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| 2. |
- Aronsen, T., et al.
(författare)
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The operational sex ratio and density influence spatial relationships between breeding pipefish
- 2013
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 24:4, s. 888-897
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Tidskriftsartikel (refereegranskat)abstract
- The operational sex ratio (ratio of sexually receptive males to females) has been extensively studied in behavioral ecology, whereas other demographic factors such as the effect of density on mating behavior have received less empirical attention. We manipulated mating competition by establishing breeding populations of the sex-role reversed broad-nosed pipefish (Syngnathus typhle) at 2 sex ratios (male biased or female biased) and 2 densities. We used mean crowding (m*) and the index of association (X) to measure spatial distributions within and between the sexes, respectively, and investigated how these measures reflect the predicted strength of mating competition. In general, female m* increased as fewer males were available for mating, which suggests increased intrasexual competition in the most competitive sex. However, male m* also increased as the operational sex ratio became more female biased, suggesting that m* did not reflect mating competition for males. Association between the sexes (X) was higher under male bias than female bias, probably because males were still available for mating under male bias. In addition, X decreased in the female-biased treatment as the operational sex ratio became even more female biased. Higher density increased m* in both sex ratios and sexes, although for both sexes in the female-biased high-density treatment the operational sex ratio did not influence m*, probably because femalefemale competition inhibits further crowding in this treatment. In this study, we show that the use of m* and X can be a useful tool in behavioral studies but their interpretation requires detailed information about the mating system. Therefore, we recommend caution with their broadscale application.
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| 3. |
- Goncalves, Ines, 1982, et al.
(författare)
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MATERNAL ALLOCATION OF RESOURCES INTO THE EGGS IN RELATION TO PARTNER SIZE IN THE
- 2007
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Ingår i: European Society for Evolutionary Biology, Uppsala, 2007.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Animals that reproduce more than once are expected to make adaptive decisions on how much to invest in each reproductive event. According to the Differential Allocation hypothesis, organisms should weigh the costs and benefits of investing into reproduction when mating with their current partner against the possibility of finding higher quality mates in the future. In the pipefish Syngnathus typhle, males care for the young in a brood pouch. Both sexes prefer large-sized mates, generating a size assortative mating pattern. Females are polyandrous and hence commonly transfer eggs to several males during each breeding season. Large males produce larger offspring than small males do, but it is unknown whether this is due solely to large males gaining access to larger females, which produce larger eggs, or if it is generated (or reinforced) by females investing more into their eggs when mating with a large male. Conversely, females might invest more into the eggs when having to mate with a small male, especially if such males provide poorer care to the eggs than large males do. This study assessed whether females show differential allocation, and whether they allocate more or less resources to the eggs, depending on the size of their mate. We let each female mate with a large and a small male, and measured diameter, weight, lipid and protein content of the eggs. Our results show that females did not invest more into the eggs when mating with a large male. Instead, the egg protein content was higher when females mated with small males, indicating a compensatory differential allocation.
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| 4. |
- Goncalves, Ines, 1982, et al.
(författare)
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Reproductive compensation in broad-nosed pipefish females : Reproductive compensation in a pipefish
- 2010
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Ingår i: Proceedings of the Royal Society B. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 277, s. 1581-1589
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Tidskriftsartikel (refereegranskat)abstract
- The differential allocation hypothesis assumes that animals should weigh costs and benefits of investing into reproduction with a current mate against the expected quality of future mates, and predicts that they should invest more into reproduction when pairing with a high-quality mate. In the broad-nosed pipefish (Syngnathus typhle), males care for the embryos in a brood pouch and females compete for access to male mating partners. Both sexes prefer mating with large partners. In the present study, we show that the same female provides both large and small mating partners with eggs of similar size, weight and lipid content when mated to two males in succession. Importantly, however, eggs provided to small males (less preferred) had higher egg protein content (11% more) than those provided to large males (preferred). Thus, contrary to the differential allocation hypothesis, eggs did not contain more resources when females mated with a larger male. Instead, the pattern observed in our results is consistent with a compensatory reproductive strategy.
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| 5. |
- Goncalves, Ines, 1982, et al.
(författare)
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Syngnathus typhle females strategically allocate resources to offspring
- 2008
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Ingår i: Evolution of Parental Effects: Conceptual Issues and Empirical Patterns, Wollongong, 2008.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Animals that reproduce more than once are expected to make adaptive decisions on how much to invest in each reproductive event. According to the Differential Allocation hypothesis, organisms should weigh the costs and benefits of investing into reproduction when mating with their current partner against the possibility of finding higher quality mates in the future. In the pipefish Syngnathus typhle, males care for the young in a brood pouch. Both sexes prefer large-sized mates, generating a size assortative mating pattern. Females are polyandrous and hence commonly transfer eggs to several males during each breeding season. Large males produce larger offspring than small males do, but it is unknown whether this is due solely to large males gaining access to larger females, which produce larger eggs, or if it is generated (or reinforced) by females investing more into their eggs when mating with a large male. Conversely, females might invest more into the eggs when having to mate with a small male, especially if such males provide poorer care to the eggs than large males do. This study assessed whether females show differential allocation, and whether they allocate more or less resources to the eggs, depending on the size of their mate. We let each female mate with a large and a small male, and measured diameter, weight, lipid and protein content of the eggs. Our results show that females did not invest more into the eggs when mating with a large male. Instead, the egg protein content was higher when females mated with small males, indicating a compensatory differential allocation.
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| 6. |
- Mobley, K. B., et al.
(författare)
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Multiple mating and a low incidence of cuckoldry for nest-holding males in the two-spotted goby, Gobiusculus flavescens
- 2009
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 9, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Background: A major question in behavioural ecology concerns the relationship between genetic mating systems and the strength of sexual selection. In this study, we investigated the genetic mating system of the two-spotted goby (Gobiusculus flavescens), a useful fish model for the study of sexual selection whose genetic mating system remains uncharacterized. We developed four polymorphic microsatellite markers and used them to conduct parentage analyses on 21 nests collected during the breeding season to examine the rates of multiple mating by males and to test for evidence of alternative mating strategies. Results: Results of this study indicate that male G. flavescens mate with multiple females and enjoy confidence of paternity. We detected only one instance of sneaking, so cuckoldry contributed a very small percentage (~0.1%) of the total fertilizations in this population. Nests were nearly full and males that maintain larger nests have higher mating and reproductive success, irrespective of body size. Conclusion: Overall, our investigation shows that G. flavescens is similar to other, related gobies in that the nests of care-giving males often contain eggs from multiple females. However, G. flavescens differs from other gobies in displaying an extremely low rate of cuckoldry. The study of ecological factors responsible for this important difference between G. flavescens and related species should be a fertile area for future work.
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| 7. |
- Mobley, Kenyon B, et al.
(författare)
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Population structure of the dusky pipefish (Syngnathus floridae) from the Atlantic and Gulf of Mexico, as revealed by mitochondrial DNA and microsatellite analyses
- 2010
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Ingår i: Journal of Biogeography. - : John Wiley & Sons. - 0305-0270 .- 1365-2699. ; 37:7, s. 1363-1377
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Tidskriftsartikel (refereegranskat)abstract
- Aim To elucidate the historical phylogeography of the dusky pipefish (Syngnathus floridae) in the North American Atlantic and Gulf of Mexico ocean basins. Location Southern Atlantic Ocean and northern Gulf of Mexico within the continental United States. Methods A 394-bp fragment of the mitochondrial cytochrome b gene and a 235-bp fragment of the mitochondrial control region were analysed from individuals from 10 locations. Phylogenetic reconstruction, haplotype network, mismatch distributions and analysis of molecular variance were used to infer population structure between ocean basins and time from population expansion within ocean basins. Six microsatellite loci were also analysed to estimate population structure and gene flow among five populations using genetic distance methods (FST, Nei’s genetic distance), isolation by distance (Mantel’s test), coalescent-based estimates of genetic diversity and migration patterns, Bayesian cluster analysis and bottleneck simulations. Results Mitochondrial analyses revealed significant structuring between ocean basins in both cytochrome b (ΦST = 0.361, P < 0.0001; ΦCT = 0.312, P < 0.02) and control region (ΦST = 0.166, P < 0.0001; ΦCT = 0.128, P < 0.03) sequences. However, phylogenetic reconstructions failed to show reciprocal monophyly in populations between ocean basins. Microsatellite analyses revealed significant population substructuring between all locations sampled except for the two locations that were in closest proximity to each other (global FST value = 0.026). Bayesian analysis of microsatellite data also revealed significant population structuring between ocean basins. Coalescent-based analyses of microsatellite data revealed low migration rates among all sites. Mismatch distribution analysis of mitochondrial loci supports a sudden population expansion in both ocean basins in the late Pleistocene, with the expansion of Atlantic populations occurring more recently. Main conclusions Present-day populations of S. floridae do not bear the mitochondrial DNA signature of the strong phylogenetic discontinuity between the Atlantic and Gulf coasts of North America commonly observed in other species. Rather, our results suggest that Atlantic and Gulf of Mexico populations of S. floridae are closely related but nevertheless exhibit local and regional population structure. We conclude that the present-day phylogeographic pattern is the result of a recent population expansion into the Atlantic in the late Pleistocene, and that life-history traits and ecology may play a pivotal role in shaping the realized geographical distribution pattern of this species.
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| 8. |
- Sagebakken, Gry, 1979, et al.
(författare)
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Brooding fathers, not siblings, take up nutrients from embryos : Embryo absorption by brooding fathers
- 2010
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Ingår i: Proceedings of the Royals Society B. - 0962-8452. ; 277:1683, s. 971-977
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that many animals with placenta-like structures provide their embryos with nutrients and oxygen. However, we demonstrate here that nutrients can pass the other way, from embryos to the parent. The study was done on a pipefish, Syngnathus typhle, in which males brood fertilized eggs in a brood pouch for several weeks. Earlier research has found a reduction of embryo numbers during the brooding period, but the fate of the nutrients from these ‘reduced’ embryos has been unknown. In this study, we considered whether (i) the brooding male absorbs the nutrients, (ii) siblings absorb them, or (iii) a combination of both. Males were mated to two sets of females, one of which had radioactively labelled eggs (using 14C-labelled amino acids), such that approximately half the eggs in the brood pouch were labelled. This allowed us to trace nutrient uptake from these embryos. We detected that 14C-labelled amino acids were transferred to the male brood pouch, liver and muscle tissue. However, we did not detect any significant 14C-labelled amino-acid absorption by the non-labelled half-siblings in the brood pouch. Thus, we show, to our knowledge, for the first time, that males absorb nutrients derived from embryos through their paternal brood pouch.
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