Multiple paternity,reproductive skew and correlates of male reproductive success in a wild population of the Trinidadian guppy

Abstract – In most species, males have a higher reproductive potential than females, leading to skewed reproductive success, particularly in mating systems where pre‐ or postcopulatory sexual selection reinforces inequality in male mating success. We investigated multiple paternity, reproductive skew and correlates of male reproductive success in a wild population of the Trinidadian guppy (Poecilia reticulata). We used nine microsatellite loci to assess the frequency of multiple paternity, number of sires per brood and reproductive skew. Across broods, the frequency of multiple paternity was high with 94% of broods having multiple sires (range: 1–5), resulting in a reproductive skew of 0.14. Variation in male reproductive success was high (range: 0–14 offspring per male), suggesting that there is considerable opportunity for sexual selection. Next, we examined correlations between male reproductive success and sexual coloration, sperm velocity and gonopodium length. Relative area of orange, black, iridescent and total coloration, and sperm velocity were not correlated with reproductive success. However, gonopodium length explained 14% of the variation in reproductive success, suggesting that gonopodium length is likely a sexually selected trait. We discuss these findings in the light of other studies that genetically dissect joint‐sex parentage and examine correlates of male reproductive success in wild populations.     

巴东富硒天麻产业建设初探

天麻作为一种药材，同时又是一种理想的保健品，市场前景可观。巴东森林资源丰富，同时恩施辖区为我国第一个高硒区，在大力开发硒产品之际，巴东富硒天麻产业基地建设势在必行。它可使我县经济增长，农民增收，同时对巳东的产业结构大调整，山区资源大开发起着不可估量的作用。     

榆林沙区黑沙蒿花粉二型性特征观察

以毛乌素沙地南缘榆林沙区的黑沙蒿为研究对象,采用扫描电镜（SEM）显微技术,对其花粉形态特征进行详细的观察描述。结果表明,黑沙蒿花粉粒属单粒小型花粉,具有蒿属植物花粉的共性特征,属于较为进化物种的花粉形态,同时其花粉粒二型性特征亦比较突出。长球形和圆球形2种形态不同的花粉粒,同时存在于同一花药中,长球形花粉粒极轴长(P)23.43（20.10～24.91）μm,赤道(E)轴长16.93（15.81～17.32）μm,P/E=1.38,极轴与赤道轴长度差异显著（P<0.05）,赤道面观椭圆形;圆球形花粉粒极轴与赤道轴近等长,极轴长17.56（16.11～18.43）μm,赤道轴长17.10（15.99～18.01）μm,P/E=1.03,极轴与赤道轴长度差异不显著（P>0.05）,赤道面观圆球形;经T检验,2种形态花粉粒的极轴与赤道轴长度比值P/E,差异达显著水平（P<0.05）。2种形态花粉萌发器官都具3孔沟,但长球形花粉的沟深而细长,边缘整齐光滑,内孔深陷,沟间稍窄,极区面积较小;圆球形花粉的沟较浅较短,沟缘粗糙,内孔外突,沟间较宽,极区面积较大;外壁表面纹饰都为退化小刺与颗粒状纹饰的组合,但刺的分布、基部大小及刺间颗粒的大小和排列等有所差异。样本中长球形花粉粒占比为64.1%,圆球形花粉粒占比为35.9%。     

Sexual compatibility of transgenic soybean and different wild soybean populations

The introduction of genetically modified (GM) soybean into farming systems raises great concern that transgenes from GM soybean may flow to endemic wild soybean via pollen. This may increase the weediness of transgenic soybean by increasing the fitness of hybrids under certain conditions and threaten the genetic diversity of wild soybean populations. Although pollen-mediated gene flow between GM crops and wild relatives is dependent on many factors, the sexual compatibility (SC) determined by their genetic backgrounds is the conclusive factor. The considerable genetic variation among wild soybean populations may cause compatibility differences between different wild and cultivated soybeans. Thus, an evaluation of the SC between transgenic soybean and different wild soybeans is essential for assessing the environmental consequences of cultivated soybean–wild soybean transgene flow. The podding and seed sets were assessed after artificial hybridization using transgenic glyphosate-resistant soybean as the paternal parent and 18 wild soybean populations as the maternal parents. Then, the average number of filled seeds produced in 200 flowers (AFS) was calculated for each wild soybean under natural self-pollination as well as under artificial crossing with transgenic soybean. Finally, the index of cross-SC was calculated (ICSC) as the ratio of the AFS of wild soybean artificially crossed with transgenic soybean and the AFS of naturally self-pollinated wild soybean. The results demonstrated that after self-pollination and crossing with transgenic soybean, the average podding rates of 18 wild soybean populations ranged within 96.50–99.50% and 4.92–18.03%, and the average filled seed numbers per pod varied from 1.70 to 2.69 and 0.20 to 0.48, respectively. The results showed that approximately 89% of wild soybeans displayed either medium or higher than medium SC with transgenic soybean (ICSC>1.0%). This implied the high possibility of gene flow via pollen from transgenic soybean to wild soybean.     

Maturity and reproduction of goneplacid crab <Emphasis Type="Italic">Carcinoplax vestita</Emphasis> (Decapoda,Brachyura) in Tokyo Bay

ABSTRACT:     Sexual maturity, morphological sexual dimorphism, and reproduction of the goneplacid crab Carcinoplax vestita were investigated in Tokyo Bay, Japan, from November 2002 to October 2003. The puberty molt in males was evidenced by changes in the relative size of the chelipeds and merus of the walking legs, and was estimated to occur at a size range of 13.20–18.85 mm carapace length. Post-pubertal females were identified by the relative size of the abdomen and puberty was estimated to occur at a size range of 12.81–15.46 mm carapace length. Sexual dimorphism in C. vestita was observed in all features that showed secondary sexual characteristics. Monthly changes of gonad index in males, and of seminal receptacle index and occurrence of sperm plugs in females were synchronized, and indicated that mating was intense in spring. Ovaries began developing in March. Ovigerous females were found in all months except December, but were clearly more abundant between August and October. Fecundity ranged from 7800 to 57 000 mature oocytes per female per batch and was highly correlated with body size. The results suggest that some females may spawn more than one batch per year.     

Protein metabolism during sexual maturation in female Atlantic salmon (Salmo salar L)

Body composition and fractional rates of protein synthesis (percentage of the protein mass synthesized per day) were determined in female Atlantic salmon returning to the River Tay, Scotland in July and in October after a 95 day period without food, during which time the animals became sexually mature. During the 95 day period of starvation/sexual maturation the ventricle and red muscle remained as a constant proportion of fresh weight whereas the liver, gill and ovary increased and the stomach and white muscle decreased. Fractional rates of protein synthesis increased markedly in the liver, stomach and ovary during the period of starvation/sexual maturation. In the gill, ventricle and white muscle fractional protein synthesis rates increased slightly or remained constant. From the estimated rates of protein loss or gain in the various tissues it is concluded that there is considerable protein turnover and repartitioning of amino acids during the period of starvation and sexual maturation. The absolute rate of protein synthesis rates in the ovary indicates that this tissue made the largest contribution to the energy and amino acid demands of the fish, whilst most of the amino acids required for maturation of the ovary were derived from white muscle, principally as the result of increased muscle protein degradation.     

Sexual dimorphism of fast muscle fibre recruitment in farmed Atlantic halibut (Hippoglossus hippoglossus L.)

Commercially farmed Atlantic halibut (Hippoglossus hippoglossus) were reared at the Aga Marin's facility located on Dønna (Norway) under ambient environmental conditions in duplicate 15 × 15 × 8 m netpens (May 2004 to May 2005). Twenty fish were sampled five times over a twelve month production period during which time the average body weight increased from 1.26 to 2.08 kg (n = 100 fish). Body mass, fork length (L_F), and the number and size distributions of fast muscle fibres were determined in male and female fish. All males matured during the autumn whereas no maturation was observed in females. From the point of maturation females had superior growth performance to males and body mass and the total cross-sectional area of muscle were 1.4-fold (P < 0.05) and 1.3-fold higher (P < 0.01) respectively by May 2005. The total number of fast muscle fibres per trunk cross-section at 0.55 L_F was 24.5% higher in females (7.58 × 10⁵) than males (5.80 × 10⁵) prior to sexual maturation. In females, muscle fibre recruitment slowed with short days and low water temperatures (< 6.5 °C), but had increased to 1.01 × 10⁶ by May 2005 (P < 0.001). In contrast, there was no growth and no increase in muscle fibre number in males following the onset of maturation. The distribution of muscle fibre diameters prior to maturation in males was also significantly different between male and female fish matched for L_F. The results illustrate a sexual dimorphism of muscle fibre recruitment patterns in Atlantic halibut and highlight the adverse affects of sexual maturation in males on muscle growth.     

A pilot study of sexual dimorphism in the head morphology of domestic dogs

The dog (Canis lupus familiaris) displays more morphological diversity than any other species. It is a direct descendant of the gray wolf (Canis lupus), but shows remarkable behavioral and morphological differences. It has been suggested that differences in skull shape that relate to brain shape and retinal ganglion cell distribution may predict behavioral differences. The aim of this pilot study was to assess head morphology in common breeds for evidence of sexual dimorphism in head length, head width, and the ratio of the 2: cephalic index (CI). When males of 80 breeds studied were compared with females, sexual dimorphism (differences in a t-test at the level of P < 0.01) emerged for head length in 5 breeds, for head width in 10 breeds and in CI for 2 breeds. The 2 breeds that showed sexual dimorphism in CI showed no difference (at the level of P < 0.01) in either length or width. These results suggest that all 3 types of dimorphism in head morphometrics must be considered separately. Although the longer and wider heads in males may be predicted because, within a breed, they are expected to be generally bigger animals, the sexual dimorphism in CI is of interest. It may belie differences in brain shape and even predict differences in health, welfare, and behavior.     

Effects of aromatase inhibitors on reproduction in male three-spined sticklebacks, Gasterosteus aculeatus, exposed to long and short photoperiods

Three-spined stickleback Gasterosteus aculeatus, males were implanted with Silastic capsules filled with different aromatase inhibitors; 1,4,6-androstatriene-3,17-dione or the non-steroidal CGS16949 A, 4-(5,6,7,8-tetrahydrimidazol [1,5-a]pyridin-5-yl) benzonitrile monohydrochloride or empty capsules. The fish were then exposed to long or short photoperiod. Under the long photoperiod most fish in all treatments displayed a hypertrophied kidney (a secondary sexual character in sticklebacks) and completed, quiescent spermatogenesis, similar as in the natural spawning period. Under the short photoperiod the controls had unstimulated kidneys and an active spermatogenesis, whereas the males implanted with both aromatase inhibitors had stimulated kidneys, though not to the extent as in the long photoperiod, and completed, quiescent spermatogenesis. These findings suggest that aromatization is of importance for the inhibitory effects of short photoperiod on reproduction in the stickleback. This revised version was published online in July 2006 with corrections to the Cover Date.     

What are the prospects for black bream Acanthopagrus butcheri (Munro) aquaculture in salt‐affected inland Australia?

Black bream are a highly regarded sport and table fish, and there has been considerable interest in their aquaculture potential for the salt‐affected agricultural regions of inland southern Australia. In many ways they are an ideal candidate species for inland saline aquaculture because they appear to be very hardy, hatchery techniques are well established for them, and high survival rates have been maintained under a variety of culture conditions and feeding regimes. However, their slow growth rate needs to be increased by at least 33% for black bream to become an economically viable aquaculture species. Growth is amenable to genetic improvement, and sub‐adult growth rate shows moderate heritability and no adverse genetic correlations with other production traits. Nevertheless fillet yield is comparatively low, and in conjunction with unpredictable and early sexual development in culture, industry‐scale meat production remains problematic. These obstacles, however, do not preclude the use of black bream as a recreational fish species for inland saline waters, where their stocking may provide an additional source of rural income and relieve fishing pressure on depleted estuarine populations.