How long is a giant sperm?

Pitnick, Scott; Spicer, Greg S.; Markow, Therese A.

doi:10.1038/375109a0

Cited by 172 publications

(110 citation statements)

References 6 publications

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“…A successful fertilization is one in which the entire sperm (ca. 1.75 mm in D. melanogaster) (Pitnick et al 1995) enters the egg and folds in a stereotypical manner (Karr 1991(Karr , 1996Karr & Pitnick 1996). We considered either the absence or partial entrance of a sperm into an egg as aǹ unsuccessful' fertilization (table 1).…”

Section: Resultsmentioning

confidence: 99%

“…Insemination reactions, which are observed in many Drosophila and other Diptera, occur in the female reproductive tract and result in sperm inactivation. Insemination reactions often result in the formation of a congealed sperm mass that is thought to block egg laying or reinsemination physically (Patterson 1946;Patterson & Stone 1952;Ward & Heed 1970;Asada & Kitagawa 1988;Asada & Fukumitsu 1990;Pitnick et al 1995;Bertram et al 1996;Polak et al 1998; but see also Markow 1997). We saw no evidence of insemination reactions in our crosses, consistent with previous reports in the melanogaster group.…”

Section: Discussionmentioning

confidence: 99%

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Gametic incompatibilities between races ofDrosophila melanogaster

Alipaz

Wu²,

Karr

2001

Proc. R. Soc. Lond. B

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Reproductive-isolating mechanisms between nascent species may involve sperm^egg recognition and have been best described in externally fertilizing organisms where such recognition is essential in preventing undesirable fertilizations. However, reproductive barriers in internally fertilizing species di¡er in signi¢cant ways, and a direct role for sperm^egg interactions has yet to be demonstrated. Females of many strains of Drosophila melanogaster from Zimbabwe, Africa, do not mate readily with cosmopolitan males. This polymorphism in mate choice is postulated to represent incipient speciation. We now report that, in one direction, crosses between the above populations produce far fewer o¡spring than reciprocal crosses due to a lower rate of egg hatch. We established that egg inviability in these crosses was due to defects in fertilization. Thus, even in taxa with internal fertilization, gametic incompatibility may be a mechanism relevant to reproductive isolation during incipient speciation.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Gametic incompatibilities between races ofDrosophila melanogaster

Alipaz

Wu²,

Karr

2001

Proc. R. Soc. Lond. B

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“…They di¡er in their geographical distribution (Patterson & Stone 1952), resource ecology (Pitnick et al 1995b), sperm morphology (e.g. head length, tail length, and tail shape; ¢gure 1), and in the duration of embryonic development.…”

Section: Discussionmentioning

confidence: 99%

Paternal products and by–products in Drosophila development

Pitnick

Karr

1998

Proc. R. Soc. Lond. B

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Tails of fertilizing spermatozoa persist throughout embryogenesis in Drosophila species and can be observed within the midguts of larvae after hatching. Throughout development, sperm proteins slowly di¡use or are stripped from the giant sperm tail residing within the embryo's anterior end. The shape and position of the sperm within the embryo are regulated such that, during organ formation, the unused portion of the sperm is enveloped by the developing midgut. This persistent, paternally derived structure is composed of the sperm's mitochondrial derivatives and appears to be defaecated by the larva soon after hatching. These complex sperm^egg interactions may represent mechanisms to avoid intragenomic con£ict by ensuring strictly maternal inheritance of mitochondrial DNA (mtDNA).

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“…Although sperms are typically viewed as being small, sperm length is extremely variable across taxa (for a review, see Pitnick et al, 2009), varying from the tiny porcupine sperm (Gage, 1998) to the enormously elongated sperm of Drosophila hydei (Pitnick et al, 1995). Some of this variation may be due to the differences in sperm competition risk, although this is not always the case (Gage, 1994;Hosken 1997;Stockley et al, 1997; for a review, see Pitnick et al, 2009).…”

Section: Introductionmentioning

confidence: 98%

Response to selection and realized heritability of sperm length in the yellow dung fly (Scathophaga stercoraria)

Dobler

Hosken

2009

Heredity

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Sperm length shows considerable phenotypic variation both inter-and intra-specifically, but a general explanation for this variation is lacking. In addition, our understanding of the genetic variation underlying sperm length variation is also limited because there have been few studies on the genetics of sperm size. One factor that could explain the variation in sperm length is that length influences sperm competitiveness, and there is some evidence for this. However, in yellow dung flies (Scathophaga stercoraria), microevolutionary responses to experimental variation at levels of sperm competition indicate that sperm length does not influence sperm competitiveness, although this lack of response may simply indicate sperm length lacks evolutionary potential (that is, it is constrained in some way), in spite of evidence that sperm length is heritable. Here we report on a laboratory study, in which we artificially selected upwards and downwards on sperm length in S. stercoraria. We found that sperm length significantly diverged after four generations of selection, but the response to selection was asymmetrical: upward selection generated a rapid response, but downward did not. We estimated the realized heritability of sperm length to be approximately 50%, which is consistent with previous sire-son estimates. We also assessed the fertility of males from upward and downward lines and found they did not differ. Results are discussed in the context of sperm competition.

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How long is a giant sperm?

Cited by 172 publications

References 6 publications

Gametic incompatibilities between races ofDrosophila melanogaster

Gametic incompatibilities between races ofDrosophila melanogaster

Paternal products and by–products in Drosophila development

Response to selection and realized heritability of sperm length in the yellow dung fly (Scathophaga stercoraria)

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