James S. Quinn

Air pollution induces heritable DNA mutations

Hundreds of thousands of people worldwide live or work in close proximity to steel mills. Integrated steel production generates chemical pollution containing compounds that can induce genetic damage (1, 2). Previous investigations of herring gulls in the Great Lakes demonstrated elevated DNA mutation rates near steel mills (3, 4) but could not determine the importance of airborne or aquatic routes of contaminant exposure, or eliminate possible confounding factors such as nutritional status and disease burden. To address these issues experimentally, we exposed laboratory mice in situ to ambient air in a polluted industrial area near steel mills. Heritable mutation frequency at tandem-repeat DNA loci in mice exposed 1 km downwind from two integrated steel mills was 1.5- to 2.0-fold elevated compared with those at a reference site 30 km away. This statistically significant elevation was due primarily to an increase in mutations inherited through the paternal germline. Our results indicate that human and wildlife populations in proximity to integrated steel mills may be at risk of developing germline mutations more frequently because of the inhalation of airborne chemical mutagens.

A COMPARISON OF POINT COUNTS AND SOUND RECORDING AS BIRD SURVEY METHODS IN AMAZONIAN SOUTHEAST PERU

Abstract We tested the ability of sound recordings relative to that of point counts to estimate species richness in the Tambopata Reserve in southeast Peru. We tested the effect of two environmental factors (estimated richness and presence of noisy species) and two attributes of species (abundance and foraging height) on estimates of species richness made by point counts and sound recordings. Sound recordings are preferred to point counts when richness is high, as during the dawn chorus, because they allow for repeated listenings. Point counts are more effective than sound recordings at detecting rarely heard species. The presence of noisy species at a station had no effect on the relative ability of the two methods to measure species richness. The foraging height of a species had no effect on its relative detectability by either method. Sound recording was found to be a suitable alternative to point counts for estimating species richness and a preferable alternative under some circumstances.

Shared Paternity among Non-Relatives is a Result of an Egalitarian Mating System in a Communally Breeding Bird, the Pukeko

With extra-pair paternity now known to be common among many species of birds, it is not surprising that males of most species exhibit behaviour that minimizes the risk of losing paternity. The most common form of paternity assurance is mate guarding whereby the male closely follows his mate during her fertile period and attempts to prevent other males from copulating with her. Even in communal or cooperative breeding species where two or more males collaborate in defending a breeding territory, mate guarding by the alpha male still occurs. Here we report that within communally breeding groups of pukeko (.Porphyrio porphyrio) dominant males do not guard their mates and rarely interrupt the copulations of unrelated rival males. This population of pukeko meets the conditions of a model that predicts that unrelated individuals who form breeding coalitions should interact in an egalitarian manner. DNA fingerprinting revealed a tendency for alpha males to father the majority of offspring in a brood, but frequent, uninterrupted copulations by subordinate birds assured that most males within the group had at least some paternity. Because the timing of ovulation is difficult to predict in female pukeko, individual males may be unable to estimate the proportion of eggs that they have fertilized, which could explain why most males participate more or less equally in parental care.

Evidence for size and sex-specific dispersal in a cooperatively breeding cichlid fish

African Great Lake cichlid populations are divided into thousands of genetic subpopulations. The low gene flow between these subpopulations is thought to result from high degrees of natal philopatry, heavy predation pressure, and a patchy distribution of preferred habitats. While predation pressure and habitat distribution are fairly straightforward to assess, data on dispersal distances and rates are scarce. In fishes, direct observations of dispersal events are unlikely, but dispersal can be studied using molecular markers. Using seven microsatellite loci, we examined dispersal in the cooperatively breeding cichlid fish, Neolamprologus pulcher. As this species is found in well‐defined groups clustered into subpopulations, we could assess dispersal on a narrow (within subpopulation) and broad (between subpopulation) scale. While fish were generally more related to others in their own subpopulation than they were to fish from other subpopulations, large males diverged from this pattern. Large males were more related to other large males from different subpopulations than they were to large males from their own subpopulation, suggesting more frequent dispersal by large males. Across subpopulations, relatedness between large males was higher than the relatedness among large females; this pattern was not detected in small males and small females. Within a subpopulation, individuals appeared to be preferentially moving away from relatives, and movement was unrestricted by the physical distance between groups. Our results highlight the importance of examining multiple spatial scales when studying individual dispersal biases.

The Invasive Round Goby (Neogobius melanostomus) in the Diet of Nestling Double-crested Cormorants (Phalacrocorax auritus) in Hamilton Harbour, Lake Ontario

Populations of the invasive round goby (Neogobius melanostomus) have expanded dramatically since their discovery in the Laurentian Great Lakes in 1990. The abundance of these fish and possible competitive displacement of native species from aquatic food webs suggest that they will become an important prey item for predatory birds and sport fish. To date, there is very little information on the predation of round gobies by piscivorous birds in the Great Lakes. We used an abdominal palpation technique to stimulate regurgitation by double-crested cormorant (Phalacrocorax auritus) chicks in ground nests from colonies in Hamilton Harbour, western Lake Ontario, during the 2002 nesting season. We collected and identified all fish species present in regurgitated boluses. For tree-nesting birds, we collected fish that were regurgitated and fell to the ground as a result of targeted disturbance of particular nest trees. At all locations and times, alewife (Alosa pseudoharengus) was the most abundant fish species present by a large margin. The second most abundant species was the round goby, which was present in the regurgitated stomach contents of chicks in a total of 18 percent of nests surveyed, and made up 1.8 to 11 percent of all individual fish specimens identified. Our results show that the round goby is already an important food item for breeding cormorants in Hamilton Harbour, despite relatively recent establishment of goby populations in western Lake Ontario. Fish species of sport or commercial interest were detected in our samples with extremely low frequency (< 0.1%).

No Evidence for Acoustic Mate-Guarding in Duetting Buff-Breasted Wrens (Thryothorus Leucotis)

There are few empirical tests of the acoustic mate-guarding hypothesis for the function of duetting in birds. This hypothesis states that when females are fertile, males initiate many songs or answer most of their mates’ solo songs to form duets and repel rival males seeking extra-pair copulations. We tested the hypothesis by comparing song initiation and answer rates of males and females in socially monogamous buff-breasted wrens (Throthorus leucotis) during pre-fertile and fertile periods. During pre-fertile periods, males often sang for short periods before being answered by their mates, yet first duets were formed earlier relative to dawn and more duets were given during the dawn chorus on pre-fertile than fertile mornings. Males initiated more songs during pre-fertile than fertile periods, whereas there was no difference between stages in female song initiation rates. The proportion of songs answered by individuals of both sexes did not differ between breeding stages. Other mate-guarding behaviours, such as frequent copulation and maintaining close proximity to mates when fertile, did not appear to be important in this species, as no copulations were observed and there was no difference in the time pairs spent in close proximity when females were fertile or not. Parentage analysis revealed that only 3% of 31 broods had young that were likely the result of extra-pair paternity. These findings do not support the acoustic mate-guarding hypothesis, and suggest that the low rate of extra-pair paternity in buff-breasted wrens was maintained without the use of acoustic or traditional paternity guards.

Sexual size dimorphism and parental care patterns in a monomorphic and a dimorphic larid

ABSTRAcr.-I examined parental care patterns of the Black Skimmer (Rynchops niger) and the Caspian Tern (Sterna caspia) to determine correlates of sexual size dimorphism and parental care. In both species, the sexes had quantitatively different parental roles, particularly during the chick-feeding period. Females were generally more involved in parental activities at the nest site than males. Caspian Tern males provided greater numbers and total mass of prey than their mates. Black Skimmer males fed chicks less frequently than did their mates (especially when the broods were very young), but males delivered substantially larger prey and thus contributed greater prey-mass, particularly as broods aged. The sexually dimorphic skimmer pattern of parental roles may have increased the feeding efficiency and reduced predation risks to the young. No overt behavioral manifestations of sexual conflict were observed between paired Caspian Terns or Black Skimmers. Received 1 March 1988, accepted 25 September 1989.

Extrapair mating system of an asynchronously breeding tropical songbird : The mangrove swallow

Variation in the extent of extrapair paternity among avian species could result from ecological differences in breeding synchrony and/or density, or the existence or absence of paternity guards. We studied the extrapair mating system and paternity-assurance behaviors of an asynchronously breeding tropical songbird, the Mangrove Swallow (Tachycineta albilinea), and compared this species with the synchronously breeding temperate zone Tree Swallow (Tachycineta bicolor). Mangrove Swallows had a moderate level of extrapair paternity (26% of broods, 15% of nestlings), low breeding synchrony (8% of females fertile simultaneously), and low breeding density (average nearest-neighbor distance 313 m). The spatial and temporal distribution of nests with and without extrapair young did not differ significantly. Males did not follow their mates closely during the females fertile period, and within-pair copulation frequency was low (0.33 copulations/h). Mangrove Swallows had a significantly lower proportion of extrapair young compared with Tree Swallows. Differences in breeding synchrony may explain the difference in extrapair paternity between the two congeners.

The Adaptive Response and Protection against Heritable Mutations and Fetal Malformation

There are a number of studies that show radiation can cause heritable mutations in the offspring of irradiated organisms. These “germ-line mutations” have been shown to occur in unique sequences of DNA called “minisatellite loci”. The high frequencies of spontaneous and induced mutations at minisatellite loci allow mutation induction to be measured at low doses of exposure in a small population, making minisatellite mutation a powerful tool to investigate radiation-induced heritable mutations. However, the biological significance of these mutations is uncertain, and their relationship to health risk or population fitness is unknown. We have adopted this mutation assay to study the role of adaptive response in protecting mice against radiation-induced heritable defects. We have shown that male mice, adapted to radiation with a low dose priming exposure, do not pass on mutations to their offspring caused by a subsequent large radiation exposure to the adapted males. This presentation and paper provide a general overview of radiation-induced mutations in offspring and explain the effect of low dose exposures and the adaptive response on these mutations. It is also known that exposure of pregnant females to high doses of radiation can cause death or malformation (teratogenesis) in developing fetuses. Malformation can only occur during a specialized stage of organ formation known as organogenesis. Studies in rodents show that radiation-induced fetal death and malformation can be significantly reduced when a pregnant female is exposed to a prior low dose of ionizing radiation. The mechanism of this protective effect, through an adaptive response, depends on the stage of organogenesis when the low dose exposures are delivered. To better understand this process, we have investigated the role of an important gene known as p53. Therefore, this report will also discuss fetal effects of ionizing radiation and explain the critical stages of development when fetuses are at risk. Research will be explained that investigates the biological and genetic systems (p53) that protect the developing fetus and discuss the role of low dose radiation adaptive response in these processes.

Non-destructive sampling of maternal DNA from the external shell of bird eggs

The use of non-destructive sampling methods to collect genetic material from wildlife allows researchers to minimize disturbance. Most avian studies employ capturing and handling of young and parents to draw blood for DNA analysis. In some cases adult female birds are difficult to catch, so maternal genotyping has required collection of contour feathers from nests, or destructive sampling of eggs. Many species do not leave contour feathers in the nest, and destructive sampling has been unreliable due to contamination with embryonic DNA. Alternative field sampling techniques for collection of maternal DNA from birds are therefore desirable. Here we demonstrate that avian maternal DNA can be isolated in a non-invasive and non-destructive way from the external surface of eggs. We used cotton swabs to collect maternal DNA from the external shells of herring gull (Larus argentatus) and Caspian tern (Sterna caspia) eggs. DNA was then amplified by the polymerase chain reaction (PCR) for microsatellite genotyping. We verified that the DNA samples were maternal by comparing microsatellite profiles to those obtained from adults and chicks from the same nests. In 100% of Caspian tern (n=16) and herring gull families (n=12), the egg swabs that amplified matched the maternal microsatellite genotype. In a screening of many nests of both species, we successfully amplified microsatellite markers from 101/115 (88%) egg swabs. Swabs from eggs with blood stains on the shell were more likely to amplify successfully than those from clean eggs. The advantages of this new method include increased parentage assignment/exclusion power, and increased availability of maternal DNA for genotyping of species that do not deposit contour feathers in nests.