Tetranucleotide microsatellite loci from the striped dolphin (Stenella coeruleoalba Meyen, 1833)

Five tetranucleotide microsatellite loci were isolated from the striped dolphin (Stenella coeruleoalba). Characterization of these loci revealed between three and 11 alleles at each locus and observed heterozygosity ranged from 0.192 to 0.775. All sets of primers amplified homologous loci when tested on four related species and showed polymorphisms in most locus–species combinations. A sixth microsatellite, which appeared to be monomorphic in the striped dolphin, was also shown to be polymorphic in three related species.     

Growth of the Stem of Agropyron repens (L.) Beauv

The growth rate of the stem of Agropyron repens (L.) Beauv.begins to decline when the sixth foliage leaf has expanded butthe relative growth rate declines throughout the period betweenthe production of one and ten mature leaves. On an absolutetime scale there is a progressive decline in growth rate ofsuccessively formed stem (node-internode) units. On a plastochronscale the relative growth rate of successive stem units declineswithin the apical region but increases behind the apex. Thedecline in the apical region is related to a decrease in therate of cell division and in the later formed stem units thereis no significant increase in cell number from the time of theirformation by the apex until the internode is initiated duringtheir fourth plastochron. These changes are related to concurrentchanges in the size of the shoot apex and in rates of leaf growth.     

The Development of the Shoot Apex of Agropyron repens (L.)Beauv.

During the phase of growth between the production of one and10 mature leaves the primary shoot apex of Agropyron repensundergoes first an increase and then a decrease in size. Theapical dome was found to attain a maximum size at the six leafstage. The changes are attributable to changes in cell number,mean cell size remaining constant after an initial decrease.The zonation pattern, and particularly the number of tunicalayers, varies with the size of the dome. The apex as a wholeundergoes a greater increase in height than in diameter, withcommensurate changes in the number of leaf primordia presentupon it. Similar changes occur in the tiller but no such obvioustrends were found in the rhizome. In an experiment in whichall axillary buds were excised from the primary shoot it wasfound that the apex continued to increase in size well beyondthe maximum attained by that of an intact plant. On this evidenceit is suggested that the eventual decline of the primary shootand tiller apices is due to an inhibitory effect on the mainshoot by the developing axillary shoots.     

Correlative Inhibition in the Shoot of Agropyron repens ( L.) Beauv

Correlative inhibition was investigated in plants of Agropyronrepens at two temperatures. Reciprocal inhibition ocrurred betweenthe main shoot apex and the outgrowing axillary shoots, withthe balance of inhibition varying with temperature. Apical dominancewas stronger at 10 °C than at 20 °C , but even at 10°C release of apical dominance by decapitation had onlyminor effects on the timing of outgrowth, growth pattern andrate of dry weight aocumulation of the axillary shoots. Dominanceof the main shoot apex by the axillary shoots was stronger at20 °C than at 10 °C. Removal of axillary buds preventeddecline in size and activity of the main shoot apex ard resultedin increased rates of primordium initiation, leaf emergenceand dry weight accumulation in the main shoot. It is suggestedthat a system of reciprocal dominance provides a mechanism formaintaining the characteristic habit of the grass plant andlimits growth in height of vegetative shoots. Agropyron repens (L.) Beauv, couch grass, correlative inhibition, apical dominance, shoot, apex     

Isolation and characterization of novel microsatellite loci for the short‐beaked common dolphin (Delphinus delphis) and cross‐amplification in other cetacean species

Seven tetranucleotide and three dinucleotide microsatellite loci were isolated from the short‐beaked common dolphin (Delphinus delphis). Number of alleles and observed heterozygosity ranged from three to twelve (mean 8.4) and from 0.087 to 0.978 (mean 0.741), respectively. All loci were tested in four other odontocete species and showed polymorphisms in most locus–species combinations. This panel of nuclear markers will be useful for the investigation of population ecology and social interactions in common dolphins and other cetacean species.     

Review of cetaceans stranded on the Irish coast, 1901–95

Published records of cetaceans stranded on the Irish coast during the period 1901–95 are reviewed. In this review the number of stranding events has been used in the analysis and includes both live strandings and those animals washed up dead. There were 529 records involving 21 species. The Harbour Porpoise (27%) was the most frequently reported species, followed by Common Dolphins (16%) and Pilot Whales (15%). Minke Whales (8%) were the most frequently reported mysticete. The number of reported strandings has increased since the 1960s which is thought to be mainly due to increased observer effort. Cetaceans have stranded on all Irish coasts but mainly along the south coast and along the western seaboard but with no apparent overall seasonal trend. There was a peak in the strandings of Common Dolphins during 1991–92 when 27% (28 records) of all strandings were reported and of White-sided Dolphins when 60% (28 records) were reported, both of which were attributed to possible interactions with fisheries. The number of Striped Dolphins stranded on the Irish coast has increased steadily since the 1980s and may reflect increasing water temperatures.
These stranding records are considered inadequate to determine the status of most species of cetaceans in Irish waters but are sufficient to identify unusual stranding events such as high mortalities due to fisheries interactions or epizootics. More observer coverage is required before the stranding data are adequate for monitoring the status of most species but a stranding scheme is considered the most effective and efficient method of long-term monitoring of cetaceans in Irish waters.     

Growth of the Shoot Apex of Agropyron repens (L.) Beauv. During Successive Plastochrons

Two kinds of size change occur in the apical dome of Agropyronrepens during development of the shoot. A cyclic increase anddecrease in size results from the production of a new stem segmentand associated leaf primordium during each plastochron. A progressiveincrease and then decrease in size, which occur over a periodof several plastochrons, is attributable to discrepancies betweenthe size increment during each plastochron and the size of thestem segment formed at the end of the plastochron. The volumedoubling time of the dome remains constant at approximatelyone plastochron. Fluctuations in mean cell generation time correlatewith changes in mean cell volume and do not contribute to thesize changes of the dome. Agropyron repens (L.), Beauv, couch grass, shoot apex, cell growth, cell divisions     

The Macquarie perch,Macquria australasica (Pisces: Percichthyidae), of Lake Eildon,Victoria

The results of a field study carried out between 1966 and 1969 indicate that the spawning migrations of Macquarie perch, Macquaria australasica, from Lake Eildon, Victoria, into the inflowing Delatite, Howqua, Jamieson, Goulburn and Big Rivers occurred when water temperatures in the rivers reached 16.5°C. Because of different temperature regimes the times of the spawning migration and spawning differed from river to river. Migrating fish were of a uniform size and were in their fifth to tenth years of life. Recaptures of tagged fish suggest that some fish use the same river each year for spawning. Observations on pre-spawning and spawning behaviour and on the characteristics of the spawning site are recorded. Fecundity of fourteen fish in the size range 305–405 mm standard length varied from 50189 to 107 724 eggs per fish. The virtual disappearance of Macquarie pereh from Lake Eildon was probably caused by a combination of several factors, including changed habitat, overfishing of the spawning stock and predation by, and competition for food with, introduced fish.