chicks that Hedged 258 females returned to nest in the study area. In different years, 3-60% of the females attempted a second clutch after a successful first brood. Clutch siz...

Fecundity is an important component of individual fitness and has major consequences on population dynamics. Despite this, the influence of individual genetic variability on egg production traits is poorly known. Here, we use two microsatellite-based measures, homozygosity by loci and internal relatedness, to analyse the influence of female genotypic variation at 11 highly variable microsatelli...

In fish, brood cycling parental males sometimes eat some or all of their eggs, a behavior termed filial cannibalism. We tested predictions of filial cannibalism models related to the cost of parental care in the male sand goby, Pomatoschistus minutus, by increasing the parental effort (fanning expenditure) through reduced levels of dissolved oxygen to 39% in an experimental group, whereas a con...

Female hymenoptera are renowned for their ability to adjust offspring sex ratio to local mate competition. When two females share a patch, they frequently produce clutches that differ in size, the female with the larger clutch optimally producing a more female-biased sex ratio and vice versa. Females can base their sex allocation on their own clutch size only ("self-knowledge") or on both femal...

We investigated the link between heterozygosity and the reaction norm attributes of reproductive performance in female house sparrows (Passer domesticus). We collected data on clutch size, egg size, hatching success and nestling survival in 2816 nesting attempts made by 791 marked individuals over a 16-year period. Pedigree analysis revealed no evidence of inbreeding. Neither parent-offspring r...

Hatchling fitness in crocodilians is affected by "runtism" or failure to thrive syndrome (FTT) in captivity. In this study, 300 hatchling C. porosus, artificially incubated at 32°C for most of their embryonic development, were raised in semi-controlled conditions, with growth criteria derived for the early detection of FTT (within 24 days). Body mass, four days after hatching (BM4d), was correl...