scholarly journals Only pollinator fig wasps have males that collaborate to release their females from figs of an Asian fig tree

2011 ◽  
Vol 8 (3) ◽  
pp. 344-346 ◽  
Author(s):  
Nazia Suleman ◽  
Shazia Raja ◽  
Stephen G. Compton

Male insects rarely collaborate with each other, but pollinator fig wasps (Hymenoptera: Agaonidae) are said to be an exception. Immature fig wasps feed on galled ovules located inside figs, the inflorescences of Ficus species (Moraceae). After mating, adult pollinator males chew communal exit-holes that allow mated females (which are often also their siblings) to escape. Figs also support non-pollinating fig wasps (NPFWs), some of which produce exit-holes independently. We determined whether collaboration between pollinator males ( Kradibia tentacularis from Ficus montana ) was necessary for the release of their females, and used the relationship between male numbers and likelihood of success to measure the extent of cooperation during exit-hole production. These attributes were then compared with those of an NPFW ( Sycoscapter sp.) from the same host plant. Pollinators were more abundant than NPFW, but their more female-biased sex ratio meant male pollinator densities were only slightly higher. Individual males of both species could produce an exit-hole. Single males of the NPFW were just as successful as single male pollinators, but only male pollinators cooperated effectively, becoming more successful as their numbers increased. The lack of cooperation among NPFW may be linked to their earlier period of intense inter-male aggression.

2006 ◽  
Vol 66 (2b) ◽  
pp. 603-610 ◽  
Author(s):  
R. A. S. Pereira ◽  
A. P. Prado

In fig wasps, mating takes place among the offspring of one or a few foundress mothers inside the fig from which mated females disperse to found new broods. Under these conditions, related males will compete with each other for mating and several studies have shown female bias in brood sex ratios as a response to Local Mate Competition (LMC). Studying Pegoscapus tonduzi which pollinates Ficus citrifolia in Brazil, we analysed the effect of LMC (number of foundresses) on the sex ratio of the offspring of pollinating wasps. The relationship between the foundress number and brood sex ratio qualitatively followed the theory, however the empirical sex ratio was more female biased than expected from theoretical values. The model for an optimal sex ratio considers that each foundress wasp contributes the same number of eggs to be bred and that the violation of this assumption may explain the lack of adjustment in relation to the theory.


2019 ◽  
Vol 17 (1) ◽  
pp. 147470491983372 ◽  
Author(s):  
Yan Wang ◽  
Yang Qu ◽  
Bowen Hou ◽  
Qian Tian

Drawing on life history theory, this research explores the moderating role of childhood economic background in the relationship between sex ratio and the female’s mate preference for male resource availability. Using different priming materials, three experiments consistently found that women with a rich childhood economic background showed a stable level of mate preference for good resource—this applied regardless of male- or female-biased sex ratio. But females with a poor childhood economic background showed a higher level of preference for male resource availability under the condition of female-biased sex ratio (vs. the condition of male-biased sex ratio). These findings support the moderating role of female childhood economic background in the relationship between sex ratio and their mating preference of good resources.


Author(s):  
Ma. Dulce C. Guillena

Gonado-somatic index and fecundity are tools for measuring the sexual maturity and ability of animals to reproduce.  This study investigates the reproduction of Trichiurus lepturus. Specifically, this aimed to determine the sex ratio, the GSI, the relationship between fecundity and total length, fecundity and total weight, fecundity and ovary weight. The Descriptive Method of research was used.  Percentage and chi-square was utilized in determining the percentage of occurrence and sex ratio respectively.   Pearson r Product Moment Coefficient of Correlation was used to determine the relationships of the parameters. The study revealed that females outnumbered males and the sex ratio for different month showed significant difference.  Spawning season was observed to occur in November and December as revealed in its GSI values and it synchronized with the full and new moon phases.  Fecundity is positively correlated with body weight, body size, and ovary weight where ovary weight is observed to be the best index for fecundity.  The results of this study could be used further for formal stock assessment of cutlassfish fishery.


Author(s):  
Ester Premate ◽  
Špela Borko ◽  
Simona Kralj‐Fišer ◽  
Michael Jennions ◽  
Žiga Fišer ◽  
...  
Keyword(s):  

2020 ◽  
Vol 168 (12) ◽  
pp. 900-910
Author(s):  
Eduardo G. Virla ◽  
María B. Aguirre ◽  
Guido A. Van Nieuwenhove ◽  
Erica B. Luft Albarracin ◽  
Guillermo A. Logarzo

1989 ◽  
Vol 67 (8) ◽  
pp. 2078-2080 ◽  
Author(s):  
Robert Poulin ◽  
Gerard J. FitzGerald

Females of the ectoparasitic crustacean Argulus canadensis must leave their fish hosts at least temporarily to deposit their eggs on the substrate. To test the hypothesis that this difference in reproductive behaviour between the two sexes could result in male-biased sex ratios on their stickleback hosts, we sampled sticklebacks in tide pools of a Quebec salt marsh from early July to early September 1986. During this period, fish harboured significantly more male than female A. canadensis. Laboratory experiments were done to test two alternative hypotheses offered to explain this biased sex ratio. The first hypothesis was that male A. canadensis were more successful than females in attacking their stickleback hosts; however, we found no differences in attack success on their hosts between the two parasite sexes. The second hypothesis was that sticklebacks ate more female than male A. canadensis. Although males were less vulnerable to fish predation than females, the difference was not significant. We conclude that sexual differences in reproductive behaviour, i.e., egg deposition behaviour of females, can account for the male-biased sex ratio of A. canadensis on sticklebacks.


The Auk ◽  
1990 ◽  
Vol 107 (4) ◽  
pp. 765-771 ◽  
Author(s):  
J. David Ligon ◽  
Sandra H. Ligon
Keyword(s):  

Oecologia ◽  
1999 ◽  
Vol 118 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Roxana Torres ◽  
Hugh Drummond

1991 ◽  
Vol 69 (1) ◽  
pp. 208-212 ◽  
Author(s):  
Dan L. Johnson ◽  
Heather C. Proctor

The effect of predator presence on the adult sex ratio of a spider mite (Panonychus ulmi) was examined in a field experiment. Phytoseiid predators (chiefly Typhlodromus occidentalis) were removed from 32 trees harboring P. ulmi populations, and allowed to remain at natural levels on 32 other trees. Both total population density and proportion of males in the prey population were significantly higher in predator-free trees. Mechanisms that could explain the increase in the proportion of males are examined. The most probable is that greater male activity results in a higher encounter rate between predator and prey, and that subsequent higher male mortality when predators are present exaggerates the female-biased sex ratio. The theoretical effects of sex-biased predation on diplo-diploid and haplo-diploid organisms are discussed.


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