Using FTA® cards to store avian blood samples for genetic studies. Their application in sex determination

FTA® cards were used for long‐term storage of avian blood samples. Blood DNA was extracted by a simple method and used in PCR for sex identification of adult and nestling Great Grey Shrikes Lanius excubitor.     

Macaca thibetana at Mt. Emei,China: III. Group composition

Data on group composition at the end of the 1986 birth season were collected from six groups of Macaca thibetana. All adult males, the members of group A, and some conspicuous animals were recognized individually. Fourhundred survey sessions were completed. The mean group size was 38.3 (SD = 13.8, range: 28–65); the number of adult females was the best correlate of total group size. The mean adult sex ratio (F:M) across groups was 3:1 (SD = 1.9, range: 1.5–6.5:1), which significantly deviated from 1:1. Sex ratios (F:M) in newborns, juveniles, and all members did not significantly deviate from 1. The ratio of immature animals to adults was 1.5 to 1 (average of groups); that is, 60% of the population was composed of immature animals, and the population was growing.     

Understanding plant reproductive diversity

Flowering plants display spectacular floral diversity and a bewildering array of reproductive adaptations that promote mating, particularly outbreeding. A striking feature of this diversity is that related species often differ in pollination and mating systems, and intraspecific variation in sexual traits is not unusual, especially among herbaceous plants. This variation provides opportunities for evolutionary biologists to link micro-evolutionary processes to the macro-evolutionary patterns that are evident within lineages. Here, I provide some personal reflections on recent progress in our understanding of the ecology and evolution of plant reproductive diversity. I begin with a brief historical sketch of the major developments in this field and then focus on three of the most significant evolutionary transitions in the reproductive biology of flowering plants: the pathway from outcrossing to predominant self-fertilization, the origin of separate sexes (females and males) from hermaphroditism and the shift from animal pollination to wind pollination. For each evolutionary transition, I consider what we have discovered and some of the problems that still remain unsolved. I conclude by discussing how new approaches might influence future research in plant reproductive biology.     

Recombination and the immortality of the germ line

Asexual populations irreversibly accumulate mildly deleterious mutations through the occasional stochastic loss of their least-loaded line, a process known as “Muller's Ratchet”. This paper explores the dynamics of this process, and the role of recombination in halting the Ratchet. Simulation studies show that an optimal class comprising n_o individuals is lost in about 10n_o generations, implying that adaptedness may deteriorate rather rapidly in geological time. Asexual organisms will persist only if they are very numerous, or if they have very small genomes, or if there is extensive negative interaction among nonallelic mutations. Otherwise, long-term persistence requires that unloaded genomes be continually generated by recombination. An approximate expression for the rate of recombination needed to halt the Ratchet is developed, and shows that substantial recombination is necessary in populations of fewer than about 10¹⁰ individuals. A further complication is introduced by mutations in sequences which specify proofreading enzymes. Since these will reduce the fidelity of their own replication, a process of positive feedback leading to an ever-accelerating loss of function is conceivable.     

The spatial arrangement of germ line cells in ovarian follicles of the mutantdicephalic inDrosophila melanogaster

Summary The pattern of intercellular connections between germ line cells has been studied in follicles of the mutantdicephalic (dic), which possess nurse cell clusters at both poles. Staining of follicles with a fluorescent rhodamine conjugate of phalloidin reveals ring canals and cell membranes and thus allows us to reconstruct the spatial organization of the follicle. Each germ line cell can be identified by the pattern of cell-cell connections which reflect the mitotic history of individual cells in the 16-cell cluster. The results indicate that in both wild-type anddicephalic cystocyte clusters one of the two cells with four ring canals normally becomes the pro-oocyte. However, in some follicles (dicephalic and wild-type) oocytes were found with fewer or more than four ring canals. Indic follicles, one or several nurse cells may become disconnected from the other cells during oocyte growth at stage 9–10. Such disconnected cells cannot later on empty their cytoplasm into the oocyte. This, in turn, might be of consequence for the determination of axial polarity of the embryo.     

Phenotypic variability in nesting success among Osmia lignaria propinqua females in a glasshouse environment: (Hymenoptera: Megachilidae)

Abstract. 1. The phenotypic variability of several estimates of fitness among seventeen nesting female O.lignaria Cresson was examined in a glasshouse provided with abundant resources.
2. Females exhibited wide variation in: (a) number of nests and cells made and in their rate of construction, (b) the incidence of mortality of offspring, and (c) the percentage of male offspring produced (52–100%).
3. In confirmation of earlier field studies: (a) more offspring of both sexes were produced during the first half of the nesting season, (b) most female offspring were produced early in the nesting season, (c) most parental investment during the last half of the flight season was made in male offspring, (d) there was a decrease in offspring size with season, with females decreasing more than males, and (e) the ratio of female/male body weight was = 1.8. These results appear to be due to ageing rather than to a reduction in resource availability.
4. No relation between female size and fecundity was evident.
5. There was no evidence that small females tended to produce a greater proportion of the smaller sex (males) than did large females.
6. Smaller offspring of both sexes had a much greater probability of dying overwinter than did large offspring. However, where the sexes overlapped in size (large males, small females), almost all females died and almost all males survived. We hypothesize that as size of offspring produced declines with season, a greater proportion of males are produced because they have a much greater probability of surviving at small body sizes.     

Isolation of phosphorylated polysaccharides from algae: the immunostimulatory principle of Chlorella pyrenoidosa

The major immunostimulatory principle in the hot aqueous extract of Chlorella pyrenoidosa has been isolated by a sequence of ethanol precipitation, precipitation with a cationic surfactant (CTAB), size exclusion chromatography, and anion exchange chromatography. A series of phosphorylated polysaccharides were obtained having different molecular masses but with similar structures. The higher molecular mass fractions showed considerable activity in the stimulation of mouse peritoneal macrophages to synthesize nitric oxide. The structure of the major polysaccharide was established by sugar analysis, configurational analysis, and 1D and 2D NMR experiments at 500 and 800 MHz on the parent polysaccharide, the de-O-acetylated polysaccharide, and on the components obtained after hydrolysis of the phosphate diesters. It had a β-d-Galp-(1→3)-β-d-Galp-(1→3)-backbone with half of the Galp units substituted at O-6 by terminal β-d-Glcp units. The remaining Galp units were substituted on O-6 by about equal amounts of α-d-Manp-1-phosphate and 3-O-Me-α-Manp-1-phosphate diesters. The substituents were not located in a regularly alternating fashion on the backbone. The O-acetyl groups were largely located on O-2 and O-4 of Galp and 35% of the Galp residues were O-acetylated. This is the second observation of a phosphorylated polysaccharide in an alga and the first where it is present to a significant extent.     

Sex ratios under asymmetrical local mate competition in the parasitoid wasp Nasonia vitripennis

Sex ratio theory has proved remarkably useful in testing theadaptive nature of animal behavior. A particularly productivearea in this respect is Hamilton's theory of local mate competition(LMC), which has been extended in numerous directions to includegreater biological realism, allowing more detailed tests inspecific organisms. We have presented one such extension, termedasymmetrical LMC, which occurs when egg laying by females ona patch is asynchronous, and emerging males do not disperse,resulting in the extent of LMC on a patch varying over time.Our aim here is to test whether the parasitoid wasp Nasoniavitripennis responds to variation in the degree of asymmetricalLMC. Specifically, we show that females adjust their offspringsex ratios in response to (1) variation in the amount of asynchronyin emergence between broods on a patch and (2) the number andproportion of previously parasitized hosts on the patch. Ourresults provide qualitative support for the predictions of theory,suggesting new levels of complexity in the sex ratio behaviorof this much-studied organism. However, our results do not alwaysprovide quantitative support for theory, suggesting furthercomplexities that must be clarified.     

Demographic population structure of black howler monkeys in fragmented and continuous forest in Chiapas,Mexico: Implications for conservation

For wild primates, demography studies are increasingly recognized as necessary for assessing the viability of vulnerable populations experiencing rapid environmental change. In particular, anthropogenic changes such as habitat loss and fragmentation can cause ecological and behavioral changes in small, isolated populations, which may, over time, alter population density and demographic structure (age/sex classes and group composition) in fragment populations relative to continuous forest populations. We compared our study population of Endangered black howler monkeys (Alouatta pigra) in 34 forest fragments around Palenque National Park (PNP), Mexico (62 groups, 407 individuals), to the adjacent population in PNP, protected primary forest (21 groups, 134 individuals), and to previous research on black howlers in fragments in our study area (18 groups, 115 individuals). We used χ² and Mann–Whitney U tests to address the questions: (a) what is the current black howler demographic population structure in unprotected forest fragments around PNP? (b) How does it compare to PNP's stable, continuous population? (c) How has it changed over time? Compared to the PNP population, the fragment populations showed higher density, a significantly lower proportion of multimale groups, and significantly fewer adult males per group. The population's age/sex structure in the fragmented landscape has been stable over the last 17 years, but differed in a higher proportion of multifemale groups, higher density, and higher patch occupancy in the present. In the context of conservation, some of our results may be positive as they indicate possible population growth over time. However, long-term scarcity of adult males in fragments and associated effects on population demographic structure might be cause for concern, in that it may affect gene flow and genetic diversity. The scarcity of adult males might stem from males experiencing increased mortality while dispersing in the fragmented landscape, whereas females might be becoming more philopatric in fragments.