Social organisation and interspecific interactions in two sympatric species of Ranidella (Anura)

Summary The socio-spatial organisation of two sympatric species of anurans was investigated by analyses of the spatial and temporal structure of breeding assemblages. Ranidella signifera breeds earlier in the year than its congener, R. parinsignifera, though there is an overlap of 6 to 8 weeks. Males of both species show high affinities for discrete spatial locations (preferred calling stations). These stations are regularly-spaced, and temporally-stable. Satellite behaviour occurs, though most satellites are past or future residential males. There appears to be a spatial-energetic limit to the number of calling residents of both species that a pond can support. There is no differentiation of calling sites between the two species, and the males of R. parinsignifera appear to displace their congeners from the preferred stations located on the land/water interface of ponds. The breeding season of R. signifera in sympatry is abbreviated relative to nearby (20 km) allopatric localities. The breeding seasons of conspecific males and females are well-synchronised, though the ratio of males to females is high early in the breeding season.     

Clinal variation in colony breeding structure and level of inbreeding in the subterranean termites Reticulitermes flavipes and R. grassei

Social insects exhibit remarkable variation in their colony breeding structures, both within and among species. Ecological factors are believed to be important in shaping reproductive traits of social insect colonies, yet there is little information linking specific environmental variables with differences in breeding structure. Subterranean termites (Rhinotermitidae) show exceptional variation in colony breeding structure, differing in the number of reproductives and degree of inbreeding; colonies can be simple families headed by a single pair of monogamous reproductives (king and queen) or they can be extended families headed by multiple inbreeding neotenic reproductives (wingless individuals). Using microsatellite markers, we characterized colony breeding structure and levels of inbreeding in populations over large parts of the range of the subterranean termites Reticulitermes flavipes in the USA and R. grassei in Europe. Combining these new data with previous results on populations of both species, we found that latitude had a strong effect on the proportion of extended‐family colonies in R. flavipes and on levels of inbreeding in both species. We examined the effect of several environmental variables that vary latitudinally; while the degree of inbreeding was greatest in cool, moist habitats in both species, seasonality affected the species differently. Inbreeding in R. flavipes was most strongly associated with climatic variables (mean annual temperature and seasonality), whereas nonclimatic variables, including the availability of wood substrate and soil composition, were important predictors of inbreeding in R. grassei. These results are the first showing that termite breeding structure is shaped by local environmental factors and that species can vary in their responses to these factors.     

5种地黄花部综合特征与繁育系统的初步研究

生殖隔离是物种分化与延续的基础,地黄属植物是否存在生殖隔离仍不清楚。通过实地观测地黄属5个物种(天目地黄、湖北地黄、裂叶地黄、地黄和茄叶地黄)自然种群的花部形态、开花动态、花蜜体积、花蜜的糖浓度及其日变化、杂交指数、花粉-胚珠比等指标,结合人工授粉套袋,对地黄属植物的花部综合特征和繁育系统进行研究。结果显示:(1)地黄属植物的花为两性花,单花花期5～7 d,种群花期40～60 d;5种地黄在花序类型、花形态、花粉量、花粉-胚珠比等方面都存在差异,其中茄叶地黄的花粉完全败育。(2)5种地黄属植物的繁育系统属于异交,部分自交亲和,需要传粉者,不具有无融合生殖特性,地黄与茄叶地黄存在强烈营养繁殖。(3)5种地黄属植物的花朵基部有蜜腺可以产生糖浓度较高的花蜜,这也支持传粉者的存在,但除地黄确定为蜜蜂传粉外,其它地黄植物在野外并未观测到有效的传粉者,可能与地黄的散生特性、生境相互隔离以及传粉观测期气象条件恶劣有关。研究认为,5种地黄属植物较长的花期能有效弥补传粉者访问频率低的不足;除遗传屏障外,推测地黄属5个物种花展示方式的差异可能吸引不同的传粉者,加之地理、生态因素的作用导致了5种地黄属植物繁育系统的分化。     

Pollen morphology of the Phyllanthus species occurring in the continental United States

Twelve native United States species have been examined. The pollen grains could be divided into five pollen types based on sexine ornamentation, aperture structure, sexine/nexine ratio and sexine 1/sexine 2 ratio. Within these types it was often possible to distinguish the grains of the different species. Two groups of types have been recognized based on the similarities in ornamentation. One group, consisting of the Phyllanthus amarus type, the P. tenellus type and the P. urinaria type, is characterized by the Tilia structure, whereas the second group of types, comprising the P. caroliniensis type and the P. liebmannianus type are microreticulate. The postulation that different subgenera show different pollen types is true in general, but there is one exception: P. niruri, taxonomically belonging to the subgenus Phyllanthus, has pollen grains of the P. caroliniensis type, a type also comprising species from the subgenus Isoclades.     

Different levels of morphometric variation in three heterogamous dogrose species (Rosa sect.Caninae, Rosaceae)

Difficulties in delimiting well-defined entities in the dogroses (Rosa sect.Caninae) has resulted in very variable taxonomic treatments. The present study was undertaken to provide a background for taxonomy as well as plant breeding. Morphometric diversity was analysed on seedlings obtained from field collections in South Sweden of three species,Rosa dumalis, R. rubiginosa andR. villosa. A canonical variates analysis showed that the three species are relatively distinct whereas two subspecies ofR. dumalis were less well discriminated. Analyses of variance demonstrated that intraspecific variation is pronounced inR. dumalis and, to a lesser extent, inR. villosa.     

BIOSYSTEMATIC INVESTIGATIONS IN SOUTH FLORIDA POPULATIONS OF RUELLIA (ACANTHACEAE)

Relationships of the putative Ruellia species, R. caroliniensis, R. ciliosa, R. heteromorpha, and R. succulenta were analyzed by population sampling, investigation of chromosome numbers, garden transplants, and hybridization experiments. Character data from 25 local, Florida populations and from transplants were evaluated. Some interfertility of these “taxa” was demonstrated, as was some interfertility with other species occurring in the eastern United States. Chromosome numbers are n = 17 and 2n = 34. The effect of different breeding systems on population structure is discussed. Total evidence suggests that the 4 “taxa” in question be considered ecological races of a single species widespread in the eastern United States, namely R. caroliniensis.     

BREEDING NOMADISM IN SOUTHERN AFRICAN SEABIRDS-CONSTRAINTS,CAUSES AND CONSERVATION

Crawford, R.J.M., Dyer, B.M. & Brooke, R.K. 1994. Breeding nomadism in southern African seabirds-constraints, causes and conservation. Ostrich 65:231-246.

Fourteen species of seabirds representing three orders and five families breed in southern Africa. Nomadism in the breeding populations of 13 of these seabirds is examined. African Penguins Spheniscus demersus, Cape Gannets Morus capensis. Bank Cormorants Phalacrocorax neglectus, Whitebreasted Cormorants P. carbo and White Pelicans Pelecanus onocrotalus show strong fidelity to specific localities. Caspian Terns Sterna caspia change breeding localities at a low frequency; Cape Cormorants P. capensis, Hartlaub's Gulls Larus hartlaubii and Swift S. bergii and Roseate S. dougallii Terns at a higher frequency. At some localities, Bank Cormorants remain at the same breeding sites for extended periods, whereas Crowned Cormorants P. coronatus, Whitebreasted Cormorants, Kelp Gulls L. dominicanus, Hartlaub's Gulls, Damara Terns S. balaenarum, Swift Terns and Roseate Terns all alter breeding sites. Where space is not limiting, African Penguins may also change sites. Constraints on nomadism include strong attachment to traditional breeding localities, unwillingness to roost at non-breeding localities, and lack of suitable alternative nesting localities. Amongst causes of nomadism are excessive disturbance by humans and South African Fur Seals Arctocephalus pusillus and competition for breeding space, which have resulted in even the least nomadic of the species changing their breeding locations. Regularly nomadic species are likely to respond to environmental cues that enable them either to reduce cost of breeding or to increase reproductive output. Therefore, they are potentially useful indicators of ecological health. Nomadic breeders additionally have the ability to establish new breeding colonies. Some species have used artificial structures to expand their breeding range, and probably also to increase their overall populations. However, nomadic tendencies complicate the conservation of breeding activities. By contrast, breeding species with strong fidelity to traditional localities are more easily protected.     

DORMANCY IN SEEDS OF FRASERA CAROLINIENSIS (GENTIAN ACEAE)

In freshly matured seeds of the long-lived monocarpic perennial, Frasera caroliniensis Walt., the embryos are underdeveloped and physiologically dormant. Dormancy was broken by a long period of stratification (chilling) at 5 C. Seventy six percent of the seeds germinated at 20 C (day)/10 C (night) after 98 days of chilling at 5 C, while seeds kept at 5 C germinated to 87% after 205 days. A warm, moist pretreatment was not required for subsequent breaking of dormancy at 5 C. Embryos in fresh seeds averaged 1.3 mm long, but after 12 weeks of chilling they averaged 4.1 mm. Thus, the embryos require a period of chilling to become fully developed, after which seeds can germinate at the afterripening temperatures (5 C) or at some higher temperature. Seeds of F. caroliniensis fit Nikolaeva's (1977) morpho-physiological complex dormancy type.     

Rat kappa-chain allotypes

The presence of rat kappa-chain allotype specificities (RI-1a and b) has been studied in 13 subspecies of the seven native Australian species ofRattus. RI-la reactivity was not detected among these rats. On the other hand, extensive cross-reactivity was seen with RI-1b, some sera cross-reacting totally (R. leucopus cooktownensis), some not at all (R. colletti), and the remainder showing at least two distinct levels ofpartial cross-reactivity, confirming the existence of multiple specificities for Rl-lb. Three subspecies show polymorphism with respect to Rl-lb cross-reactivity (R. sordidus, R. colletti, andR. l. leucopus) and in one case (leucopus) breeding studies have indicated that there is allelic inheritance of this trait. The segregation of RI-1b reactivity has been studied in crosses and backcrosses made between species differing in their RI-1b reactivity, and the results are consistent with the existance of codominant alleles at a single locus. The fact that these species differ extensively in their karyotype opens the door to possible chromosomal localization of this and other genetic traits.     

Sexual dimorphism in the snub-nosed langurs (Colobinae: Rhinopithecus)

Sexual dimorphism in the dentition and skeleton of the four extant species of snub-nosed langurs, Rhinopithecus (R.) bieti, R. (R.) brelichi, R. (R.) roxellana and R. (Presbytiscus) avunculus, was studied. The species shared a similar general pattern of sexual dimorphism, but were found to differ in respects that appear to reflect the influence of disparate socioecological and environmental factors. All the species showed marked canine dimorphism, but the very high degree of canine dimorphism in R. bieti appeared to be due to the intensity of intermale competition for mates during a temporally restricted breeding season, and possibly also to the intensity of competition between males for other resources during other times of the year. Sexual dimorphism in the postcranial skeleton of Rhinopithecus species was also most pronounced in R. bieti and may be related to the relatively higher frequency of terrestrial locomotion in males of the species. © 1995 Wiley-Liss, Inc.     

Reproductive isolation in alpine gingers: How do coexisting Roscoea (R. purpurea and R. tumjensis) conserve species integrity?

Multiple barriers may contribute to reproductive isolation between closely related species. Understanding the relative strength of these barriers can illuminate the ecological factors that currently maintain species integrity and how these factors originally promoted speciation. Two Himalayan alpine gingers, Roscoea purpurea and R. tumjensis, occur sympatrically in central Nepal and have such similar morphology that it is not clear whether or how they maintain a distinct identity. Our quantitative measurements of the components of reproductive isolation show that they are, in fact, completely isolated by a combination of phenological displacement of flowering, earlier for R. tumjensis and later for R. purpurea, and complete fidelity of visitation by different pollinator species, bumblebees for R. tumjensis and a long‐tongued fly for R. purpurea. Furthermore, the nectar of R. tumjensis flowers is available to the shorter tongued bumblebees while R. purpurea nectar is less accessible, requiring deep probing from long‐tongued flies. Although flowering phenology is a strong current barrier that seemingly obviates any need for pollinator discrimination, this current pattern need not reflect selective forces occurring at the initial divergence of R. tumjensis. There has been considerable pollinator switching during the radiation of the Himalayan Roscoea, and the association of flowering time with type of pollinator in these sympatric species may have originated among the earliest or latest flowering individuals or populations of an ancestor to exploit either bumblebee activity early in the breeding season or long‐tongued fly abundance later in the season. These two sympatric Roscoea species add to accumulating evidence of the primacy of prezygotic pollination traits in speciation among angiosperms even in the absence of postzygotic incompatibility.     

Low relatedness among cooperatively breeding workers of the greenhead ant Rhytidoponera metallica

The greenhead ant Rhytidoponera metallica has long been recognized as posing a potential challenge to kin selection theory, because it has large queenless colonies where apparently many of the morphological workers are mated and reproducing. However, this species has never been studied genetically and important elements of its breeding system and kin structure remain uncertain. We used microsatellite markers to measure the relatedness among nestmates, unravel the fine‐scale population genetic structure, and infer the breeding system of R. metallica. The genetic relatedness among worker nestmates is very low but significantly greater than zero (r=0.082 ± 0.015), which demonstrates that nests contain many distantly related breeders. The inbreeding coefficient is very close to and not significantly different from zero, indicating random mating and lack of microgeographic genetic differentiation. On average, closely located nests are not more similar genetically than distant nests, which is surprising, as new colonies form by budding and female dispersal is restricted. Lack of inbreeding and absence of population viscosity indicates high gene flow mediated by males. Overall, the genetic pattern detected in R. metallica suggests that a high number of moderately related workers mate with unrelated males from distant nests. This breeding system results in the lowest relatedness among nestmates reported for social insect species where breeders and helpers are not morphologically differentiated.     

Testicular and androgen dependence of skin gland morphology in the anurans,Xenopus laevis and Rana pipiens

In anuran amphibians, there is increasing evidence that exocrine glands dispersed throughout the general integument are secondary sex characters (SSC). Following the recent discovery of sexually dimorphic “breeding glands” in the dorsum of male Rana pipiens, we studied the effects of castration and testosterone treatment on the dorsal skin glands of male Xenopus laevis and R. pipiens to determine whether the dorsal breeding glands, or any other dorsal skin glands, are androgen dependent. The dorsal skin glands of X. laevis were unaffected by androgen status. By contrast, in R. pipiens, breeding, mucous, and seromucous glands responded to testosterone stimulation. Mucous glands were significantly (P < 0.05) larger in testosterone-treated frogs than in castrates. There was a large, but statistically insignificant, increase in the size of the dorsal breeding glands. Testosterone treatment also increased the epithelial cell height of breeding and seromucous glands (P < 0.05). In the skins of castrated and testosterone-treated frogs, there was a reciprocal relationship between the abundance of seromucous and breeding glands: in castrates, seromucous glands were abundant and breeding glands virtually absent, whereas in testosterone-treated frogs, breeding glands were abundant and seromucous glands less common. The total number of the two gland types was similar in both treatment groups. Glands that appeared to be intermediate in form between seromucous and breeding glands were observed in some frogs. These data suggest that seromucous glands may be the regressed form of breeding glands in the dorsal skin of R. pipiens and that the dorsal skin of R. pipiens is a SSC. © 1993 Wiley-Liss, Inc.     

SHORT NOTES

Earlé, R. A. 1981. Factors governing avian breeding in Acacia savanna, Pietermaritzburg, Part 3: Breeding success, recruitment and clutch size. Ostrich 52:235-243.

The clutch size and breeding success of eight species of birds were monitored over a two year period in Acacia savanna. The mean clutch size fluctuated within the breeding season and four patterns of clutch size variation were noted. A smaller proportion of large clutches were laid in the 1979 season when less food was available. Breeding success was higher in the dry 1979 season but fewer breeding attempts were made and the overall recruitment was thus lower. At the peak of the breeding season, in mid-November, breeding success was at its lowest. Predation on nests was the greatest factor reducing breeding success although rain and strong winds affected some species.     

Mating System,Resource Defence and Sex Change in the Anemonefish Amphiprion akallopisos

Ecology and mating system of A. akallopisos were investigated at Aldabra Atoll and data compared with A. bicinctus from the Red Sea. A. akallopisos inhabits Radianthus ritteri, a colonial species forming aggregations up to 198 anemones. A. bicinctus occupies Gyrostoma helianthus, a solitary-living anemone. Both Amphiprion species are monogamous. A. akallopisos, on its larger host clusters, forms groups of up to 9 adults, consisting of a large breeding ♂, a functional breeding ♂ and a varying number of non-breeding ♂♂. A size-dependent aggressive hierarchy exists; as the breeding ♂ prevents all others from mating with the ♀, monogamy obtains even in larger groups. The ♀ — a breeding ♂♂ having changed sex — defends and monopolizes a territory and so attracts and controls potential mates. The ♀-dominance system, resource defence and distribution, inter- and intrasexual competition are discussed in the light of Emlen and Oring's (1977) theories. The many A. akallopisos non-breeding ♂♂ in the overall population and in groups are suggested to be helpers. In Amphiprion helping would not mean caring for the eggs to increase the breeders' reproductive success. One could speculate that nonbreeding adults improve their own reproductive chances by remaining on the breeders' territory and waiting for a vacant breeding position.     

Resistance to Botrytis cinerea in canes of Rubus idaeus and some related species

Mycelial inoculation of canes with Botrytis cinerea proved a useful method for assessing Rubus material for resistance. When canes were inoculated in summer resistant genotypes developed relatively small lesions which produced few small sclerotia in the following spring. The size of lesions in autumn generally provided the best discrimination between genotypes. Very strong resistance was found in several species, of which Rubus pileatus and R. occidentalis are the most useful for breeding; hybrids of raspberry with these species or with R. crataegifolius also had strong resistance. The resistance shown by a derivative of red raspberry cv. Chief was less strong, as was the resistance conferred by gene H, which determines cane pubescence.     

ENROL IN THE SOCIETY

Earlé, R. A. 1981. Factors governing avian breeding in Acacia savanna, Pietermaritzburg, Part 2: Intrinsic factors. Ostrich 52:74-83.

The most important factor governing avian breeding in Acacia savanna is the body condition (protein reserve) of the bird. Breeding can take place only if the female has a large enough protein reserve to form eggs. The protein reserve is dependent on an adequate food supply which is once again dependent on climatic factors. Both the protein reserve and body weight of several species were found to be at their lowest towards the end of the breeding season. Moult and breeding were found to be largely separated in time. In most species examined testis activity was at its lowest between April and June and highest from September to January. Colius striatus showed a less seasonal pattern of testis activity while Nectarinia talatala showed very early testis activity and had fully active testes in May.     

头花杜鹃、陇蜀杜鹃及杜鹃属植物叶绿体基因组比较分析

头花杜鹃(Rhododendron capitatum)和陇蜀杜鹃(R. przewalskii)是极具观赏价值的野生花卉和药用植物。为探讨头花杜鹃和陇蜀杜鹃叶绿体基因组的遗传结构及进化特征,该研究利用 Illumina HiSeq 4000 平台对头花杜鹃和陇蜀杜鹃的叶绿体全基因组进行测序,经组装和注释后,结合 7 个已发表的杜鹃属植物叶绿体全基因组进行比较基因组学分析和系统发育分析。结果表明:(1)头花杜鹃和陇蜀杜鹃叶绿体全基因组呈典型的环状四分体结构,均由一个大单拷贝区(105 990、109 191 bp)、一个小单拷贝区(2 617、2 606 bp)和一对反向重复区(45 825、47 516 bp)构成,全长分别为200 257、206 829 bp。(2)头花杜鹃和陇蜀杜鹃叶绿体基因组中共鉴定出 263 个SSR位点,大部分 SSR 偏好使用 A/T 碱基,密码子偏好使用 A/U 结尾。(3)杜鹃属植物叶绿体全基因组中普遍存在基因丢失以及基因组重排等结构变异现象。该研究丰富了杜鹃属植物的基因组资源,为头花杜鹃、陇蜀杜鹃的资源开发、遗传进化、育种及系统发育相关研究提供了理论参考。     

Reproductive biology of the Red List species Polemonium caeruleum (Polemoniaceae)

The majority of flowering plants, including many rare and threatened species, are pollinated by animals, but little is known of pollination and breeding systems of many endangered species. Polemonium caeruleum (Polemoniaceae) is a red‐listed species and is regarded as dichogamous, self‐compatible and bee pollinated. However, some studies show that it is visited by a vast assemblage of anthophilous insects from many taxonomic orders and that breeding systems vary greatly between closely related taxa of this genus. Over a period of 3 years we investigated breeding system, dichogamy, nectar secretion and composition, insect visitations and pollen loads in flowers of P. caeruleum in north‐eastern Poland to determine whether the reproductive biology of the plant explains its rarity. Contrary to published data, our study plants were self‐incompatible and showed a high degree of outcrossing. Our experimental work confirmed the occurrence of protandry in this species, revealed that nectar is sucrose‐dominant and proline‐rich and, for the first time for Polemoniaceae, that nectar secretion and nectar sugar concentration in flowers of P. caeruleum is female‐biased. Although flowers were visited by at least 39 species of insects from five taxonomic orders, overall the plant exhibited many characters associated with bee pollination, and analysis of insect performance showed that bumblebees and honeybees are the key pollinators; occasionally hoverflies and butterflies may also be involved. We conclude that, in terms of pollination system, P. caeruleum demonstrates high apparent generalization, but low realized generalization, and is a functional specialist, as most pollinators belong to a single functional group (guild). Its conservation status, at least in our study population, cannot be explained in terms of the biological properties of its breeding or pollination systems; rather, the present decline of the species is caused by habitat loss. However, if this process and bumblebee decline in Europe continue, P. caeruleum populations may diminish in numbers and density and, owing to the self‐incompatibility of the species, quickly become severely pollen‐limited, thereby accelerating further local extinctions. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 92–107.     

玫瑰种群生物学研究进展

玫瑰(Rosa rugosa Thunb.)原产于我国东部沿海、日本、朝鲜半岛和俄罗斯远东地区,18世纪作为园艺种引入欧洲后逃逸并入侵至北海和波罗的海周边多个国家以及北美沙质海岸,而中国野生种群却在过去30年间持续萎缩,成为珍稀濒危物种。从玫瑰种群生物学角度,通过文献比较和综合,在阐明玫瑰生态学特性和野生分布变化的基础上,全面论述了玫瑰种群在我国的生境退化、种群动态、种子繁殖、遗传多样性、濒危机理、保育方面的成果和悬疑问题;并结合欧洲入侵种群分布范围和敏感生境、对本地群落和物种的影响、种子繁殖、遗传变异、种群扩张和模拟预测、管理和控制方面的研究进展,分析了濒危种群和入侵种群数量动态、群落组成、幼苗更新、遗传变异、管理策略方面的差异及其影响因素;进而提出未来的玫瑰研究可从濒危种群和入侵种群的比较研究、种群和灌丛的动态监测、适合度相关性状的变异及其遗传基础、基于种群生物学的保育或控制4个方面为切入点,集中探索玫瑰种群濒危和入侵动态的规律、遗传基础和主要驱动力,为玫瑰保育和管理提供理论依据,为相似物种的适应和进化机制研究提供例证。