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Cramer ERA, Yilma ZB, Lifjeld JT. Selection on sperm size in response to promiscuity and variation in female sperm storage organs. J Evol Biol 2023; 36:131-143. [PMID: 36357998 PMCID: PMC10100110 DOI: 10.1111/jeb.14120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 09/30/2022] [Accepted: 10/05/2022] [Indexed: 11/12/2022]
Abstract
Sperm cells are exceptionally morphologically diverse across taxa. However, morphology can be quite uniform within species, particularly for species where females copulate with many males per reproductive bout. Strong sexual selection in these promiscuous species is widely hypothesized to reduce intraspecific sperm variation. Conversely, we hypothesize that intraspecific sperm size variation may be maintained by high among-female variation in the size of sperm storage organs, assuming that paternity success improves when sperm are compatible in size with the sperm storage organ. We use individual-based simulations and an analytical model to evaluate how selection on sperm size depends on promiscuity level and variation in sperm storage organ size (hereafter, female preference variation). Simulations of high promiscuity (10 mates per female) showed stabilizing selection on sperm when female preference variation was low, and disruptive selection when female preference variation was high, consistent with the analytical model results. With low promiscuity (2-3 mates per female), selection on sperm was stabilizing for all levels of female preference variation in the simulations, contrasting with the analytical model. Promiscuity level, or mate sampling, thus has a strong impact on the selection resulting from female preferences. Furthermore, when promiscuity is low, disruptive selection on male traits will occur under much more limited circumstances (i.e. only with higher among-female variation) than many previous models suggest. Variation in female sperm storage organs likely has strong implications for intraspecific sperm variation in highly promiscuous species, but likely does not explain differences in intraspecific sperm variation for less promiscuous taxa.
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Affiliation(s)
- Emily R A Cramer
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, Oslo, Norway
| | | | - Jan T Lifjeld
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, Oslo, Norway
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2
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Cramer ERA, Grønstøl G, Lifjeld JT. Flagellum tapering and midpiece volume in songbird spermatozoa. J Morphol 2022; 283:1577-1589. [PMID: 36260518 PMCID: PMC9828668 DOI: 10.1002/jmor.21524] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 01/19/2023]
Abstract
In contrast to numerous studies on spermatozoa length, relatively little work focuses on the width of spermatozoa, and particularly the width of the midpiece and flagellum. In flagellated spermatozoa, the flagellum provides forward thrust while energy may be provided via mitochondria in the midpiece and/or through glycolysis along the flagellum itself. Longer flagella may be able to provide greater thrust but may also require stronger structural features and more or larger mitochondria to supply sufficient energy. Here, we use scanning electron microscopy to investigate the ultrastructure of spermatozoa from 55 passerine species in 26 taxonomic families in the Passerides infraorder. Our data confirm the qualitative observation that the flagellum tapers along its length, and we show that longer flagella are wider at the neck. This pattern is similar to mammals, and likely reflects the need for longer cells to be stronger against shearing forces. We further estimate the volume of the mitochondrial helix and show that it correlates well with midpiece length, supporting the use of midpiece length as a proxy for mitochondrial volume, at least in between-species studies where midpiece length is highly variable. These results provide important context for understanding the evolutionary correlations among different sperm cell components and dimensions.
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Ahmed L, Al-Najjar Y, Cramer ERA, Thareja G, Suhre K, Chen KC. Development and characterization of microsatellite primers for Triops granarius (Branchiopoda: Notostraca) using MiSeq technology. Mol Biol Rep 2022; 49:10121-10125. [PMID: 36057875 PMCID: PMC9515016 DOI: 10.1007/s11033-022-07804-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 07/15/2022] [Indexed: 12/03/2022]
Abstract
Background Next-generation sequencing technology has allowed for the rapid development of microsatellites, neutral polymorphic markers that can be used for the analysis of population structure. Methods and Results In this study, we performed whole-genome sequencing using the Illumina MiSeq system and de novo assembly to design microsatellite primers for Triops granarius populations in Qatar. The developed microsatellites are suitable for future studies of genetic structuring among geographically isolated freshwater pools. A total of 23 different primer pairs produced typical microsatellite results, with each pair successfully amplified in up to 40 individuals. Only five of the loci produced a significant departure from Hardy-Weinberg equilibrium. Conclusions Some of the underlying mechanisms regarding the few loci that deviated from HWE may be further investigated to determine the source of deviation. As T. granarius is the most widely distributed species of the family, the development of these molecular markers would be useful for conducting population genetics and biogeographical studies broadly.
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Affiliation(s)
- Lina Ahmed
- Department of Medical Education Education City, Qatar Foundation, Weill Cornell Medicine - Qatar, 24144, Doha, Qatar
| | - Yousef Al-Najjar
- Department of Medical Education Education City, Qatar Foundation, Weill Cornell Medicine - Qatar, 24144, Doha, Qatar
| | - Emily R A Cramer
- Natural History Museum, University of Oslo, Sars Gate 1, 0562, Oslo, Norway
| | - Gaurav Thareja
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar Education City, Qatar Foundation, P.O. Box 24144, Doha, Qatar
| | - Karsten Suhre
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar Education City, Qatar Foundation, P.O. Box 24144, Doha, Qatar
| | - Kuei-Chiu Chen
- Department of Premedical Education, Weill Cornell Medicine-Qatar Education City, Qatar Foundation, P.O. Box 24144, Doha, Qatar.
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Cramer ERA, Grønstøl G, Maxwell L, Kovach AI, Lifjeld JT. Sperm length divergence as a potential prezygotic barrier in a passerine hybrid zone. Ecol Evol 2021; 11:9489-9497. [PMID: 34306637 PMCID: PMC8293778 DOI: 10.1002/ece3.7768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 11/09/2022] Open
Abstract
The saltmarsh sparrow Ammospiza caudacuta and Nelson's sparrow A. nelsoni differ in ecological niche, mating behavior, and plumage, but they hybridize where their breeding distributions overlap. In this advanced hybrid zone, past interbreeding and current backcrossing result in substantial genomic introgression in both directions, although few hybrids are currently produced in most locations. However, because both species are nonterritorial and have only brief male-female interactions, it is difficult to determine to what extent assortative mating explains the low frequency of hybrid offspring. Since females often copulate with multiple males, a role of sperm as a postcopulatory prezygotic barrier appears plausible. Here, we show that sperm length differs between the two species in the hybrid zone, with low among-male variation consistent with strong postcopulatory sexual selection on sperm cells. We hypothesize that divergence in sperm length may constitute a reproductive barrier between species, as sperm length co-evolves with the size of specialized female sperm storage tubules. Sperm does not appear to act as a postzygotic barrier, as sperm from hybrids was unexceptional.
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Affiliation(s)
| | | | - Logan Maxwell
- Natural Resources and the EnvironmentUniversity of New HampshireDurhamNHUSA
| | - Adrienne I. Kovach
- Natural Resources and the EnvironmentUniversity of New HampshireDurhamNHUSA
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Cramer ERA, Garcia-del-Rey E, Johannessen LE, Laskemoen T, Marthinsen G, Johnsen A, Lifjeld JT. Longer Sperm Swim More Slowly in the Canary Islands Chiffchaff. Cells 2021; 10:cells10061358. [PMID: 34073133 PMCID: PMC8228216 DOI: 10.3390/cells10061358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/25/2021] [Accepted: 05/29/2021] [Indexed: 12/19/2022] Open
Abstract
Sperm swimming performance affects male fertilization success, particularly in species with high sperm competition. Understanding how sperm morphology impacts swimming performance is therefore important. Sperm swimming speed is hypothesized to increase with total sperm length, relative flagellum length (with the flagellum generating forward thrust), and relative midpiece length (as the midpiece contains the mitochondria). We tested these hypotheses and tested for divergence in sperm traits in five island populations of Canary Islands chiffchaff (Phylloscopus canariensis). We confirmed incipient mitochondrial DNA differentiation between Gran Canaria and the other islands. Sperm swimming speed correlated negatively with total sperm length, did not correlate with relative flagellum length, and correlated negatively with relative midpiece length (for Gran Canaria only). The proportion of motile cells increased with relative flagellum length on Gran Canaria only. Sperm morphology was similar across islands. We thus add to a growing number of studies on passerine birds that do not support sperm morphology-swimming speed hypotheses. We suggest that the swimming mechanics of passerine sperm are sufficiently different from mammalian sperm that predictions from mammalian hydrodynamic models should no longer be applied for this taxon. While both sperm morphology and sperm swimming speed are likely under selection in passerines, the relationship between them requires further elucidation.
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Affiliation(s)
- Emily R. A. Cramer
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, 0318 Oslo, Norway; (L.E.J.); (T.L.); (G.M.); (A.J.); (J.T.L.)
- Correspondence:
| | - Eduardo Garcia-del-Rey
- Macaronesian Institute of Field Ornithology, 38001 Santa Cruz de Tenerife, Canary Islands, Spain;
| | - Lars Erik Johannessen
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, 0318 Oslo, Norway; (L.E.J.); (T.L.); (G.M.); (A.J.); (J.T.L.)
| | - Terje Laskemoen
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, 0318 Oslo, Norway; (L.E.J.); (T.L.); (G.M.); (A.J.); (J.T.L.)
| | - Gunnhild Marthinsen
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, 0318 Oslo, Norway; (L.E.J.); (T.L.); (G.M.); (A.J.); (J.T.L.)
| | - Arild Johnsen
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, 0318 Oslo, Norway; (L.E.J.); (T.L.); (G.M.); (A.J.); (J.T.L.)
| | - Jan T. Lifjeld
- Sex and Evolution Research Group, Natural History Museum, University of Oslo, 0318 Oslo, Norway; (L.E.J.); (T.L.); (G.M.); (A.J.); (J.T.L.)
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Abstract
Abstract
Extrapair paternity should contribute to sexual selection by increasing the number of potential mates available to each individual. Potential copulation partners are, however, limited by their proximity. Spatial constraints may therefore reduce the impact of extrapair paternity on sexual selection. We tested the effect of spatial constraints on sexual selection by simulating extrapair copulations for 15 species of socially monogamous songbirds with varying rates of extrapair paternity. We compared four metrics of sexual selection between simulated populations without spatial constraints and populations where extrapair copulations were restricted to first- and second-order neighbors. Counter to predictions, sexual selection as measured by the Bateman gradient (the association between the number of copulation partners and offspring produced) increased under spatial constraints. In these conditions, repeated extrapair copulations between the same individuals led to more offspring per copulation partner. In contrast, spatial constraints did somewhat reduce sexual selection—as measured by the opportunity for selection, s’max, and the selection gradient on male quality—when the association between simulated male quality scores and copulation success (e.g., female preferences or male–male competition) was strong. Sexual selection remained strong overall in those populations even under spatial constraints. Spatial constraints did not substantially reduce sexual selection when the association between male quality and copulation success was moderate or weak. Thus, spatial constraints on extrapair copulations are insufficient to explain the absence of strong selection on male traits in many species.
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Affiliation(s)
- Emily R A Cramer
- Premedical Education Department, Weill Cornell Medicine-Qatar, Qatar Foundation-Education City, Doha, Qatar
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Abstract
Sexual selection studies widely estimate several metrics, but values may be inaccurate because standard field methods for studying wild populations produce limited data (e.g., incomplete sampling, inability to observe copulations directly). We compared four selection metrics (Bateman gradient, opportunity for sexual selection, opportunity for selection, and smax') estimated with simulated complete and simulated limited data for 15 socially monogamous songbird species with extrapair paternity (4%-54% extrapair offspring). Inferring copulation success from offspring parentage creates nonindependence between these variables and systematically underestimates copulation success. We found that this introduces substantial bias for the Bateman gradient, opportunity for sexual selection, and smax'. Notably, 47.5% of detected Bateman gradients were significantly positive for females, suggesting selection on females to copulate with multiple males, although the true Bateman gradient was zero. Bias generally increased with the extent of other sources of data limitations tested (nest predation, male infertility, and unsampled floater males). Incomplete offspring sampling introduced bias for all of the metrics except the Bateman gradient, while incomplete sampling of extrapair sires did not introduce additional bias when sires were a random subset of breeding males. Overall, our findings demonstrate how biases due to field data limitations can strongly impact the study of sexual selection.
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Albrecht T, Opletalová K, Reif J, Janoušek V, Piálek L, Cramer ERA, Johnsen A, Reifová R. Sperm divergence in a passerine contact zone: Indication of reinforcement at the gametic level. Evolution 2019; 73:202-213. [DOI: 10.1111/evo.13677] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 12/19/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Tomáš Albrecht
- Faculty of Science, Department of ZoologyCharles University in Prague Praha 2 , CZ‐12844 Czech Republic
- Institute of Vertebrate Biology, v.v.i.The Czech Academy of Sciences Brno CZ‐60365 Czech Republic
| | - Kamila Opletalová
- Faculty of Science, Department of ZoologyCharles University in Prague Praha 2 , CZ‐12844 Czech Republic
| | - Jiří Reif
- Faculty of Science, Institute for Environmental StudiesCharles University in Prague Praha 2 CZ‐12100 Czech Republic
| | - Václav Janoušek
- Faculty of Science, Department of ZoologyCharles University in Prague Praha 2 , CZ‐12844 Czech Republic
| | - Lubomír Piálek
- Faculty of Science, Department of ZoologyUniversity of South Bohemia České Budějovice CZ‐370 05 Czech Republic
| | | | - Arild Johnsen
- Natural History MuseumUniversity of Oslo 0318 Oslo Norway
| | - Radka Reifová
- Faculty of Science, Department of ZoologyCharles University in Prague Praha 2 , CZ‐12844 Czech Republic
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Taugbøl A, Mazzarella AB, Cramer ERA, Laskemoen T. Salinity-induced phenotypic plasticity in threespine stickleback sperm activation. Biol Lett 2018; 13:rsbl.2017.0516. [PMID: 29021318 DOI: 10.1098/rsbl.2017.0516] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 09/18/2017] [Indexed: 02/02/2023] Open
Abstract
Phenotypic expression may be and often is influenced by an organism's developmental environment, referred to as phenotypic plasticity. The sperm cells of teleosts have been found to be inactive in the seminal plasma and are activated by osmotic shock for most fish species, through release in either hypertonic (for marine fish) or hypotonic (for freshwater fish) water. If this is the case, the regulatory system of sperm mobility should be reversed in salt- and freshwater fish. We tested this hypothesis by first activating sperm of salt- and freshwater populations of threespine stickleback in salt- and freshwater. The sperm from saltwater stickleback could be activated in either salinity, which matches the freshwater colonization history of the species, whereas the sperm from the freshwater population acted as predicted by the osmotic shock theory and was activated in freshwater only. As the freshwater population used here was calculated to be thousands of years old, we went on to test whether the trait(s) were plastic and sperm from freshwater males still could be activated in saltwater after individuals were exposed to saltwater. After raising freshwater stickleback in saltwater, we found the mature males to have active sperm in both saltwater and freshwater. Further, we also found the sperm of wild-caught freshwater stickleback to be active in saltwater after exposing those mature males to saltwater for only 2 days. This illustrates that the ability for stickleback sperm to be activated in a range of water qualities is an environmentally induced plastic trait.
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Affiliation(s)
- Annette Taugbøl
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Bioscience, University of Oslo, 0316 Oslo, Norway .,Norwegian Institute for Nature Research, 2624 Lillehammer, Norway
| | - Anna B Mazzarella
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Bioscience, University of Oslo, 0316 Oslo, Norway
| | - Emily R A Cramer
- Natural History Museum, University of Oslo, PO Box 1172, Blindern, 0381 Oslo, Norway
| | - Terje Laskemoen
- Natural History Museum, University of Oslo, PO Box 1172, Blindern, 0381 Oslo, Norway
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10
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Sætre CLC, Johnsen A, Stensrud E, Cramer ERA. Sperm morphology, sperm motility and paternity success in the bluethroat (Luscinia svecica). PLoS One 2018; 13:e0192644. [PMID: 29509773 PMCID: PMC5839561 DOI: 10.1371/journal.pone.0192644] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 01/26/2018] [Indexed: 12/24/2022] Open
Abstract
Postcopulatory sexual selection may select for male primary sexual characteristics like sperm morphology and sperm motility, through sperm competition or cryptic female choice. However, how such characteristics influence male fertilization success remains poorly understood. In this study, we investigate possible correlations between sperm characteristics and paternity success in the socially monogamous bluethroat (Luscinia svecica svecica), predicting that sperm length and sperm swimming speed is positively correlated with paternity success. In total, 25% (15/61) of broods contained extra-pair offspring and 10% (33/315) of the offspring were sired by extra-pair males. Paternity success did not correlate significantly with sperm morphology or any aspects of sperm motility. Furthermore, sperm morphology and sperm motility did not correlate significantly with male morphological characters that previously have been shown to be associated with paternity success. Thus, the sperm characteristics investigated here do not appear to be strong predictors of paternity success in bluethroats.
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Affiliation(s)
| | - Arild Johnsen
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Even Stensrud
- Natural History Museum, University of Oslo, Oslo, Norway
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11
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Cramer ERA, Kaiser SA, Webster MS, Sillett TS, Ryder TB. Characterizing selection in black-throated blue warblers using a sexual network approach. J Evol Biol 2017; 30:2177-2188. [PMID: 28986958 DOI: 10.1111/jeb.13183] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 08/19/2017] [Accepted: 09/27/2017] [Indexed: 11/28/2022]
Abstract
Our understanding of trait evolution is built upon studies that examine the correlation between traits and fitness, most of which implicitly assume all individuals experience similar selective environments. However, accounting for differences in selective pressures, such as variation in the social environment, can advance our understanding of how selection shapes individual traits and subsequent fitness. In this study, we test whether variation in the social environment affects selection on individual phenotype. We apply a new sexual network framework to quantify each male's social environment as the mean body size of his primary competitors. We test for direct and social selection on male body size using a 10-year data set on black-throated blue warblers (Setophaga caerulescens), a territorial species for which body size is hypothesized to mediate competition for mates. We found that direct selection on body size was weak and nonsignificant, as was social selection via the body size of the males' competitors. Analysing both types of selection simultaneously allows us to firmly reject a role for body size in competitive interactions between males and subsequent male fitness in this population. We evaluate the application of the sexual network approach to empirical data and suggest that other phenotypic traits such as song characteristics and plumage may be more relevant than body size for male-male competition in this small passerine bird.
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Affiliation(s)
- E R A Cramer
- Migratory Bird Center, Smithsonian Conservation Biology Institute, Washington, DC, USA.,Cornell Lab of Ornithology, Ithaca, NY, USA
| | - S A Kaiser
- Center for Conservation Genomics, Smithsonian Conservation Biology Institute, Washington, DC, USA
| | | | - T S Sillett
- Migratory Bird Center, Smithsonian Conservation Biology Institute, Washington, DC, USA
| | - T B Ryder
- Migratory Bird Center, Smithsonian Conservation Biology Institute, Washington, DC, USA
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LaBarbera K, Cramer ERA, Veronese D, Lovette IJ. Growth benefit to house wren nestlings of having an asynchronously late-hatching nestmate is greater for extra-pair offspring. Behav Ecol Sociobiol 2017. [DOI: 10.1007/s00265-017-2283-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Cramer ERA, Ålund M, McFarlane SE, Johnsen A, Qvarnström A. Females discriminate against heterospecific sperm in a natural hybrid zone. Evolution 2016; 70:1844-55. [DOI: 10.1111/evo.12986] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 05/22/2016] [Accepted: 06/01/2016] [Indexed: 01/15/2023]
Affiliation(s)
- Emily R. A. Cramer
- Natural History Museum; University of Oslo; 0318 Oslo Norway
- Current Address: Smithsonian Migratory Bird Center; PO Box 37012 MRC5503, Washington, District of Columbia 20008, and Cornell Lab of Ornithology Ithaca New York 14850
| | - Murielle Ålund
- Department of Ecology and Genetics; Animal Ecology, Uppsala University; Uppsala 75236 Sweden
| | - S. Eryn McFarlane
- Department of Ecology and Genetics; Animal Ecology, Uppsala University; Uppsala 75236 Sweden
| | - Arild Johnsen
- Natural History Museum; University of Oslo; 0318 Oslo Norway
| | - Anna Qvarnström
- Department of Ecology and Genetics; Animal Ecology, Uppsala University; Uppsala 75236 Sweden
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Cramer ERA, Stensrud E, Marthinsen G, Hogner S, Johannessen LE, Laskemoen T, Eybert MC, Slagsvold T, Lifjeld JT, Johnsen A. Sperm performance in conspecific and heterospecific female fluid. Ecol Evol 2016; 6:1363-77. [PMID: 26855769 PMCID: PMC4733106 DOI: 10.1002/ece3.1977] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 12/08/2015] [Accepted: 01/03/2016] [Indexed: 12/11/2022] Open
Abstract
Divergent sexual selection within allopatric populations may result in divergent sexual phenotypes, which can act as reproductive barriers between populations upon secondary contact. This hypothesis has been most tested on traits involved in precopulatory sexual selection, with less work focusing on traits that act after copulation and before fertilization (i.e., postcopulatory prezygotic traits), particularly in internally fertilizing vertebrates. However, postcopulatory sexual selection within species can also drive trait divergence, resulting in reduced performance of heterospecific sperm within the female reproductive tract. Such incompatibilities, arising as a by‐product of divergent postcopulatory sexual selection in allopatry, can represent reproductive barriers, analogous to species‐assortative mating preferences. Here, we tested for postcopulatory prezygotic reproductive barriers between three pairs of taxa with diverged sperm phenotypes and moderate‐to‐high opportunity for postcopulatory sexual selection (barn swallows Hirundo rustica versus sand martins Riparia riparia, two subspecies of bluethroats, Luscinia svecica svecica versus L. s. namnetum, and great tits Parus major versus blue tits Cyanistes caeruleus). We tested sperm swimming performance in fluid from the outer reproductive tract of females, because the greatest reduction in sperm number in birds occurs as sperm swim across the vagina. Contrary to our expectations, sperm swam equally well in fluid from conspecific and heterospecific females, suggesting that postcopulatory prezygotic barriers do not act between these taxon pairs, at this stage between copulation and fertilization. We therefore suggest that divergence in sperm phenotypes in allopatry is insufficient to cause widespread postcopulatory prezygotic barriers in the form of impaired sperm swimming performance in passerine birds.
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Affiliation(s)
- Emily R A Cramer
- Natural History Museum University of Oslo PO Box 1172 Blindern 0318 Oslo Norway
| | - Even Stensrud
- Natural History Museum University of Oslo PO Box 1172 Blindern 0318 Oslo Norway
| | - Gunnhild Marthinsen
- Natural History Museum University of Oslo PO Box 1172 Blindern 0318 Oslo Norway
| | - Silje Hogner
- Natural History Museum University of Oslo PO Box 1172 Blindern 0318 Oslo Norway
| | | | - Terje Laskemoen
- Natural History Museum University of Oslo PO Box 1172 Blindern 0318 Oslo Norway
| | | | - Tore Slagsvold
- Department of Biosciences Center for Ecological and Evolutionary Synthesis (CEES) University of Oslo PO Box 1066 Blindern 0316 Oslo Norway
| | - Jan T Lifjeld
- Natural History Museum University of Oslo PO Box 1172 Blindern 0318 Oslo Norway
| | - Arild Johnsen
- Natural History Museum University of Oslo PO Box 1172 Blindern 0318 Oslo Norway
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Rowe M, Albrecht T, Cramer ERA, Johnsen A, Laskemoen T, Weir JT, Lifjeld JT. Postcopulatory sexual selection is associated with accelerated evolution of sperm morphology. Evolution 2015; 69:1044-52. [PMID: 25655075 DOI: 10.1111/evo.12620] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/16/2015] [Indexed: 01/31/2023]
Abstract
Rapid diversification of sexual traits is frequently attributed to sexual selection, though explicit tests of this hypothesis remain limited. Spermatozoa exhibit remarkable variability in size and shape, and studies report a correlation between sperm morphology (sperm length and shape) and sperm competition risk or female reproductive tract morphology. However, whether postcopulatory processes (e.g., sperm competition and cryptic female choice) influence the speed of evolutionary diversification in sperm form is unknown. Using passerine birds, we quantified evolutionary rates of sperm length divergence among lineages (i.e., species pairs) and determined whether these rates varied with the level of sperm competition (estimated as relative testes mass). We found that relative testes mass was significantly and positively associated with more rapid phenotypic divergence in sperm midpiece and flagellum lengths, as well as total sperm length. In contrast, there was no association between relative testes mass and rates of evolutionary divergence in sperm head size, and models suggested that head length is evolutionarily constrained. Our results are the first to show an association between the strength of sperm competition and the speed of sperm evolution, and suggest that postcopulatory sexual selection promotes rapid evolutionary diversification of sperm morphology.
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Affiliation(s)
- Melissah Rowe
- Natural History Museum, University of Oslo, PO Box 1172, Blindern, 0318, Oslo, Norway; Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, PO Box 1066, Blindern, 0316, Oslo, Norway.
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Cramer ERA, Laskemoen T, Stensrud E, Rowe M, Haas F, Lifjeld JT, Saetre GP, Johnsen A. Morphology-function relationships and repeatability in the sperm of Passer sparrows. J Morphol 2014; 276:370-7. [PMID: 25427840 DOI: 10.1002/jmor.20346] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 10/14/2014] [Accepted: 11/08/2014] [Indexed: 11/11/2022]
Abstract
Sperm performance is likely to be an important determinant of male reproductive success, especially when females copulate with multiple males. Understanding sperm performance is therefore crucial to fully understand the evolution of male reproductive strategies. In this study, we examined the repeatability of sperm morphology and motility measures over three breeding seasons, and we studied relationships between sperm morphology and function. We conducted this study in wild-derived captive house sparrows (Passer domesticus) and Spanish sparrows (P. hispaniolensis). Results for the two species were similar. As predicted from results in other passerine species, total sperm length was highly repeatable across ejaculates, and repeatability for the length of other components was moderate. The repeatability of sperm swimming speed across ejaculates was lower, but statistically significant, suggesting that sperm velocity may be a relatively dynamic trait. Surprisingly, swimming speed did not correlate with the relative length of the midpiece, and it correlated negatively with the relative length of the flagellum and with total sperm length. This pattern is the opposite of what theory predicts and differs from what has been found in house sparrows before. Also contrary to previous work, we found no evidence that total sperm length correlates with sperm longevity. These results therefore highlight the need for a better understanding of relationships between sperm morphology and function in passerine birds.
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Affiliation(s)
- Emily R A Cramer
- Natural History Museum, University of Oslo, Blindern, 0318, Oslo, Norway
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Cramer ERA, Laskemoen T, Kleven O, LaBarbera K, Lovette IJ, Lifjeld JT. No evidence that sperm morphology predicts paternity success in wild house wrens. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1594-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Physically challenging signals are likely to honestly indicate signaler quality. In trilled bird song two physically challenging parameters are vocal deviation (the speed of sound frequency modulation) and trill consistency (how precisely syllables are repeated). As predicted, in several species, they correlate with male quality, are preferred by females, and/or function in male-male signaling. Species may experience different selective pressures on their songs, however; for instance, there may be opposing selection between song complexity and song performance difficulty, such that in species where song complexity is strongly selected, there may not be strong selection on performance-based traits. I tested whether vocal deviation and trill consistency are signals of male quality in house wrens (Troglodytes aedon), a species with complex song structure. Males' singing ability did not correlate with male quality, except that older males sang with higher trill consistency, and males with more consistent trills responded more aggressively to playback (although a previous study found no effect of stimulus trill consistency on males' responses to playback). Males singing more challenging songs did not gain in polygyny, extra-pair paternity, or annual reproductive success. Moreover, none of the standard male quality measures I investigated correlated with mating or reproductive success. I conclude that vocal deviation and trill consistency do not signal male quality in this species.
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Affiliation(s)
- Emily R A Cramer
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, United States of America.
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LaBarbera K, Llambías PE, Cramer ERA, Schaming TD, Lovette IJ. Synchrony does not explain extrapair paternity rate variation in northern or southern house wrens. Behav Ecol 2010. [DOI: 10.1093/beheco/arq052] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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de Kort SR, Eldermire ERB, Cramer ERA, Vehrencamp SL. The deterrent effect of bird song in territory defense. ACTA ACUST UNITED AC 2008; 20:200-206. [PMID: 19337589 DOI: 10.1093/beheco/arn135] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 09/13/2008] [Accepted: 09/17/2008] [Indexed: 11/13/2022]
Abstract
Using the responses of territory owners to playback to infer the territorial function of acoustic signals is common practice. However, difficulties with interpreting the results of such experiments have obscured our understanding of territorial signalling. For instance, a stronger response to playback is often interpreted as more aggressive, but there is no consensus as to whether this should be in response to the least or most threatening simulated intruder. Rather than following a gradual increase or decrease, the relationship between signal intensity and response strength may instead describe a peaked curve. We manipulated banded wren (Thryophilus pleurostictus) songs to simulate low-, median-, and high-performance singers and used these songs as stimuli in playback experiments. Banded wrens were less likely to approach the high-performance stimulus compared with the low- and median-performance stimuli. However, the birds that did approach the high-performance stimulus sang more than those that approached the low-performance stimulus. In addition, birds were more likely to match the songs when exposed to the median- and high-performance stimuli compared with the low-performance stimuli, and song matching predicted approach behavior. These results are in accordance with theoretical models of aggressive encounters in which low-performance opponents are challenged without further assessment. Median- and high-performance opponents, however, may require further assessment, and the latter may be perceived as too intimidating for approach.
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Cramer ERA, Stenzler L, Talaba AL, Makarewich CA, Vehrencamp SL, Lovette IJ. Isolation and characterization of SNP variation at 90 anonymous loci in the banded wren (Thryothorus pleurostictus). CONSERV GENET 2008; 9:1657-1660. [PMID: 19060959 DOI: 10.1007/s10592-008-9511-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Single nucleotide polymorphisms (SNPs) are becoming more commonly used as molecular markers in conservation studies. However, relatively few studies have employed SNPs for species with little or no existing sequence data, partly due to the practical challenge of locating appropriate SNP loci in these species. Here we describe an application of SNP discovery via shotgun cloning that requires no pre-existing sequence data and is readily applied to all taxa. Using this method, we isolated, cloned and screened for SNP variation at 90 anonymous sequence loci (51kb total) from the banded wren (Thryothorus pleurostictus), a Central American species with minimal pre-existing sequence data. We identified 168 SNPs (a mean of one SNP/305 bp, with SNPs unevenly distributed across loci). Further characterization of variation at 41 of these SNP loci among 256 individuals including 37 parent-offspring families suggests that they provide substantial information for defining the genetic mating system of this species, and that SNPs may be generally useful for this purpose when other markers are problematic.
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Affiliation(s)
- Emily R A Cramer
- Fuller Evolutionary Biology Program, Laboratory of Ornithology, Cornell University, Ithaca, New York 14850, USA
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