Colony sex ratios vary with breeding system but not relatedness asymmetry in the facultatively polygynous ant Pheidole pallidula

Abstract.— We investigated sex allocation in a Mediterranean population of the facultatively polygynous (multiple queen per colony) ant Pheidole pallidula . This species shows a strong split sex ratio, with most colonies producing almost exclusively a single-sex brood. Our genetic (microsatellite) analyses reveal that P. pallidula has an unusual breeding system, with colonies being headed by a single or a few unrelated queens. As expected in such a breeding system, our results show no variation in relatedness asymmetry between monogynous (single queen per colony) and polygynous colonies. Nevertheless, sex allocation was tightly associated with the breeding structure, with monogynous colonies producing a male-biased brood and polygynous colonies almost only females. In addition, sex allocation was closely correlated with colony total sexual productivity. Overall, our data show that when colonies become more productive (and presumably larger) they shift from monogyny to polygyny and from male production to female production, a pattern that has never been reported in social insects.     

Prevalence of antibodies to Sendai virus and rotavirus in laboratory rabbits

One hundred and sixty rabbit sera from 10 breeding colonies and 13 laboratory colonies were tested for antibodies to Sendai virus and rotavirus by enzyme-linked immunosorbent assay (ELISA). Antibodies were detected to Sendai virus in 53% and to rotavirus in 81%, indicating the prevalence of these viral infections in laboratory rabbit colonies.     

Experimentally induced helper dispersal in colonially breeding cooperative cichlids

The ‘benefits of philopatry’ hypothesis states that helpers in cooperatively breeding species derive higher benefits from remaining home, instead of dispersing and attempting to breed independently. We tested experimentally whether dispersal options influence dispersal propensity in the cooperatively breeding Lake Tanganyika cichlids Neolamprologus pulcher and N. savoryi. Cooperative groups of these fishes breed in densely packed colonies, surrounded by unoccupied, but apparently suitable breeding habitat. Breeding inside colonies and living in groups seems to benefit individuals, for example by early detection and deterrence of predators. We show that despite a slight preference of both species for habitat with a higher stone cover, 40% of the preferred habitat remained unoccupied. On average, the colonies contained a higher number of (1) predators of adults, juveniles and eggs, (2) shelter competitors, and (3) other species including potential food competitors, compared to the outside colony habitat. Apparently, habitat differences cannot explain why these cichlids breed in colonies. Accordingly, dispersal may not be limited by a lack of suitable breeding shelters, but by the relatively higher risk of establishing an outside- compared to a within-colony breeding territory. To test whether cichlids prefer within- to outside-colony breeding territories, we provided breeding shelters inside the colony and at the colony edge and studied helper dispersal. As expected, significantly more shelters were occupied within the colony compared to the edge. New breeding pairs with several helpers occupied these shelters. We conclude that although breeding habitat is plentiful outside the colonies, helpers delay dispersal to obtain a higher quality breeding position within the group or colony eventually, or they disperse in groups. Our results suggest that (1) group augmentation and Allee effects are generally important for dispersal decisions in cooperatively breeding cichlids, consistent with the ‘benefits of philopatry hypothesis’, and (2) habitat saturation cannot fully explain delayed dispersal in these species.     

Restricted mating dispersal and strong breeding group structure in a mid-sized marsupial mammal (Petrogale penicillata)

Ecological genetic studies have demonstrated that spatial patterns of mating dispersal, the dispersal of gametes through mating behaviour, can facilitate inbreeding avoidance and strongly influence the structure of populations, particularly in highly philopatric species. Elements of breeding group dynamics, such as strong structuring and sex-biased dispersal among groups, can also minimize inbreeding and positively influence levels of genetic diversity within populations. Rock-wallabies are highly philopatric mid-sized mammals whose strong dependence on rocky terrain has resulted in series of discreet, small colonies in the landscape. Populations show no signs of inbreeding and maintain high levels of genetic diversity despite strong patterns of limited gene flow within and among colonies. We used this species to investigate the importance of mating dispersal and breeding group structure to inbreeding avoidance within a 'small' population. We examined the spatial patterns of mating dispersal, the extent of kinship within breeding groups, and the degree of relatedness among brush-tailed rock-wallaby breeding pairs within a colony in southeast Queensland. Parentage data revealed remarkably restricted mating dispersal and strong breeding group structuring for a mid-sized mammal. Breeding groups showed significant levels of female kinship with evidence of male dispersal among groups. We found no evidence for inbreeding avoidance through mate choice; however, anecdotal data suggest the importance of life history traits to inbreeding avoidance between first-degree relatives. We suggest that the restricted pattern of mating dispersal and strong breeding group structuring facilitates inbreeding avoidance within colonies. These results provide insight into the population structure and maintenance of genetic diversity within colonies of the threatened brush-tailed rock-wallaby.     

Socialization strategies and disease transmission in captive colonies of nonhuman primates

In captive research environments for nonhuman primates (NHP), social housing strategies are often in conflict with protocols designed to minimize disease transmission. This is particularly true in breeding colonies, and is especially relevant when attempting to eliminate specific pathogens from a population of primates. Numerous strategies have been used to establish such specific pathogen free (SPF) breeding colonies (primarily of macaques), ranging from nursery rearing of neonates to single housing of socially reared yearlings to the rearing of infants in large social groups. All these strategies attempt to balance the effects of the chosen socialization strategy on parameters related to disease transmission, including the ultimate elimination of the target pathogens. Such strategies may affect the overall disease states of NHP breeding colonies through selective breeding processes. This can occur either by creating subpopulations of animals that do not have target diseases (SPF colonies), but may have other issues; or by creating situations in which the "best" animals are sold and the breeding colony is stocked with animals that may be more disease susceptible than those that were sold. The disease states of NHP research colonies also may be affected by selective utilization programs, in which animals removed from the breeding colony for health/behavior reasons, are preferentially chosen for use in scientific investigations. Such utilization criteria raise the question of whether ideal subjects are being chosen for use in research. Finally, captive primate colonies, where both socialization and disease states are intensely managed, may provide opportunities for those testing predictions from models of the interactions of socialization and disease transmission in the evolution of wild populations of NHP. This would be especially true for some extreme conditions of these disease ecology models, given the exceedingly high social densities and levels of pathogen control that exist in many captive nonhuman primate colonies.     

Successful maintenance of a stingless bee population despite a severe genetic bottleneck

Stingless bees play an important ecological role as pollinators of many wild plant species in the tropics and have significant potential for the pollination of agricultural crops. Nevertheless, conservation efforts as well as commercial breeding programmes require better guidelines on the amount of genetic variation that is needed to maintain viable populations. In this context, we carried out a long-term genetic study on the stingless bee Melipona scutellaris to evaluate the population viability consequences of prolonged breeding from a small number of founder colonies. In particular, it was artificially imposed a genetic bottleneck by setting up a population starting from only two founder colonies, and continued breeding from it for a period of over 10?years in a location outside its natural area of occurrence. We show that despite a great reduction in the number of alleles present at both neutral microsatellite loci and the sex-determining locus relative to its natural source population, and an increased frequency in the production of sterile diploid males, the genetically impoverished population could be successfully bred and maintained for at least 10?years. This shows that in stingless bees, breeding from a small stock of colonies may have less severe consequences than previously suspected. In addition, we provide a simulation model to determine the number of colonies that are needed to maintain a certain number of sex alleles in a population, thereby providing useful guidelines for stingless bee breeding and conservation efforts.     

Colonial breeding in Mute swans (Cygnus olor) associated with an allozyme of lactate dehydrogenase

The Mute swan ( Cygnus olor Gmelin (Anatidae)) is a common water bird of lowland freshwaters and coastal shallows. Its typical breeding system involves lifelong monogamous pairs which vigorously defend large breeding territories, sometimes killing intruding swans that are unable to escape. However, in some unusual circumstances (superabundant food coupled with limited nesting sites) Mute swans may nest colonially. At the only two colonies in southern England a rare allele for lactate dehydrogenase (LDH) was found to be unusually common and colony swans carrying this allele were shown to breed more successfully. This isolated finding could, however, have originated either from a chance 'founder' effect or from human management of the main colony. We now show that this allele is also significantly commoner at two recently formed colonies in Denmark, implying that the association between the allele and colonial breeding may be widespread and longstanding.     

High connectivity in a long-lived high-Arctic seabird,the ivory gull <Emphasis Type="Italic">Pagophila eburnea</Emphasis>

Species may cope with rapid habitat changes by distribution shifts or adaptation to new conditions. A common feature of these responses is that they depend on how the process of dispersal connects populations, both demographically and genetically. We analyzed the genetic structure of a near-threatened high-Arctic seabird, the ivory gull (Pagophila eburnea) in order to infer the connectivity among gull colonies. We analyzed 343 individuals sampled from 16 localities across the circumpolar breeding range of ivory gulls, from northern Russia to the Canadian Arctic. To explore the roles of natal and breeding dispersal, we developed a population genetic model to relate dispersal behavior to the observed genetic structure of worldwide ivory gull populations. Our key finding is the striking genetic homogeneity of ivory gulls across their entire distribution range. The lack of population genetic structure found among colonies, in tandem with independent evidence of movement among colonies, suggests that ongoing effective dispersal is occurring across the Arctic Region. Our results contradict the dispersal patterns generally observed in seabirds where species movement capabilities are often not indicative of dispersal patterns. Model predictions show how natal and breeding dispersal may combine to shape the genetic homogeneity among ivory gull colonies separated by up to 2800 km. Although field data will be key to determine the role of dispersal for the demography of local colonies and refine the respective impacts of natal versus breeding dispersal, conservation planning needs to consider ivory gulls as a genetically homogeneous, Arctic-wide metapopulation effectively connected through dispersal.     

Range of the Greater Flamingo, Phoenicopterus roseus , metapopulation in the Mediterranean: new insights from Turkey

Metapopulation conservation should rely on a flyway approach aiming at assessing the spatial range of metapopulations by estimating the level of exchanges among local populations. In the western Mediterranean, Greater Flamingos have been shown to constitute a metapopulation with natal and breeding dispersal among colonies. In this paper, we examine whether this metapopulation reaches Turkey using a band-resighting study. Our results are the first evidence of natal and breeding dispersal from the western Mediterranean to Turkey, and suggest that the Gediz Delta, one of the two Turkish breeding colonies, can play a significant role in the recruitment of flamingos from the western Mediterranean. In 2003 and 2004, breeders of western Mediterranean origin accounted for more than 1.2 and 1.9% of the estimated breeding population of the Gediz Delta, respectively. Our observations also indicate that the western Mediterranean and Southwest Asia may constitute two sets of populations, which overlap in Turkey. Finally, the resightings of flamingos banded in Turkey show that post-fledging dispersal from Turkey reaches both the eastern and western Mediterranean wetlands. Future data on the natal and breeding dispersal of flamingos born in Turkey could clarify further the connection between Turkey and the western Mediterranean metapopulation.     

Population trends and reproductive success of the European shag Phalacrocorax aristotelis on the Iberian Peninsula following the Prestige oil spill

In 2003, immediately following the Prestige oil spill in Galicia, Spain, we studied the population trends and reproductive performance of European shags (Phalacrocorax aristotelis) at oiled and unoiled colonies. This bird is an important member of the nearshore marine community, breeding in the area affected by the Prestige oil spill. The European shag feeds around the breeding colonies throughout the year, making it a useful indicator of environmental change. Before the oil spill, population trends were similar between oiled and unoiled colonies. Nevertheless, colonies located within the path of the oil suffered greater declines (ca. 10%) compared with pre-spill trends and with population trends at unoiled colonies. In 2003, the breeding success was 50% lower in oiled colonies compared with unoiled colonies. The data available from pre-spill years suggest that the annual reproductive success did not differ among colonies before the impact. European shags breeding at colonies affected by oil showed a negative initial impact from the Prestige oil spill. The reduction in reproductive success at oiled colonies may be due to sub-lethal effects of oil exposure or low food availability after the oil spill.     

Outlier analyses to test for local adaptation to breeding grounds in a migratory arctic seabird

Investigating the extent (or the existence) of local adaptation is crucial to understanding how populations adapt. When experiments or fitness measurements are difficult or impossible to perform in natural populations, genomic techniques allow us to investigate local adaptation through the comparison of allele frequencies and outlier loci along environmental clines. The thick‐billed murre (Uria lomvia) is a highly philopatric colonial arctic seabird that occupies a significant environmental gradient, shows marked phenotypic differences among colonies, and has large effective population sizes. To test whether thick‐billed murres from five colonies along the eastern Canadian Arctic coast show genomic signatures of local adaptation to their breeding grounds, we analyzed geographic variation in genome‐wide markers mapped to a newly assembled thick‐billed murre reference genome. We used outlier analyses to detect loci putatively under selection, and clustering analyses to investigate patterns of differentiation based on 2220 genomewide single nucleotide polymorphisms (SNPs) and 137 outlier SNPs. We found no evidence of population structure among colonies using all loci but found population structure based on outliers only, where birds from the two northernmost colonies (Minarets and Prince Leopold) grouped with birds from the southernmost colony (Gannet), and birds from Coats and Akpatok were distinct from all other colonies. Although results from our analyses did not support local adaptation along the latitudinal cline of breeding colonies, outlier loci grouped birds from different colonies according to their non‐breeding distributions, suggesting that outliers may be informative about adaptation and/or demographic connectivity associated with their migration patterns or nonbreeding grounds.     

Spatio‐temporal shifts of the dynamic Cape fur seal population in southern Africa,based on aerial censuses (1972–2009)

A time series of aerial censuses of Cape fur seal colonies, spanning four decades (1972–2009) and three countries (South Africa, Namibia, and Angola), was analyzed to assess spatio‐temporal changes in population numbers. A weighted quantile regression approach was used to estimate trends in pup counts that were used as proxies for numbers of older animals at breeding colonies. There was a 74% increase in the number of breeding colonies over the study period, from 23 in 1973 to 40 in 2009. There was also a significant northward shift in the distribution of the breeding population. This was largely attributable to events in the northern part of the population's range coinciding with Namibia, where seal numbers declined at most colonies in the south of Namibia while several new breeding colonies developed in the northern part of Namibia and one in southern Angola. Despite range expansion and the development of new colonies, the overall size of the population in 2009 was similar to that of the early 1990s, according to the pup count models. Potential mechanisms for the observed changes, and their management implications, are discussed.     

SYNCHRONY AND SOCIAL STIlMULATION IN COLONIES OF THE BLACK-HEADED WEAVER PLOCEUS CUCULLATUS AND VIEILLOT'S BLACK WEAVER MELANOPTERYX NIGERRIMUS

The paper is concerned with the relative importance of environmental changes and social stimulation in bringing about synchronized social breeding in Ploceus cucullatus and Melanopteryx (Ploceus) nigerrimus . Field work was carried out in central Uganda.
Observations on a single colony of each species extending over a complete breeding period showed that breeding started abruptly with the arrival of a large number of males and the construction of new nests. The majority of females arrived later within a relatively short space of time. Subsequently the number of birds and the amount of activity declined gradually. Nests were repeatedly destroyed and reconstructed in the same positions. In P. cucullatus an entrance funnel was generally added only after occupation of the nest by a female.
Studies extending over a large number of colonies showed that main breeding seasons correspond approximately with the two rainy seasons each year. Isolated colonies may be active between seasons, however.
Nest-building and breeding are highly synchronized within colonies. Uniform responses to rain may partly account for this synchrony, but fluctuations of activity in neighbouring colonies are relatively unsynchronized, suggesting that social stimulation is also an important factor. This is supported by direct observations of social interactions and by the fact that small colonies are relatively less successful than larger ones, apparently because the pair-formation process may fail in the absence of sufficient social stimulation.     

Effects of experimental food provisioning on reproduction in the Jackdaw Corvus monedula, a semi-colonial species

Two Jackdaw Corvus monedula colonies were given supplementary food before and during breeding in 1983. Breeding density and cavity use were compared with those of the same colonies in previous years, when no food was provided. Predation rate and reproductive parameters were compared with those in the same colonies in previous years and with those of two control colonies, without experimental food. Jackdaws preferred safe cavities with small minimum nest-entrance dimensions and avoided those with a high risk of nest predation. In experimental (fed) colonies, however, there was a tendency to use all cavities, which resulted in an increased breeding density. No nests were preyed upon by Ravens Corvus corax in the experimental colonies because supplemental food favoured group defence by increasing colony size and by increasing the time the Jackdaws spent in the colony. Additional food advanced laying date, increased clutch size independently of laying date and increased fledging success. Supplementary food significantly increased fledging success in less than half of all experimental studies on birds. We suggest that the key to this problem is the species' breeding strategy, and we show that supplementary food significantly increased fledging success in brood-reduction strategist species but not in species which directly adjusted their clutch size.     

Behavioral research in breeding colonies of Old World monkeys.

The existence of an active behavioral research program using animals in primate breeding colonies was considered to be not only a compatable multiple use of animals, but a way of materially improving the management and efficiency of the breeding colonies. In colonies of monkeys specifically established for behavioral research programs directed at the examination of social relationships, incidental breeding resulted in levels of reproductive success equivalent to or greater than that normally experienced in colonies devoted entirely to breeding. Behavioral research revealed patterns of seasonality, fostering, kidnapping, and infant care which would otherwise have escaped notice and which would significantly influence culling and management choices in a breeding colony. Many young males and certain low ranking adult males actively contributed to reproduction. Females born and reared in the colonies were the most productive, exceeding wild born or other introduced females in reproductive efficiency. Specific recommendations for establishing, expanding and culling of nonhuman primate breeding colonies were derived from the behavioral research.     

Genetic and morphological differentiation between the two largest breeding colonies of Audouin's Gull Larus audouinii

We assessed the genetic and morphological differences between the two largest breeding colonies of Audouin's Gull Larus audouinii , an endemic seabird species of the Mediterranean region. The two colonies comprise c. 75% of the total world population and are 655 km apart. The Ebro Delta colony was formed recently and, after dramatic growth mainly due to high rates of both immigration and reproductive success, is now the largest in the world (more than 60% of the total population). The Chafarinas Islands support an ancient colony with relatively little fluctuation in breeding numbers. The two colonies also differ greatly in environmental conditions, with the Ebro Delta being a higher quality breeding site. Very little movement occurs between the two colonies. We collected morphological data and blood samples from both colonies. Polymorphic microsatellite markers were used to study the genetic differentiation. These showed no significant variation between colonies, nor evidence of a founder effect in the Ebro Delta. Individuals from the Ebro Delta were larger than those from Chafarinas, the difference being greater for males. This probably reflects a stronger male susceptibility to worse environmental conditions during chick growth at the Chafarinas Islands.     

ASPECTS OF THE BREEDING BIOLOGY OF HERRING GULLS LARUS ARGENTATUS IN URBAN COLONIES

Herring Gulls nesting on rooftops in South Shields and Sunderland were observed during 1974–76. These colonies, then around 200 pairs in each town, have expanded rapidly despite culls. Ringing results identified the Forth area as an important source of recruits, and also suggested that females are more likely to breed away from their natal area than males. It is clear from the high breeding success that these towns provide favourable alternatives to more typical breeding sites. The gulls in the towns nest at low densities, other than on flat roofs. Their breeding success, averaging 1.2–1.6 chicks per pair, was higher than that recorded at more typical colonies, and on structurally isolated rooftop sites was almost double that on flat roofs. This high success is attributed to the absence of cannibalism in these small colonies and the lack of territorial aggression at the structurally isolated sites.     

Experimental test on public information use in the colonial Lesser Kestrel

The formation of colonies and the evolution of coloniality have been suggested to be a by-product of the use of public information to select breeding habitats. In this study we performed an experimental test to investigate whether the Lesser Kestrel (Falco naumanni) uses breeding success of conspecifics as a source of public information to select a breeding colony. We considered four potential cues based on reproductive performance of conspecifics in each colony: mean and variance of breeding success measured in both all pairs (TRS, total reproductive success), and only successful pairs (PRS, partial reproductive success). Both mean PRS and mean TRS could be predictive cues of the future reproductive output at a given site, because they varied among colonies and were autocorrelated from one year to the next. To dissociate any relationship between habitat quality and reproductive success we manipulated the mean brood sizes by transferring chicks among ten colonies. In five colonies, all the broods with at least two nestlings were reduced in one chick and in other five colonies all broods were enlarged by one chick. In the following year, we found that the number of adult immigrant kestrels settled at a colony was only explained by mean PRS in the previous year. We also examined the settlement of yearlings, which lack of information on breeding success in previous years. Unlike adult immigrant kestrels, yearlings tended to settle more frequently in those colonies with low mean PRS in the previous year, probably because of the lower pressure for occupation in those colonies. A multiple regression analysis showed that the growth of colonies was positively dependent on the mean PRS in the experimental year, and negatively on the number of predated nests. This study provides a solid support to the hypothesis that colonial species can use mean breeding success of successful pairs as a source of public information to make settlement decisions.     

Subsocial spiders in space and time: A fine scale approach to the dynamics of dispersal

Less than 0.2% of all spider species live in close associations with conspecifics. Among these, subsocial spiders show characteristics of both solitary spiders (e.g., individuals disperse for breeding) and social spiders (e.g., prolonged cooperative behaviours at least prior to independent reproduction). Dispersing individuals build small webs, usually with one inhabitant, whereas colonies are large webs with plant debris and harbouring multiple females. We studied the spatiotemporal dynamics of dispersal in the subsocial spider Anelosimus baeza. We followed the occupancy of all colonies and dispersal webs over the breeding season by mapping the number and sex of spiders with respect to their location in three dimensions. We studied the settlement patterns of new webs and fluctuation in web occupancy through movement between occupied and abandoned webs of colonies and dispersal webs. The occupancy of webs was highly dynamic with changes occurring at small time scales. The similarity in the patterns of web occupancy by females among dispersal webs was partially explained by their spatial and their temporal proximity. Our results suggest that dispersal webs may be used by spiders as a temporary refuge by both sexes during the breeding season. Patterns described here suggest new approaches to dispersal studies in group living spiders.     

Conservation implications of complex population structure: lessons from the loggerhead turtle (Caretta caretta)

Complex population structure can result from either sex-biased gene flow or population overlap during migrations. Loggerhead turtles (Caretta caretta) have both traits, providing an instructive case history for wildlife management. Based on surveys of maternally inherited mtDNA, pelagic post-hatchlings show no population structure across the northern Atlantic (phi(ST) < 0.001, P = 0.919), subadults in coastal habitat show low structure among locations (phi(ST) = 0.01, P < 0.005), and nesting colonies along the southeastern coast of the United States have strong structure (phi(ST) = 0.42, P < 0.001). Thus the level of population structure increases through progressive life history stages. In contrast, a survey of biparentally inherited microsatellite DNA shows no significant population structure: R(ST) < 0.001; F(ST) = 0.002 (P > 0.05) across the same nesting colonies. These results indicate that loggerhead females home faithfully to their natal nesting colony, but males provide an avenue of gene flow between regional nesting colonies, probably via opportunistic mating in migratory corridors. As a result, all breeding populations in the southeastern United States have similar levels of microsatellite diversity (H(E) = 0.70-0.89), whereas mtDNA haplotype diversity varies dramatically (h = 0.00-0.66). Under a conventional interpretation of the nuclear DNA data, the entire southeastern United States would be regarded as a single management unit, yet the mtDNA data indicate multiple isolated populations. This complex population structure mandates a different management strategy at each life stage. Perturbations to pelagic juveniles will have a diffuse impact on Atlantic nesting colonies, mortality of subadults will have a more focused impact on nearby breeding populations, and disturbances to adults will have pinpoint impact on corresponding breeding populations. These findings demonstrate that surveys of multiple life stages are desirable to resolve management units in migratory marine species.