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1 June 2002 TIBIAL SPUR FEEDING IN GROUND CRICKETS: LARGER MALES CONTRIBUTE LARGER GIFTS (ORTHOPTERA: GRYLLIDAE)
Author Affiliations +
Abstract

Many male insects provide somatic nuptial gifts that may strongly influence reproductive fitness by insuring an effective copulation or by increasing paternal investment. In the striped ground cricket, Allonemobius socius (Scudder), females receive a nuptial gift by chewing on a specialized spur on the male’s hind tibia during copulation. Using a series of no-choice trials, we attempted to quantify gift magnitude and to determine the relationships between male size, gift contribution, and male mating success. Tibial spur chewing duration was a significant predictor of gift contribution (F1,17 = 17.02, P < 0.001) and the magnitude of the gift ranged between 0.2% and 8% of the male’s body mass, implying that females receive mostly hemolymph. Large males produced bigger gifts than small males (2.52 ± 0.59 mg vs. 1.33 ± 0.28 mg, t17 = 1.88, P < 0.05, respectively) and females were more likely to mate with larger males (F1,39 = 4.76, P < 0.05). If gift size is shown to influence female reproductive fitness, then nuptial gifts may play a large role in the evolution of male body size.

In many birds and insects, males offer nuptial gifts to females prior to and/or during copulation (Wiggins and Morris 1986; Gwynne and Brown 1994; Simmons 1995; Neuman et al. 1998). These offerings include captured prey, somatic tissue, synthesized secretions and suicidal food transfers (see Andersson 1994 and references therein). The function of these gifts may vary, serving as a form of male mating effort by increasing fertilization success (Alexander & Borgia 1979; Sakaluk 1984) and/or as paternal investment by increasing reproductive fitness (e.g., increasing egg size, offspring number or offspring viability; Gwynne 1984; Reinhold 1999). For instance, in the hangingfly, Hylobittacus apicalis (Byers), nuptial prey functions to increase mating effort by increasing copulation duration, which is in turn associated with the volume of sperm transferred (Thornhill 1976). In contrast, nuptial feeding in the osprey, Pandion haliaetus (Linnaeus), acts as paternal investment since it was positively associated with offspring growth rate (Green and Krebs 1995). Regardless of the precise functional significance, these associations suggest that variation in nuptial gift mass may have strong fitness implications for both sexes.

Nuptial gifts are generally transferred to females via external, intermediate packages such as prey items or self-contained somatic secretions (Andersson 1994), permitting an easy quantification of their mass. However, in some animal genera the gift is internally transferred making the magnitude and the fitness implications of such gifts difficult to assess. For instance, in the cricket genus Allonemobius (Orthoptera: Gryllidae), males internally deliver a nuptial gift through a specialized spur on each hind tibia that is chewed by the female during copulation (Fig. 1). Although chewing damages the spur, males can mate multiple times and females do not discriminate among males based on the spur’s condition (unpublished data). This somatic gift has previously been described as a limited glandular contribution contained within the spur that is exuded once the tip is removed (Fulton 1931; Mays 1971; Forrest 1991). However, a preliminary study suggested that, when the spur tip is artificially amputated and a capillary tube attached, the volume of the extract exceeds the volume of the spur (unpublished data). Thus, the spur may provide females with direct access to the male’s hemo-lymph, making male mass a potential limiting factor in gift contribution. This is important since the evolutionary trajectory of male body size and sexual size dimorphism may be modified if positive selection on the gift exists, coupled with a genetic correlation between body and gift size. Unfortunately, no mass measure of this or any other internally transferred nuptial gift exists.

Using the striped ground cricket, Allonemobius socius (Scudder), we attempted to quantify the magnitude of an internally transferred gift. We predicted that male A. socius donate more than a limited glandular contribution, and may offer females a continuous supply of hemolymph. Furthermore, we predicted that male contribution is constrained by male mass, with the largest males capable of offering the largest gift. Therefore, females should prefer large males if gift mass is positively related to male mass and to female fitness.

Materials and Methods

A. socius is a small chirping ground cricket found throughout the southeastern United States, with closely related sister taxa ranging throughout North America (Alexander & Thomas 1959; Howard & Furth 1986; Mousseau & Roff 1989). All crickets used in this experiment were second-generation lab-reared individuals originating from a single population near Asheville, North Carolina. Crickets were maintained in 10 × 10 × 8 cm plastic cages containing ground cat food, a carrot slice, water vial and strips of brown paper towel for cover. Every three days the food, carrot and paper towel were replaced. Cages were kept in a constant environment at 28°C and a 12:12 [L:D] photoperiod provided by a Percival incubator. The age of all experimental crickets was held constant at 12 ± 2 days post eclosion.

A. socius males perform a calling song used to attract distant females. Once a potential mate is encountered, males switch to a courtship song and dance that culminates with the male orienting his abdomen toward the stationary female. If the female is receptive, she will briefly mount the male in a “mock copulation” lasting only a few seconds. Once an effective mock copulation is achieved (this may take several attempts) the male will cease courting and begin to form a spermatophore (approximately 20 min). When complete, he will renew his courtship behavior, again enticing the female to mount. At this time, the couple will adjoin abdomens as the male adheres the spermatophore to the female’s genitalia. The male will then bring his hind tibia forward allowing the female to chew on his spur until the couple separates (upwards of 30 min). Once apart, the female will remove and consume the spermatophore. If a spermatophore is formed but not attached, no spur chewing will take place and the spermatophore will be removed and consumed by the male (Alexander & Thomas 1959; Mays 1971).

Virgin males and females were randomly paired (n = 41 pairs), placed into a mating arena (6 cm diameter petri dish) and allowed to mate once. Although crickets mate multiply in the wild (Walker 1980; Sakaluk and Cade 1983), only one mating bout is needed to detect the mass changes used in estimating the size of the nuptial gift. Two groups were created depending on the outcome of the mating trial. Males who attached their spermatophore to the female were grouped as successful. Males who formed a spermatophore, but failed to re-attract a female for copulation were grouped as unsuccessful. In both cases, spermatophores were collected after removal to avoid consumption. Male, female and petri dish mass were recorded before and after each mating trial. The mass gain in the petri dish gave us a measure of mass loss due to defecation. In addition, spermatophore mass, trial duration, spermatophore attachment duration, tibial spur chewing duration, and post-chewing spermatophore attachment duration (i.e., the amount of time it takes the female to remove the spermatophore after chewing the tibial spur) were recorded. Since by nature of the mating ritual, a positive association between chewing duration and spermatophore attachment seems inherent, post-chewing spermatophore attachment duration was examined to assess whether larger gifts satiate females to where they will postpone removal and consumption of the spermatophore. Mass was measured using a Sartorius scale (Bohemia, NY) accurate to 0.01 mg. Trial duration was defined as the time elapsed from the onset of male courtship to the removal of the spermatophore by the female (successful) or the male (unsuccessful).

The mass of the gift contribution was estimated for each successful trial by taking the total change in male mass (Δm) and subtracting out the mass lost to defecation (Δp), spermatophore mass (s), and respiration (r), such that,

i0015-4040-85-2-317-e1.gif

The term Δp was halved since we assumed that the rate of defecation was equal between the sexes. To estimate r, we first estimated the average mass lost per minute, R, from the unsuccessful male data while controlling for defecation and spermatophore production,

i0015-4040-85-2-317-e2.gif

where t is the duration of the trial. We assumed that R was equal for successful and unsuccessful males. Thus, for each successful trial, r was estimated by multiplying R by the duration of the mating trial, t. A second independent estimate of the nuptial gift, G[f], was based on female mass gain and obtained by substituting the change in female mass, (Δf), for (Δm) into equations one and two and dropping s. All data analyses were performed using SAS 8.1.

Results

Since the ejaculate contained within the spermatophore that is transferred directly to the female genitalia may confound our estimate of gift mass, we compared the mass of the successful male’s depleted spermatophore (mean ± se: 1.03 ± 0.01 mg; n = 19) with the unsuccessful male’s intact spermatophore (0.99 ± 0.07 mg; n = 22) to estimate ejaculate contribution. No difference existed between these two groups (one tailed t-test: t39 = -0.93, NS), suggesting that the ejaculate mass was negligible. There was no effect of male body size on spermatophore mass (F1,39 = 2.07, NS) or estimated respiratory mass loss (F1,17 = 0.17, NS). Average male mass was 77.55 ± 1.24 mg and the average G[m] was 1.89 ± 0.33 mg. Thus, the average nuptial gift was approximately 2.44% of the male’s initial body mass. When coupled with average spermatophore size (1.03 ± 0.01 mg) males invested approximately 3.77% of their total mass into a single copulation. This is a large investment considering that males are promiscuous and that a substantial proportion of their mass is attributable to exoskeleton.

When we replaced Δm with Δf  in equations one and two, average G[f] was estimated to be 1.01 ± 0.45 mg, providing a second, independent measure of gift size. Although this estimate is lower than the male estimate, they are not significantly different (two tailed t-test: t36 = 1.53, NS). Six G[f] estimates were negative (Fig. 2), and were most likely the result of the error inherent in the methodology used to estimate the mass lost to respiration, r. All six negative G[f] estimates were well within one standard deviation in r away from a positive estimate. As a consequence, our estimate of the average G[f] is conservative.

Since no difference existed between the successful and unsuccessful groups with regard to spermatophore mass (s), mass lost to defecation (0.58 ± 0.02 mg and 0.67 ± 0.02 mg, respectively; Δp two tailed t-test: t39 = 0.52, NS), and the duration of the trial (two tailed t-test: t39 = -0.72, NS), we calculated two additional estimates of gift mass, G[lm] and G[lf], using the least squares means difference in Δm and Δf  between the two groups, respectively. These estimates were calculated because they are free of the error attributed to estimating mass lost to respiration and defecation. Since initial male mass was significantly associated with Δm (F1,39 = 4.41, P < 0.05), we used an analysis of covariance with initial male mass as the covariate (ANCOVA: F2,38 = 14.75, P < 0.001; no interaction between covariate and group). Using this method G[lm] was estimated to be 1.75 mg. Likewise, G[lf] was estimated to be 1.28 mg. Considering that the tibial spur weighs less than 0.001 mg, these estimates suggest that the gift far exceeds the capacity of the spur. Moreover, these gift estimates exceed the weight of the entire male tibia (0.75 ± 0.05 mg), implying that the gift is comprised mostly or entirely of hemolymph.

Chewing duration covaried with both the male estimate (Fig. 2a; G[m]: F1,17 = 17.02, P < 0.001) and the female estimate (Fig. 2b; G[f]: F1,17 = 6.67, P < 0.05) of the nuptial gift implying that females who chewed longer received a larger gift contribution. The size of the gift ranged from 0.2% to 8% of initial male mass. Although, the rate of male gift contribution and female gift gain (Fig. 2) were not significantly different (F1,16 = 2.12, NS), G[f] exceeded G[m] in four trials. In three of these trials the differences were small and, as with the negative estimates of G[f], fell well within 1 standard deviation of our estimate of r. The remaining trial discrepancy showed female mass gain to be 3.94 mg greater than the male contribution, and cannot be reconciled with the previous argument suggesting that it may be the result of measurement error. However, when this observation was removed, the relationship between chewing duration and G[m] and G[f] remained unchanged (F1,17 =15.68, P < 0.001, R2 = 0.50 and F1,17 = 10.21, P < 0.01, R2 = 0.40, respectively).

In addition, male mass was significantly associated with spur chewing duration (Fig. 3: F1,17 = 4.24, P = 0.05) implying that larger males provide a larger gift. In turn, spur chewing duration was significantly associated with spermatophore attachment duration (F1,17 = 4.51, P < 0.05), which is expected since the spermatophore is attached at the onset of spur chewing. However, chewing duration was not associated with post-chewing spermatophore attachment duration (F1,17 = 0.06, NS), implying that females do not delay removal of the spermatophore if a larger gift is received.

Successful males were significantly larger than unsuccessful males (F1,39 = 4.76, P < 0.05). This may be the result of female choice or a mechanical constraint of small male size. In crickets, copulation may be impeded if the size difference of a mating pair is too great, making proper genitalic alignment and spermatophore transfer difficult (Sakaluk, pers. comm.). However, there was no distinction between successful and unsuccessful males with regard to male and female size differences (F1,39 = 1.28, NS), suggesting that large male success was not due to small male inability in passing a spermatophore, but perhaps to female preference for larger mates.

Although chewing duration was related to both male mass and estimated gift mass, male mass and gift mass were not directly related. To further investigate the relationship between body and gift mass, we separated the successful males into two groups, large and small, based on their mass relative to the mean (82.30 ± 1.27 mg). The ten males who fell below the mean were placed into the ‘small male’ group, and the nine males who fell above the mean were placed into the ‘large male’ group. On average, larger males were chewed upon twice as long and provided nearly twice as much gift as did smaller males (chewing duration: 15.46 ± 2.38 min vs. 7.01 ± 1.20 min, t17 = - 3.27, P < 0.01; gift donation: 2.52 ± 0.59 mg vs. 1.33 ± 0.28 mg, t17 = 1.88, P < 0.05, respectively. T-tests were one tailed). Using this analysis, male mass was significantly associated with gift mass, suggesting that the magnitude of the nuptial gift may be constrained by male size.

Discussion

In ground crickets (Neonemobius sp.), females are attracted to larger males and this preference was previously speculated to be based on the male’s ability to provide a larger nuptial gift (Forrest et al. 1991). In this study, we have shown that larger males are more successful at attracting and copulating with females. More importantly, we have shown that male mass was positively associated with the magnitude of gift contribution, providing a mechanism for the maintenance of female preference. This body size and gift size relationship coupled with sexual selection on gift size via female choice may have profound evolutionary implications.

In insects, the common pattern of female-biased size dimorphism is usually attributed to the reproductive advantages of being large (Shine 1988). However, if gift mass is related to female fitness, then the strength of size selection on males may surpass females, eventually increasing male size and modifying degree of dimorphism (e.g., Leimar et al. 1994). An association between gift mass and female fitness is common in Orthoptera (Gwynne 1983, Gwynne 1984; Brown 1997; Calos & Sakaluk 1998; Reinhold 1999). However, an association between male mass and gift mass is not (Wedell 1997), though an association between male mass and a spermatophylax gift/sperm ampulla complex has also been shown in some species (Gwynne 1982; Sakaluk 1985). To elucidate the implications of the nuptial gift on male size evolution in this system, we are presently examining the impact of gift mass on female fitness along with the selective pressures and underlying genetic architecture surrounding these traits.

Currently, it is unknown whether gift mass is shaped through male mating effort (e.g., by increasing sperm transfer) or paternal investment (i.e., by increasing the number and fitness of the gift givers offspring). Our data suggest that mating effort is a plausible hypothesis since gift size (i.e., chewing duration) was highly associated with spermatophore attachment duration. These results run contrary to a previous study by Bidochka and Snedden (1985) that examined mating behavior in a closely related sister species, Allonemobius fasciatus. In this study female access to the tibial spur was manipulated through three treatments (spur covered, surrounding spur area covered - spur uncovered, and spur uncovered) and subsequent copulation duration (an approximation of chewing duration and hence nuptial gift size) and spermatophore attachment duration recorded. They found that females who were denied access to the spur had a significantly shorter copulation duration than the other two treatments. In addition, they concluded no association between treatment and spermatophore attachment duration. However, if we compare the published summary statistics for the covered (16.72 ± 3.59 min, n = 30) and uncovered treatments (29.26 ± 5.35 min, n = 19) only, they are significantly different (two tailed t-test: t47 = -2.023, P < 0.05), suggesting that spermatophore attachment duration may be related to copulation duration in A. fasciatus, supporting our results.

In the wild, male and female ground crickets are promiscuous and mate with numerous individuals throughout the breeding season, exceeding the mating rate necessary to continually produce offspring prior to senescence. Promiscuous behavior often carries associated costs including increased time and energy expenditure (Thornhill & Alcock 1983), increased predation risk (Arnqvist 1989), increased disease susceptibility (Hurst et al. 1995), and/or caustic seminal fluids that potentially reduce fitness (Fowler & Partridge 1989; Rice 1996). The large size of the nuptial gift in A. socius described here provides the opportunity for these costs to be offset by increasing female fitness through increasing reproductive rate, reproductive longevity or fecundity. Associations between gift size and female reproductive fitness components are common in insects (Gwynne 1984; Andersson 1994).

Currently, the contents of the gift in A. socius are unclear though our data suggest it is mostly hemolymph and not simply a limited glandular secretion. Other systems have shown that nuptial gifts may contain oviposition inducing hormones (Friedel & Gilliot, 1977), or act as indicators of important male chemical resources that may affect offspring fitness (Eisner et al. 1996). Considering the relationship between gift size, male size and large male mating success in our data, gift quantity may be more important than gift quality.

Acknowledgments

We thank Jacqueline Litzgus, Scott Sakaluk and Wade Winterhalter for their insightful comments on this manuscript. This research was supported in part by a grant from the National Science Foundation (NSF 0090177) to T.A.M. and by a GAANN fellowship to K.M.F.

References Cited

1.

R. D. Alexander and E. S. Thomas . 1959. Systematic and behavioral studies on the crickets of the Nemobius fasciatus group (Orthoptera: Gryllidae: Nemobiinae). Ann. Entomol. Soc. Amer. 52::591–605. Google Scholar

2.

R. D. Alexander and G. Borgia . 1979. On the origin and basis of the male-female phenomenon,. pp. 417-440. In M. S. Blum and N. A. Blum (eds.), Sexual selection and reproductive competition in insects. New York: Academic Press.  Google Scholar

3.

M. Andersson 1994. Sexual Selection. Princeton, NJ: Princeton University Press.  Google Scholar

4.

G. Arnqvist 1989. Multiple mating in a water strider: mutual benefits or intersexual conflict? Animal Behav. 38::749–756. Google Scholar

5.

M. J. Bidochka and W. A. Snedden . 1985. Effect of nuptial feeding on the mating behaviour of female ground crickets. Canadian J. Zool. 63::207–208. Google Scholar

6.

W. D. Brown 1997. Courtship feeding in tree crickets increases insemination and female reproductive life span. Animal Behav. 54::1369–1382. Google Scholar

7.

J. B. Calos and S. K. Sakaluk . 1998. Paternity of offspring in multiply mated female crickets: the effect of nuptial food gifts and the advantage of mating first. Proc. Royal Soc. London 265::2191–2195. Google Scholar

8.

T. Eisner, S. R. Smedley, D. K. Young, M. Eisner, B. Roach, and J. Meinwald . 1996. Chemical basis of courtship in a beetle (Neopyrochroa flabellata): cantharidin as precopulatory ‘enticing’ agent. Proc. Nat. Acad. Sci., USA, 93::6499–6503. Google Scholar

9.

T. G. Forrest, J. L. Sylvester, S. Testa, S. W. Smith, A. Dinep, T. L. Cupit, J. M. Huggins, K. L. Atkins, and M. Eubanks . 1991. Mate choice in ground crickets (Gryllidae: Nemobiinae). Florida Entomol. 71::74–80. Google Scholar

10.

K. Fowler and L. Partridge . 1989. A cost of mating in female fruit flies. Nature 338::760–761. Google Scholar

11.

T. Friedel and C. Gillott . 1977. Contribution of male-produced proteins to vitellogenesis in Melanoplus sanguinipes. J. Insect Physiol. 23::145–151. Google Scholar

12.

B. B. Fulton 1931. A study of the genus Nemobius. (Orthoptera: Gryllidae). Ann. Entomol. Soc. Amer. 24::205–237. Google Scholar

13.

D. J. Green and E. A. Krebs . 1995. Courtship feeding in ospreys Pandion hallaetus - a criterion for mate assessment. Ibis. 137::35–43. Google Scholar

14.

D. T. Gwynne 1982. Mate selection by female katydids (Orthoptera: Tettigoniidae, Conocephalus nigropleurum). Animal Behav. 30::734–738. Google Scholar

15.

D. T. Gwynne 1983. Male nutritional investment and the evolution of sexual differences in Tettigoniidae and other Orthoptera,. pp. 337-366. In D. T. Gwynne and G. K. Morris (eds.), Orthopteran mating systems: Sexual competition in a diverse group of insects. Boulder, Colorado: Westview Press.  Google Scholar

16.

D. T. Gwynne 1984. Courtship feeding increases female reproductive success in bushcrickets. Nature 307::361–363. Google Scholar

17.

D. T. Gwynne and W. D. Brown . 1994. Mate feeding, offspring investment, and sexual differences in katydids (Orthoptera, Tettigoniidae). Behavioral Ecology 5::267–272. Google Scholar

18.

D. J. Howard and D. G. Furth . 1986. Review of the Allonemobius faciatus (Orthoptera: Gryllidae) complex with the description of two new species separated by electrophoresis, songs, and morphometrics. Ann. Entomol. Soc. Amer. 79::472–481. Google Scholar

19.

G. D D. Hurst, R. G. Sharpe, A. H. Broomfield, L. E. Walker, T. M O. Majerus, I. A. Zakharov, and M. E N. Majerus . 1995. Sexually transmitted disease in a promiscuous insect, Adalia bipunctata. Ecol. Entomol. 20::230–236. Google Scholar

20.

O. Leimar, B. Karlsson, and C. Wiklund . 1994. Unpredictable food and sexual size dimorphism in insects. Proc. Royal Soc. London 258::121–125. Google Scholar

21.

D. L. Mays 1971. Mating behavior of nemobiine crickets Hygronemobius, Nemobius and Pteronemobius (Orthoptera: Gryllidae). Florida Entomol. 54::113–126. Google Scholar

22.

T. A. Mousseau and D. A. Roff . 1989. Adaptation to seasonality in a cricket - patterns of phenotypic and genotypic variation in body size and diapause expression along a cline in season length. Evolution 43::1483–1496. Google Scholar

23.

J. Neuman, J. W. Chardine, and J. M. Porter . 1998. Courtship feeding and reproductive success in black-legged kittiwakes. Colonial Waterbirds 21::73–80. Google Scholar

24.

K. Reinhold 1999. Paternal investment in Poecilimon veluchianus bushcrickets: beneficial effects of nuptial feeding on offspring viability. Behav. Ecol. Sociobiol. 45::293–299. Google Scholar

25.

S. K. Sakaluk and W. Cade . 1983. The adaptive significance of female multiple matings in house and field crickets,. pp. 319-336. In D. T. Gwynne and G. K. Morris (eds.), Orthopteran mating systems: Sexual competition in a diverse group of insects Boulder, Colorado: Westview Press.  Google Scholar

26.

S. K. Sakaluk 1984. Male crickets feed females to ensure complete sperm transfer. Science 223::609–610. Google Scholar

27.

S. K. Sakaluk 1985. Spermatophore size and its role in the reproductive behaviour of the cricket, Gryllodes supplicans (Orthoptera: Gryllidae). Canadian J. Zool. 63::1652–1656. Google Scholar

28.

R. Shine 1988. The evolution of large body size in females: a critique of Darwin’s ‘fecundity advantage’ model. American Naturalist 131::124–131. Google Scholar

29.

L. W. Simmons 1995. Correlates of male quality in the field cricket, Gryllus campestris L: Age, size and symmetry determine pairing success in field populations. Behav. Ecol. 6::376–381. Google Scholar

30.

R. Thornhill 1976. Sexual selection and paternal investment in insects. American Naturalist 110::153–163. Google Scholar

31.

R. Thornhill and J. Alcock . 1983. The evolution of insect mating systems. Harvard University Press, Cambridge.  Google Scholar

32.

K. Vahed 1998. The function of nuptial feeding in insects: a review of empirical studies. Biol. Rev. 73::43–78. Google Scholar

33.

T. J. Walker 1980. Reproductive behavior and mating success of male short-tailed crickets: differences within and between demes. Evol. Biol. 13::219–260. Google Scholar

34.

N. Wedell 1997. Ejaculate size in bushcrickets: the importance of being large. J. Evol. Biol. 10::315–325. Google Scholar

35.

D. A. Wiggins and R. D. Morris . 1988. Courtship feeding and copulatory behavior in the common tern Sterna hirundo. Ornis Scandinavica 19::163–165. Google Scholar

Appendices

Fig. 1.

The tibial spur. This specialized spur delivers a somatic nuptial gift directly to the female through courtship feeding. The spur on the right has been chewed by a female whereas the left is still intact indicating a male’s previous mating success.

i0015-4040-85-2-317-f01.gif

Fig. 2.

Nuptial gift contribution as a function of spur chewing duration. A) As females chewed on the tibial spur, male gift contribution increased (y = 0.1496x + 0.2444, R2 = 0.50). B) The relationship between female mass gain and courtship feeding also provided a rate of male contribution (y = 0.1547x - 0.6922, R2 = 0.28). Both male (G[m]) and female (G[f]) estimates of the nuptial gift were controlled for mass lost to defecation, respiration and spermatophore production. The arrows indicate a potential outlier in the female G[f] estimate and the corresponding G[m] estimate.

i0015-4040-85-2-317-f02.gif

Fig. 3.

Spur chewing duration as a function of male mass. Large males were chewed longer than small males (y = 564.18x - 35.419, R2 = 0.20) suggesting that male size may ultimately constrain gift size.

i0015-4040-85-2-317-f03.gif
Kenneth M. Fedorka and Timothy A. Mousseau "TIBIAL SPUR FEEDING IN GROUND CRICKETS: LARGER MALES CONTRIBUTE LARGER GIFTS (ORTHOPTERA: GRYLLIDAE)," Florida Entomologist 85(2), 317-323, (1 June 2002). https://doi.org/10.1653/0015-4040(2002)085[0317:TSFIGC]2.0.CO;2
Published: 1 June 2002
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