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Sharing of potential nest sites by Etheostoma olmstedi males suggests mutual tolerance in an alloparental species.

Stiver KA, Wolff SH, Alonzo SH - PLoS ONE (2013)

Bottom Line: Fish were generally more likely to use and share larger sites, in accordance with the greater relative surface area they offered.We discuss how one or both sharing males may potentially benefit, and how male sharing of potential nest sites could relate to female mating preferences.Thus, the suggestion that they may also share sites and maintain social contact with reproductive competitors highlights the importance of increased focus on the potential complexity of reproductive systems.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, Southern Connecticut State University, New Haven, Connecticut, USA. stiverk1@southernct.edu

ABSTRACT
When reproductive competitors tolerate or cooperate with one another, they may gain particular benefits, such as collectively guarding resources or attracting mates. Shared resources may be those essential to reproduction, such as a breeding site or nest. Using the tessellated darter, a species where males but not females compete over potential nest sites, we examined site use and sharing under controlled conditions of differing competitor density. Sharing was observed even when competitor density was low and individuals could have each occupied a potential nest site without same-sex sharing. Males were more likely to share a nest site with one other when the difference in size between them was larger rather than smaller. There was no evidence that female sharing was dependent on their relative size. Fish were generally more likely to use and share larger sites, in accordance with the greater relative surface area they offered. We discuss how one or both sharing males may potentially benefit, and how male sharing of potential nest sites could relate to female mating preferences. Tessellated darter males are known to provide alloparental care for eggs but this occurs without any social contact between the alloparent and the genetic father of the young. Thus, the suggestion that they may also share sites and maintain social contact with reproductive competitors highlights the importance of increased focus on the potential complexity of reproductive systems.

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Rate of sharing and difference in relative size between same-sex pairs.Mean body size ratio difference ± SE for same-sex pairs of males (in grey) and females (in white) grouped by whether they were sharing a tile for 0, 25, 50, 75 or 100% of the four checks of a replicate (excluding trials for which only three checks could be completed). The differences between groups mirror correlational analyses (see text): sharing among males was more commonly observed when males were more different in size, whereas there was no relationship between difference in size and proportion of the checks for which female pairs shared a tile (One-way ANOVA, randomization version, males: F4,198  =  5.19, p  =  0.002; post-hoc (two-sample randomization tests with Holm's correction): pairs that shared on no checks were closer in size than those who shared on three (p  =  0.03) or four (0.005) checks ; females: F4,194  =  0.71, p  =  0.57).
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pone-0056041-g002: Rate of sharing and difference in relative size between same-sex pairs.Mean body size ratio difference ± SE for same-sex pairs of males (in grey) and females (in white) grouped by whether they were sharing a tile for 0, 25, 50, 75 or 100% of the four checks of a replicate (excluding trials for which only three checks could be completed). The differences between groups mirror correlational analyses (see text): sharing among males was more commonly observed when males were more different in size, whereas there was no relationship between difference in size and proportion of the checks for which female pairs shared a tile (One-way ANOVA, randomization version, males: F4,198  =  5.19, p  =  0.002; post-hoc (two-sample randomization tests with Holm's correction): pairs that shared on no checks were closer in size than those who shared on three (p  =  0.03) or four (0.005) checks ; females: F4,194  =  0.71, p  =  0.57).

Mentions: Absolute size of males did not relate to their mean rate of sharing with other males (Ordinary least-squares regression with randomization test for slope  =  0, r  =  0.07, N  =  186, p  =  0.34; because this and additional tests of absolute size showed no significant results, tests of absolute size are not further reported here). However, males who were more different in size had a higher rate of sharing (body size ratio of the pair: r  =  0.280, N  =  207, p  =  0.0002; figure 2), and there was a trend suggesting that male pairs not adjacent in the size hierarchy shared a tile more often than males that were adjacent in the size hierarchy did (Two-sample randomization test, test stat = −0.077, N  =  124, 83, p  =  0.053). Similar to males, absolute size of females did not relate to their mean rate of sharing with other females (r  =  0.03, N  =  184, p  =  0.71; again, tests of absolute size are from this point omitted). However, neither differences in size nor adjacency in the size hierarchy related to the rate at which pairs of females shared (body size ratio of the pair: r  =  0.109, N  =  203, p  =  0.12; figure 2; adjacency: test stat  =  0.011, N  =  123, 81, p  =  0.79). Thus, males are more likely to share with those males most different from them in size, regardless of absolute size. In females, the rate of sharing is independent of their relative and absolute size.


Sharing of potential nest sites by Etheostoma olmstedi males suggests mutual tolerance in an alloparental species.

Stiver KA, Wolff SH, Alonzo SH - PLoS ONE (2013)

Rate of sharing and difference in relative size between same-sex pairs.Mean body size ratio difference ± SE for same-sex pairs of males (in grey) and females (in white) grouped by whether they were sharing a tile for 0, 25, 50, 75 or 100% of the four checks of a replicate (excluding trials for which only three checks could be completed). The differences between groups mirror correlational analyses (see text): sharing among males was more commonly observed when males were more different in size, whereas there was no relationship between difference in size and proportion of the checks for which female pairs shared a tile (One-way ANOVA, randomization version, males: F4,198  =  5.19, p  =  0.002; post-hoc (two-sample randomization tests with Holm's correction): pairs that shared on no checks were closer in size than those who shared on three (p  =  0.03) or four (0.005) checks ; females: F4,194  =  0.71, p  =  0.57).
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Related In: Results  -  Collection

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pone-0056041-g002: Rate of sharing and difference in relative size between same-sex pairs.Mean body size ratio difference ± SE for same-sex pairs of males (in grey) and females (in white) grouped by whether they were sharing a tile for 0, 25, 50, 75 or 100% of the four checks of a replicate (excluding trials for which only three checks could be completed). The differences between groups mirror correlational analyses (see text): sharing among males was more commonly observed when males were more different in size, whereas there was no relationship between difference in size and proportion of the checks for which female pairs shared a tile (One-way ANOVA, randomization version, males: F4,198  =  5.19, p  =  0.002; post-hoc (two-sample randomization tests with Holm's correction): pairs that shared on no checks were closer in size than those who shared on three (p  =  0.03) or four (0.005) checks ; females: F4,194  =  0.71, p  =  0.57).
Mentions: Absolute size of males did not relate to their mean rate of sharing with other males (Ordinary least-squares regression with randomization test for slope  =  0, r  =  0.07, N  =  186, p  =  0.34; because this and additional tests of absolute size showed no significant results, tests of absolute size are not further reported here). However, males who were more different in size had a higher rate of sharing (body size ratio of the pair: r  =  0.280, N  =  207, p  =  0.0002; figure 2), and there was a trend suggesting that male pairs not adjacent in the size hierarchy shared a tile more often than males that were adjacent in the size hierarchy did (Two-sample randomization test, test stat = −0.077, N  =  124, 83, p  =  0.053). Similar to males, absolute size of females did not relate to their mean rate of sharing with other females (r  =  0.03, N  =  184, p  =  0.71; again, tests of absolute size are from this point omitted). However, neither differences in size nor adjacency in the size hierarchy related to the rate at which pairs of females shared (body size ratio of the pair: r  =  0.109, N  =  203, p  =  0.12; figure 2; adjacency: test stat  =  0.011, N  =  123, 81, p  =  0.79). Thus, males are more likely to share with those males most different from them in size, regardless of absolute size. In females, the rate of sharing is independent of their relative and absolute size.

Bottom Line: Fish were generally more likely to use and share larger sites, in accordance with the greater relative surface area they offered.We discuss how one or both sharing males may potentially benefit, and how male sharing of potential nest sites could relate to female mating preferences.Thus, the suggestion that they may also share sites and maintain social contact with reproductive competitors highlights the importance of increased focus on the potential complexity of reproductive systems.

View Article: PubMed Central - PubMed

Affiliation: Psychology Department, Southern Connecticut State University, New Haven, Connecticut, USA. stiverk1@southernct.edu

ABSTRACT
When reproductive competitors tolerate or cooperate with one another, they may gain particular benefits, such as collectively guarding resources or attracting mates. Shared resources may be those essential to reproduction, such as a breeding site or nest. Using the tessellated darter, a species where males but not females compete over potential nest sites, we examined site use and sharing under controlled conditions of differing competitor density. Sharing was observed even when competitor density was low and individuals could have each occupied a potential nest site without same-sex sharing. Males were more likely to share a nest site with one other when the difference in size between them was larger rather than smaller. There was no evidence that female sharing was dependent on their relative size. Fish were generally more likely to use and share larger sites, in accordance with the greater relative surface area they offered. We discuss how one or both sharing males may potentially benefit, and how male sharing of potential nest sites could relate to female mating preferences. Tessellated darter males are known to provide alloparental care for eggs but this occurs without any social contact between the alloparent and the genetic father of the young. Thus, the suggestion that they may also share sites and maintain social contact with reproductive competitors highlights the importance of increased focus on the potential complexity of reproductive systems.

Show MeSH
Related in: MedlinePlus