Territory quality affects female preference in a Lake Victoria cichlid fish

Mate preferences on male colour have been implicated in generating and maintaining species diversity among haplochromine cichlid fish. Their lek-like mating system suggests that not only male colour but also territory quality is instrumental in mate choice. We assessed the relative importance of territory quality and male colour in mate choice by testing whether territory quality can override the female preference for males of her own colour in the Lake Victoria cichlid genus Pundamilia. First, we showed in experimental groups that the dominant male preferentially monopolised a large tube relative to a small tube. The situation mimics quality difference in rocky crevices that serves as a focal point for male courtship display. Second, in mate-choice tests, Pundamilia nyererei females were allowed to choose between closely related P. nyererei and P. pundamilia males; these species differ strikingly in male nuptial coloration, but little else. We gave either both males the same small tube or one of them a large tube. The preference of P. nyererei females for P. nyererei males in the control situation (where both males had a small tube) was significantly diminished in favour of P. pundamilia males when the latter had the large tube. The results provide experimental evidence that differences in territory quality can override the female preference for males of her own colour. This finding is critical for a recent hypothesis proposing that male competition for mating territories can facilitate the process of sympatric speciation by sexual selection.     

Why male orangutans do not kill infants

Infanticide is widespread among mammals, is particularly common in primates, and has been shown to be an adaptive male strategy under certain conditions. Although no infanticides in wild orangutans have been reported to date, several authors have suggested that infanticide has been an important selection pressure influencing orangutan behavior and the evolution of orangutan social systems. In this paper, we critically assess this suggestion. We begin by investigating whether wild orangutans have been studied for a sufficiently long period that we might reasonably expect to have detected infanticide if it occurs. We consider whether orangutan females exhibit counterstrategies typically employed by other mammalian females. We also assess the hypothesis that orangutan females form special bonds with particular “protector males” to guard against infanticide. Lastly, we discuss socioecological reasons why orangutan males may not benefit from infanticide. We conclude that there is limited evidence for female counterstrategies and little support for the protector male hypothesis. Aspects of orangutan paternity certainty, lactational amenorrhea, and ranging behavior may explain why infanticide is not a strategy regularly employed by orangutan males on Sumatra or Borneo.     

微纳尺度SiO2对雄性大鼠生殖功能损伤的实验研究

为了探讨纳米与微米尺度SiO2对雄性大鼠的生殖毒性作用,选择不同剂量的纳米SiO2(20～40nm)与微米SiO2(1～10μm)采用气管滴注方式对雄性Wistar大鼠分组染毒.于染毒5周后处死大鼠,检查附睾精子形态,并检测睾丸组织和血清中睾丸功能标志酶活性变化以及性激素含量的变化.结果表明:1)高、低剂量的纳米和微米SiO2染毒均可使大鼠发生程度不同的精子数量减少、精子活动率降低、精子畸形率升高;2)纳米SiO2染毒可使大鼠睾丸组织SDH、LDH和血清中ACP活性显著降低,而微米SiO2染毒对这些指标的影响不显著;3)纳米SiO2和高剂量微米SiO2染毒可使大鼠血清T和睾丸匀浆T浓度显著降低,而对血清LH没有显著影响;4)与微米SiO2相比,纳米SiO2对大鼠生殖功能的损伤有更严重的趋势,但相同剂量下,纳米SiO2和微米SiO2相比,各指标均无显著性差异.以上结果表明,微米和纳米尺度SiO2染毒均可使大鼠生殖功能产生损伤,使部分生殖功能指标发生显著变化;与微米SiO2相比,纳米SiO2对大鼠生殖功能的损伤有更严重的趋势.     

Remote Forest Refugia for Fijian Wildlife

Abstract:  On Pacific islands non-native rats and mongooses threaten many native species. In Fiji we compared visitation rates of rats and mongooses at bait stations and measured biomass of leaf-litter invertebrates to assess the relative predation pressure from these species in forest areas at different distances from the forest edge. Forest areas over 5 km from the forest edge had significantly fewer baits encountered by rats or mongooses than did natural forest areas nearer agricultural and urban habitats. Remote forest areas may function as a last refuge for island species threatened by predation from non-native rats and mongooses. The biomass of leaf-litter invertebrates in remote forest areas was higher, indicating a refuge effect for some taxa targeted by rats and mongooses. Protection of the few remaining large blocks of natural forests on Pacific islands may be the most cost-effective approach for conserving many island endemics threatened by rats and mongooses. Logging roads can compromise this refuge effect by acting as dispersal routes for rats into natural forests.     

Physiological Rearrangements in the Progeny of White Rats in the Zone of the Chernobyl Accident

Studies on six generations of white rats kept at the experimental station in Chernobyl showed that the dynamics of hormonal rearrangements and endocrine responses evoked by additional stress (hypokinesia) were generation- and sex-dependent. The male rats of the first five generations were characterized by hypercorticoidism, early involutional shifts, and decreased reactivity in response to hypokinesia. By the sixth and seventh generations, the hormonal profiles shifted toward an increase in the background level of sex hormones and their role in the response to hypokinesia. In female rats, the hormonal indices and reactivity changed less significantly.     

Effects of sub‐chronic low‐level dietary intake of chlordane on rats with cirrhosis of the liver.

Abstract

Male rats, 60 days old, were treated with chlordane during or after induction of liver cirrhosis with carbon tetrachloride to determine the effect of treatment with chlordane on the response of the rats to the disease. When liver cirrhosis was induced simultaneously with chlordane treatment the disease symptoms were aggravated; the lipid content of the tissue was lowered significantly, growth rate was significantly lower than controls and there was no apparent replacement of damaged liver tissue by liver growth. The cytochrome P₄₅₀ content of the liver was similar after both treatments. Continuation of the chlordane treatment after termination of the carbon tetrachloride treatment brought about a more rapid recovery from the induced cirrhotic condition. All these responses were to a dose range one tenth the recommended “no effect”; level for healthy animals.     

Male Mutation Bias and Possible Long‐Term Effects of Human Activities

Abstract: The ability of a population to adapt to changing environments depends critically on the amount and kind of genetic variability it possesses. Mutations are an important source of new genetic variability and may lead to new adaptations, especially if the population size is large. Mutation rates are extremely variable between and within species, and males usually have higher mutation rates as a result of elevated rates of male germ cell division. This male bias affects the overall mutation rate. We examined the factors that influence male mutation bias, and focused on the effects of classical life‐history parameters, such as the average age at reproduction and elevated rates of sperm production in response to sexual selection and sperm competition. We argue that human‐induced changes in age at reproduction or in sexual selection will affect male mutation biases and hence overall mutation rates. Depending on the effective population size, these changes are likely to influence the long‐term persistence of a population.     

The subchronic toxicity of acridine in the rat

Abstract

The subchronic toxicity of acridine was investigated in rats following dietary exposure at 0, 1, 10, 100 and 500 ppm for 13 weeks. The growth rate and food consumption were not affected by treatment and no clinical signs of toxicity were observed. There was a slight but significant decrease in spleen weight, both in absolute terms and as a percent of body weight, in the 500 ppm males and a slight increase in absolute thymus weight in the females of the same dose group. Both hepatic ethoxyresorufin O‐deethylase (EROD) and pentoxyresorufin O‐dealkylase (PROD) activities were slightly, but significantly, elevated in females in the 500 ppm dose group. No haematological or other biochemical changes were observed. Females also displayed dose‐related increases in inorganic phosphate and uric acid levels. Treatment‐related histopathological changes were seen in the thyroid, liver and kidney and included hepatic anisokaryosis and vesiculation of nuclei and glomerular adhesions, reticulin sclerosis and nuclear pyknosis in the kidney. Residue data showed a dose‐dependent accumulation of acridine in liver, kidney and adipose with the highest concentration being found in the fat of the 500 ppm dose group. Based on these data, the no observable adverse effect level of acridine was judged to be 100 ppm or 12 mg/kg bw/day.     

Detecting points as developmental delay based on the life-history development and urosome deformity of the harpacticoid copepod, Tigriopus japonicus sensu lato, following exposure to benzo(a)pyrene

To identify ecotoxicological responses to an endocrine disrupter, benzo(a)pyrene, we examined the life-history of the harpacticoid copepod, Tigriopus japonicus sensu lato. Based on the life-history of copepods, survival rate of nauplii (NSR) and copepodites (CSR), copepodite emergence day (CED) and adult male emergence day (AMED), sex ratio (MER), brooding success rate (BSR), and first brooding day of adult females (FBD) were measured. Significant differences were observed in the survival and development of nauplii (NSR and CED) and sex ratio (MER) of exposed and non-exposed copepods. Moreover, high concentration of BaP can be lethal to copepodite and exhibited a delay of growth. In this study, the CED and AMED among ecotoxicological response based on life-history developments were delayed and the body characteristics decreased in response to exposure to benzo(a)pyrene. The dwarfism and urosome deformity of the T. japonicus s.l. was exhibited in response to chemical exposure. Specifically, the body characteristics and biomass of dwarf copepods that had been exposed to benzo(a)pyrene were 30% and 50% lower than the control group, respectively. The incidence of abnormal urosomes was divided into two types. The first deformity type was signs of shrinkage in the middle of the urosome or the entire urosome was narrower than those of the control organisms. In the second type, the anal somite and the distal side of the urosome had abnormally swelled. Taken together, the nauplii and copepodid development of T. japonicus s.l. can be used as a useful biomaker for detecting developmental delay based on their entire life-history. In addition, the urosome deformity was used a good potential monitoring tool invading various chemicals and environmental contamination into water system.     

原尾蜥虎(Hemidactylus bowringii)雄性生殖周期的研究

对福州产的原尾蜥虎（Ｈｅｍｉｄａｃｔｙｌｕｓｂｏｗｒｉｎｇｉｉ） 雄性生殖周期的研究结果表明：１０ 月份精子发生开始新的周期性复生，精原细胞发育进入增殖期，中旬曲细精管除精原细胞外尚有较多的初级精母细胞；１１ 月初已有较多的精细胞，曲细精管管腔中开始出现少量的精子；１２ 月份，生精活动非常活跃，输精管始见有成熟的精子，１２ 月下旬进入冬眠期，成熟的精子释放到输精管中过冬，冬眠期间生精活动趋于停滞，表现为曲细精管管径和生精上皮厚度都有所下降；次年３ 月底４ 月初陆续出蛰，生精活动又恢复并逐渐增强，４、５ 月份精子发生相当活跃，６ 月份是精子发生的高峰期，也是交配繁殖的高峰期；原尾蜥虎一年只繁殖一次，繁殖期过后，７ ～９ 月份，生精活动逐渐减弱，曲细精管的管腔逐渐消失，初级、次级精母细胞、精细胞逐渐减少、退化，精子逐渐退化、消失，到９ 月下旬曲细精管和输精管都见不到精子，此时的曲细精管主要由精原细胞组成，一个周期到此结束．