Displaying publications 1 - 20 of 40 in total

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  1. Fulltext Sex differences in human mate preferences vary across sex ratios
    Walter KV, Conroy-Beam D, Buss DM, Asao K, Sorokowska A, Sorokowski P, et al.
    Proc Biol Sci, 2021 Jul 28;288(1955):20211115.
    PMID: 34284630 DOI: 10.1098/rspb.2021.1115
    A wide range of literature connects sex ratio and mating behaviours in non-human animals. However, research examining sex ratio and human mating is limited in scope. Prior work has examined the relationship between sex ratio and desire for short-term, uncommitted mating as well as outcomes such as marriage and divorce rates. Less empirical attention has been directed towards the relationship between sex ratio and mate preferences, despite the importance of mate preferences in the human mating literature. To address this gap, we examined sex ratio's relationship to the variation in preferences for attractiveness, resources, kindness, intelligence and health in a long-term mate across 45 countries (n = 14 487). We predicted that mate preferences would vary according to relative power of choice on the mating market, with increased power derived from having relatively few competitors and numerous potential mates. We found that each sex tended to report more demanding preferences for attractiveness and resources where the opposite sex was abundant, compared to where the opposite sex was scarce. This pattern dovetails with those found for mating strategies in humans and mate preferences across species, highlighting the importance of sex ratio for understanding variation in human mate preferences.
    Matched MeSH terms: Sex Ratio*
  2. Fulltext Sex ratio and age of onset in AQP4 antibody-associated NMOSD: a review and meta-analysis
    Arnett S, Chew SH, Leitner U, Hor JY, Paul F, Yeaman MR, et al.
    J Neurol, 2024 Aug;271(8):4794-4812.
    PMID: 38958756 DOI: 10.1007/s00415-024-12452-8
    BACKGROUND: Aquaporin-4 (AQP4) antibody-associated neuromyelitis optica spectrum disorder (NMOSD) is an antibody-mediated inflammatory disease of the central nervous system. We have undertaken a systematic review and meta-analysis to ascertain the sex ratio and mean age of onset for AQP4 antibody associated NMOSD. We have also explored factors that impact on these demographic data.

    METHODS: A systematic search of databases was conducted according to the PRISMA guidelines. Articles reporting sex distribution and age of onset for AQP4 antibody-associated NMSOD were reviewed. An initially inclusive approach involving exploration with regression meta-analysis was followed by an analysis of just AQP4 antibody positive cases.

    RESULTS: A total of 528 articles were screened to yield 89 articles covering 19,415 individuals from 88 population samples. The female:male sex ratio was significantly influenced by the proportion of AQP4 antibody positive cases in the samples studied (p sex ratio was 8.89 (95% CI 7.78-10.15). For paediatric populations the estimate was 5.68 (95% CI 4.01-8.03) and for late-onset cases, it was 5.48 (95% CI 4.10-7.33). The mean age of onset was significantly associated with the mean life expectancy of the population sampled (p sex ratio and the mean age of onset of AQP4 antibody-associated NMOSD are significantly higher than MS. The sex ratio increases with the proportion of cases that are positive for AQP4 antibodies and the mean age of onset increases with population life expectancy.

    Matched MeSH terms: Sex Ratio
  3. Fulltext Meiotic drive reduces egg-to-adult viability in stalk-eyed flies
    Finnegan SR, White NJ, Koh D, Camus MF, Fowler K, Pomiankowski A
    Proc Biol Sci, 2019 Sep 11;286(1910):20191414.
    PMID: 31480972 DOI: 10.1098/rspb.2019.1414
    A number of species are affected by Sex-Ratio (SR) meiotic drive, a selfish genetic element located on the X-chromosome that causes dysfunction of Y-bearing sperm. SR is transmitted to up to 100% of offspring, causing extreme sex ratio bias. SR in several species is found in a stable polymorphism at a moderate frequency, suggesting there must be strong frequency-dependent selection resisting its spread. We investigate the effect of SR on female and male egg-to-adult viability in the Malaysian stalk-eyed fly, Teleopsis dalmanni. SR meiotic drive in this species is old, and appears to be broadly stable at a moderate (approx. 20%) frequency. We use large-scale controlled crosses to estimate the strength of selection acting against SR in female and male carriers. We find that SR reduces the egg-to-adult viability of both sexes. In females, homozygous females experience greater reduction in viability (sf = 0.242) and the deleterious effects of SR are additive (h = 0.511). The male deficit in viability (sm = 0.214) is not different from that in homozygous females. The evidence does not support the expectation that deleterious side effects of SR are recessive or sex-limited. We discuss how these reductions in egg-to-adult survival, as well as other forms of selection acting on SR, may maintain the SR polymorphism in this species.
    Matched MeSH terms: Sex Ratio*
  4. Gender difference in academic performance of nursing students in a Malaysian university college
    Wan Chik WZ, Salamonson Y, Everett B, Ramjan LM, Attwood N, Weaver R, et al.
    Int Nurs Rev, 2012 Sep;59(3):387-93.
    PMID: 22897191 DOI: 10.1111/j.1466-7657.2012.00989.x
    To examine differences in academic performance between male and female nursing students, and to identify whether professional identity and language usage were explanatory factors of academic performance.
    Matched MeSH terms: Sex Ratio*
  5. Fulltext Evidence of adult male scarcity associated with female-skewed offspring sex ratios in sea turtles
    Hays GC, Laloë JO, Lee PLM, Schofield G
    Curr Biol, 2023 Jan 09;33(1):R14-R15.
    PMID: 36626854 DOI: 10.1016/j.cub.2022.11.035
    Climate change is a clear and present threat to species survival. For species with temperature-dependent sex determination, including all sea turtles, it has been hypothesised that climate change may drive the creation of sex-ratio biases leading to population extinctions1. Through a global analysis across multiple species, we present the first direct empirical evidence for a demographic consequence of male scarcity in sea turtle populations, with a lower incidence of multiple paternity being found in populations with more extreme female-biased hatchling sex-ratio skews. For green turtles, when the female bias in hatchling sex ratio was >90%, the incidence of multiple paternity was low compared to other nesting sites, being 24.5% in the eastern Mediterranean (Cyprus), 36.4% on Redang Island (Malaysia) and 15.4% on the southern Great Barrier Reef (Heron Island, Australia) compared to higher values (range 61.1-91.7%) at other sites globally. These results suggest that a low incidence of multiple paternity may serve as a harbinger of future problems with egg fertility if males become even scarcer. Assessments of the incidence of multiple paternity at sites where adult males are expected to become scarce, such as Raine Island on the northern Great Barrier Reef in Australia, may help to identify when a lack of males raises the threat of local extinctions. In such cases, intervention to increase the production of male hatchlings may be needed.
    Matched MeSH terms: Sex Ratio
  6. Sex ratio, spawning season and the size at maturity of Parapenaeopsis sculptilis (Heller 1862) in the coastal waters of Perak, Peninsular Malaysia
    Arshad A, Amani AA, Amin SMN, Yusoff FM
    J Environ Biol, 2016 07;37(4 Spec No):709-13.
    PMID: 28779730
    Parapenaeopsis sculptilis (Heller, 1862) locally referred to as ?udang kulit keras? in Malaysia has profound biological, ecological, aquacultural and conservational significance. The reproductive biology of this important penaeid from the coastal waters of Perak, Peninsular Malaysia, was studied during the period between February 2012 to January 2013. Females outnumbered males with a sex ratio of M: F= 1:3 (P < 0.05). Four maturity stages of female gonads viz., immature, maturing, mature and spent stages were distinguished. The first stage of sexual maturity was attained at a length of 9.3 cm, and female P. sculptilis showed a peak gonadosomatic index during the month of April, August and October, indicating that P. sculptilis potentially breeds throughout the year. The findings of this study would greatly contribute towards the understanding of gonadal maturation, spawning season and breeding biology, which could be important for the effective population management of this prawn species.
    Matched MeSH terms: Sex Ratio
  7. Biological aspects of channa limbata(cuvier, 1831) in ta bo - huai yai wildlife sanctuary, Phetchabun province, Thailand
    Khoomsab K, Wannasri S
    Sains Malaysiana, 2017;46:851-858.
    The biological aspects of Channa limbata were studied between November 2013 and October 2014. A total of 346 fish specimens, 185 male and 161 female, were collected from Ta Bo, Huai Yai Wildlife Sanctuary, Phetchabun Province, Thailand. Specimens range from 7.3-17.2 cm in length with body weight 8-31 g; sex ratio between males and females was 1: 0.7. The length (L), weight (W) relationship for mixed sexes was W = 0.2064 L1.85 (R2=0.90). Gonadosomatic indices for males and females were measured monthly and varied from 0.21-0.65% and 1.96-3.74%, respectively. Condition factors for males and females ranged between 0.54 - 2.20 and 0.58 - 2.72, respectively, with fecundity range 956 to 4,652 eggs in females. Fecundity (F) to weight relationship was F = 189.53 W0.59 (R2 = 0.71) and fecundity to length relationship was F = 68.82 L1.15 (R2 = 0.77). The ratio between the intestine length and total length was 1:2, indicating that C. limbata was a carnivorous feeder. Analysis of the stomach contents gave 84% insects and 16% aquatic weed. These results can be applied to conserve efforts to prevent the extinction of C. limbata in protected areas.
    Matched MeSH terms: Sex Ratio
  8. Demographic, clinical and immunological features of 134 Malaysian patients with systemic lupus erythematosus
    Azizah MR, Ainol SS, Kong NCT, Normaznah Y, Rahim MN
    International Medical Journal (Tokyo), 2001;8(1):45-50.
    Objective: SLE is an autoimmune disease which affects multiple organ system. Clinical and immunological expression of the disease have been widely studied and variations occur in different ethnic groups. Here in this study, we have analyzed the clinical manifestations and immunological features of Malaysian patients with Systemic lupus erythematosus (SLE) and compared them with SLE population from some of the Asian countries. Study design: A total of 134 Malaysian patients attending the SLE Clinic of The National University Hospital of Malaysia, Kuala Lumpur and who satisfy the revised ACR (American College of Rheumatology) criteria for the classification of SLE were enrolled into the study. Data on the demography, clinical and immunological features were obtained from medical records. Materials and Methods: The female to male ratio in the study cohort was 10:1 and consisted of the Malay, Chinese and Indian races. Past clinical and immunological features were entered into a prepared questionnaire. At study entry patients were seen by a rheumatologist for assessment of present clinical condition and blood obtained for immunological tests (Antinuclear, antids DNA, antiSm, antiU1RNP, antiSSA(Ro), antiSSB(La), anticardiolipin (IgG and IgM) antibodies and complements C3 and C4). Chi-square, Fisher's exact test and Mann Whitney U Test were used to analyze data. Results: Clinical features expressed at disease presentation in order of frequency was mucocutaneous (72%), followed by musculoskeletal (58%) and renal involvement (45%) which was also similar during the course of the disease (90%, 72% and 64% respectively). A high prevalence of antiSSB (La) antibodies was found (48%). Conclusion: This study provides the literature on the clinical and immunological features of Malaysian SLE patients and further shows the different spectrum of disease profile when compared to other ethnic groups. The roles of racial and genetic factors are suggested.
    Matched MeSH terms: Sex Ratio
  9. Fulltext The effect of mating on the eggs’ fertility and fecundity of Helopeltis antonii (Heteroptera: Miridae)
    Siswanto, Rita Muhamad, Dzolkhifli Omar, Elna Karmawati
    Trop Life Sci Res, 2009;20(1):-.
    MyJurnal
    Helopeltis antonii is the major pest affecting cashew plants in Indonesia and causes potential damage to the plant. The development of the population was influenced by the fecundity and fertility of their eggs. The effect of mating on the eggs’ fecundity and the fertility of H. antonii was studied. Laboratory studies at Wonogiri Estate Service in Ngadirojo District, Wonogiri, Indonesia investigated the sexual maturity, the influence of female to male sex ratio on the females’ fecundity and longevity, and the influence of mating frequency to fecundity and the eggs hatchability of H. antonii. The study reveals that H. antonii females and males are ready to mate when they are two days old. The number of eggs laid and the longevity of the females’ lives were not significantly affected by the sex ratio; however, female to male sex ratios of 2:1 and 1:2 tended to produce a greater number of eggs. The fecundity of the female was not significantly influenced by the number of times the female mated. Unmated females laid fewer eggs than females paired with a mature male. The study shows that females need to mate to produce fertile eggs.
    Matched MeSH terms: Sex Ratio
  10. Horseshoe crab, Tachypleus gigas (Müller, 1785) spawning population at Balok Beach, Kuantan, Pahang, Malaysia
    Tan AN, Christianus A, Shakibazadeh S, Hajeb P
    Pak J Biol Sci, 2012 Jul 01;15(13):610-20.
    PMID: 24218930
    Local and regional decline of Asian horseshoe crabs has spurred a study on its spawning population at Balok Beach, Kuantan, Pahang, Malaysia. This location was identified as spawning site due to the occurrence of horseshoe crab spawning pairs and nests. Size-frequency, length-weight relationships, sex ratio and epibiont infestation of Tachypleus gigas were studied. Instar stage was estimated based on prosomal width. Condition of the horseshoe crab carapace was reported. Visual search technique of horseshoe crab was conducted during high tide of new and full moons. Prosomal, opisthosomal and telson length and weight of each horseshoe crab were measured. Largest female was recorded with mean prosomal length and width of 154.4 and 246.9 mm, respectively. About 69.8% of the males belonged to size group of 151-200 mm and 53.3% of females were grouped into 201-250 mm. All individuals were of fourteenth to sixteenth instar stages. Sex ratio varied from 0.313 to 2.5 and attributed to commercial harvest and monsoon season. Sand sediment of study site showed 93% of fine sands with grain size ranged from 120 to 250 microm. Acorn and pedunculate barnacle, conical and flat slipper shells were found on the carapace of the specimens. Most males had damaged eyes and carapaces while females with broken telsons. Body damages of about 19.9% on the specimens were likely due to nearby fishing activities. Lack of satellite male indicated low spawning population. The finding of this study showed that the species is extremely threatened by human activities and coastal development.
    Matched MeSH terms: Sex Ratio
  11. Fulltext The Population Size of the Lesser Bandicoot (Bandicota bengalensis) in Three Markets in Penang, Malaysia
    Khairuddin NL, Raghazli R, Sah SA, Shafie NJ, Azman NM
    Trop Life Sci Res, 2011 Dec;22(2):81-92.
    PMID: 24575219 MyJurnal
    A study of the population size of Bandicota bengalensis rats in three markets in Penang was conducted from April 2004 through May 2005. Taman Tun Sardon Market (TTS), Batu Lanchang Market (BTLG) and Bayan Lepas Market (BYNLP) were surveyed. Six sampling sessions were conducted in each market for four consecutive nights per session. The total captures of B. bengalensis in TTS, BTLG and BYNLP were 92%, 73% and 89% respectively. The total population of B. bengalensis in TTS was estimated as 265.4 (with a 95% confidence interval of 180.9-424.2). The total population at BTLG was estimated as 69.9 (with a 95% confidence interval of 35.5-148.9). At BYNLP, the total population was estimated as 134.7 (with a 95% confidence interval of 77.8-278.4). In general, adult male rats were captured most frequently at each site (55.19%), followed by adult females (31.69%), juvenile males (9.84%) and juvenile females (3.27%). The results showed that the number of rats captured at each site differed significantly according to sex ratio and maturity (χ(2) = 121.45, df = 3, p<0.01). Our results suggest that the population sizes found by the study may not represent the actual population size in each market owing to the low numbers of rats recaptured. This finding might have resulted from the variety of foods available in the markets.
    Matched MeSH terms: Sex Ratio
  12. Fulltext Molecular sexing and preliminary assessment of population sex ratio of the endangered Malayan tapir (Tapirus indicus) in Peninsular Malaysia
    Lim QL, Tan YL, Ng WL, Yong CSY, Ismail A, Rovie-Ryan JJ, et al.
    Sci Rep, 2020 03 04;10(1):3973.
    PMID: 32132572 DOI: 10.1038/s41598-020-60552-y
    A molecular sexing method by polymerase chain reaction (PCR) amplification of a portion of the sex-determining region Y (SRY) and the zinc finger (ZF) gene, as well as six equine Y-chromosome-specific microsatellite markers, were tested in the Malayan tapir (Tapirus indicus). While the microsatellite markers did not yield any male-specific amplicons for sex-typing, the SRY/ZF marker system produced reliable molecular sexing results by accurately sex-typing 31 reference Malayan tapirs, using whole blood, dried blood spot (DBS), or tissue samples as materials for DNA extraction. The marker system was also tested on 16 faecal samples, and the results were in general consistent with the pre-determined sexes of the animals, despite some amplification failures. A preliminary estimation of wild Malayan tapir population sex ratio was estimated from the Wildlife Genomic Resource Bank (WGRB) database of the Malaysian Department of Wildlife and National Parks (PERHILITAN), zoos, and the Sungai Dusun Wildlife Conservation Centre (WCC), as well as from the results of molecular sexing 12 samples of unknown sex. The overall sex ratio favoured females, but the deviation from parity was statistically not significant when tested using the binomial test (p > 0.05), which may be due to reduced statistical power caused by small sample sizes.
    Matched MeSH terms: Sex Ratio*
  13. Fulltext Rapidly shifting sex ratio across a species range
    Hornett EA, Charlat S, Wedell N, Jiggins CD, Hurst GD
    Curr Biol, 2009 Oct 13;19(19):1628-31.
    PMID: 19747825 DOI: 10.1016/j.cub.2009.07.071
    Sex ratios are subject to distortion by a range of inherited parasites. Although it has been predicted that the presence of these elements will result in spatial and temporal variation in host sex ratio, testing of this hypothesis has been constrained by availability of historical data. We here determine spatial and temporal variation in sex ratio in a interaction between a butterfly and male-killing Wolbachia bacteria by assaying infection presence in museum specimens, and from this inferring infection prevalence and phenotype in historical populations. Comparison of contemporary and museum samples revealed profound change in four of five populations examined. Two populations become extremely female biased, associated with spread of the male-killer bacterium. One evolved from extremely female biased to a sex ratio near parity, resulting from the infection losing male-killing activity. The final population fluctuated widely in sex ratio, associated with varying frequency of the male killer. We conclude that asynchronous invasion and decline of sex-ratio distorters combines with the evolution of host suppressors to produce a rapidly changing mosaic of sex ratio. As a consequence, the reproductive ecology of the host species is likely to be fundamentally altered over short time scales. Further, the study demonstrates the utility of museum specimens as "silent witnesses" of evolutionary change.
    Matched MeSH terms: Sex Ratio*
  14. Sex ratio, gonad development and fecundity of Miyakella nepa (Crustacea, Stomatopoda) of Pantai Remis coastal waters of Malaysia
    Zamri Z, Arshad A, Amin SMN, Rahman MA, Al Khayat JA
    J Environ Biol, 2016 07;37(4 Spec No):677-83.
    PMID: 28779726
    The sex ratio, gonad development and fecundity of Miyakella nepa (Latreille, 1828), in the coastal waters of Pantai Remis, Perak, were investigated from February 2012 to January 2013. Sex identification was done by identifying stomatopod's genitalia organs, and the ovaries were dissected out and preserved for further analysis. Female stomatopods with mature or near spawning stages were used for fecundity estimation. A total of 951 specimens of M. nepa, with 565 females and 386 males were examined. Results showed a sex ratio of 1:1.46 (male:females). Maximum GSI was estimated to be 5.80, while lowest was 2.95. Sexual maturity for female M. nepa was observed at 100 mm total length. The mean fecundity of M. nepa was 425,657 (? 1,8701) eggs which was observed to increase with increased body length.
    Matched MeSH terms: Sex Ratio
  15. A 2-year prospective study on childhood acute bacterial meningitis in Tengku Ampuan Afzan Hospital, Kuantan, Pahang
    Wahab, J.A., Fadzil, A.A., Zainab, K., Affendi, A.M., Naznin, M.
    Malaysian Journal of Paediatrics and Child Health, 2000;12(1):48-54.
    MyJurnal
    During a 24-month period, 21 children with acute bacterial meningitis were identified and studied. The majority of the children was from low socio-economic group and the male:female sex ratio was equal. Seventeen children (81%) were aged twelve months or below. In 15 (71.5%) of the children. Haemophilus influenzae type b was recovered, while Streptococcus pneumoniae was isolated from 4 children. Neisseria spp and Salmonella spp were identified respectively in each of the other two cases. The case fatality was four (19.0%) with nine others (42%) exhibiting neurological sequelae. Except for the Salmonella spp strain that was resistant to the cephalosporin, the rest of the bacterial species were sensitive to the commonly used antibiotics. As Haemophilus influenzae type b is still the most prevalent cause of acute bacterial meningitis, it is therefore strongly recommended that the national immunisation programme in this country should include the vaccine for it in our effort to minimise the mortality and morbidity caused by this organism.
    Matched MeSH terms: Sex Ratio
  16. Risk factors associated with flea infestation on cats
    Azrizal-Wahid N, Sofian-Azirun M, Low VL
    Trop Biomed, 2019 Dec 01;36(4):810-821.
    PMID: 33597453
    Fleas are the common cause of skin disorders in cats. They are well-known for transmitting various pathogens to both cats and humans. Accordingly, this study was conducted to gain insights on the risk factors associated with flea infestation on cats. Flea combing conducted on 426 cats from four distinct regions in Peninsular Malaysia revealed a relatively high rate of flea infestation on 306 cats (71.83%). A total of 651 fleas were collected, all of them were identified as Ctenocephalides felis with the total intensity of 2.13 and abundance of 1.53. The sex ratio of fleas was female-biased at 2.5:1 (♀=464, ♂=187). Statistical analysis of the data revealed that flea infestation was significantly (P<0.05) associated with several risk factors including region, age, weight, status (stray, sheltered, pet), body condition, and hair length. Higher flea prevalence was also observed in female cats (77.99%), big-sized cats (91.76%), stray cats (84.94%), cats with clean body condition (73.35%), and cats with long hairs (78.38%) as compared to their contemporaries within the same comparison variables. The high infestation of fleas in this study is indicative of cats as a flea reservoir particularly C. felis. Thus the findings of this study and the knowledge gained on the risk factors can be used to develop and improve control measures and management of flea infestations.
    Matched MeSH terms: Sex Ratio
  17. The importance of males: larval diet and adult sugar feeding influences reproduction in Culex molestus
    Kassim NF, Webb CE, Russell RC
    J Am Mosq Control Assoc, 2012 Dec;28(4):312-6.
    PMID: 23393755
    Culex molestus is an obligatory autogenous mosquito that is closely associated with subterranean habitats in urban areas. The objective of our study was to investigate the influence of larval and adult nutrition on the role of males in determining the expression of autogeny in Cx. molestus. Mosquitoes raised at low and high larval diets had sex ratio, wing length, mating rates, autogenous egg raft size, and hatching rates recorded. There was a higher ratio of males to females when raised at a low larval diet. Mean wing lengths of both males and females were significantly greater when raised at the high larval diet regime. Regardless of larval or adult diet, males mated with only a single female. Mosquitoes raised at the higher larval diet regimes developed significantly more autogenous eggs. However, the egg raft size was reduced when adult females were denied access to sugar. The results of this study indicate that the performance of males in the reproductive process is influenced by both larval diet and adult sugar feeding.
    Matched MeSH terms: Sex Ratio
  18. Reproductive parameters over a 37-year period of free-ranging female Borneo orangutans at Sepilok Orangutan Rehabilitation Centre
    Kuze N, Sipangkui S, Malim TP, Bernard H, Ambu LN, Kohshima S
    Primates, 2008 Apr;49(2):126-34.
    PMID: 18297473 DOI: 10.1007/s10329-008-0080-7
    We analysed the reproductive parameters of free-ranging female orangutans at Sepilok Orangutan Rehabilitation Centre (SORC) on Borneo Island, Sabah, Malaysia. Fourteen adult females produced 28 offspring in total between 1967 and 2004. The average censored interbirth interval (IBI) (i.e. offspring was still alive when mother produced a next offspring) was 6 years. This was shorter than censored IBIs reported in the wild but similar to IBIs reported for those in captivity. The nonparametric survival analysis (Kaplan-Meier method) revealed a significantly shorter IBI at SORC compared with wild orangutans in Tanjung Putting. The infant (0-3 years) mortality rate at SORC of 57% was much higher than rates reported both in the wild and captivity. The birth sex-ratio was significantly biassed toward females: 24 of the 27 sex-identified infants were females. The average age at first reproduction was 11.6 years, which is younger than the age in the wild and in captivity. The high infant mortality rate might be caused by human rearing and increased transmission of disease due to frequent proximal encounters with conspecifics around the feeding platforms (FPs). This young age of first reproduction could be because of the uncertainty regarding estimated ages of the female orangutans at SORC. It may also be affected by association with other conspecifics around FPs, which increased the number of encounters of the females with males compared with the number of encounters that would take place in the wild. Provision of FPs, which improves the nutritional condition of the females, caused the shorter IBI. The female-biassed birth sex-ratio can be explained by the Trivers and Willard hypothesis. The female-biassed sex ratio could be caused by the mothers being in poor health, parasite prevalence and/or high social stress (but not food scarcity) due to the frequent encounters with conspecifics around FPs.
    Matched MeSH terms: Sex Ratio
  19. Developmental stages and caste composition of a mature and incipient colony of the drywood termite, Cryptotermes dudleyi (Isoptera: Kalotermitidae)
    Neoh KB, Lee CY
    J Econ Entomol, 2011 Apr;104(2):622-8.
    PMID: 21510214
    The caste composition and sex ratio in a mature and an incipient colony of Cryptotermes dudleyi Banks (Isoptera: Kalotermitidae) was studied. Biometric descriptors of both immature and sexual castes were developed. Morphometric analysis revealed that there are four larval instars, a pseudergate, and three nymphal instars in the development of C. dudleyi. To differentiate between the fourth larval instars and the pseudergate, pronotal width and tibial length must be taken into account, because the head width overlaps between the two groups. The number of antennal segments increases in parallel with instar development. The mature colony was headed by a pair of physogastric nymphoid neotenics; the colony also contained multiple pairs of nonphysogastric de-alates and wing-torn alates. The majority of eggs and larvae were confined to galleries that connected to locations where nymphoid neotenics were found, whereas in general only pseudergates and nymphs were found together with de-alates and wing-torn alates. In contrast, the incipient colony contained only a pair of primary reproductives. Nymphs formed a major group in both mature and incipient colonies, as did pseudergates. The sex ratio of the mature colony was slightly but significantly biased in favor of females, whereas it was skewed toward males in the incipient colony. The data also suggested that the soldier caste was female skewed.
    Matched MeSH terms: Sex Ratio
  20. Novel life-history data for threatened seahorses provide insight into fishery effects
    Lawson JM, Foster SJ, Lim AC, Chong VC, Vincent AC
    J Fish Biol, 2015 Jan;86(1):1-15.
    PMID: 25307290 DOI: 10.1111/jfb.12527
    Life-history variables for three incidentally captured species of seahorse (Kellogg's seahorse Hippocampus kelloggi, the hedgehog seahorse Hippocampus spinosissimus and the three-spot seahorse Hippocampus trimaculatus) were established using specimens obtained from 33 fisheries landing sites in Peninsular Malaysia. When samples were pooled by species across the peninsula, sex ratios were not significantly different from unity, and height and mass relationships were significant for all species. For two of these species, height at physical maturity (HM ) was smaller than the height at which reproductive activity (HR ) commenced: H. spinosissimus (HM = 99·6 mm, HR = 123·2 mm) and H. trimaculatus (HM = 90·5 mm, HR = 121·8 mm). For H. kelloggi, HM could not be estimated as all individuals were physically mature, while HR = 167·4 mm. It appears that all three Hippocampus spp. were, on average, caught before reproducing; height at 50% capture (HC ) was ≥HM but ≤HR . The results from this study probe the effectiveness of assessment techniques for data-poor fisheries that rely heavily on estimates of length at maturity, especially if maturity is poorly defined. Findings also question the sustainability of H. trimaculatus catches in the south-west region of Peninsular Malaysia, where landed specimens had a notably smaller mean height (86·2 mm) and markedly skewed sex ratio (6% males) compared with samples from the south-east and north-west of the peninsula.
    Matched MeSH terms: Sex Ratio
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