Optimization of foraging and diet by the piscivorous Othos dentex (Serranidae)

The aim of this study was to determine the dietary characteristics and mouth morphology of Othos dentex and to use these data, together with in situ observations of feeding behaviour, to elucidate how foraging and diet are optimized by this piscivorous serranid. Seasonal spear and line fishing over reefs in south‐western Australia yielded 426 O. dentex (total length, L_T, 183–605 mm), among which the stomachs of 95 contained food. The food in the stomachs of 76 fish was sufficiently undigested to be seen to contain, almost invariably, a single fish prey, which was typically identifiable to family and often to species. The prey of O. dentex, which were measured (L_T), represented 10 families, of which the Labridae and Pempheridae constituted nearly two‐thirds of the prey volume. Two‐way crossed analysis of similarities of volumetric data for stomach contents showed that the dietary compositions of the different length classes of O. dentex in the various seasons were significantly related to length class of prey, but not to prey family, length class within the various prey families or season. Furthermore, an inverse (Q‐mode) analysis, including one‐way analysis of similarities, showed that the patterns in the prey consumed by the different length classes of O. dentex in the various seasons were related more strongly to length class than prey family. The former trend is exemplified in a shade plot, by a marked diagonality of the length classes of prey with increasing predator size. The ingestion of typically a single teleost prey, whose body size increases as that of O. dentex increases, reduces the frequency required for seeking prey, thus saving energy and reducing the potential for intraspecific competition for food. The ability of O. dentex to ingest large prey is facilitated by its possession of a very large gape, prominent recurved teeth, dorsal and independently‐moveable eyes, cryptic colouration and effective ambush behaviour. Othos dentex has thus evolved very cost‐effective mechanisms for optimizing its foraging and diet.     

Age and size compositions, growth and reproductive biology of the breaksea cod Epinephelides armatus, a gonochoristic serranid

Details of the reproductive biology, size and age compositions and growth of the breaksea cod Epinephelides armatus , the sole representative of Epinephelides , were obtained by collecting monthly samples of a wide total length ( L _T) range of individuals from coastal marine waters at 31–32° S on the lower west coast of Australia. Although the modal L _T class of females (250–299 mm) was markedly less than that of males (400–449 mm), the modal ages of the two sexes were similar, i.e. 4 v. 5 years, respectively. The similarity in the age compositions and the histological demonstration that the gonads of all E. armatus consist solely of either ovarian or testicular tissues demonstrate that this species is gonochoristic, which is highly unusual for an anthiinine serranid. The absence of a central, membrane-lined 'ovarian' lumen in the testes of juveniles would account for adult testes containing neither this ovarian remnant nor the peripherally located sperm sinuses that are found in the mature testes of almost all other serranids. The results demonstrate that E. armatus exhibits a very unusual pattern of sexual development for a serranid. The spawning period of E. armatus lasts for c. 9 months, which is long for a species in temperate Western Australian waters, but comparable with that of many other relatively small serranids elsewhere. Females grow slower than males, attaining L _T at 3, 5 and 10 years of c. 200, 285 and 420 mm, respectively, compared with c. 215, 315 and 450 mm, respectively. Females, however, attain maturity at a greater L _T and older age than males.     

红花木莲有性繁殖和生态生物学特性的研究

红花木莲是木莲属中较原始的种类,是我国珍贵的用材及观赏树种,被列为国家保护植物。由于它自然更新能力差,加上人为的破坏,成年植株逐渐减少,已陷人濒危的境地。本文探索了其种子生理及萌发特性,掌握了有性繁殖中的关键技术措施,并通过引种栽培观测其生态生物学特性,认为在昆明引种栽培区内具有较强的适应性。提出了在扩大迁地保护的同时,将其一部分苗木返回自然生境中,进行种群重建,以扩大其种群,对保护和持续利用这一珍贵树种具有深远意义．     

Sexual development and reproductive seasonality of hogfish (Labridae: Lachnolaimus maximus), an hermaphroditic reef fish

The seasonality, size, age, colour phases and sexual dimorphism of 13 reproductive classes of hogfish Lachnolaimus maximus are described. Analysis of histological sections of gonads ( n = 1662) confirmed earlier conclusions that L. maximus is a monandric, protogynous hermaphrodite. Sex change was initiated at the end of the spawning season and over a broad range of sizes and ages. It occurred after a functional female phase (postmaturation) and proceeded more slowly (months) than previously believed. Eventually all individuals changed sex to a terminal male phase. Females were batch spawners, spawning as often as every day during winter and spring. There was no evidence of precocious sperm crypts in active females, sperm competition or other alternative male sexual strategies. Mating has been reported elsewhere to be haremic. The sexual development of L. maximus appears to be adaptive in terms of Ghiselin's size-advantage model, which links monandric protogyny and polygyny. The slow rate of sex change, however, poses problems when fishing pressure is high because harvest of a single male has the potential to reduce the reproductive output of an entire harem.     

Gonad structure and sexual pattern in two threadfin breams and possible function of the dorsal accessory duct

A dorsal accessory duct (DAD) structure was found on the dorsal side of a functional testis in all males of both Nemipterus virgatus and N. japonicus , and determined to be homologous to the ovary, based on structural, histological and cytological evidence. Secretions, in the DAD varied according to reproductive season and were particularly marked in N. virgatus. The sexual pattern of both species was functional gonochorism. The secretions of the DAD suggest some unknown function, possibly associated with spawning, which has evidently arisen de novo within a rudimentary ovary: this is the only example of its type reported among hermaphroditic fishes.     

Activity pattern, reproductive behaviors and gonadal hormones in the raccoon dog (Nyctereutes procyonoides)

The objectives of this study were to (1) assess year-round behaviors and activity patterns of captive raccoon dogs (Nyctereutes procyonoides) and (2) characterize the species' reproductive endocrinology. Behaviors and activity patterns of 12 (5.7) animals were recorded over a 1-year period. During that time, fecal samples were collected 2-7 times/week from 16 (7.9) individuals (six of these were included in the behavioral study) for the analysis of testosterone, progesterone and estrogen metabolite concentrations. Activity pattern and excretion of gonadal steroids followed a seasonal pattern. Specifically, dogs were cathemeral in summer, and primarily nocturnal in winter. In the males, testosterone concentrations were at baseline from April through September, began to rise in October and reached peak concentrations in February (P<0.05). In the females, elevated estrogen (P<0.05) was observed in March followed by an increase in progestagen concentrations from March through May (P<0.05) in both pregnant and pseudopregnant animals. Gender significantly influenced monthly testosterone/estrogen ratio (P<0.01); values were higher in males than in females throughout the year with overall percentage of overlapping values between males and females being 28%. In summary, this study characterized cirannual fluctuations in behaviors and gonadal steroid metabolites in the raccoon dog maintained in captivity. Because there is no obvious sexual dimorphism, the differences in testosterone/estrogen ratio may be useful for gender differentiation (72% accuracy), especially among individuals living in the wild.     

Sperm competition,sexual selection and the diverse reproductive biology of Osteoglossiformes

Osteoglossiformes are an order of “bony tongue” fish considered the most primitive living order of teleosts. This review seeks to consolidate known hypotheses and identify gaps in the literature regarding the adaptive significance of diverse reproductive traits and behaviour of osteoglossiforms within the context of sperm competition and the wider lens of sexual selection. Many of the unusual traits observed in osteoglossiforms indicate low levels of sperm competition; most species have unpaired gonads, and mormyroids are the only known vertebrate species with aflagellate sperm. Several osteoglossiform families have reproductive anatomy associated with internal fertilization but perform external fertilization, which may be representative of the evolutionary transition from external to internal fertilization and putative trade-offs between sperm competition and the environment. They also employ every type of parental care seen in vertebrates. Geographically widespread and basally situated within teleosts, osteoglossiforms present an effective study system for understanding how sperm competition and sexual selection have shaped the evolution of teleost reproductive behaviour, sperm and gonad morphology, fertilization strategies, courtship and paternal care, and sexual conflict. The authors suggest that the patterns seen in osteoglossiform reproduction are a microcosm of teleost reproductive diversity, potentially signifying the genetic plasticity that contributed to the adaptive radiation of teleost fishes.     

Relationships of reproductive traits and body size with attainment of sexual maturity and age in Blanding's turtles (Emydoidea blandingi)

To place associations among body size, age at maturity, age, and reproductive traits of a long-lived organism in the context of current life history models based on the concept of norms of reaction, we examined data from a mark-recapture study of Blanding's turtles (Emydoidea blandingi) in southeastern Michigan during 24 of the years between 1953 and 1988. Females matured between 14 and 20 years of age. Both the smallest and largest adult females in the population were reproducing for the first time in their lives. This result suggests that a combination of differences in juvenile growth rates and ages at maturity, and not indeterminate growth, are the primary cause of variation in body size among adults. Body size variation among individuals was not related to age at sexual maturity. Females that had slower growth rates as juveniles matured later at similar mean body size compared to those with more rapid growth that matured at an earlier age. As a result, a linear model of age at sexual maturity with growth rates of primiparous females between hatching and maturity was significant and negative (R² = 0.76). Frequency of reproduction of the largest and smallest females was not significantly different. Clutch size did not vary significantly with age among either primiparous or multiparous females. Clutch sizes of primiparous females and multiparous females were not significantly different. However, older females (>55 years minimum age) reproduced more frequently than did younger females (minimum age <36 y).     

半夏的繁殖生物学研究

对“泰半夏”（Ｐｉｎｅｌｌｉａｔｅｒｎａｔａ（Ｔｈｕｎｂ．）Ｂｒｅｉｔ．）的块茎和珠芽栽培观察结果表明：（１）不同繁殖体的叶形和珠芽所发生的变化与实验用的播种材料有关,珠芽发生频率与叶形变化呈正相关;（２）半夏倒苗既是对不利环境条件的一种适应,也是一种有效的无性繁殖方式;（３）半夏有性繁殖是属于同株异花传粉类型,但与无性繁殖相比,有性繁殖在种质繁衍上仅起着次要作用。     

Biology of Galaxiella munda McDowall (Teleostei: Galaxüdae), including a comparison of the reproductive strategies of this and three other local species

The reproductive biology, growth and diet of Galaxiella munda McDowall in a south-western Australian river are described. Monthly trends in gonadosomatic indices, stages in ovarian development and the size and maturity of oocytes show that spawning extended from July to October and peaked in late August to early September. Histology of ovaries indicated that G. munda produced clutches of eggs which it released at intervals. Data on length-frequencies, otoliths and gonads demonstrate that G. munda typically died in the few months after spawning. By age I, the females and males of G. munda had reached 47 mm (≡ 0.54 g) and 43 mm (≡ 0.42 g), respectively. The respective von Bertalanffy growth curve parameters for L., K and to were 48.6 mm, 3.702 and -0.0014 for females and 44.3 mm, 4.217 and -0.0012 for males. Galaxiella munda fed predominantly on terrestrial fauna on the water surface, cladocerans and copepods in the water column, and dipteran larvae in the benthos. Comparisons are made between the above aspects of the biology of G. munda and those recorded for three other locally endemic species ( Galaxias occidentalis Ogilby, Bostockia porosa Castelnau and Edelia vittata Castelnau) and wherever possible with other Galaxiella species. Such comparisons have emphasized the relationship between size and age at first maturity and spawning mode.     

The role of sexual and natural selection in shaping patterns of sexual dichromatism in the largest family of songbirds (Aves: Thraupidae)

Males and females can be under different evolutionary pressures if sexual and natural selection is differentially operating in each sex. As a result, many species have evolved sexual dichromatism, or differences in coloration between sexes. Although sexual dichromatism is often used as an index of the magnitude of sexual selection, sexual dichromatism is a composite trait. Here, we examine the evolution of sexual dichromatism in one of the largest and most ecologically diverse families of birds, the tanagers, using the avian visual perspective and a species‐level phylogeny. Our results demonstrate that the evolutionary decreases of sexual dichromatism are more often associated with larger and more frequent changes in male plumage coloration, and evolutionary increases are not more often associated with larger changes in either sex. Furthermore, we show that the crown and ventral plumage regions are correlated with sexual dichromatism in males, and that only male plumage complexity is positively correlated with sexual dichromatism. Finally, we demonstrate that light environment is important in shaping both plumage brilliance and complexity. By conducting a multilevel analysis of plumage evolution in males and females, we show that sexual dichromatism evolves via a mosaic of sexual and natural selection in both sexes.     

Among-population variation in adipose fin size parallels the expression of other secondary sexual characteristics in sockeye salmon (Oncorhynchus nerka)

The small, non-rayed adipose fin is present in eight extant orders of fishes, including the Salmoniformes (salmon and trout) but the functional significance of the trait is unknown. Recent evidence suggests a hydrodynamic function in juvenile salmonids, and observations of sexually dimorphic adipose fin expression and female preference for males with large fins indicate a role in reproduction by mature individuals. To the extent that the adipose fin functions in reproduction, it might be expected to evolve in parallel with other sexually dimorphic traits, such as body depth and jaw length. To test this hypothesis, we quantified adipose fin size of mature male sockeye salmon, Oncorhynchus nerka, among five populations. Populations differed significantly in adipose fin size after correcting for variation in body length and body depth. Adipose fin size tended to parallel the development of other secondary sexual characteristics, but was more closely related to body length and body depth than jaw length. Interestingly, shallow bodied populations from small creeks with high brown bear, Ursus arctos, predation during spawning tended to have smaller size-adjusted adipose fins than populations spawning in deeper water. However, it remains unclear whether adipose fin size is being selected independently of other traits or if it is pleoitropically linked to a trait under selection (e.g., body size or shape).     

The biology of the panga, Pterogymnus laniarius (Teleostei: Sparidae), on the Agulhas Bank, South Africa

Aspects of the biology of the panga, Pterogymnus laniarius, a commercially important endemic southern African, demersal sparid fish species, are described from material collected monthly between February 1994 and July 1995 on the Agulhas Bank, South Africa. Growth studies based on sectioned sagittal otoliths revealed that the panga is relatively slow growing with ages of 16 years being recorded. Growth was best described by the von Bertalanffy growth model as L_t = 379.4 (1-e^{–0.13(t+1.78)}). Estimates of total mortality, natural and fishing mortality were estimated at 0.36 year^–1 0.28 year^–1 and 0.08 year^–1, respectively. Detailed histological examination revealed that panga are late gonochorists, males and females maturing after a non-functional intersexual interval. Females mature at approximately 200 mm fork length or 4 years of age. Reproductive activity occurs throughout the year, peaking slightly in winter when small pelagic eggs are spawned. Gametogenesis was found to be similar to that of other sparid fishes and marine teleosts in general. The panga feeds predominantly on crustaceans with a distinct ontogenetic shift in feeding habits. Juvenile fish feed predominantly in the water column on mysids after which they move to the benthos with subadult fish feeding on ophiuroids and amphipods. Adult fish remain on or near the benthos, feeding predominantly on crabs with polychaetes, ophiuroids and fishes also present in the diet in smaller quantities. Several aspects of the panga's biology such as it's late gonochoristic reproductive style, protracted spawning season, maturation before recruitment and the ability to utilise large areas of the Agulhas Bank by feeding on soft substratum prey are thought to enable this species to sustain a higher fishing pressure than other sympatric sparid species. The panga's longevity, slow growth and high natural mortality rate mitigates against these factors and needs to be considered in the development of a management strategy.     

Phylogeny and evolution of dorsal pattern in the Mexican endemic lizard genus Barisia (Anguidae: Gerrhonotinae)

The phylogeny of the Mexican lizard genus Barisia was assessed using an 878 bp fragment of the mtDNA ND4 gene and a section of associated tRNA genes, as well as 16 external morphological characters. The terminal taxa comprised the currently recognized members of Barisia, including the four subspecies of the polytypic Barisia imbricata and individuals from different populations of the widespread B. i. imbricata and Barisia i. ciliaris, although for Barisia levicollis only morphology could be examined. The ‘step‐matrix frequency’ and the ‘step‐matrix gap‐weighting’ coding approaches were employed simultaneously for the morphological data set, and three different scaling methods were evaluated for the last approach. Maximum parsimony (MP) analyses were performed for the separate and combined data sets and Bayesian analysis was also performed for the mtDNA sequence data. The hypothesis obtained from the simultaneous MP analysis strongly supports the monophyly of Barisia, but the ‘exclusivity’ of B. imbricata as well as of B. i. imbricata and B. i. ciliaris were not recovered. Moreover, inclusion of the morphological data showed B. levicollis nested within a clade together with the taxa assigned to B. i. ciliaris. This, together with the genetic distances and geographic concordance among the haplotypes examined, confirms that B. imbricata represents several species, although the actual species limits in this composite taxon are still unclear. Applying previously published rates of molecular evolution to the mtDNA data gives ages of divergence similar to the times proposed for some Pleistocene–Miocene geological and climatic phenomena that occurred in the Mexican territory. Variation of the dorsal pattern within Barisia was mapped onto the simultaneous morphological and molecular phylogeny, indicating that the two main states present in the taxa assigned to B. imbricata, an adult dorsal pattern present in females and absent in males and the absence of any pattern in both sexes, occur each in separate lineages. This suggests a possible scenario, where sexual dichromatism within Barisia has been repeatedly lost in different lineages.     

Ontogenetically stable dimorphism in a lacertid lizard (Acanthodactylus boskianus) with tests of methodology and comments on life-history

Recent arguments in the literature prompted us to compare methods for assessing sexual dimorphism in body proportions of lacertid lizards, using Acanthodactylus boskianus . Although expressing body-part measurements as proportional to head length was the most effective method, we recommend using trunk length for the baseline as a general method for lizards. We also argue that, when aiming to assess sexual dimorphism in body proportions of lizards, if the context is ecological, all available adults should be included. However, for morphology and taxonomy, small sub-samples of the largest individuals that maximally express their genetic morphological potential should be used. In A. boskianus , the sexual dimorphism of mensural characters in adults was typical: males were larger, with relatively larger head and appendages. However, the ontogeny of this dimorphism was unusual in that the differences existed already in youth and thereafter persisted isometrically. The sexual dimorphism of meristic characters was male-biased in numbers of femoral pores and of caudal vertebrae, and female-biased in numbers of ventral plates along the trunk and of precaudal vertebrae. Size dimorphism may conceivably play a role in sex recognition because two potential visual cues (i.e. size dimorphism and dichromatism) appear to complement each other.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society 2009, 97 , 275–288.     

The influence of light and sea water temperature on the reproductive cycle of Lineus ruber (Heteronemertea)

The cerebral ganglia of Lineus ruber secretes a neurohormone named gonad-inhibiting hormone (GIH) controlling reproduction. As L. ruber undergoes repeated annual cycles of reproduction during its life, the way the neuroendocrine activity of the worm is seasonally regulated is an important ecophysiological question. In other words, what environmental ‘key factors’ influences the beginning of spawning season in L. ruber? In the present work we show that light is not a timer which controls the annual reproductive cycle progress of L. ruber. On the other hand our results suggest that thermoperiod is a good candidate for this function. Further work is still necessary to clarify the transduction mechanism of thermal stimuli in GIH discharge.     

Effects of dominance and female presence on secondary sexual characteristics in male tufted capuchin monkeys (Sapajus apella)

Alpha status may lead to physiological changes that enhance secondary sexual characteristics, which may serve as competitive signals to conspecific males, sexual signals to females, or possibly a combination of both. Here, we report measurements of secondary sexual characteristics in captive dominant and subordinate male tufted capuchin monkeys (Sapajus apella) with varying access to females. An adult male (who had previously been subordinate while housed with other males) was paired with an adult female. This male–female pair was introduced into a room that housed three other male–male pairs with stable hierarchy arrangements. We analyzed weight, body measurements, facial photographs, and hair cortisol before, during, and after introducing a female into the room. While there were no differences in weight or measurements between alphas and subordinates without physical access to the female prior to or during the female''s presence, we found that direct access to the female resulted in dramatic changes in facial appearance, body size, and testicular volume in the male who was paired with her. Overall, we found little evidence to suggest that alpha males advertise their status within all‐male groups via sexual secondary characteristics. However, direct physical access to females appears to trigger the development of such characteristics in alpha males. It remains of continued interest to identify the endocrine mechanisms responsible for the development, and possible loss, of secondary sexual characteristics.     

Relative growth and morphological sexual maturity of the caridean shrimp Nematopalaemon schmitti (Decapoda: Caridea: Palaemonidae) in an upwelling region in the Western Atlantic*

In crustaceans, successful reproductive processes, such as the transition from juvenile to adult, exhibit important morphological changes that can be detected by analyzing relative growth. This study describes the relative growth of body structures in Nematopalaemon schmitti and its secondary sexual characteristics, and also estimates the morphological sexual maturity of this species in a region influenced by upwelling. The carapace length (CL), second pleuron length (PlL), cheliped carpus length (CaL), cheliped propodus length (PrL) and the length of appendix masculina (AML) of the shrimp were measured. The relationships that best demonstrated the changes in allometric coefficient between demographic categories were AML vs. CL for males, and PlL vs. CL for females. The estimated CL for morphological sexual maturity in males was 8.51 mm and 9.30 in females. Our results showed the appendix masculine and the second pleuron were secondary sexual characteristics that play roles in reaching the morphological sexual maturity necessary for reproductive success and to assure the life cycle of this species.