Parental Expenditure and Offspring Sex Ratios in the Dioecious Plant Silene alba (= Silene latifolia)

Whilst most animals invest equally in males and females when they reproduce, a variety of vertically transmitted parasites has evolved the ability to distort the offspring sex ratios of their hosts. One such group of parasites are male-killing bacteria. Here we report the discovery of females of the ladybirdAnisosticta novemdecimpunctatathat produced highly female-biased offspring sex ratios associated with a 50% reduction in egg hatch rate. This trait was maternally transmitted with high efficiency, was antibiotic sensitive and was infectious following experimental haemolymph injection. We identified the cause as a male-killingSpiroplasmabacterium and phylogenetic analysis of rDNA revealed that it belongs to theSpiroplasma ixodetisclade in which other sex ratio distorters lie. We tested the potential for interspecific horizontal transfer by injection from an infectedA. novemdecimpunctataline into uninfected individuals of the two-spot ladybirdAdalia bipunctata. In this novel host, the bacterium was able to establish infection, transmit vertically and kill male embryos.

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Evidence that mammalian sex ratios at birth are partially controlled by parental hormone levels around the time of conception

Journal of Endocrinology ◽

10.1677/joe-07-0446 ◽

2007 ◽

Vol 198 (1) ◽

pp. 3-15 ◽

Cited By ~ 102

Author(s):

William H James

Keyword(s):

Sex Ratios ◽

Hormone Levels ◽

Offspring Sex ◽

Almost All

An attempt is made to summarize the evidence that the offspring sex ratios (proportions male at birth) of mammals (including man) are causally related to the hormone levels of both parents around the time of conception. Almost all of the cited studies were reported by non-endocrinologists. This being so, it would seem desirable to have comments of endocrinologists on this topic. The purpose of this article is to elicit such comment. Readers are requested to read the accompanying editorial (Clark & Davis 2008) to gain a better perspective of this hypothesis article.

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A Multinomial Model of Fertility Choice and Offspring Sex Ratios in India

The Journal of Development Studies ◽

10.1080/00220380903012755 ◽

2010 ◽

Vol 46 (3) ◽

pp. 417-438 ◽

Cited By ~ 4

Author(s):

Rubiana Chamarbagwala ◽

Martin Ranger

Keyword(s):

Sex Ratios ◽

Multinomial Model ◽

Fertility Choice ◽

Offspring Sex

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Analysis of BAC clones containing homologous sequences on the end of the Xq arm and on chromosome 7 in the dioecious plant Silene latifolia

Genome ◽

10.1139/g10-008 ◽

2010 ◽

Vol 53 (4) ◽

pp. 311-320 ◽

Cited By ~ 4

Author(s):

Kotaro Ishii ◽

Yasuhito Amanai ◽

Yusuke Kazama ◽

Miho Ikeda ◽

Hiroshi Kamada ◽

...

Keyword(s):

Satellite Dna ◽

Sex Chromosome ◽

Artificial Chromosome ◽

Chromosome 7 ◽

Silene Latifolia ◽

Dioecious Plant ◽

Homologous Sequences ◽

Autosomal Region ◽

Single Primer

Silene latifolia is a model dioecious plant with morphologically distinguishable XY sex chromosomes. The end of the Xq arm is quite different from that of the Yp arm, although both are located at opposite ends of their respective chromosomes relative to a pseudo-autosomal region. The Xq arm does not seem to originate from the same autosome as the Yp arm. Bacterial artificial chromosome clone #15B12 has an insert containing a 130-kb stretch in which a 313-bp satellite DNA is repeated 420 times. PCR with a single primer revealed that this 130-kb stretch consists of three reversals of the orientation of the satellite DNA. A non-long terminal repeat retroelement and two sequences that share homology with an Oryza sativa RING zinc finger and a putative Arabidopsis thaliana protein, respectively, were found in the sequences that flank the satellite DNA. Fluorescence in situ hybridization carried out using this low-copy region of #15B12 as a probe confirmed that these sequences originated from the X chromosome and that homologous sequences exist at the end of chromosome 7. The region distal to DD44X on the Xq arm is postulated to have recombined with a region containing satellite DNA on chromosome 7 during the process of sex chromosome evolution.

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