Pairs Of Colonies Research Articles

The system of underground passages in Macrotermes subhyalinus and comparison of laboratory bioassays to field evidence of intraspecific encounters in M. subhyalinus and M. bellicosus (Isoptera, Termitidae)

The system of underground passages and storage pits used in foraging have been excavated in two nests of the termite Macrotermes subhyalinus in West Africa (Ivory Coast). A detailed qualitative description of the morphology and the dimensions of the passage network is given. Three types of passages could be distinguished: radial passages, big cross passages and small cross passages. These varied in their dimensions and their functional significance. Density values for the different types of passages and the storage pits in various zones of the two mounds were calculated. Density of total passages varied between 1.46 m/m2 and 1.80 m/m2 being in the order of other Macrotermes species with a comparable foraging behaviour.¶In the second part of the study intraspecific behavioural tests between pairs of colonies of M. subhyalinus and M. bellicosus were performed in neutral arenas and the zones of contact between the corresponding colonies were then excavated. Hints of agonism such as cemeteries with dry head capsules of termites, passage blockings and phenomena of horizontal or vertical passage segregation were found. Generally colonies displaying strong reaction in behavioural tests reacted in the natural context upon contact with deadly conflicts. On the other hand, colonies with a weak behavioural reaction withdrew and blocked the passages without deadly conflicts. For the first time results of laboratory bioassays were connected to unmanipulated field evidence of termite agonism.

Breeding performance of gentoo penguins ( Pygoscelis papua ) at a colony exposed to high levels of human disturbance

Port Lockroy, situated on the Antarctic Peninsula, is one of the most visited tourist sites in Antarctica. The effects of visitor disturbance on the breeding performance of gentoo penguins (Pygoscelis papua) at Goudier Island, Port Lockroy was investigated during the austral summer of 1996/1997 by comparing pairs in treatment areas (visited by 35–55 tourists every 1–2 days) and control colonies (not visited by tourists). There were no differences between the two groups in the proportion of birds that laid, in hatching success or the proportion of single-chick broods. Pairs in treatment colonies laid a higher proportion of single-egg clutches, but this was related to colony location and unusually high snow accumulation. Most treatment colonies were situated on low-lying ground or in the lee of buildings, and probably had more late layers at the initial census. Only 11% of tourist visits had occurred by laying, making human disturbance an unlikely explanation for the higher proportion of single-egg clutches. Nests monitored in a disturbed colony and a control colony showed no differences in chick mass or survival up to 20 days of age. The overall breeding success, based on counts of creched birds, was similar to other southern populations of gentoo penguins, after correcting for mortality between creching and fledging. Historical data from Goudier Island indicate that the colony established itself in 1985 and has rapidly increased in size since then. The neighbouring colony at Alice Creek, which has been regularly visited by tourists for at least a decade, has also shown a population increase, although this expansion has been at a slower rate. We conclude that disturbance from tourist visits is unlikely to have been a major determinant of gentoo population change at Port Lockroy.

Genetic Variability and Isolation of Cory's Shearwater Colonies in the Northeast Atlantic

DNA fingerprinting was used to compare levels of genetic variability within and among eight colonies of Cory's Shearwater (Calonectris diomedea borealis) in the Madeira, Azores. Canarias, and Berlenga archipelagoes in the Northeast Atlantic. Fingerprint diversity, as measured by one probe and two restriction enzymes, showed very little correlation with population size, suggesting that genetic diversity reflects historical rather than current population sizes. Mean band sharing between pairs of colonies did not show any relation with between-population geographic distance. However, all between-population similarity indexes were lower than the corresponding within-population similarity index, a trend that suggests a small degree of population structure across the breeding range of this subspecies. Despite banding records suggesting high levels of philopatry, gene flow seems sufficient to prevent considerable divergence at these loci. Alternative and equally plausible explanations for the results also are discussed.

Differences in pollen sources of Apis cerana and Apis mellifera at a primary beech forest in central Japan

SUMMARYPlant taxa of pollen sources for Apis cerana japonica and A. mellifera ligustica at a primary beech forest in Ashiu (Kyoto, Japan) were compared. Most pollen sources were shared between the two honey bee species. Seasonal variation in the pollen utilization of the two bee species were similar from April to October. Pollen source overlap in interspecific pairs of colonies was smaller than that in intraspecific pairs at the start and end of the season. Pollen collection from seven plant taxa differed between A. cerana and A. mellifera; A. cerana preferred tall trees, while A. mellifera favoured short herbs. Dioecious and andromonoecious flowers with green petals were preferred by A. cerana. These findings suggest differences in both resource location and visual attractiveness of pollen sources between the two honey bee species, which were emphasized when air temperature was low.

Mutual Nonaggression Pact May Aid Ant Spread

Argentine ants have become common pests worldwide. Researchers have thought that one reason the invaders flourish is because they lose some of their natural aggressiveness against their own kind. Work reported on page 949 now provides the first direct evidence for that idea. It shows that pairs of Argentine ant colonies that don9t fight reach higher population numbers than pairs of warring colonies, possibly because the peaceful ants waste less time and energy. The new findings may spark ideas about how to control Argentine ant invasions.

Loss of intraspecific aggression in the success of a widespread invasive social insect

Despite the innumerable ecological problems and large economic costs associated with biological invasions, the proximate causes of invasion success are often poorly understood. Here, evidence is provided that reduced intraspecific aggression and the concomitant abandonment of territorial behavior unique to introduced populations of the Argentine ant contribute to the elevated population densities directly responsible for its widespread success as an invader. In the laboratory, nonaggressive pairs of colonies experienced lower mortality and greater foraging activity relative to aggressive pairs. These differences translated into higher rates of resource retrieval, greater brood production, and larger worker populations.

NATAL AND BREEDING PHILOPATRY IN A BLACK BRANT,BRANTA BERNICLA NIGRICANS,METAPOPULATION

We estimated natal and breeding philopatry and dispersal probabilities for a metapopulation of Black Brant (Branta bernicla nigricans) based on observations of marked birds at six breeding colonies in Alaska, 1986–1994. Both adult females and males exhibited high (>0.90) probability of philopatry to breeding colonies. Probability of natal philopatry was significantly higher for females than males. Natal dispersal of males was recorded between every pair of colonies, whereas natal dispersal of females was observed between only half of the colony pairs. We suggest that female-biased philopatry was the result of timing of pair formation and characteristics of the mating system of brant, rather than factors related to inbreeding avoidance or optimal discrepancy. Probability of natal philopatry of females increased with age but declined with year of banding. Age-related increase in natal philopatry was positively related to higher breeding probability of older females. Declines in natal philopatry with year of banding corresponded negatively to a period of increasing population density; therefore, local population density may influence the probability of nonbreeding and gene flow among colonies.

Diet selection and foraging distances of African and European-African hybrid honey bee colonies in Costa Rica

Summary Diet selection and foraging distances were compared among 3 pairs of matched colonies of African an European-African hybrid honey bees in Northwestern Costa Rica. Mitochondrial DNA (mtDNA) analysis was used to classify each colony as neotropical African (possessing African mtDNA) or hybrid (possessing European mtDNA, and therefore containing workers arising from a European queen mated to African drones). African and hybrid colonies did not differ significantly in population size, the areas of comb devoted to brood rearing and food storage, flight activity, pollen foraging activity, or the distances traveled to pollen and nectar sources. These nonsignificant differences suggest that the foraging behavior of the two colony types may have been more influenced by environmental factors than by genetically determined dietary or movement preferences. Conversely, such genetically determined preferences may have been expressed, but African-like preferences may have been dominant within both colony types. However, while no significant differences were observed, colonies with African mtDNA maintained slightly greater levels of brood rearing, had 1.5 times the level of pollen foraging activity, and traveled on the average 600 m less per round trip of foraging. The potential influence of these slight but consistent differences on the long-term, relative success of African versus hybrid colonies is discussed.

Size-dependent neural integration between genetically different colonies of a marine bryozoan

Although the formation of genetic chimeras is rare in the animal kingdom, it has long been known that colonial marine invertebrates fuse under natural conditions, forming genetic chimeras. I report here an example of selective, partial fusion. When small colonies of the encrusting marine bryozoan Membranipora membranacea grow into contact, they usually become behaviorally coordinated: if one colony is disturbed, both colonies will simultaneously retract their feeding structures (lophophores). As a first step towards understanding the fitness consequences of this type of apparent fusion, I examine its mechanistic basis. Using assays of zooid behavior, electrophysiological recordings and 14C-labeled metabolites, I demonstrate that physiological integration between M. membranacea colonies is both partial and temporary. Specifically, this study demonstrates (1) that behavioral coordination is the result of neural integration between colonies, (2) that coordinated colony pairs do not exchange metabolites, and (3) that neural integration is a temporary phenomenon that is terminated as colonies grow larger. Additionally, I show that only those zooids at the middle of the intercolony border mediate neural integration. Partial physiological integration between M. membranacea colonies could be a highly specific interaction that increases the potential benefits of fusion (i.e. neural integration) while minimizing the potential costs (i.e. resource parasitism).

Microsite Tolerance of Four Bryophytes in a Mature Black Spruce Stand: Reciprocal Transplants

In the feather moss community under mature upland Picea mariana in northern Ontario, four bryophyte species coexist over periods of decades. The bryophytes comprise a thick, dense carpet with more or less discrete patches of Ptilium crista-castrensis, Dicranum polysetum, and Ptilidium ciliare in a matrix of Pleurozium schreberi. A previous study showed that the four species occupy microsites which overlap in temperature, light, moisture, and litter input. We used three experiments to determine whether spatial pattern was attributable to microhabitat in existing microsites. 1) Individual shoots and 10 cm diameter colonies of the four species within one stand were transplanted reciprocally and grown for one and three years, respectively. Shoot growth was evaluated as elongation; colony growth was assessed as a ratio of final:starting biomass. 2) Colonies of Ptilidium from one stand were transplanted to three microsites in a stand from which the species was absent, and growth assessed as above. 3) A thick layer of spruce needle litter was applied to one of each pair of preweighed colonies, and growth assessed as above. All four species were cabable of surviving in all microsites currently occupied by others in their community, at least over three growing seasons. A single episode ofheavy needle deposition enhanced growth ofallfour species. This suggests that spatial pattern is not due to habitat partitioning, but does not rule out slow competitive exclusion by vigorous/invasive growers.

Population Dynamics of the Barnacle Goose Branta leucopsis in the Baltic Area: Density-Dependent Effects on Reproduction

1. The three largest breeding colonies of barnacle geese Branta leucopsis in the Baltic area were studied from their natural establishments in 1971, 1982 and 1987, respectively, to 1993. The number of breeding pairs increased from one pair in 1971 to 1550, 225 and 150 pairs in the largest, second largest, and third largest colonies, respectively, in 1993. 2. Data on clutch size and number of hatched and fledged young were collected from the beginning or the middle of the 1980s. In the largest colony most data on reproductive success were obtained from observations of individually marked geese. 3. Mean clutch size differed among years and colonies. However, there was no trend for decreasing mean clutch size with increasing density in any of the colonies. Hatching success did not decrease with increasing density in the largest colony. 4. The production of fledged young per breeding pair declined drastically in the largest colony as numbers of breeding pairs rose. This decline was mainly caused by an increasing proportion of the breeding pairs failing to produce any fledged young at all. 5. The relative contribution of the smaller colonies to the total production of fledged young in the Baltic area increased considerably over the study years. In 1993, colony 2 hosted only about 13% of the number of breeding pairs in colonies 1 and 2 combined, but it produced about 38% of the fledged young. 6. Our results point out the need to study populations of colonially nesting geese on a colony by colony basis in order to detect density-dependent effects on reproduction.

Mating type of isolates derived from the spermogonial state of Puccinia coronata var. coronata

Hyphal confrontation between two haploid cultures originating from single basidiospores was used to determine the mating type ofPuccinia coronata var.coronata. Pairs of 15 single-basidiospore cultures were placed approximately 1 mm apart on the medium in all possible combinations. Hyphae of the pairs of colonies came into contact with each other in all combinations approximately two weeks after confrontations. When the nuclear number of hyphal cells in a contact zone was investigated one month after confrontation, monokaryotic hyphae were observed in selfing combination. On the other hand, dikaryotic hyphae were observed in 90.5% of crossing combinations between different cultures. Two isolates are considered compatible if dikaryotic hyphae are present in the contact zone but incompatible if they are absent. The mating type of the fungus was found to be characterized by multiple-allelomorphic tetrapolar incompatibility controlled by the “A” and “B” incompatible factors.

The effect of drifting honey bees on the spread of American foulbrood infections

SUMMARYTwenty-five pairs of honey bee (Apis mellifera) colonies were established with the hives in each pair touching and the entrances facing the same direction. One colony in each pair had a light American foulbrood (AFB) infection (<50 larvae with clinical symptoms) while the other (control) was uninfected. The pairs remained together for 5–388 days (average 103 days). Any heavily infected colonies (< 50 larvae with clinical symptoms) were removed from the trial. Only 2 of the control colonies developed AFB. In a separate trial with two pairs of colonies established in the same way, an average of 5.72% of marked bees were in the wrong hive after two days. Trials where 20 uninfected nucleus colonies were fed 50 000, 500 000 or 5 million Bacillus larvae spores in sugar syrup indicated that the control colonies were not particularly resistant to AFB; four of five colonies fed 5 million spores developed AFB. The results suggest that drifting of honey bees is not a particularly important cause of the spread of AFB.

Morphine attenuates antipredator ultrasonic vocalizations in mixed-sex rat colonies

Mixed-sex groups of laboratory rats living in a visible burrow system (VBS) emit 18–27 kHz ultrasound and retreat to the burrow when a cat is placed in the open area of the VBS. The total duration of ultrasonic vocalizations was reliably reduced by pretreatment with 5 mg/kg morphine. In a subsequent study using male-female colony pairs, presentation of a cat to individual rats in the absence of their colony mate indicated significant gender differences in base frequency, degree of emission, and characteristics of pulses elicited. Specifically, females showed a greater number and duration of vocalizations, of higher frequency(kHz), and with shorter individual pulse durations than males. In the same study, morphine (5 mg/kg) produced a general decrease in the level of ultrasonic emissions in both sexes, reduced the mean base frequency (kHz), and increased the mean duration of individual pulses. These data suggest that endogenous opioid mechanisms may be involved in the mediation of ultrasonic vicalization in response to a predator, and are discussed with reference to known involvement of such systems in defensive responding.

Interpopulational allogeneic reactions in the colonial protochordate Botryllus schlosseri

Botryllus schlosseri is a cosmopolitan encrusting colonial tunicate which undergoes a natural transplantation reaction. When the growing edges of two colonies come into direct contact by interaction between their extracorporeal blood vessel termini, the ampullae, they either reject each other or fuse. This phenomenon is controlled by a single gene locus (Fu/HC) with multiple codominantly expressed alleles. Rejecting colonies share no alleles. Here we analyze allogeneic responses of Monterey (Mon), California, versus Woods Hole (WH), Massachusetts, colonies. Of 42 Mon x WH pairs tested, allogeneic rejection reactions occurred in all. Necrotic lesions (points of rejection, PORs) were produced and developed only by Woods Hole ampullae, either within the Woods Hole tunic, in the borderline between the paired colonies, or within the Monterey tunic. Four types of PORs were characterized. All types involved reactions of blood cells and vessels, including infiltration, hemorrhage formation, retraction and ampullae amputation. These findings were observed in single WH x Mon pairs, in multiple subclones of WH x Mon from two parental colonies (seven independent colony pairs were assayed), and on multiple repeats of interactions from pairs that had already undergone a rejection reaction. In all cases, the range of reaction types, the location of PORs, and the timing of the responses could be found in primary as well as repeat reactions.

Failure to find alloimmune memory in the resorption phenomenon of Botryllus cytomictical chimera

It has been previously shown that mixed-cell chimeras may be established between different colonies of the compound tunicate Botryllus schlosseri given that they share one allele in common on the fusibility locus. However, one of the partners in each chimera is often resorbed. Here we tested for the existence of a memory component to this response, as measured by the accelerated interval to resorption of a second set of semiallogeneic colonies. Eight genetically unrelated colonies gave rise to eighteen chimeras. After a complete resorption of the "inferior" partners in these chimeras, secondary and tertiary sets of chimeras were established with some of them by fusion of the "superior" with naive subclones of the "inferior" partners. It is shown here that (a) when multiple chimeras are prepared using the same pair of colonies, subclones of only one of the partners are resorbed; (b) high variation in the time for resorption is recorded when several chimeras are prepared from any specific pair of colonies, and (c) the time for resorption is not related to the number of vessels connecting between the partners in the chimera, nor to their relative body sizes. Allospecific memory is not documented here and reasons for its absence are discussed.

Ants distinguish neighbors from strangers.

Ants are known to distinguish their own nests and nestmates from all others, using colony-specific odors. Here I show that harvester ants (Pogonomyrmex barbatus) can further distinguish between two kinds of non-nestmates of the same species: neighbors and strangers. Interactions between colonies were thought to depend on the numbers of alien ants that each colony encounters on its territory. The results described here show that such interactions also depend on information about colony identity. Encounters on foraging trails with ants from neighboring colonies, deter foraging more than encounters with ants from distant ones. The history of interactions between particular pairs of colonies may have important effects on intraspecific competition for food.

Mother-infant interactions in captive slow lorises (Nycticebus coucang).

Information is presented about mother-infant interactions and infant development in a rarely studied prosimian primate, the slow loris (Nycticebus coucang). Four dyads were observed, by means of closed circuit TV, in a semi-natural environment for 1 hour per day three times a week. Infants were inactive for the first 6-8 weeks. Although mothers carried infants, they also left them alone for substantial periods of time after the 1st week. Over the 20-week study period, there was a significant decline in ventral contact but not in sitting within 12 inches or engaging in active social interactions. By the end of the study, infants were not yet fully independent. Three of the 4 were primarily responsible for maintaining physical closeness to the mother; they made most of the approaches and mothers made most of the departures. However, only 2 of the 4 infants had assumed responsibility for the initiation and maintenance of social interactions with the mother. By comparison with other nocturnal prosimians of similar size, the rate of development is relatively slow. Unlike many anthropoids, mothers were not strongly protective or rejecting. They did not bring infants back to a fixed location or try to prevent infants from leaving them; and the decline in ventral contact was not accompanied by fights between the pair. The 3 group-living mothers were more protective than the single individually housed mother, and it would seem advisable to isolate mother-infant pairs in laboratory breeding colonies.

Algal overgrowth of alcyonacean soft corals

Colonies of the soft coral Lobophytum pauciflorum (Ehrenberg, 1834) (Coelenterata: Octocorallia: Alcyonacea: Alcyoniidae), some of which were heavily overgrown by the algae Ceranium flaccidum (Kuetzing) Ardissone and Enteromorpha sp., and other minor epizoites, were collected at Taylor Reef (17°50′S; 146°35′E) in the Great Barrier Reef. Overgrown colonies contained the diterpene 2-epi-sarcophytoxide as the major secondary metabolite, while conspecific colonies with clean polyparies contained two diterpenes in approximately equal amounts: 14-hydroxycembra-1,3,7,11-tetraene and 15-hydroxycembra-1,3,7,11-tetraene. By contrast, twenty conspecific pairs of overgrown and clean colonies of other alcyoniid soft corals collected from Pelorus Channel, Palm Island Group (18°34′S; 146°29′E), showed no chemical differences within in the pairs. Cultures of a common species of Ceramium [C. codii (Richards) Mazoyer] were incubated with different concentrations of nine soft-coral-derived diterpenes and significant algal growth inhibition was observed in many cases. It appears that terpenoids from soft coral may contribute to the lack of epizoic organisms on soft-coral polyparies.

Chemical heterogeneity of soldier defensive secretions in the desert subterranean termite, Amitermes wheeleri

Soldier defensive secretions were analyzed by GC/MS in eight spatially separated groups of Amitermes wheeleri collected in Arizona and California. Eleven sesquiterpenoids, four of known structure, were isolated. Quantitative and qualitative differences among the groups of termites were extensive; composition of the defensive secretions among colonies varied from one to six components. Intraspecific differences between pairs of sympatric colonies at six sites were much less pronounced. The variability found in A. wheeleri suggests that soldier defensive secretions in the genus Amiterines are not reliable markers for interspecific systematic comparisons.