Relationship between dental morphology, sex, body length and age in Pontoporia blainvillei and Sotalia fluviatilis (Cetacea) in Northern Rio de Janeiro, Brazil

The relationship between dental morphology, sex, body length and age of small cetaceans can be used to determine ontogeny, sexual dimorphism and geographical variation. The objective of this study was to determine the relationship between dental morphology, sex, body size and age. A total of 91 specimens of P. blainvillei and 80 specimens of S. fluviatilis accidentally captured in fisheries or stranded in northern Rio de Janeiro (21 masculine37'-22 masculine25'S), from September 1988 to November 1996 were analysed. The teeth root diameter in P. blainvillei was significantly different between the sex; the values for females were larger than males. In neither species aid we observed significant in variations dimension and number of teeth, thickness of dentine and cemental layers and in the maximum width of cement as a function of body size. Age was related to increases in tooth length, root and cingulum diameters, and maximum width of cement in individuals of P. blainvillei, and tooth and crown lengths and maximum width of cement in individuals of S. fluviatilis. The observation of a linear growth between maximum width of cement and age in both species indicates that the equations obtained can be used to estimate relative age in P. blainvillei and S. fluviatilis in northern of Rio de Janeiro.     

REPRODUCTIVE MATURITY AND SEASONALITY OF MALE SPOTTED DOLPHINS, STENELLA ATTENUATA, IN THE EASTERN TROPICAL PACIFIC

We estimated age at attainment of sexual maturity and examined reproductive seasonality for male spotted dolphins, Stenella attenuata , from the eastern tropical Pacific Ocean. Maturity was determined by histological examination of testes. Average age at sexual maturation was 14.7 yr (the mean of two readers' age estimates). Testis and epididymis weight and seminiferous tubule diameters were reliable indicators of maturity, whereas age, length and color phase were less reliable. Seasonality was determined by changes in testis and epididymis weight, relative quantity of spermatids and spermatozoa, and lumen diameter, as well as an index of testis development (weight of the right testis and epididymis divided by length of the right testis). Testis and epididymis weights and index values peaked in July and August, midway between two predicted mating seasons for the northern offshore stock, but spermatozoa levels were elevated during the predicted breeding seasons.     

Relative growth,morphological sexual maturity,heterochely, and handedness in Panopeus occidentalis (Brachyura,Panopeidae)

Studies on relative growth and sexual maturity are important to understand the reproductive biology of a species. The aims of this study were to determine the relative growth and to estimate the size of Panopeus occidentalis at morphological sexual maturity, as well as to confirm whether this species demonstrates heterochely or handedness. Individuals were collected every two months from March 2013 to July 2014 in the intertidal estuarine zone of Cananeia, São Paulo, Brazil. The following measurements were taken: carapace width (CW), carapace length (CL), right and left cheliped propodus length (CPL), right and left cheliped propodus height (CPH), right and left cheliped propodus width (CPW), abdomen width (AW), and first pleopod length (FPL). The morphometric relationship used to estimate the size at morphological sexual maturity were CW vs. AW for females and CW vs. FPL for males; these comparisons yielded estimated CW values of 15.60 mm and 16.67 mm, respectively. Heterochely was observed but handedness was not present. The species has a major cheliped on one side, but the side is not constant. This study provides the first insights on the relative growth, sexual maturity, heterochely, and handedness on a population of P. occidentalis in a conserved area.     

Size at the onset of sexual maturity in the anomuran crab, Aegla uruguayana (Aeglidae)

The size at maturity was studied in the crab Aegla uruguayana from the Areco River (31°14′ S, 59°28′ W), Argentina. Size at sexual maturity was determined according to three criteria: morphometric (change in the relative growth of reproductive characters), histological (first maturation of gonads) and functional (capability to mate and carry eggs). Regarding females, morphometric maturity occurred at a carapace length (CL) of 11.50 mm, considering abdomen width as a reproductive character. Gonad maturity of females could be observed at a minimum size ranging from 15 to 17 mm CL. The smallest ovigerous female observed in the field was 15.60 mm CL, although a relevant population incidence of ovigerous females (86.6%) has just been observed at values higher than 17 mm CL. As for males, the relative growth of the left chela length changed at a value of 15.40 mm CL, while morphological changes in sexual tube occurred between CL of 14 and 16 mm. Testicular maturation occurred at a CL ranging from 17 to 19 mm. The smallest size of males having spermatozoids in their vasa deferentia was 18.70 mm CL. The results obtained indicated that, in both sexes, functional maturity occurred after morphometric maturity and at a size similar to that of gonad maturity. Comparing sexes, females acquired sexual maturity (morphometric, gonad and functional maturity) at sizes statistically smaller than those of males.     

Characterization of male killer whale (Orcinus orca) sexual maturation and reproductive seasonality

Longitudinal serum testosterone concentrations (n=10 males) and semen production (n=2 males) in killer whales were evaluated to: (1) characterize fluctuations in serum testosterone concentrations with respect to reproductive maturity and season; (2) compare morphologic changes to estimated age of sexual maturity, based on changes in serum testosterone concentrations; and (3) evaluate seasonal changes in sperm production. Classification of reproductive status and age class was based on differences (P < 0.05) in serum testosterone concentrations according to age; juvenile males ranged from 1 to 7 years (mean+/-S.D. testosterone, 0.13+/-0.20 ng/mL), pubertal males from 8 to 12 years (2.88+/-3.20 ng/mL), and sexually mature animals were 13 years and older (5.57+/-2.90 ng/mL). For captive-born males, serum testosterone concentrations, total body length and height to width ratio of the dorsal fin were 0.7+/-0.7 ng/mL, 495.6+/-17.5 cm and 1.14+/-0.13c m, respectively, at puberty; at sexual maturity, these end points were 6.0+/-3.3 ng/mL, 548+/-20 cm and 1.36+/-0.1cm. Serum testosterone concentrations were higher (P<0.05) from March to June than from December to February in pubertal animals (4.2+/-3.4 ng/mL versus 1.4+/-2.6 ng/mL) and than from September to December in sexually mature animals (7.2+/-3.3 ng/mL versus 4.0+/-2.0 ng/mL). Ejaculates (n = 90) collected from two males had similar (P > 0.05) sperm concentrations across all months. These data represent the first comprehensive study on male testosterone concentrations during and after sexual maturation, and on reproductive seasonality in the killer whale.     

Precopulation Sexual Selection in Nysius huttoni White (Heteroptera: Lygaeidae) in Relation to Morphometric Traits

Nysius huttoni White is a polygamous bug, endemic to New Zealand, and an important pest of wheat and brassicas. This bug has a female-biased sexual size dimorphism but relative to body length, males have longer antennae, suggesting that the allometric scales of antennal–body relationships may be highly selective in sexual selection. Body weight and most morphometric traits measured have no effect on mating success of either sex. Males significantly preferred mating with females having thicker abdomens, more mature eggs, and longer ovipositors. This result suggests that males may select their mates on the basis of immediate reproductive benefit: fertilizing more eggs and ensuring better survival of these eggs. Males with large genital structures have mating advantages over those with small ones, suggesting that precopulation sexual selection in this species act on male genital traits rather than body weight and nonsexual traits. Finally, females significantly preferred males with greater slopes for the antennal-body relationship for mating. The allometry in the male antennal length may be an indicator of male reproductive fitness.     

COMPARATIVE GROWTH ANALYSIS OF TWO POPULATIONS OF PONTOPORIA BLAINVILLEI ON THE BRAZILIAN COAST

The von Bertalanffy growth model was applied to franciscana dolphins ( Pontoporia blainvillei ) incidentally caught in fishing nets on the São Paulo/Paraná coasts (25°00'–25°58'S), and compared with the growth of franciscanas incidentally caught on the Rio Grande do Sul coast (29°–33°S). In both locations, a difference was noted between the growth of males and females, confirming the sexual dimorphism of the body proportions of this dolphin. The growth curves of the dolphins from São Paulo/Paraná were significantly different ( P < 0.01) from those obtained from Rio Grande do Sul, with significantly smaller animals in the former area. On the São Paulo/Paraná coast, the stabilization of the growth curves happened at a total length of 113 and 129 cm for males ( n = 23) and females ( n = 18), respectively. In Rio Grande do Sul, they stabilized at 130 cm for the males ( n = 59) and at 146 cm ( n = 48) for the females. These results corroborate the morphometric differences previously mentioned in the literature, which resulted in the identification of a smaller northern form and a larger southern form of P. blainvillei . The data here presented can be used for future comparisons of changes in growth parameters of these two franciscana stocks and help to develop proper conservation programs for the species.     

Age and size at sexual maturity for the winter skate, <Emphasis Type="Italic">Leucoraja ocellata</Emphasis>, in the western Gulf of Maine based on morphological,histological and steroid hormone analyses

Synopsis We determined age and size at sexual maturity in male and female winter skates, Leucoraja ocellata, from the western Gulf of Maine. Age estimated from vertebral band counts resulted in an Index of Average Percent Error (IAPE) of 5.6%, suggesting that this method represents an accurate approach to the age assessment of L. ocellata. Size at sexual maturity was assessed by evaluating three endpoints: steroid hormone concentrations, and morphological and histological criteria. Our results suggest that 50% maturity in males occurs at a total length of 730 mm and at 11 years of age. For females, our results suggest that 50% maturity occurs at a total length of 760 mm and between 11 and 12 years of age. Collectively, our study suggests that analyzing a combination of reproductive parameters offers an accurate estimation of sexual maturity in the winter skate. Moreover, our results indicate that L. ocellata is a late-maturing and long-lived species, characteristics which make it highly susceptible to over-exploitation by commercial fisheries.     

Reproductive biology of the male Cape porcupine, Hystrix africaeaustralis

The reproductive tract of the male Cape porcupine is morphologically and histologically similar to that of New World hystricomorph rodents. Males are reproductively active throughout the year and attained sexual maturity (complete spermatogenesis) at an age of 8-18 months. Testes weight, epididymides weight and seminiferous tubule diameter attained asymptotic values at the age of 23-30 months. A tendency towards seasonality in the activity of accessory glands, preceded and accompanied by an increase in circulating plasma testosterone values, may be considered as a factor enforcing seasonal breeding in females. Testosterone concentrations in pubertal males were significantly higher than those recorded in sexually mature males.     

青藏高原褐背拟地鸦表型特征的性别差异与地理变异

将数值分类用于鸟类分类学研究时,对于雌雄的形态特征差异没有被重视,尤其是对于雌雄同形的鸟类。本文以雌雄同形的褐背拟地鸦Pseudopodoces humilis为材料,运用SPSSl0．0FORwINDOwS统计分析软件对108号褐背拟地鸦标本(51♀♀,57♂♂)的数量性状(体长、跗跖长、翅长、尾长、嘴宽、嘴高、上喙长、下喙长、嘴裂、第3趾爪长、第1趾爪长)的原始数据进行分析,结果表明雌、雄性状在翅长(n＝51,P＝0．012)和嘴高(n＝57,P＝0．043)上有明显差异,但在体长、跗跖长、尾长、嘴宽、上喙长、下喙长、嘴裂、第3趾爪长、第1趾爪长等数值特征上却没有明显的差异。所以在以后对于褐背拟地鸦的地理种群变异和亚种分化的研究中,翅长和嘴高两特征应该根据雌雄分别讨论。通过对不同性状量度和纬度的相关回归分析,发现在测量标本所涉及的采集地范围内,即主要在青藏高原东南部地区,褐背拟地鸦体长和雄乌的翅长在地理分布上随纬度的增加而变小,而其它性状特征没有明显的地理分布纬度上的变化。     

Testes development and maturity classification of albacore (Thunnus alalunga ( Bonaterre, 1788)) from the Eastern Mediterranean Sea

The criteria of testicular maturity during the spawning season and for maturity rates are described according to age for 140 male albacore (Thunnus alalunga, Bonnaterre, 1788) sampled between April and August, 2002–2008 in the Eastern Mediterranean Sea. Histology of gonad samples was used to determine maturity status. Spermatogenesis and its relation to reproductive biology are reported. Fish ranged in fork length (FL) from 63 to 90 cm. The reproductive classes were based upon changes in the testicular morphology and stages of the germinative cells, i.e. immature, developing, maturing, spawning, and spent. Mature stages of testes including the smallest sample of a 63 cm male were observed from May to August of each year during the study. The reported evidence indicates that the size and age of first sexual maturity values of males of the Eastern Mediterranean population are nearly the same as in the Western Mediterranean population, but lower than in the Atlantic stock. The results of this histological investigation, conducted for the first time on this species in the Mediterranean Sea, will enable more precise future estimations for sustainability of the male albacore stock in the Eastern Mediterranean.     

Biological Studies of the Pearl Spot Etroplus suratensis (Pisces,Cichlidae) from three Different Habitats in Sri Lanka

The morphometry, feeding habits and reproductive biology of Etroplus suratensis, an indigenous cichlid food fish, were studied for a period of one year on specimens from three different habitats in Sri Lanka. The morphometric studies implied that the length weight relationships are curvilinear. Macrophytic fragments formed the most important component of food, although detritus, diatoms, and animal matter are also ingested. First sexual maturity is attained in the length ranges 8.0-9.0 cm in females from brackish water habitats. Fecundity ranged from 700-3900 eggs in mature specimens. The wide range of the gonadosomatic index suggests that spawning occurs several times during the year.     

瓦氏黄颡鱼的繁殖生物学研究

研究了长江中游嘉鱼至新滩口江段瓦氏黄颡鱼的繁殖生物学。性腺发育可分为6个时期。4-7月性成熟系数较高,为繁殖季节。雌、雄鱼的肥满度和脂肪系数在繁殖前和繁殖后各出现1个峰值,繁殖期出现最小值。绝对繁殖力为1088-19765(粒),平均7728±4093(粒);相对繁殖力为23-88(粒),平均55±16(粒)。绝对繁殖力与体长、体重和年龄呈显著的正相关,其中体重与绝对繁殖力的关系最密切。群体性比接近1:1。属一次性产卵类型。两性最小性成熟年龄均为2龄。为补充群体占优势的繁殖群体。     

养殖美洲鲥的生长特性

通过对各周年生长阶段的养殖美洲鲥(Alosa sapidissima)体长、体重的测量与分析,研究了工厂化养殖美洲鲥的周年生长特性。养殖美洲鲥雌雄鱼的体长与体重关系均呈幂函数增长相关,其方程分别为,雌:W=0.8062×10~(-5) L~(3.1113)(n=122,R~2=0.997 5,P0.01);雄:W=1.0047×10~(-5) L~(3.0574)(n=125,R~2=0.997 5,P0.01),b均接近于3,呈等速生长;雌雄鱼生长均可分快速生长期(0~+龄)、稳定生长期(1~+龄)、生长衰老期(2~+龄)三个时期,雌鱼生长快于雄鱼。拟合出von Bertallanffy生长方程,雌:Lt=467.92(1﹣e~(-0.5748(t+0.1710))),Wt=1637.72(1﹣e~(-0.5748(t+0.1710)))~(3.1113);雄:Lt=389.21(1﹣e~(-0.7374(t+0.1975))),Wt=834.08(1﹣e~(-0.7374(t+0.7189)))~(3.0574)。雌雄鱼体重生长拐点分别位于1.517 8 a和1.224 7 a,属性成熟拐点,拐点前生长较快;拐点后,特别是性成熟后(2龄),2~+龄鱼的生长速度明显降低;同时,2龄鱼繁殖季节过后会出现大量死亡。建议商业化工厂化养殖美洲鲥以2龄前上市为宜。     

Head morphometric changes in cryopreserved ram spermatozoa are related to sexual maturity

The importance of understanding the sperm changes after the cryopreservation process has been emphasized in human and veterinary andrology. In previous studies, we have shown that the morphometric characteristics assessed by computer-assisted analysis following the freeze-thawing process revealed differences in terms of dimension and shape between individuals that may be related to bio-physiologic factors such as sexual maturity. The purpose of this study was to determine if there are differences associated with cryoresistence and sperm head morphometric dimensions in individuals with different sexual maturity ratings (SMRs; 12, 30 and 96 months of age). Ejaculates from nine normospermic fertile rams with different SMRs were analyzed in an attempt to quantify the morphometric dimensions and the shape of sperm heads from each group after the cryopreservation process. The mean values of sperm concentration among individuals with different SMRs were significantly different (P < 0.01). Cryopreservation substantially reduced sperm motility and plasma membrane integrity irrespective of SMR assessed, with young animals being the most affected (P < 0.01). Sperm quality at thawing for all sperm parameters evaluated was significantly higher for old individuals than for middle-aged or young individuals (P < 0.01). There were no significant differences in the sperm head dimension or shape among middle-aged and old individuals (P > 0.05). However, significant differences were detected in area, perimeter and width (lower values) and length, ellipticity and elongation (higher values) in old or middle-aged individuals compared with young individuals (P < 0.01). In conclusion, this study confirms that ram age is related to sperm morphometric dimensions, and sperm size and shape may affect spermatozoa survival, being good indicators of freezability. Therefore, the present study provides information on the morphometric maturation of ram sperm and supports the idea that the dimensions of spermatozoa may be taken as an approximate indication of its relative maturity.     

Size distribution,length–weight relationship and size at the onset of sexual maturity of the orange mud crab,Scylla olivacea,in Malaysian waters

The size distribution, length–weight relationship and size at the onset of sexual maturity of the orange mud crab (Scylla olivacea) from four geographically distinct locations (Taiping, Setiu, Kota Marudu and Lundu) representing Malaysian waters were analysed and estimated. Scylla olivacea was found in the size range of 47–134?mm carapace width. Males were significantly smaller in size but heavier than females. Geographical variation in carapace width and body weight were significant, but no interaction was found between sexes and locations. As shown by the length–weight relationships of S. olivacea, the males exhibited positive growth allometry whereas the females exhibited negative growth allometry. Males mature physiologically prior to attaining morphometric sexual maturity. Females, however, achieve physiological and morphometric sexual maturity in synchrony. No significant variation was found in the estimates of size at the onset of sexual maturity of males and females among different locations. We recommend the use of the third right walking leg merus length and carapace width to estimate the size at the onset of sexual maturity (morphometric maturity) for S. olivacea. Data obtained in this study serve as important baseline data for future mud crab resource management in Malaysia and were used to recommend minimum landing sizes for S. olivacea in each respective location based on the largest size at the onset of sexual maturity estimates were suggested.     

Using the composite variables of reproductive morphology, histology and steroid hormones to determine age and size at sexual maturity for the thorny skate Amblyraja radiata in the western Gulf of Maine

Age at size was linked to sexual maturity in 77 male and 93 female thorny skates Amblyraja radiata from the western Gulf of Maine using three criteria: 1) gross reproductive morphology, 2) histology and 3) steroid hormone concentrations. Age-bias plots and the coefficient of variation from vertebral band counts suggested that the ageing method represented a non-biased and precise approach to the age assessment of A. radiata . Maturity ogives for males, based on data gathered for clasper length, circulating testosterone concentrations and proportion of mature spermatocysts within the testes, predicted that 50% maturity occurred at a total length ( L _T) of 865 mm and c. 10·90 years of age. For females, maturity ogives, based on data gathered for ovary mass, shell gland mass, follicle size and circulating oestradiol concentrations, predicted that 50% maturity occurred at 875 mm L _T and c. 11·00 years of age. Collectively, the results suggest that analysis of several contemporaneous reproductive variables offers an accurate determination of sexual maturity in the thorny skate.     

Mating system evolution in sperm-heteromorphic Drosophila

In Drosophila species of the obscura group, males exhibit sperm-heteromorphism, simultaneously producing both long sperm, capable of fertilization, and short sperm that are not. The production of multiple sperm types calls into question whether mating system correlates, such as sperm length and number trade-offs and female remating behavior, are the same as previously described in sperm-monomorphic systems. We examine three obscura group species, D. pseudoobscura, D. persimilis, and D. affinis that differ significantly in the lengths of their long fertilizing sperm, to test predictions about the relationship between sperm length and four mating system characters: male age at sexual maturity; sperm number; female remating; and male reproductive output. In D. affinis, where males produce the longest fertilizing sperm, their sexual maturity is delayed and they produce fewer long sperm compared to the other two species, as predicted if long sperm are costly to produce. Female D. affinis, although they receive fewer sperm than females of the other two species, do not remate more frequently or produce fewer progeny from a single mating. Different responses between sperm-heteromorphic and sperm-monomorphic systems underscore the complex nature of the coevolution between male and female mating system characters.     

Influence of season of birth on growth and reproductive development of Brahman bulls

Seasonal effects on reproduction are more dramatic in Bos indicus than Bos taurus cattle. This experiment evaluated reproductive development of fall- (n=7) versus spring- (n = 10) born Brahman bulls to determine if season of birth affects reproductive development. Measurements of growth and reproductive development began after weaning and continued at bi-weekly intervals until each bull reached sexual maturity. Different stages of sexual development were classified according to characteristics of the ejaculate and included first sperm in the ejaculate, puberty (> 50 x 10(6) sperm/ejaculate), and sexual maturity (two ejaculates with > 500 = 10(6) sperm/ejaculate). Average daily increases in all measured traits were similar in fall- and spring-born bulls and there were no differences in age, body weight, scrotal circumference, or paired testis volume between groups at first sperm or puberty. However, fall-born bulls were older (P < 0.05) than spring-born bulls at sexual maturity (553 days versus 481 days, respectively) as the interval between puberty and sexual maturity was longer (P < 0.05) in fall- than in spring-born bulls (82 days versus 54 days, respectively). The prolonged interval between puberty and sexual maturity in fall-born calves coincided with a short photoperiod (winter) whereas the short interval between puberty and sexual maturity in spring-born calves coincided with a long photoperiod (summer). In conclusion, season of birth affected sexual development; photoperiod might be involved in regulating testicular function immediately after puberty in Brahman bulls.     

Length–weight and length–length relationships,gonadosomatic indices and size at first maturity of Eugerres mexicanus (Steindachner, 1863) (Percoidei: Gerreidae) from the Usumacinta River,Mexico

This study examines the length‐weight (L‐W) and length‐length (L‐L) relationships, gonadosomatic indices, and size at sexual maturity for individuals of the endemic Mexican mojarra, Eugerres mexicanus (Steindachner, 1863) from the Usumacinta River Basin, Tabasco, Mexico. From April 2008 to January 2010, 360 specimens were examined, including 151 (41.9%) male, 179 (49.7%) female and 30 unsexed (8.3%) individuals. Overall female:male ratio was 1.2 : 1. Gonadosomatic index (GSI) values indicate increased reproductive activity during February, with significant differences between males (GSI = 2.07) and females (GSI = 5.48). The mean size at first maturity (L₅₀) was 17.3 cm TL for males and 20.5 cm TL for females.