Parent–offspring conflict and selection on egg size in turtles

The trade‐off between offspring size and number can present a conflict between parents and their offspring. Because egg size is constrained by clutch size, the optimal egg size for offspring fitness may not always be equivalent to that which maximizes parental fitness. We evaluated selection on egg size in three turtle species (Apalone mutica, Chelydra serpentina and Chrysemys picta) to determine if optimal egg sizes differ between offspring and their mothers. Although hatching success was generally greater for larger eggs, the strength and form of selection varied. In most cases, the egg size that maximized offspring fitness was greater than that which maximized maternal fitness. Consistent with optimality theory, mean egg sizes in the populations were more similar to the egg sizes that maximized maternal fitness, rather than offspring fitness. These results provide evidence that selection has maximized maternal fitness to achieve an optimal balance between egg size and number.     

Phylogeny of the Eurasian freshwater turtles of the genus Mauremys Gray 1869 (Testudines), with special reference to a close affinity of Mauremys japonica with Chinemys reevesii

Phylogenetic relationships of the freshwater turtles of the genus Mauremys and representatives of several other batagurid genera were inferred from variations in 863 base positions of mitochondrial 12S and 16S rRNA genes. Results strongly suggested the non-monophyly of Mauremys by indicating the closest affinity of Mauremys japonica with Chinemys reevesii , the type species of the genus Chinemys . Recent morphological analyses of the batagurid genera suggested that Mauremys is a basal stock of the subfamily Geoemydinae, whereas Chinemys is a member of the subfamily Batagurinae as supported by several putative synapomorphs with other batagurine genera. It is thus probable that the morphological character states used to define Mauremys actually represent symplesiomorphy, and that morphological character states shared between Chinemys and other batagurine genera have resulted from convergence. Also, our results did not support a sister-group relationship between Mauremys annamensis and Mauremys mutica , which has been implicitly or explicitly assumed by a number of previous authors on the basis of morphological data. Instead, M. annamensis was indicated to be closest to Mauremys i versoni , a species assumed to be most divergent among the East Asian Mauremys by previous authors.     

黄喉拟水龟的繁殖生物学研究

1998年4-11月对黄喉拟水龟的繁殖生物学进行了研究,在广东,黄喉拟水龟的产卵高峰期在5-6月,窝卵量1-7枚,平均2.5枚;卵重平均13.95g;长径平均4.34cm;短径平均2.23cm。卵重与卵长径呈正相关关系,在25-32℃、沙床含水量5-10%孵化条件下,孵化时间平衡73.8d,孵化率84.2%。初生稚龟均重9.75g。背甲长平均3.77cm;背甲宽平均2.91cm。稚龟体重与背甲长、宽呈极显著的正相关关系,稚龟经8-11月3个月生长,平均日增重0.149g。稚龟体重、背甲长、宽与日龄呈极显著的正相关关系。稚龟体重与背甲长宽也呈极显著的正相关关系。     

White pulp compartments in the spleen of the turtle Mauremys caspica

Summary The aim of the present study was to analyze the nature of lymphoid and non-lymphoid cellular components occurring in distinct histological compartments of the splenic white pulp of the turtle, Mauremys caspica, in order to define their possible correlations with those of the spleen of higher vertebrates, principally mammals. The white pulp of M.caspica consisted of 3 clearly distinguishable regions: (1) the periateriolar lymphoid sheath, and (2) the inner and (3) the outer zones of the periellipsoidal lymphoid sheath. Reticular cells intimately associated with reticular fibres constituted an extensive meshwork in the periarteriolar lymphoid sheath which housed principally Ig-negative lyphoid cells, mature and immature plasma cells, and interdigitating cells. A few Ig-positive cells were also present in the peripheral region of the periarteriolar lymphoid sheath. The inner and outer zones of the periellipsoidal lymphoid sheath were separated by a discontinuous layer of reticular cell processes. In the inner zone, surface Ig-positive lymphoid cells predominated as well as dendritic cells, resembling ultrastructurally the mammalian follicular dendritic cells, although no germinal centres were found in the turtle spleen. Macrophages, some cytoplasmic Ig-positive cells, and Ig-negative lymphoid cells appeared in the outer zone of the periellipsoidal lymphoid sheath. These results allow us to speculate on a phylogenetic relationship between the periarteriolar lymphoid sheath and the inner and the outer zones of the periellipsoidal lymphoid sheath of the spleen of M. caspica and the periarteriolar lymphoid tissue, the lymphoid follicles and the marginal zone, respectively, of the mammalian splenic white pulp.     

Assessing reliability of microsatellite genotypes from kit fox faecal samples using genetic and GIS analyses

Noninvasive faecal DNA sampling has the potential to provide a wealth of information necessary for monitoring and managing endangered species while eliminating the need to capture, handle or observe rare individuals. However, scoring problems, and subsequent genotyping errors, associated with this monitoring method remain a great concern as they can lead to misidentification of individuals and biased estimates. We examined a kit fox scat data set (353 scats; 80 genotypes) for genotyping errors using both genetic and GIS analyses, and evaluated the feasibility of combining both approaches to assess reliability of the faecal DNA results. We further checked the appropriateness of using faecal genotypes to study kit fox populations by describing information about foxes that we could deduce from the 'acceptable' scat genotypes, and comparing it to information gathered with traditional field techniques. Overall, genetic tests indicated that our data set had a low rate of genotyping error. Furthermore, examination of distributions of scat locations confirmed our data set was relatively error free. We found that analysing information on sex primer consistency and scat locations provided a useful assessment of scat genotype error, and greatly limited the amount of additional laboratory work that was needed to identify potentially 'false' scores. 'Acceptable' scat genotypes revealed information on sex ratio, relatedness, fox movement patterns, latrine use, and size of home range. Results from genetic and field data were consistent, supporting the conclusion that our data set had a very low rate of genotyping error and that this noninvasive method is a reliable approach for monitoring kit foxes.     

不同蛋白质水平的饵料对黄喉拟水龟生长影响的研究

依据单因子梯度设计原理,采用进口鱼粉、豆粕为主要蛋白源制成蛋白质含量分别为50.2%、47.3%、44.3%和41.4%共4种试验饵料,研究不同蛋白质水平饵料对黄喉拟水龟生长的影响.结果 表明,经过120 d对80只黄喉拟水龟幼龟的饲养,当饵料的蛋白质含量为47.3%时,黄喉拟水龟的生长速度最快,均显著高于其他3个组(P<0.05);蛋白质效率最高,极显著高于50.2%组(P<0.01),也分别显著高于44.3%组和41.4%组(P<0.05);耗料增重比最低,分别极显著低于44.3%组和50.2%组(P<0.01),也显著低于41.4%组(P<0.05).但不同蛋白质水平的饵料对黄喉拟水龟龟体蛋白质含量没有明显的影响(P>0.05).     

Competition between three Chihuahuan desert species: evidence from plant size-distance relations and root distribution

Abstract. Using size-distance data we tested the intensity and importance of competition between Hilaria mutica (a tussock grass), Larrea tridentata (a microphyllous shrub) and Opuntia rastrera (a succulent) in the Chihuahuan desert. We also compared the vertical and horizontal distribution of roots to assess the potential degree of overlap in the use of soil resources. The relationships between sizes and distances of nearest-neighbour plants suggested that intraspecific competition is generally more important than interspecific competition. However, evidence of stronger inter than intraspecific competition was found in some cases. Species combinations showing significant interspecific competition involved always Opuntia, whereas Larrea and Hilaria did not influence each other. The analysis of the symmetry of competition showed that Opuntia was adversely affected by the presence of Hilaria or Larrea. Although differences were found in the distribution of roots, the results of the size-distance study support the idea that, (particularly) Opuntia, below-ground niche differentiation is not sufficiently important to totally avoid the negative effects of plant competition.