The genetic architecture of pheromone production between populations distant from the hybrid zone of the pine engraver, <Emphasis Type="Italic">Ips pini</Emphasis>

Summary. Across North America, populations of the pine engraver, Ips pini, differ in their expressed ratios of the two enantiomers of ipsdienol, the main component of its aggregation pheromone. We confirm previous studies, showing that the percentage of (+)-ipsdienol ranged from approximately 40 to 70% for New York (NY) males and less then 5% for California (CA) males. We performed line crosses including the F1, F2, and backcross generations between these populations. These line crosses showed that most F1 hybrids produced an intermediate enantiomeric blend of ipsdienol that was closer to the CA blend, with a frequency distribution peak near 15% (+)-ipsdienol. There was also strong segregation to either parental type in the F2 and backcross generations, but not in a pattern that could be clearly described by a single autosomal locus. There was also an X-linked effect that caused some individuals in the F1 to have phenotypes more characteristic of NY populations. Generation means analysis confirms this X-linked effect, and also suggests a complicated autosomal dominance by dominance epistatic interaction. Despite the appearance of segregation, these results suggest a more complicated system of pheromone blend control than the single major gene previously found between divergent lines for high and low (+)-ipsdienol blends from the hybrid zone in British Columbia.      

Reproductive Parameters of Adult Birds and Morphophysiological Characteristics of Chicks in the Pied Flycatcher (<Emphasis Type="Italic">Ficedula hypoleuca</Emphasis> Pall.) in Technogenically Polluted Habitats

Effects of toxic emissions (heavy metals and sulfur dioxide) on reproductive parameters of adult pied flycatchers (Ficedula hypoleuca Pall.) and morphophysiological characteristics of their progeny have been studied in the vicinity of the Middle Ural Copper-Smelting Plant. In polluted areas, the fecundity of adult birds is lower, mortality among the progeny is higher, and changes in the physiological parameters of birds are observed. The effects of toxic load are better manifested in nestlings than in adult birds. They include an increase in the liver index, the reduction of hemoglobin concentration, and an increase in the proportion of immature erythrocytes in the peripheral blood. The proportion of anemic birds also increases. The weakening of nestlings facilitates their infestation by the larvae of parasitic flies. Changes in the differential blood count of nestlings reflect the combined impact of toxic pollutants and parasites.     

白眉蝮蛇（Agkistrodon halys ussuriensis）蛇毒精氨酸酯酶对小鼠的生殖毒性及F1子代的影响

研究了白眉蝮蛇蛇毒中分离的纯精氨酸酯酶对小鼠的一般生殖毒性及对F1代小鼠的影响 .0 .36U/kg剂量使雄性F0 小鼠体重增长缓慢 ,并使睾丸系数增大 (P <0 .0 5 ) ,但病理学检验睾丸和附睾正常 ;该剂量处理孕鼠 ,减轻了胎鼠和新生F1代小鼠的体重 (P <0 .0 5 ) ,但对F0 雌性小鼠的生殖功能及F1代小鼠的一般体征、中枢神经系统发育及生殖机能均无影响 (P >0 .0 5 ) .纯精氨酸酯酶对小鼠生殖无毒剂量为 0 .18U/kg .表 2参 9     

Sperm characteristics associated with different male reproductive tactics in bluegills (Lepomis macrochirus)

We examined the availability and motility of sperm from parental and sneaker male bluegills (Lepomis macrochirus), a colonially nesting sunfish (Family Centrarchidae) with male parental care and a high incidence of cuckoldry by both sneaker and satellite males. We found no differences between sneakers and parentals in length and swimming speed of sperm, or percent and duration of sperm activity. In sneaker milt, however, sperm was almost 50% more concentrated than in parental milt (16.5×10⁶ vs 11.5×10⁶ sperm/μl of milt, respectively). Despite this difference in sperm concentration, stripped ejaculates from sneakers contained almost 400 million fewer sperm (only 32% as many sperm) than those from parentals due to their much smaller stripped ejaculate volumes (only about 19% that of parentals). Thus unless sneakers can compensate by releasing more sperm or gaining closer proximity to eggs at the time of spawning, they may be at a disadvantage with respect to sperm competition. We discuss these results in relation to models for the evolution of alternative reproductive behaviours in this species and suggest that the cuckolders may be making the best of a bad situation. Received: 18 February 2000 / Revised: 23 March 2000 / Accepted: 14 September 2000     

Parentage analysis of multi-male social groups of tasmanian native hens (Tribonyx mortierii): genetic evidence for monogamy and polyandry

Accurate estimates of male reproductive success are essential to understanding the evolution of polyandrous mating systems. Here, we use multilocus DNA fingerpinting to assess parentage in an island population of Tasmanian native hens (Tribonyx mortierii), which often live in multi-male and/or multi-female social groups. This isolated population presented special challenges to this technique because it was artificially founded from a small number of individuals in the recent past. DNA profiles from four multilocus minisatellite probes were analyzed for adults and offspring from six social groups using two methods: (1) significance of band-sharing coefficients and (2) distribution among a group's offspring of fragments unique to certain adults. Traditional band-sharing analyses did not provide sufficient resolution to establish parentage in this population due to the high level of band-sharing between adults within groups. In contrast, the distribution of unique fragments suggests that in most cases, all offspring within a group have the same male and female genetic parents, so that monogamy may be the predominant genetic mating system of this species. This forces a rexamination of the evolutionary basis of polyandry in these birds. It also demonstrates some of the difficulties in using these highly polymorphic genetic markers for parentage analyses when putative parents are closely related.     

Delayed plumage maturation in Lazuli buntings: tests of the female mimicry and status signalling hypotheses

The evolutionary importance of delayed plumage maturation (DPM) in passerines, the condition when more than 1 year is required to achieve adult-like coloration, remains highly contentious. Adaptive hypotheses propose that aggression from after 2nd-year (ASY) males or predation favors DPM in 2nd-year (SY) males, thereby increasing SY male survivorship or reproductive success. However, each hypothesis suggests a distinct selective mechanism explaining “how” this is accomplished. Alternatively, DPM may be a consequence of a nonadaptive molt constraint. We tested the female mimicry and status signalling hypotheses in territorial ASY male lazuli buntings (Passerinaamoena) using three sets of model presentation experiments. The female mimicry hypothesis proposes that dull SY male plumage deceptively mimics female plumage, and predicts that ASY males can not distinguish SY male from female plumage. The status signalling hypothesis proposes that dull SY male plumage honestly signals low competitive threat, and predicts that ASY males respond less aggressively to dull versus bright, ASY-like plumage. Contrary to the female mimicry hypothesis, ASY males distinguished between SY male and female plumage, as they were aggressive to SY male models exclusively and attempted to copulate with female models. Supporting the status signalling hypothesis, ASY males were significantly less aggressive to SY versus ASY male plumage. While DPM may result from a physiological constraint on bright SY male plumage, our results support the idea that dull plumage in an SY male's first breeding season may be maintained by selection to reduce aggression from ASY males, serving as a signal of competitive status. Received: 21 February 1997 / Accepted after revision: 16 June 1997     

Yield loss in conventional and natural rice farming systems

Compared to modern, conventional agriculture, alternative agricultural production systems may rely on biologically different mechanisms (syndromes) to attain similar production goals. Yield loss to rice in conventional and natural farming rice paddies in Japan was evaluated by simulated injury (leaf-clipping) and monitoring plants damaged by insect herbivores. Rice grown under natural farming practices was more tolerant of simulated injury and injury from Oulema oryzae than rice grown under conventional practices. Natural farming rice retained proportionately more tillers and had a higher proportion of mature seeds than conventionally grown rice. In conventional paddies, the simulated injury may have made the rice plants more susceptible to plant pathogens than their non-injured counterparts, resulting in higher disease attack and proportionately greater yield loss. These results suggest that, pests may affect yield loss independently in natural farming, but in conventional paddies, multiple pest injury may interact synergistically, compounding yield loss.     

On the functional extinction of the Passenger Pigeon

The Passenger Pigeon (Ectopistes migratorius) was a social breeder, and it has been suggested that the species experienced functional extinction, defined as a total reproductive failure, prior to its actual extinction in the early years of the 20th century. We applied a novel randomization test based on the relative times of the most recent egg‐ and skin‐specimen sightings (i.e., recorded date of specimen collection) to test for functional extinction. For a total of 6 eggs and 27 skins, the observed significance level was 0.38, which indicated that the species did not become functionally extinct. Thus, proposals to reverse its rapid decline in the late 19th century could have been successful.     

Organochlorine levels in viperine snake Natrix maura carcasses from the ebro delta (NE Spain): Sexual and size-related differences

Organochlorine compounds (PCBs, DDTs and HCB) in carcasses from a population of the Viperine Snake (Natrix maura) living in the Ebro Delta were analyzed. This is a wetland area on the Mediterranean coast where the natural ecosystem has been partially substituted by rice fields. High levels of pollutants (mainly DDTs and PCBs) have been detected in several species living in this area, due to the production of these compounds by a former industrial activity upstream as well as agricultural activity in the Delta. Organochlorines were analyzed in adult males and females, and in immature snakes. DDTs (mainly p,p′-DDE) were the most abundant pollutant present. The DDT/PCB ratio was higher than expected, which is consistent with the position of the Viperine Snake in the trophic web as well as the type of prey consumed. Immature snakes had more organochlorines than adults. However, the broad range of concentrations shown by immature snakes, suggested that part of the organochlorine load is transferred from gravid females to their eggs. In adults, organochlorine concentrations increased with carcass weight in both males and females. This increase was higher in males since females lost contaminants through fat investment during vitellogenesis. Seasonally, PCBs and DDTs levels increased in spring when snakes showed higher feeding activity, whereas higher levels of HCB were present at the end of summer, when the river input increased. Furthermore, HCB does not seem to biomagnify well across the trophic chain. Organochlorine concentrations in Viperine Snake carcasses were high since: 1) the dry tissue had less than 5% of fat, and 2) snakes were caught many years after the DDT ban, supporting the fact that cleaning of the ecosystem does not occur easily. These results indicate that snakes are adequate as indicators of the contamination in natural ecosystems but sex and body size of the samples should be taken into account for interpretation of results.