一种间接估计阿根廷城市湿地海狸鼠多度的方法

我们设计了一种利用洞穴大小和空间散布来估计海狸鼠(Myocastor coypus)绝对数量的间接方法,并使用个体移除法对绝对数量的估计进行了检验。利用参数相关和效能检验对这两种方法的方程式斜率差异进行了检验,两者间存在高度正相关(r=0·963 ,P=0·002)。以洞穴大小和空间散布估计海狸鼠数量的方程斜率与1·0没有显著性差异(P=0·05) ,其差异检出效能为93 %。因此,利用洞穴大小和空间散布估计海狸鼠绝对数量的这种间接数量估计方法既不影响动物又不扰乱生境,其结果精确且易于实施。     

Role of the furrow of the proximal colon in the production of soft and hard feces in nutrias, Myocastor coypus

The bacterial level of soft feces is higher than that of hard feces in nutrias. This suggests the heterogeneity of bacterial density in the large intestine. To show the heterogeneity of bacteria in the contents of the large intestine in nutrias, we divided the contents of the large intestine into 12 regions, then measured the nitrogen (N), total amino acids (TAA) and diaminopimelic acid (DAP), a bacterial marker, of these regions. Levels of N, TAA and DAP varied along the cross section of the proximal colon. The greater curvature of the main lumen and furrow had higher N, TAA and DAP concentrations than the lesser curvature. We also examined the involvement of the furrow in producing two types of feces differing in bacterial nitrogen content by surgically preventing the flow of the furrow contents. We compared the concentrations of N, TAA and DAP between soft and hard feces among operated, sham-operated and intact animals. Surgical closure of the furrow abolished the difference in levels of N, TAA and DAP between soft and hard feces, suggesting that the furrow of the proximal colon is responsible for making the bacterial density higher in soft feces than in hard feces. Accepted: 13 July 2000     

The eradication of muskrats and coypus from Britain

Introduced vertebrates can cause massive environmental damage but most attempts to remove feral populations have failed. This paper discusses the eradication campaigns against feral muskrats, Ondatra Zibethicus and coypus, Myocastor coypus in Britain. Both specks were introduced in the 1920s to be farmed for pelts and feral populations became established following escapes. The risk of environmental damage by muskrats was well known from Europe and;in eradication campaign started promptly in 1932 making use of overseas expertise and a control strategy designed by pest control specialists. The campaign was brought to a successful conclusion in 1939 when at least 4388 muskrats had been killed.
In the 1930s, few believed that coypus would cause significant environment damage and early trapping efforts were inadequate. An early campaign achieved only limited success partly because of the lack of biological information. The eradication campaign which started in 1981, was based on a long tem study of population ecology. The effect of trapping and cold weather was quantified and detailed population simulations were used to plan the numbers of trappers, the time needed for eradication arid thus the likely cost of the campaign. An incentive bonus scheme was designed to overcome the problem that trappers would be reluctant to work themselves out of a job. Trapper deployment was planned using capture/trapping effort ratios and progress was checked by Ministry of Agriculture field staff.
The muskrat campaigns succeeded because technical information to help plan the work was available and because action was taken quickly. Where an introduced population is well established, as with coypus in Britain, a closely integrated programme involving applied population ecology and a well-planned control organization may he essential for succesful removal.     

Prediction of social structure and genetic relatedness in colonies of the facultative polygynous stingless bee Melipona bicolor (Hymenoptera, Apidae)

Stingless bee colonies typically consist of one single-mated mother queen and her worker offspring. The stingless bee Melipona bicolor (Hymenoptera: Apidae) shows facultative polygyny, which makes this species particularly suitable for testing theoretical expectations concerning social behavior. In this study, we investigated the social structure and genetic relatedness among workers from eight natural and six manipulated colonies of M. bicolor over a period of one year. The populations of M. bicolor contained monogynous and polygynous colonies. The estimated genetic relatedness among workers from monogynous and polygynous colonies was 0.75 ± 0.12 and 0.53 ± 0.16 (mean ± SEM), respectively. Although the parental genotypes had significant effects on genetic relatedness in monogynous and polygynous colonies, polygyny markedly decreased the relatedness among nestmate workers. Our findings also demonstrate that polygyny in M. bicolor may arise from the adoption of related or unrelated queens.     

Polymorphic social organization in an ant

Identifying species exhibiting variation in social organization is an important step towards explaining the genetic and environmental factors underlying social evolution. In most studied populations of the ant Leptothorax acervorum, reproduction is shared among queens in multiple queen colonies (polygyny). By contrast, reports from other populations, but based on weaker evidence, suggest a single queen may monopolize all reproduction in multiple queen colonies (functional monogyny). Here we identify a marked polymorphism in social organization in this species, by conclusively showing that functional monogyny is exhibited in a Spanish population, showing that the social organization is stable and not purely a consequence of daughter queens overwintering, that daughter queen re-adoption is frequent and queen turnover is low. Importantly, we show that polygynous and functionally monogynous populations are not genetically distinct from one another based on mtDNA and nDNA. This suggests a recent evolutionary divergence between social phenotypes. Finally, when functionally monogynous and polygynous colonies were kept under identical laboratory conditions, social organization did not change, suggesting a genetic basis for the polymorphism. We discuss the implications of these findings to the study of reproductive skew.     

Restricted gene flow between two social forms in the ant Formica truncorum

We studied genetic differentiation between two social forms (M-type: single queen, independent nest founding; P-type: multiple queens, dependent nest founding, building of colonial networks) of the ant Formica truncorum in a locality where the social types characterize two sympatric populations. The genetic results indicate restricted gene flow between the social forms. Female gene flow between the forms appears to be absent as they did not share mitochondrial haplotypes. Significant nuclear differentiation and the distribution of private alleles suggest that male gene flow between the forms is weak. However, the assignment analysis indicates some gene flow with P males mating with M females. The results have potentially important implications concerning social evolution within the forms but they need to be confirmed in other localities before they can be generalized. The colonies in the M-type population have earlier been shown to produce split sex ratios, depending on the mating frequency of the queens. The inferred gene flow from the P to the M type means that the split sex ratio is partly suboptimal, possibly because the P populations are not long-lived enough to influence the behavioural decisions in the M colonies.     

Social organization in Eulipotyphla: evidence for a social shrew

Shrews and their close relatives (order Eulipotyphla) are typically considered to be solitary. This impacts our understanding of mammalian social evolution: (i) the ancestor of mammals is believed to have been shrew-like, and even though Eulipotyphla are not more basal than other mammalian orders, this might have been one reason why the first mammals have been assumed to be solitary-living; (ii) Eulipotyphla are the third largest mammalian order, with hundreds of species entering comparative analyses. We review primary field studies reporting the social organization of Eulipotyphla, doing a literature research on 445 species. Primary literature was only available for 16 of the 445 species. We found 56% of the studied species to be social (38% were living in pairs), which is in sharp contrast to the 0.5 and 8% reported in other databases. We conclude that the available information indicates that shrews are more sociable than generally believed. An interesting alternative hypothesis is that the mammalian ancestor might have been pair-living. To understand the social evolution of mammals, comparative studies must be based on reliable and specific information, and more species of all orders must be studied in the field.     

Regional differences in hindgut structure and function in the nutria,Myocastor coypus

Summary Morphologically the large intestine of the nutria resembles that of other caviomorphs, notably the guinea pig. The cecum is voluminous: it contributes 8.6% of the total intestinal length and 12.7% of the total intestinal surface area (considering the surface enlargement factor). It contains 27–32% of the wet ingesta and 20–23% of the dry matter in the gastrointestinal tract. In the colon the corresponding figures are: 21.8% of length, 12.6% of surface area, 16–21% of wet ingesta, and 16–40% of dry matter. The colon can be subdivided both structurally and functionally into two sections, the proximal and the distal colon, the border between the two being the apical flexure of a long parallel loop. The proximal colon (42% of colonic length) displays on the mucosal surface of its mesenterial side a narrow furrow bordered by ridges, which is absent in the distal colon. The ridges contain subepithelial accumulations of coiled tubuloalveolar mucoid glands, entwined by bundles of muscle fibers. Determinations of nitrogen in the contents near the furrow suggest a concentration of bacteria in this part of the lumen. It is hypothesized that the structural differentiations of the proximal colon provide mechanisms for the transport of bacteria from the proximal colon back into the cecum to maintain the fermentation function. The slopes of the longitudinal profiles for dry matter and for concentrations of sodium, potassium and calcium in the luminal contents change at the tip of the parallel loop. The electrical potential difference intestinal lumen — blood is particularly large in the proximal colon, indicating active electrogenic ion transport in this region. SEF surface enlargement factor - CSM colonic separation mechanism - PEG polyethylene glycol - DM dry matter Dedicated to Prof. K.-E. Wohlfarth-Bottermann, Institut für Cytologie und Mikromorphologie der Universität Bonn, Bonn, Federal Republic of Germany, on the occasion of his 65th birthday     

The success of alternative reproductive tactics in monogyne populations of the ant Solenopsis invicta: significance for transitions in social organization

Newly produced queens from monogyne (single-queen) coloniesof the ant Solenopsis invicta usually initiate reproductionindependently, that is, without worker assistance. However,some recently mated queens attempt to bypass this risky phaseof new colony foundation by entering established nests to reproduce,although it is unclear how often these queens are successfulin natural populations. We surveyed a mature monogyne populationof S. invicta in both 1995 and 1996 for colonies headed by queensincapable of independent colony founding (diploid-male-producingqueens) in order to estimate the frequency of colonies thatare headed by queens that initiated reproduction within establishednests (adopted queens). Using the frequency of diploid-male-producingqueens among the recently mated queens in this population, weestimated that the overall rate of queen replacement by adoptedqueens is about 0.7% per colony per year. Although theory suggeststhat a change to a novel queen reproductive tactic could beassociated with a fundamental change in social organization(queen number), this does not appear to be the case in monogyneS. invicta. However, the evolution of nest-infiltrating reproductivetactics by queens in a monogyne population and the evolutionof multiple-queen societies may result from similar ecologicalpressures facing newly mated queens. We therefore incorporatethis strategy into an existing theoretical framework that wasdeveloped to explain the evolution of alternative social organizationsin ants, providing testable predictions regarding the distributionand frequency of queen adoption in other single-queen ant societies.     

The social organization of giraffes in Niger

The social organization of the last population of giraffes ( Giraffa camelopardalis ) in West Africa was studied between October 1996 and December 1997. Population size increased from 51 to 63 individuals during the study period. Groups were larger during the rainy season (mean group size 9.4) than during the dry season (mean group size 6; U = 4131; P < 0.01). Giraffes did not show strong preferential associations. Group types observed were similar to those expected on the assumption that associations are independent of sex and age. Inter-individual associations were low (mean simple ratio value = 0.1), with an individual associating with only half of its partners of the previous day. Young males interacted more frequently than other classes did. Agonistic interactions occurred mostly among males. Contact interactions (i.e. non-agonistic or sexual) occurred between both sexes and most age classes. Links between local communities, domestic animals, fauna and the environment suggest that environment and development cannot be dissociated in the sustainable exploitation of natural resources.     

Propagule pressure and colony social organization are associated with the successful invasion and rapid range expansion of fire ants in China

We characterized patterns of genetic variation in populations of the fire ant Solenopsis invicta in China using mitochondrial DNA sequences and nuclear microsatellite loci to test predictions as to how propagule pressure and subsequent dispersal following establishment jointly shape the invasion success of this ant in this recently invaded area. Fire ants in Wuchuan (Guangdong Province) are genetically differentiated from those found in other large infested areas of China. The immediate source of ants in Wuchuan appears to be somewhere near Texas, which ranks first among the southern USA infested states in the exportation of goods to China. Most colonies from spatially distant, outlying areas in China are genetically similar to one another and appear to share a common source (Wuchuan, Guangdong Province), suggesting that long‐distance jump dispersal has been a prevalent means of recent spread of fire ants in China. Furthermore, most colonies at outlier sites are of the polygyne social form (featuring multiple egg‐laying queens per nest), reinforcing the important role of this social form in the successful invasion of new areas and subsequent range expansion following invasion. Several analyses consistently revealed characteristic signatures of genetic bottlenecks for S. invicta populations in China. The results of this study highlight the invasive potential of this pest ant, suggest that the magnitude of international trade may serve as a predictor of propagule pressure and indicate that rates and patterns of subsequent range expansion are partly determined by the interplay between species traits and the trade and transportation networks.     

Distribution and use of burrows and tunnels ofChaetophractus villosus (Mammalia, Xenarthra) in the eastern Argentinean pampas

Burrows and tunnels built byChaetophractus villosus (Desmarest, 1804) (hairy armadillo) were studied in a farming area located in the Argentinean pampas, Buenos Aires Province, Argentina. Fifty-six structures were selected and carefully excavated for this study. Data on diameter, form, and orientation of the entrance, angle, length, and depth of the galleries, and spatial distribution of the structures were recorded. The structures were separated into two types: simple and complex, both located in high terrain. Simple structures are shorter than complex ones and are built when animals are in search of food or as temporary shelters. Complex structures are built as home burrows. The orientation of the entrances of both kinds of burrows is related to the prevalent wind direction.     

Intraspecific support for the polygyny-vs.-polyandry hypothesis in the bulldog ant Myrmecia brevinoda

The number of queens per colony and the number of matings per queen are the most important determinants of the genetic structure of ant colonies, and understanding their interrelationship is essential to the study of social evolution. The polygyny-vs.-polyandry hypothesis argues that polygyny and polyandry should be negatively associated because both can result in increased intracolonial genetic variability and have costs. However, evidence for this long-debated hypothesis has been lacking at the intraspecific level. Here, we investigated the colony genetic structure in the Australian bulldog ant Myrmecia brevinoda. The numbers of queens per colony varied from 1 to 6. Nestmate queens within polygynous colonies were on average related (r(qq) = 0.171 ± 0.019), but the overall relatedness between queens and their mates was indistinguishable from zero (r(qm) = 0.037 ± 0.030). Queens were inferred to mate with 1-10 males. A lack of genetic isolation by distance among nests indicated the prevalence of independent colony foundation. In accordance with the polygyny-vs.-polyandry hypothesis, the number of queens per colony was significantly negatively associated with the estimated number of matings (Spearman rank correlation R = -0.490, P = 0.028). This study thus provides the rare intraspecific evidence for the polygyny-vs.-polyandry hypothesis. We suggest that the high costs of multiple matings and the strong effect of multiple mating on intracolonial genetic diversity may be essential to the negative association between polygyny and polyandry and that any attempt to empirically test this hypothesis should place emphasis upon these two key underlying aspects.     

Population genetics of the socially polymorphic ant <Emphasis Type="Italic">Formica podzolica</Emphasis>

Summary. We used microsatellite markers to analyze the hierarchical genetic structure of the North American mound building ant, Formica podzolica. About one-third of all colonies were headed by a single queen (monogynous) whose effective mating frequency was close to one (nestmate worker relatedness r = 0.70), while the remaining colonies were polygynous, with low average nestmate relatedness (r = 0.16). The low worker relatedness found in most polygynous colonies furthermore suggested that the numbers of queens in polygynous colonies of this ant are usually high. Contrary to what has been described from other ants with a queen number dichotomy, we did not find an effect of social form variation on the partitioning of genetic variation above the level of the colony. We found no significant differentiation between the sympatric social forms of F. podzolica, nor did differentiation among populations appear to be affected by colony social organization. These unexpected patterns of genetic structure may have resulted from differences either in the spatial distribution of the social forms or in their social flexibility.Received 12 January 2004; revised 23 February 2004; accepted 10 March 2004.     

Comprehensive paternity assignment: genotype,spatial location and social status in song sparrows,Melospiza Melodia

Comprehensive, accurate paternity assignment is critical to answering numerous questions in evolutionary ecology. Yet, most studies of species with extra‐pair paternity (EPP) fail to assign sires to all offspring. Common limitations include incomplete and biased sampling of offspring and males, particularly with respect to male location and social status, potentially biasing estimated patterns of paternity. Studies that achieve comprehensive sampling and paternity assignment are therefore required. Accordingly, we genotyped virtually all males and >99% of 6‐day‐old offspring over 16 years in a song sparrow (Melospiza melodia) population and used three complementary statistical methodologies to attempt complete paternity assignment for all 2207 offspring. Assignments were highly consistent across maximum likelihood methods that used solely genotype data, and heuristic and integrated Bayesian analyses that included data describing individual locations. Sires were assigned to >99% of all genotyped offspring with ≥95% confidence, revealing an EPP rate of c. 28%. Extra‐pair sires primarily occupied territories neighbouring their extra‐pair offspring; spatial location was therefore highly informative for paternity assignment. EPP was biased towards paired territorial males, although unpaired territorial and floater males sired c. 13% of extra‐pair offspring. Failing to sample and include unpaired males as candidate sires would therefore substantially reduce assignment rates. These analyses demonstrate the integration of genetic and ecological information to achieve comprehensive paternity assignment and direct biological insight, illustrate the potential biases that common forms of incomplete sampling could have on estimated patterns of EPP, and provide an essential basis for understanding the evolutionary causes and consequences of EPP.     

Levels of social organization and male-female bonding in the genus Papio

Pair-bonding in the genus Papio seems to be the result of fusion of troops as well as fission. When troop segments regularly split and join again, males who permanently maintain exclusive access to a few females may have an advantage over males who compete for all females who are in estrus. When two or more troops regularly fuse, this advantage may be greatly increased.     

Foundress behaviors and interactions in polygynous colonies of the haplometrotic Japanese paper wasp Polistes snelleni (Hymenoptera: Vespidae)

Only two out of 959 pre‐emergence colonies of the paper wasp Polistes snelleni de Saussure surveyed between 1989 and 1996 in Sapporo, northern Japan, were found to be two‐foundress colonies, and the others were single‐foundress colonies. The two foundresses in one of the two colonies showed neither aggressive dominance behavior nor clear division of labor between them during a total of approximately 30 h in the first half of the pre‐emergence stage. Although both of the foundresses foraged for pulp and laid eggs, only one foundress foraged for prey and delivered it to the other.