Sex ratio under conditional sex expression

Frank, Steven A.; Swingland, Ian R.

doi:10.1016/s0022-5193(88)80256-x

Cited by 72 publications

(68 citation statements)

References 3 publications

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“…We first tested the prediction that the sex ratio should be biased towards the first sex (Charnov 1982(Charnov , 1993Frank and Swingland 1988;Charnov and Bull 1989;Frank 1998). All our analyses supported this prediction.…”

Section: Direction Of Sex Change and The Sex Ratiomentioning

confidence: 90%

“…First, why is the sex ratio predicted to be biased toward the sex that individuals mature as first (Charnov 1982(Charnov , 1993Frank and Swingland 1988;Charnov and Bull 1989;Charnov and Skuladottir 2000)? This can be explained following Charnov (1993).…”

Section: Sex Change Theorymentioning

confidence: 99%

“…Possible explanations for these differences fall into three broad categories. First, the sex ratio is predicted to depend upon a number of factors (Charnov 1982(Charnov , 1993Charnov and Bull 1989;Frank and Swingland 1988;Frank 1998;Charnov and Skuladottir 2000), thus the effect of proportion of early maturers may be confounded by other variables. Analyzing the data with independent contrasts can get around this problem (Harvey and Pagel 1991;Mayhew and Pen 2002), as our analyses have shown, but in other cases FIG.…”

Section: Early Maturers and The Sex Ratiomentioning

confidence: 99%

“…In this case natural selection favors individuals who mature as the sex whose reproductive value increases more slowly with age (first sex), and then change to the other sex (second sex) when older (Ghiselin 1969;Leigh et al 1976;Charnov 1982; Warner 1988a,b Sex allocation theory is able to make three predictions for the overall breeding sex ratio in species where sex change occurs. First, the sex ratio should be biased toward the sex that individuals mature as, termed the first sex (Charnov 1982;Frank and Swingland 1988;Charnov and Bull 1989; Charnov 1993). Second, the sex ratio is predicted to show less extreme biases in partially sex changing species in which some individuals mature as the second sex (Charnov 1989).…”

mentioning

confidence: 99%

“…First, the sex ratio should be biased toward the sex that individuals mature as, termed the first sex (Charnov 1982;Frank and Swingland 1988;Charnov and Bull 1989;Charnov 1993). Second, the sex ratio is predicted to show less extreme biases in partially sex changing species in which some individuals mature as the second sex (Charnov 1989).…”

mentioning

confidence: 99%

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Sex-Ratio Evolution in Sex Changing Animals

Allsop

West

2004

Evolution

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Abstract. Sex allocation theory is often able to make clear predictions about when individuals should facultatively adjust their offspring sex ratio (proportion male) in response to local conditions, but not the consequences for the overall population sex ratio. A notable exception to this is in sex changing organisms, where theory predicts that: (1) organisms should have a sex ratio biased toward the ''first'' sex; (2) the bias should be less extreme in partially sex changing organisms, where a proportion of the ''second'' sex matures directly from the juvenile stage; and (3) the sex ratio should be more biased in protogynous (female first) than in protandrous (male first) species. We tested these predictions with a comparative study using data from 121 sex changing animal species spanning five phyla, covering fish, arthropods, echinoderms, molluscs, and annelid worms. We found support for the first and third predictions across all species. The second prediction was supported within the protogynous species (mainly fish), but not the protandrous species (mainly invertebrates).Key words. Comparative analysis, protandrous, protogynous, sequential hermaphrodite, sex allocation, sex ratio.Received October 16, 2003. Accepted January 8, 2004 Sex allocation theory describes how organisms should divide their resources between male and female reproduction (Charnov 1982). Some of the most striking successes of sex allocation theory have been in explaining cases in which individuals facultatively adjust their offspring sex ratios (proportion male) in response to local conditions (Charnov 1982;Hardy 2002;West et al. 2002a), as originally suggested by Trivers and Willard (1973). For example, numerous parasitic wasps have been shown to lay male eggs on relatively small hosts and female eggs on large hosts, because female offspring gain a greater fitness benefit from extra resources and larger body size (West and Sheldon 2002). In contrast, when such facultative sex ratio adjustment occurs, sex allocation theory has been much less successful in predicting and explaining variation in the overall population or breeding sex ratio (West et al. 2002a). The reason for this is that the population sex ratio is often predicted to depend upon biological details that are rarely known, such as the details of male and female life histories, and whether other behaviors such as clutch size are also facultatively adjusted (Frank 1987(Frank , 1990Weissing 2000, 2002;West and Sheldon 2002).Here we consider a case in which it is possible to make clear predictions for the overall population sex ratio. We are concerned with species in which sex change occurs, also termed sex reversal or sequential hermaphroditism. This has been documented in a variety of fish, invertebrates, and plants (Charnov 1982;Policansky 1982;Allsop and West 2003a). Sex allocation theory suggests that sex change is favored when the reproductive value of an individual varies with age or size, and the relationship is different for males and females. In this case natural select...

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Section: Direction Of Sex Change and The Sex Ratiomentioning

confidence: 90%

Section: Sex Change Theorymentioning

confidence: 99%

Section: Early Maturers and The Sex Ratiomentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Sex-Ratio Evolution in Sex Changing Animals

Allsop

West

2004

Evolution

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Parasitoid Sex Ratios and Biological Control

Ode¹,

Hardy²

2008

Behavioral Ecology of Insect Parasitoids

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Sex ratios of sea turtles

1994

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Estimates of sex ratios of hatchling sea turtles range from approximately 50% female (Chelonia mydas and Dermochelys coriacea in Suriname) to approximately 90% female (Caretta caretta in Florida). Seasonal sex production profiles (SSPPs) show how similar overall sex ratios can be achieved in dissimilar ways. Possible explanations of the data include sampling error, constraints on evolutionary adjustment of pivotals or behavior to local thermal conditions, and violations of assumptions required by classical Fisherian theory. o

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Sex ratio under conditional sex expression

Cited by 72 publications

References 3 publications

Sex-Ratio Evolution in Sex Changing Animals

Sex-Ratio Evolution in Sex Changing Animals

Parasitoid Sex Ratios and Biological Control

Sex ratios of sea turtles

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