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1.  Transgenerational effects of food availability on age at maturity and reproductive output in an asexual collembolan species 
Biology Letters  2011;7(5):755-758.
Transgenerational effects of environmental conditions can have several important ecological and evolutionary implications. We conducted a fully factorial experiment manipulating food availability across three generations in the collembolan Folsomia candida, a springtail species that inhabits soil and leaf litter environments which vary in resource availability. Maternal and grandmaternal food availability influenced age at maturity and reproductive output. These effects appear to be cumulative rather than adaptive transgenerational life-history adjustments. Such cumulative effects can profoundly influence eco-evolutionary dynamics in both stable and fluctuating environments.
doi:10.1098/rsbl.2011.0139
PMCID: PMC3169046  PMID: 21411448
maternal effect; adaptive plasticity; resource variability
3.  Free radicals run in lizard families 
Biology Letters  2008;4(2):186-188.
In the ageing individual, the production of reactive oxygen species (ROS) accelerates with cell senescence. Depending on the heritability of the underlying processes that determine net ROS levels, this may influence ageing per se and its evolutionary direction and rate of change. In order to understand the inheritance and evolution of net ROS levels in free-ranging lizards, we used flow cytometry together with ROS-sensitive fluorogenic probes to measure ROS in lizard blood cells. We measured basal levels of (i) non-specific ROS (superoxide, singlet oxygen, H2O2 and peroxynitrite), (ii) superoxide specifically and (iii) superoxide after CCCP treatment, which elevated ROS production in the mitochondria. The cumulative level of non-specific ROS was higher in adults than juveniles and superoxide level showed high heritability and variability among families. We suggest that the evolution of ROS dynamics may be ROS species specific and perhaps depend on the relative degree of uni- or biparental inheritance of ROS main regulatory pathways.
doi:10.1098/rsbl.2007.0611
PMCID: PMC2429935  PMID: 18211861
reactive oxygen species; mitochondrial inheritance; heritability
4.  Sons are made from old stores: sperm storage effects on sex ratio in a lizard 
Biology Letters  2007;3(5):491-493.
Sperm storage is a widespread phenomenon across taxa and mating systems but its consequences for central fitness parameters, such as sex ratios, has rarely been investigated. In Australian painted dragon lizards (Ctenophorus pictus), we describe elsewhere that male reproductive success via sperm competition is largely an effect of sperm storage. That is, sperm being stored in the female reproductive tract out-compete more recently inseminated sperm in subsequent ovarian cycles. Here we look at the consequences of such sperm storage for sex allocation in the same species, which has genetic sex determination. We show that stored sperm have a 23% higher probability of producing sons than daughters. Thus, shifts in sex ratio, for example over the reproductive season, can partly be explained by different survival of son-producing sperm or some unidentified female mechanism taking effect during prolonged storage.
doi:10.1098/rsbl.2007.0196
PMCID: PMC2391176  PMID: 17650477
sperm storage; sex ratios; lizard
5.  Consistent sex ratio bias of individual female dragon lizards 
Biology Letters  2006;2(4):569-572.
Sex ratio evolution relies on genetic variation in either the phenotypic traits that influence sex ratios or sex-determining mechanisms. However, consistent variation among females in offspring sex ratio is rarely investigated. Here, we show that female painted dragons (Ctenophorus pictus) have highly repeatable sex ratios among clutches within years. A consistent effect of female identity could represent stable phenotypic differences among females or genetic variation in sex-determining mechanisms. Sex ratios were not correlated with female size, body condition or coloration. Furthermore, sex ratios were not influenced by incubation temperature. However, the variation among females resulted in female-biased mean population sex ratios at hatching both within and among years.
doi:10.1098/rsbl.2006.0526
PMCID: PMC1834013  PMID: 17148290
sex ratio; sex allocation; TSD; Ctenophorus pictus
6.  Differential sex allocation in sand lizards: bright males induce daughter production in a species with heteromorphic sex chromosomes 
Biology Letters  2005;1(3):378-380.
In sand lizards (Lacerta agilis), males with more and brighter nuptial coloration also have more DNA fragments visualized in restriction fragment length polymorphism analysis of their major histocompatibility complex class I loci (and, hence, are probably more heterozygous at these loci). Such males produce more viable offspring, with a particularly strong viability effect on daughters. This suggests that females should adjust both their reproductive investment and offspring sex ratio in relation to male coloration (i.e. differential allocation). Our results show that experimental manipulation of partner coloration in the wild results in significantly higher maternal effort and a 10% higher proportion of daughters than sons. This supports the hypothesis that females increase their maternal energetic expenditure and adjust their offspring sex ratio in response to high-quality partners. However, it also suggests that this has probably evolved through natural selection for increased offspring viability (primarily through production of daughters), rather than through increased mate attraction (e.g. sexy sons).
doi:10.1098/rsbl.2005.0327
PMCID: PMC1617163  PMID: 17148211
sex allocation; maternal allocation; male attractiveness; major histocompatibility complex; heteromorphic sex chromosomes

Results 1-6 (6)