| 1. |
- Aronsen, Tonje, et al.
(författare)
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Sex Ratio And Density Affect Sexual Selection In A Sex-Role Reversed Fish
- 2013
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 67:11, s. 3243-3257
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how demographic processes influence mating systems is important to decode ecological influences on sexual selection in nature. We manipulated sex ratio and density in experimental populations of the sex-role reversed pipefish Syngnathus typhle. We quantified sexual selection using the Bateman gradient (beta'ss), the opportunity for selection (I), and sexual selection (Is), and the maximum standardized sexual selection differential (s(max)). We also measured selection on body length using standardized selection differentials (s') and mating differentials (m'), and tested whether the observed I and Is differ from values obtained by simulating random mating. We found that I, Is, and s'(max), but not beta'(ss), were higher for females under female than male bias and the opposite for males, but density did not affect these measures. However, higher density decreased sexual selection (m similar to but not s') on female length, but selection on body length was not affected by sex ratio. Finally, Is but not I was higher than expected from random mating, and only for females under female bias. This study demonstrates that both sex ratio and density affect sexual selection and that disentangling interrelated demographic processes is essential to a more complete understanding of mating behavior and the evolution of mating systems.
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| 2. |
- Braga Gonçalves, Inês, et al.
(författare)
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Effects of female mating order and male size on embryo survival in a pipefish.
- 2015
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 114:3, s. 639-645
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Tidskriftsartikel (refereegranskat)abstract
- In species that provide parental care, individuals should invest adaptively in their offspring in relation to the preand post-zygotic care provided by their partners. In the broad-nosed pipefish, Syngnathus typhle L., females transfer large, nutrient-rich eggs into the male brood pouch during mating. The male broods and nourishes the embryos for several weeks before independent juveniles emerge at parturition. Given a choice, females clearly prefer large partners. Yet, females provide protein-richer eggs when the same individual mates with a smaller than a larger male. In the present study, we allowed each female to mate with one small and one large male, in alternated order. We found a strong effect of female mating order, with larger clutches and higher embryo mortality in first- than second-laid broods, which may suggest that eggs over-ripen in the ovaries or reflect the negative effects of high embryo density in the brood pouch. In either case, this effect should put constraints on the possibility of a female being selective in mate choice. We also found that small and large males produced embryos of similar size and survival, consistent with the reproductive compensation hypothesis, suggesting that, in this species, larger males provide better nourishment to the embryos than smaller males.
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| 3. |
- Braga Goncalves, Ines, et al.
(författare)
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Reproductive compensation in broad-nosed pipefish females
- 2010
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 277:1687, s. 1581-1587
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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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| 4. |
- Kasper, Claudia, et al.
(författare)
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Genetics and developmental biology of cooperation
- 2017
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083. ; 26:17, s. 4364-4377
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Forskningsöversikt (refereegranskat)abstract
- Despite essential progress towards understanding the evolution of cooperative behaviour, we still lack detailed knowledge about its underlying molecular mechanisms, genetic basis, evolutionary dynamics and ontogeny. An international workshop “Genetics and Development of Cooperation,” organized by the University of Bern (Switzerland), aimed at discussing the current progress in this research field and suggesting avenues for future research. This review uses the major themes of the meeting as a springboard to synthesize the concepts of genetic and nongenetic inheritance of cooperation, and to review a quantitative genetic framework that allows for the inclusion of indirect genetic effects. Furthermore, we argue that including nongenetic inheritance, such as transgenerational epigenetic effects, parental effects, ecological and cultural inheritance, provides a more nuanced view of the evolution of cooperation. We summarize those genes and molecular pathways in a range of species that seem promising candidates for mechanisms underlying cooperative behaviours. Concerning the neurobiological substrate of cooperation, we suggest three cognitive skills necessary for the ability to cooperate: (i) event memory, (ii) synchrony with others and (iii) responsiveness to others. Taking a closer look at the developmental trajectories that lead to the expression of cooperative behaviours, we discuss the dichotomy between early morphological specialization in social insects and more flexible behavioural specialization in cooperatively breeding vertebrates. Finally, we provide recommendations for which biological systems and species may be particularly suitable, which specific traits and parameters should be measured, what type of approaches should be followed, and which methods should be employed in studies of cooperation to better understand how cooperation evolves and manifests in nature.
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| 5. |
- Kvarnemo, C., et al.
(författare)
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Evidence of paternal nutrient provisioning to embryos in broad-nosed pipefish Syngnathus typhle
- 2011
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 78:6, s. 1725-1737
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Tidskriftsartikel (refereegranskat)abstract
- In two experiments, radioactively labelled nutrients (either H-3-labelled amino-acid mixture or C-14-labelled glucose) were tube-fed to brooding male Syngnathus typhle. Both nutrients were taken up by the males and radioactivity generally increased in the brood pouch tissue with time. Furthermore, a low but significant increase of H-3-labelled amino acids in embryos was found over the experimental interval (48 h), whereas in the C-14-glucose experiment the radioactivity was taken up by the embryos but did not increase over the experimental time (320 min). Uptake of radioisotopes per embryo did not differ with embryo size. A higher uptake mg(-1) tissue of both H-3-labelled amino acids and C-14-labelled glucose was found in smaller embryos, possibly due to a higher relative metabolic rate or to a higher surface-area-to-volume ratio compared to larger embryos. Uptake in embryos was not influenced by male size, embryonic developmental advancement or position in the brood pouch. It is concluded that brooding males provide amino acids, and probably also glucose, to the developing embryos in the brood pouch.
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| 6. |
- Kvarnemo, Charlotta, 1963, et al.
(författare)
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Evidence of paternal nutrient provisioning to embryos in the pipefish Syngnathus typhle
- 2011
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 78:6, s. 1725-1737
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Tidskriftsartikel (refereegranskat)abstract
- In two experiments, radioactively labelled nutrients (either 3H-labelled amino-acid mixture or 14Clabelled glucose) were tube-fed to brooding male Syngnathus typhle. Both nutrients were taken up by the males and radioactivity generally increased in the brood pouch tissue with time. Furthermore, a low but significant increase of 3H-labelled amino acids in embryos was found over the experimental interval (48 h), whereas in the 14C-glucose experiment the radioactivity was taken up by the embryos but did not increase over the experimental time (320 min). Uptake of radioisotopes per embryo did not differ with embryo size. A higher uptake mg−1 tissue of both 3H-labelled amino acids and 14C-labelled glucose was found in smaller embryos, possibly due to a higher relative metabolic rate or to a higher surface-area-to-volume ratio compared to larger embryos. Uptake in embryos was not influenced by male size, embryonic developmental advancement or position in the brood pouch. It is concluded that brooding males provide amino acids, and probably also glucose, to the developing embryos in the brood pouch.
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| 7. |
- Mobley, Kenyon B.
(författare)
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Grandfathering in a new era of parentage analysis
- 2011
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 20:6, s. 1080-1082
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Tidskriftsartikel (refereegranskat)abstract
- The advent of DNA fingerprinting and microsatellite techniques has revolutionized the way in which we investigate genetic pedigrees in the wild (Pemberton 2008). With large and often incomplete data sets consisting of hundreds to thousands of individuals over multiple generations becoming commonplace, new methods in parentage analysis are being developed to rise to the next generation of questions and challenges. In this issue, Christie et al. (2011) provide a simple yet elegant solution to the problem of identifying missing parents and assessing hybrid fitness in a mixed population of wild and hatchery steelhead trout (Oncorhynchus mykiss) where not all individuals can be sampled effectively. They develop a new method of grandparent analysis where parental genotypes can be reconstructed using data from candidate grandparent crosses and F2 offspring genotypes, allowing for new explorations of hybridization, migration and gene flow in wild populations.
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| 8. |
- Mobley, Kenyon B., et al.
(författare)
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Morphological and genetic divergence in Swedish postglacial stickleback (Pungitius pungitius) populations
- 2011
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Ingår i: BMC Evolutionary Biology. - London : BioMed Central. - 1471-2148. ; 11, s. 287-
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Tidskriftsartikel (refereegranskat)abstract
- Background: An important objective of evolutionary biology is to understand the processes that govern phenotypic variation in natural populations. We assessed patterns of morphological and genetic divergence among coastal and inland lake populations of nine-spined stickleback in northern Sweden. Coastal populations are either from the Baltic coast (n = 5) or from nearby coastal lakes (n = 3) that became isolated from the Baltic Sea (< 100 years before present, ybp). Inland populations are from freshwater lakes that became isolated from the Baltic approximately 10,000 ybp; either single species lakes without predators (n = 5), or lakes with a recent history of predation (n = 5) from stocking of salmonid predators (~50 ybp).Results: Coastal populations showed little variation in 11 morphological traits and had longer spines per unit of body length than inland populations. Inland populations were larger, on average, and showed greater morphological variation than coastal populations. A principal component analysis (PCA) across all populations revealed two major morphological axes related to spine length (PC1, 47.7% variation) and body size (PC2, 32.9% variation). Analysis of PCA scores showed marked similarity in coastal (Baltic coast and coastal lake) populations. PCA scores indicate that inland populations with predators have higher within-group variance in spine length and lower within-group variance in body size than inland populations without predators. Estimates of within-group PST (a proxy for QST) from PCA scores are similar to estimates of FST for coastal lake populations but PST > FST for Baltic coast populations. PST > FST for PC1 and PC2 for inland predator and inland no predator populations, with the exception that PST < FST for body size in inland populations lacking predators.Conclusions: Baltic coast and coastal lake populations show little morphological and genetic variation within and between groups suggesting that these populations experience similar ecological conditions and that time since isolation of coastal lakes has been insufficient to demonstrate divergent morphology in coastal lake populations. Inland populations, on the other hand, showed much greater morphological and genetic variation characteristic of long periods of isolation. Inland populations from lakes without predators generally have larger body size, and smaller spine length relative to body size, suggesting systematic reduction in spine length. In contrast, inland populations with predators exhibit a wider range of spine lengths relative to body size suggesting that this trait is responding to local predation pressure differently among these populations. Taken together the results suggest that predation plays a role in shaping morphological variation among isolated inland populations. However, we cannot rule out that a causal relationship between predation versus other genetic and environmental influences on phenotypic variation not measured in this study exists, and this warrants further investigation.
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| 9. |
- Mobley, Kenyon B., et al.
(författare)
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No evidence that stickleback spines directly increase risk of predation by an invertebrate predator
- 2013
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Ingår i: Evolutionary Ecology Research. - 1522-0613 .- 1937-3791. ; 15:2, s. 189-198
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Tidskriftsartikel (refereegranskat)abstract
- Background: Some populations of stickleback have a reduced number and/or relative size of spines. Hypothesis: Macroinvertebrate predators such as dragonfly larvae cause selective pressure against spines by capturing more stickleback with pelvic spines than stickleback that are spineless. Organisms: Ninespine stickleback (Pungitius pungitius) and dragonfly larvae (Aeshna grandis). Methods: We used 10 stickleback, five with pelvic spines and five with their pelvic spines removed. We put them in containers with two dragonfly larvae. Every day for 4 days we monitored how many stickleback were captured by the larvae. We repeated this experiment ten times at two different densities of fish and predators. We also developed a model to determine whether selection for spinelessness can be distinguished from drift. Results: Dragonfly larvae caught as many stickleback with spines as without. The absence of spines was not associated with a decrease in predation risk. We substituted Bayesian estimates of the selection coefficient into quantitative genetic models of allele frequency change, and the results of the models suggest that the selective advantage of spine loss is so small that its effects cannot be distinguished from drift.
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| 10. |
- 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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| 11. |
- Mobley, Kenyon B., et al.
(författare)
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The effect of maternal body size on embryo survivorship in the broods of pregnant male pipefish
- 2011
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 65:6, s. 1169-1177
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) provides an exceptionally fertile system in which to investigate issues related to the evolution of parental care. Here, we take advantage of this unique reproductive system to study the influence of maternal body size on embryo survivorship in the brood pouches of pregnant males of the broad-nosed pipefish, Syngnathus typhle. Males were mated with either two large females, two small females, a large then a small female, or a small then a large female. Our results show that offspring survivorship depends on an interaction between female body size and the number of eggs transferred by the female. Eggs of larger females deposited in large numbers are more likely to result in viable offspring than eggs of smaller females laid in large numbers. However, when females deposited smaller numbers of eggs, the eggs from smaller females were more likely to produce viable offspring compared to those from larger females. We found no evidence that this result was based on mating order, the relative sizes of competing females, or egg characteristics such as dry weight of eggs. Additionally, male body size did not significantly influence the survivorship of offspring during brooding. Our results suggest that the factors underlying offspring survivorship in pipefish may be more complex than previously believed, with multiple factors interacting to determine the fitness of individual offspring within the broods of pregnant males.
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| 12. |
- Mobley, Kenyon B., et al.
(författare)
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The genetics and genomics of Syngnathidae : pipefishes, seahorses and seadragons.
- 2011
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 78:6, s. 1624-1646
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Forskningsöversikt (refereegranskat)abstract
- The goal of this review was to provide a historical overview of how molecular techniques have increased the understanding of the ecology and evolution of the family Syngnathidae (pipefishes, seahorses and seadragons). Molecular studies based primarily on mitochondrial DNA markers have proved their worth by elucidating complex phylogenetic relationships within the family. Phylogeographic studies, which have revealed how life-history traits and past climatic events shape geographic distributions and patterns of genetic variation within syngnathid species, also provide interesting case studies for the conservation and management of threatened species. The application of microsatellite DNA markers has opened a floodgate of studies concerned with the breeding biology of these fishes, which are interesting due to their unique reproductive mode of male pregnancy. Research in this area has contributed significantly to the understanding of mating patterns and sexual selection. Molecular markers may also be employed in studies of demography, migration and local breeding population sizes. Genomic studies have identified genes that are probably involved in male pregnancy and promise additional insights into various aspects of syngnathid biology at the level of the gene. Despite these advances, much more remains to be explored. Goals for future research should include: (1) a more inclusive phylogeny to resolve outstanding issues concerning the relationships within the family and higher order taxa, (2) a broader use of molecular studies to aid management and conservation efforts, (3) the inclusion of more genera in comparative behavioural studies and (4) the continued development of genomic resources for syngnathids to facilitate comparative genomic work.
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| 13. |
- Monroe, Melanie J., et al.
(författare)
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Seasonal variation in male alternative reproductive tactics
- 2016
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Ingår i: Journal of Evolutionary Biology. - : Wiley-Blackwell. - 1010-061X .- 1420-9101. ; 29:12, s. 2362-2372
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Tidskriftsartikel (refereegranskat)abstract
- Genetic parentage analyses reveal considerable diversity in alternative reproductive behaviours (e.g. sneaking) in many taxa. However, little is known about whether these behaviours vary seasonally and between populations. Here, we investigate seasonal variation in male reproductive behaviours in a population of two-spotted gobies (Gobiusculus flavescens) in Norway. Male two-spotted gobies guard nests, attract females and care for fertilized eggs. We collected clutches and nest-guarding males early and late in the breeding season in artificial nests and used microsatellite markers to reconstruct parentage from a subset of offspring from each nest. We hypothesized that mating, reproductive success and sneaking should be more prevalent early in the breeding season when competition for mates among males is predicted to be higher. However, parentage analyses revealed similar values of mating, reproductive success and high frequencies of successful sneaking early (30% of nests) and late (27% of nests) in the season. We also found that multiple females with eggs in the same nest were fertilized by one or more sneaker males, indicating that some males in this population engage in a satellite strategy. We contrast our results to previous work that demonstrates low levels of cuckoldry in a population in Sweden. Our results demonstrate marked stability in both the genetic mating system and male alternative reproductive tactics over the breeding season. However, sneaking rates may vary geographically within a species, likely due to local selection influencing ecological factors encountered at different locations.
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| 14. |
- Sagebakken, Gry, et al.
(författare)
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Brooding fathers, not siblings, take up nutrients from embryos
- 2010
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 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 C-14-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 C-14-labelled amino acids were transferred to the male brood pouch, liver and muscle tissue. However, we did not detect any significant C-14-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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| 15. |
- Svensson, Ola, 1971, et al.
(författare)
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Offspring recognition and the influence of clutch size on nest fostering among male sand gobies, Pomatoschistus minutus
- 2010
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Ingår i: Behavioral Ecology and Sociobiology. - Heidelberg : Springer. - 0340-5443 .- 1432-0762. ; 64:8, s. 1325-1331
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Tidskriftsartikel (refereegranskat)abstract
- When parental care is costly, parents should avoid caring for unrelated young. Therefore, it is an advantage to discriminate between related and unrelated offspring so that parents can make informed decisions about parental care. In the present study, we test the hypothesis that male sand gobies (Pomatoschistus minutus) recognize and differentially care for their own offspring when given a choice between a nest with sired eggs and a second nest with eggs sired by an unrelated male. The sand goby is a species with exclusive and costly paternal care. Male parasitic spawnings (e.g., sneaking) as well as nest takeovers by other males are common. Our results show that nests containing sired eggs were preferred and received significantly more care, as measured by nest building and nest occupancy, than nests with foreign eggs even when males cared for both nests. These findings suggest that males respond to paternity cues and recognize their own clutches. Relative clutch size also had a significant effect on male parental care. When sired clutches were larger than foreign clutches, males preferred to care for their own nest. In the few cases where males chose to take care of foreign nests, the foreign clutch was larger than their own clutch. Taken together, our results provide evidence that both paternity cues and clutch size influence parenting decisions among male sand gobies.
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| 16. |
- Öhlund, Gunnar, 1977-, et al.
(författare)
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Ecological speciation in European whitefish is driven by a large‐gaped predator
- 2020
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Ingår i: Evolution Letters. - : John Wiley & Sons. - 2056-3744. ; 4:3, s. 243-256
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Tidskriftsartikel (refereegranskat)abstract
- Lake‐dwelling fish that form species pairs/flocks characterized by body size divergence are important model systems for speciation research. Although several sources of divergent selection have been identified in these systems, their importance for driving the speciation process remains elusive. A major problem is that in retrospect, we cannot distinguish selection pressures that initiated divergence from those acting later in the process. To address this issue, we studied the initial stages of speciation in European whitefish (Coregonus lavaretus) using data from 358 populations of varying age (26–10,000 years). We find that whitefish speciation is driven by a large‐growing predator, the northern pike (Esox lucius). Pike initiates divergence by causing a largely plastic differentiation into benthic giants and pelagic dwarfs: ecotypes that will subsequently develop partial reproductive isolation and heritable differences in gill raker number. Using an eco‐evolutionary model, we demonstrate how pike's habitat specificity and large gape size are critical for imposing a between‐habitat trade‐off, causing prey to mature in a safer place or at a safer size. Thereby, we propose a novel mechanism for how predators may cause dwarf/giant speciation in lake‐dwelling fish species.
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| 17. |
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