scholarly journals Host and symbiont genetic contributions to fitness in a Trichogramma–Wolbachia symbiosis

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4655 ◽  
Author(s):  
James E. Russell ◽  
Leonard Nunney ◽  
Michael Saum ◽  
Richard Stouthamer

The fitness effects associated with Wolbachia infection have wide-ranging ecological and evolutionary consequences for host species. How these effects are modulated by the relative influence of host and Wolbachia genomes has been described as a balancing act of genomic cooperation and conflict. For vertically transmitted symbionts, like cytoplasmic Wolbachia, concordant host–symbiont fitness interests would seem to select for genomic cooperation. However, Wolbachia’s ability to manipulate host reproductive systems and distort offspring sex ratios presents an evolutionary conflict of interest with infected hosts. In the parthenogenesis-inducing (PI) form of Wolbachia found in many haplodiploid insects, Wolbachia fitness is realized through females and is enhanced by their feminization of male embryos and subsequent parthenogenetic reproduction. In contrast, as long as Wolbachia is not fixed in a population and sexual reproduction persists, fitness for the host species is realized through both male and female offspring production. How these cooperating and competing interests interact and the relative influence of host and Wolbachia genomes were investigated in the egg parasitoid Trichogramma kaykai, where Wolbachia infection has remained at a low frequency in the field. A factorial design in which laboratory cultures of Wolbachia-infected T. kaykai were cured and re-infected with alternative Wolbachia strains was used to determine the relative influence of host and Wolbachia genomes on host fitness values. Our results suggest fitness variation is largely a function of host genetic background, except in the case of offspring sex ratio where a significant interaction between host and Wolbachia genomes was found. We also find a significant effect associated with the horizontal transfer of Wolbachia strains, which we discuss in terms of the potential for coadaptation in PI-Wolbachia symbioses.

Author(s):  
Nuwan Weerawansha ◽  
Qiao Wang ◽  
Xiong Zhao He

Animals can adjust reproductive strategies in favour of corporation or competition in response to local population size and density, the two key factors of social environments. However, previous studies usually focus on either population size or density but ignore their interactions. Using a haplodiploid spider mite, Tetranychus ludeni Zacher, we carried out a factorial experiment in the laboratory to examine how ovipositing females adjust their fecundity and offspring sex ratio during their early reproductive life under various population size and density. We reveal that females laid significantly more eggs with increasing population size and significantly fewer eggs with increasing population density. This suggests that large populations favour cooperation between individuals and dense populations increase competition. We demonstrate a significant negative interaction of population size and density that resulted in significantly fewer eggs laid in the large and dense populations. Furthermore, we show that females significantly skewed the offspring sex ratio towards female-biased in small populations to reduce the local mate competition among their sons. However, population density incurred no significant impact on offspring sex ratio, while the significant positive interaction of population size and density significantly increased the proportion of female offspring in the large and dense populations, which will minimise food or space competition as females usually disperse after mating at crowded conditions. These results also suggest that population density affecting sex allocation in T. ludeni is intercorrelated with population size. This study provides evidence that animals can manipulate their reproductive output and adjust offspring sex ratio in response to various social environments, and the interactions of different socio-environmental factors may play significant roles.


2012 ◽  
Vol 102 (6) ◽  
pp. 698-709 ◽  
Author(s):  
P.F. Rugman-Jones ◽  
M.S. Hoddle ◽  
R. Amrich ◽  
J.M. Heraty ◽  
C.E. Stouthamer-Ingel ◽  
...  

AbstractBean thrips, Caliothrips fasciatus, is native to western North America. Once considered a pest of several crops in its native area, its pest status has waned over recent decades. However, due to its habit of aggregating in the navel of navel oranges, bean thrips remains economically important because some countries importing oranges from California have designated it a quarantine pest. Despite continued propagule pressure, bean thrips has never established outside North America. We examined genetic variation in mitochondrial DNA among Californian populations of C. fasciatus and found that potentially two cryptic species are present (supported by Kimura 2-P distances): a common widespread form B and a rarer form A with a very limited distribution. Form B showed strong phylogeographic structure, with many haplotypes having a limited geographic distribution. Inter-population crossing experiments between three geographically isolated populations of form B resulted in the production of some female offspring, indicating a degree of compatibility between these populations of this haplodiploid species. However, substantial outbreeding depression was also detected. A low frequency of offspring production by hetero-population pairs was evidence of pre-mating isolation, while post-mating isolation was also evident in the elevated mortality of fertilized eggs in successful hetero-population crosses. One surprising finding was the total lack of offspring production by virgin females when isolated individually. However, virgin females did produce sons in the presence of other virgin females. A test for the presence of Wolbachia showed that form B was not infected, but that some populations of the rarer form A were.


2007 ◽  
Vol 125 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Serena Santolamazza-Carbone ◽  
Montserrat Pestaña Nieto ◽  
Adolfo Cordero Rivera

2018 ◽  
Vol 29 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Jing Li ◽  
Yu Wang ◽  
Cheng-Jie Zhu ◽  
Min Zhang ◽  
Hao-Yuan Hu

Localmate competition (LMC) models predict a female-biased offspring sex ratio when a single foundress oviposits alone in a patch and an increasing proportion of sons with increasing foundress number. We tested whether the solitary pupal parasitoid, Trichopria drosophilae (Hymenoptera: Diapriidae), adjusted offspring sex ratio with foundress number when parasitizing Drosophila melanogaster pupae. Mean number of female offspring was higher than that of males, with a male proportion of 26 ± 16% when only one foundress oviposited. However, male proportion reached 58 ± 26%, 48 ± 22%, and 51 ± 19% in three-, five and seven-foundress cohorts. That the male proportion of offspring increased with foundress number is consistent with LMC models.


2016 ◽  
Vol 12 (11) ◽  
pp. 20160627 ◽  
Author(s):  
Nicola Khan ◽  
Richard A. Peters ◽  
Emily Richardson ◽  
Kylie A. Robert

The hormone fluctuations that an animal experiences during ovulation can have lifelong effects on developing offspring. These hormones may act as an adaptive mechanism, allowing offspring to be ‘pre-programmed’ to survive in an unstable environment. Here, we used a transgenerational approach to examine the effects of elevated maternal corticosterone (CORT) on the future reproductive success of female offspring. We show that female zebra finches ( Taeniopygia guttata ) exposed to embryonic CORT produce daughters that have equal reproductive success (clutch sizes, fertility, hatching success) compared with the daughters produced from untreated mothers, but their offspring had accelerated post-hatching growth rates and were significantly heavier by nutritional independence. Although there was no significant effect on primary offspring sex ratio, females from CORT-treated mothers produced significantly female-biased clutches by nutritional independence. To the best of our knowledge, this is the first record of a transgenerational sex ratio bias in response to elevated maternal CORT in any avian species.


2002 ◽  
Vol 80 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Matthew B Lovern ◽  
Kelly M Passek

We examined the relationships between maternal size, breeding season stage, and offspring sex at hatching for the oviparous lizard Anolis carolinensis. Specifically, we tested two hypotheses: (1) large females produce offspring with male-biased sex ratios and small females produce offspring with female-biased sex ratios; and (2) females, regardless of size, produce offspring with male-biased sex ratios early in the breeding season and female-biased sex ratios late in the breeding season. We found no support for either hypothesis. Rather, we found that individual females of all sizes and throughout the breeding season alternated offspring sex of sequentially laid eggs. Because female anoles also alternate the ovary that produces successive eggs, we tested a third hypothesis: females produce eggs of only one sex with each ovary. Both palpation to track which ovary produced which eggs, and unilateral ovariectomies, leaving females with only one functioning ovary, failed to support this hypothesis. Regardless of whether an ovary was removed, females were capable of producing both male and female offspring from either ovary. To account for this and potentially other unusual patterns of offspring production, we provide evidence that maternal hormone levels around the time of fertilization may affect offspring sex.


1995 ◽  
Vol 127 (2) ◽  
pp. 245-254 ◽  
Author(s):  
J.A. Leatemia ◽  
J.E. Laing ◽  
J.E. Corrigan

AbstractThe role of adult nutrition in longevity, progeny production, and offspring sex ratio of Trichogramma minutum Riley was examined. On average, honey-fed females lived 26.4 days and produced 260 offspring; unfed females lived 3.5 days and produced 80 offspring. Feeding on fructose or sucrose also significantly increased longevity and fecundity over unfed females (fructose, 23 days and 230 offspring; sucrose, 21 days and 230 offspring) but to a lesser degree than feeding on pure honey. Females fed yeast suspension or water had no significant increases in longevity or fecundity compared to unfed females. Offspring sex ratios of long-lived females were male-biased (50–62% males), those of short-lived females were female-biased (74–82% females). Lifetime reproduction of honey-fed females was highest at 20–25 °C and relative humidities of 20–80%, but short-term offspring production (during the first 2 days after emergence) was highest at 30 °C and 60–80% RH. Females that had access to honey for only a 24-h period did not increase their offspring production over the first 4 days of their lives when compared to unfed females. The potential benefits of feeding adult T. minutum for mass-rearing and field release are discussed.


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