Character displacement theory predicts that closely-related co-occurring species should diverge in relevant traits to reduce costly interspecific interactions such as competition or hybridization. While many studies document character shifts in sympatry, few provide corresponding evidence that these shifts are driven by the costs of co-occurrence. Black-capped (Poecile atricapillus) and mountain chickadees (P. gambeli) are closely-related, ecologically similar, and broadly distributed songbirds with both allopatric and sympatric populations. In sympatry, both species appear to suffer costs of their co-occurrence: 1) both species are in worse body condition compared to allopatry and 2) hybridization sometimes yields sterile offspring. Here, we explored character displacement in the songs of black-capped and mountain chickadees by characterizing variation in male songs from sympatric and allopatric populations. We found that mountain chickadees sing differently in sympatry versus allopatry. Specifically, they produced more notes per song, were more likely to include an extra introductory note, and produced a smaller glissando in their first notes compared to all other populations. Combined with previous research on social dominance and maladaptive hybridization between black-capped and mountain chickadees, we posit that differences in sympatric mountain chickadee song are population-wide shifts to reduce aggression from dominant black-capped chickadees and/or prevent maladaptive hybridization.
{"title":"Chickadees sing different songs in sympatry versus allopatry.","authors":"Olivia Taylor, Kathryn Grabenstein, Angela Theodosopoulos, Harriet Leeson, Scott Taylor, Carrie Branch","doi":"10.1093/jeb/voae114","DOIUrl":"https://doi.org/10.1093/jeb/voae114","url":null,"abstract":"<p><p>Character displacement theory predicts that closely-related co-occurring species should diverge in relevant traits to reduce costly interspecific interactions such as competition or hybridization. While many studies document character shifts in sympatry, few provide corresponding evidence that these shifts are driven by the costs of co-occurrence. Black-capped (Poecile atricapillus) and mountain chickadees (P. gambeli) are closely-related, ecologically similar, and broadly distributed songbirds with both allopatric and sympatric populations. In sympatry, both species appear to suffer costs of their co-occurrence: 1) both species are in worse body condition compared to allopatry and 2) hybridization sometimes yields sterile offspring. Here, we explored character displacement in the songs of black-capped and mountain chickadees by characterizing variation in male songs from sympatric and allopatric populations. We found that mountain chickadees sing differently in sympatry versus allopatry. Specifically, they produced more notes per song, were more likely to include an extra introductory note, and produced a smaller glissando in their first notes compared to all other populations. Combined with previous research on social dominance and maladaptive hybridization between black-capped and mountain chickadees, we posit that differences in sympatric mountain chickadee song are population-wide shifts to reduce aggression from dominant black-capped chickadees and/or prevent maladaptive hybridization.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142394848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F Francesco Boatta, Jurgen van Hal, Leo W Beukeboom, Jacintha Ellers
Dietary change can be a strong evolutionary force and lead to rapid adaptation in organisms. High-fat and high-sugar diets can challenge key metabolic pathways, negatively affecting other life-history traits and inducing pathologies such as obesity and diabetes. In this study we use experimental evolution to investigate the plastic and evolutionary responses to nutritionally unbalanced diets. We reared replicated lines of larvae of the housefly Musca domestica on a fat-enriched (FAT), a sugar-enriched (SUG), and a control (CTRL) diet for thirteen generations. We measured development time in each generation, and larval growth and fat accumulation in generation 1, 7, and 13. Subsequently all lines were reared for one generation on the control diet to detect any plastic and evolutionary changes. In the first generation, time to pupation decreased on a fat-rich diet and increased on a sugar-rich diet. The fat-rich diet increased fat accumulation and, to a lesser extent, dry weight of the larvae. Multigenerational exposure to the unbalanced diets caused compensatory changes in development time, dry weight, as well as absolute and relative fat content, although pattern and timing depended on diet and trait. When put back on a control diet, many of the changes induced by the unbalanced diets disappeared, indicating that diet has large plastic effects. Nevertheless, fat-evolved lines still grew significantly larger than the sugar-evolved lines, and sugar-evolved lines had consistently lower fat content. This can be an effect of parental diet or an evolutionary change in nutrient metabolism as a consequence of multigenerational exposure to unbalanced diets.
{"title":"High-fat and high-sugar diets induce rapid adaptations of fat storage in the house fly Musca domestica L.","authors":"F Francesco Boatta, Jurgen van Hal, Leo W Beukeboom, Jacintha Ellers","doi":"10.1093/jeb/voae122","DOIUrl":"https://doi.org/10.1093/jeb/voae122","url":null,"abstract":"<p><p>Dietary change can be a strong evolutionary force and lead to rapid adaptation in organisms. High-fat and high-sugar diets can challenge key metabolic pathways, negatively affecting other life-history traits and inducing pathologies such as obesity and diabetes. In this study we use experimental evolution to investigate the plastic and evolutionary responses to nutritionally unbalanced diets. We reared replicated lines of larvae of the housefly Musca domestica on a fat-enriched (FAT), a sugar-enriched (SUG), and a control (CTRL) diet for thirteen generations. We measured development time in each generation, and larval growth and fat accumulation in generation 1, 7, and 13. Subsequently all lines were reared for one generation on the control diet to detect any plastic and evolutionary changes. In the first generation, time to pupation decreased on a fat-rich diet and increased on a sugar-rich diet. The fat-rich diet increased fat accumulation and, to a lesser extent, dry weight of the larvae. Multigenerational exposure to the unbalanced diets caused compensatory changes in development time, dry weight, as well as absolute and relative fat content, although pattern and timing depended on diet and trait. When put back on a control diet, many of the changes induced by the unbalanced diets disappeared, indicating that diet has large plastic effects. Nevertheless, fat-evolved lines still grew significantly larger than the sugar-evolved lines, and sugar-evolved lines had consistently lower fat content. This can be an effect of parental diet or an evolutionary change in nutrient metabolism as a consequence of multigenerational exposure to unbalanced diets.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142394850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Animal nests provide a beneficial environment for offspring development and as such contribute to fitness. Gathering and transporting materials to construct nests is energetically costly, but the life history trade-offs associated with the types of nests built are largely unknown. Who contributes to building the nest could also mediate these trade-offs, as building a nest as a couple is expected to be less costly per individual than building alone. Using a comparative analysis on 227 songbird species globally, we found a fecundity cost associated with the type of nest a species builds. Species that build domed nests produce fewer broods per year than species building cups or platforms. Dome nesting species also have larger clutch sizes than open nesting species, but only when the nest is built by a couple and not when females build nests alone. This suggests that building domed nests represents a trade-off with investment in young, especially when females are solely responsible for nest building. More broadly, our results could explain macroevolutionary patterns, such as the recent finding that females, building on their own, more often build open cup rather than domed nests.
{"title":"The fecundity costs of building domed nests in birds.","authors":"Claire J Taylor, Mark C Mainwaring, Iliana Medina","doi":"10.1093/jeb/voae117","DOIUrl":"10.1093/jeb/voae117","url":null,"abstract":"<p><p>Animal nests provide a beneficial environment for offspring development and as such contribute to fitness. Gathering and transporting materials to construct nests is energetically costly, but the life history trade-offs associated with the types of nests built are largely unknown. Who contributes to building the nest could also mediate these trade-offs, as building a nest as a couple is expected to be less costly per individual than building alone. Using a comparative analysis on 227 songbird species globally, we found a fecundity cost associated with the type of nest a species builds. Species that build domed nests produce fewer broods per year than species building cups or platforms. Dome nesting species also have larger clutch sizes than open nesting species, but only when the nest is built by a couple and not when females build nests alone. This suggests that building domed nests represents a trade-off with investment in young, especially when females are solely responsible for nest building. More broadly, our results could explain macroevolutionary patterns, such as the recent finding that females, building on their own, more often build open cup rather than domed nests.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142331498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dispersal can evolve as an adaptation to escape competition with conspecifics or kin. Locations with a low density of conspecifics, however, may also lead to reduced opportunities for mating, especially in sessile marine invertebrates with proximity-dependent mating success. Since there are few experimental investigations, we performed a series of field experiments using an experimentally tractable species (the bryozoan Bugula neritina) to test the hypothesis that the density, spatial arrangement, and genetic relatedness of neighbors differentially affects survival, growth, reproduction, paternity, and sperm dispersal. We manipulated the density and relatedness of neighbors and found that increased density reduced survival but not growth rate, and that there was no effect of relatedness on survival, growth, or fecundity, in contrast to previous studies. We also manipulated the distances to the nearest neighbor and used genetic markers to assign paternity within known mother-offspring groups to estimate how proximity affects mating success. Distance to the nearest neighbor did not affect the number of settlers produced, the paternity share, or the degree of multiple paternity. Overall, larger than expected sperm dispersal led to high multiple paternity, regardless of the distance to the nearest neighbor. Our results have important implications for understanding selection on dispersal distance: in this system there are few disadvantages to the limited larval dispersal that does occur, and limited advantages for larvae to disperse further than a few 10s of meters.
{"title":"Fitness consequences of marine larval dispersal: the role of neighborhood density, arrangement, and genetic relatedness on survival, growth, reproduction, and paternity in a sessile invertebrate.","authors":"Danielle K Barnes, Scott C Burgess","doi":"10.1093/jeb/voae125","DOIUrl":"https://doi.org/10.1093/jeb/voae125","url":null,"abstract":"<p><p>Dispersal can evolve as an adaptation to escape competition with conspecifics or kin. Locations with a low density of conspecifics, however, may also lead to reduced opportunities for mating, especially in sessile marine invertebrates with proximity-dependent mating success. Since there are few experimental investigations, we performed a series of field experiments using an experimentally tractable species (the bryozoan Bugula neritina) to test the hypothesis that the density, spatial arrangement, and genetic relatedness of neighbors differentially affects survival, growth, reproduction, paternity, and sperm dispersal. We manipulated the density and relatedness of neighbors and found that increased density reduced survival but not growth rate, and that there was no effect of relatedness on survival, growth, or fecundity, in contrast to previous studies. We also manipulated the distances to the nearest neighbor and used genetic markers to assign paternity within known mother-offspring groups to estimate how proximity affects mating success. Distance to the nearest neighbor did not affect the number of settlers produced, the paternity share, or the degree of multiple paternity. Overall, larger than expected sperm dispersal led to high multiple paternity, regardless of the distance to the nearest neighbor. Our results have important implications for understanding selection on dispersal distance: in this system there are few disadvantages to the limited larval dispersal that does occur, and limited advantages for larvae to disperse further than a few 10s of meters.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142331494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Suzanne Edmands, Jacob R Denova, Ben A Flanagan, Murad Jah, Scott L Applebaum
Eukaryotic energy production requires tight coordination between nuclear and mitochondrial gene products. Because males and females often have different energetic strategies, optimal mitonuclear coordination may be sex-specific. Previous work found evidence for sex-specific mitonuclear effects in the copepod Tigriopus californicus by comparing two parental lines and their reciprocal F1 crosses. However, an alternative hypothesis is that the patterns were driven by the parental source of nuclear alleles. Here we test this alternative hypothesis by extending the same cross to F2 hybrids, who receive both maternal and paternal nuclear alleles from F1 hybrids. Results confirm mitonuclear effects on sex ratio, with distorted ratios persisting from the F1 to F2 generations, despite reduced fitness in F2 hybrids. No sex by cross interactions were found for other phenotypic traits measured. Mitochondrial DNA content was higher in females. Both routine metabolic rate and oxidative DNA damage were lower in F2 hybrids than in parentals. The persistence of sex-specific mitonuclear effects, even in the face of F2 hybrid breakdown, attests to the magnitude of these effects, which contribute to the maintenance of within-population mitochondrial DNA polymorphisms.
真核生物的能量生产需要核基因和线粒体基因产品之间的紧密配合。由于雄性和雌性通常具有不同的能量策略,因此最佳的有丝分裂核协调可能具有性别特异性。以前的研究通过比较两个亲本品系及其互交 F1,发现了桡足类加州虎尾蛙有丝分裂核效应具有性别特异性的证据。然而,另一种假设是,这种模式是由亲本的核等位基因来源驱动的。在这里,我们通过将相同的杂交扩展到 F2 杂交种来验证这一替代假设,F2 杂交种从 F1 杂交种中获得了母本和父本核等位基因。结果证实了有丝分裂核对性别比例的影响,尽管 F2 杂交种的适应性降低,但扭曲的性别比例从 F1 代持续到 F2 代。在测量的其他表型性状中,没有发现性别与杂交的相互作用。雌性的线粒体 DNA 含量较高。F2杂交种的常规代谢率和氧化DNA损伤均低于亲本。性别特异性有丝分裂核效应的持续存在,即使在 F2 杂交种破裂的情况下,也证明了这些效应的严重性,它们有助于维持种群内线粒体 DNA 的多态性。
{"title":"Mitonuclear effects on sex ratio persist across generations in interpopulation hybrids.","authors":"Suzanne Edmands, Jacob R Denova, Ben A Flanagan, Murad Jah, Scott L Applebaum","doi":"10.1093/jeb/voae123","DOIUrl":"https://doi.org/10.1093/jeb/voae123","url":null,"abstract":"<p><p>Eukaryotic energy production requires tight coordination between nuclear and mitochondrial gene products. Because males and females often have different energetic strategies, optimal mitonuclear coordination may be sex-specific. Previous work found evidence for sex-specific mitonuclear effects in the copepod Tigriopus californicus by comparing two parental lines and their reciprocal F1 crosses. However, an alternative hypothesis is that the patterns were driven by the parental source of nuclear alleles. Here we test this alternative hypothesis by extending the same cross to F2 hybrids, who receive both maternal and paternal nuclear alleles from F1 hybrids. Results confirm mitonuclear effects on sex ratio, with distorted ratios persisting from the F1 to F2 generations, despite reduced fitness in F2 hybrids. No sex by cross interactions were found for other phenotypic traits measured. Mitochondrial DNA content was higher in females. Both routine metabolic rate and oxidative DNA damage were lower in F2 hybrids than in parentals. The persistence of sex-specific mitonuclear effects, even in the face of F2 hybrid breakdown, attests to the magnitude of these effects, which contribute to the maintenance of within-population mitochondrial DNA polymorphisms.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142331495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luis Rodrigo Arce-Valdés, Andrea Viviana Ballén-Guapacha, Anais Rivas-Torres, Jesús Ramsés Chávez-Ríos, Maren Wellenreuther, Bengt Hansson, Rosa Ana Sánchez Guillén
Theoretical work suggests that reinforcement can cause the strengthening of prezygotic isolation in sympatry by mitigating the costs of maladaptive hybridization. However, only a handful of studies have simultaneously tested multiple predictions of this theory in natural populations. We investigated reinforcement in a mottled hybrid zone between the damselflies Ischnura elegans and I. graellsii, which are characterized by incomplete and asymmetric reproductive isolation and exhibit reproductive character displacement in mating-related structures. We tested the conditions for reinforcement by quantifying whether hybridization was costly and prezygotic isolation stronger in sympatry compared with allopatry. Additionally, we investigated two specific predictions of reinforcement: i) greater premating asymmetries in sympatry; and ii) weaker postzygotic isolation in sympatry than in allopatry. Our findings indicate the presence of maladaptive hybrids, which suggests Bateson-Dobzhansky-Müller incompatibilities in allopatry. We also found that reinforcement has strengthened mechanical isolation, at least in one direction in sympatry. We observed evidence for greater premating asymmetries in sympatry than in allopatry, which is consistent with reinforcement. However, fully testing the prediction of weaker postzygotic isolation in sympatry compared to allopatry was hindered by the highly asymmetrical levels of reproductive isolation between the two reciprocal cross directions. Our study highlights a case where reinforcement and heterospecific gene flow exert opposite effects on reproductive isolation between reciprocal crosses, where reinforcement increases reproductive isolation in one direction while gene flow weakens it in the opposite direction.
{"title":"Testing the predictions of reinforcement: long-term empirical data from a damselfly mottled hybrid zone.","authors":"Luis Rodrigo Arce-Valdés, Andrea Viviana Ballén-Guapacha, Anais Rivas-Torres, Jesús Ramsés Chávez-Ríos, Maren Wellenreuther, Bengt Hansson, Rosa Ana Sánchez Guillén","doi":"10.1093/jeb/voae124","DOIUrl":"https://doi.org/10.1093/jeb/voae124","url":null,"abstract":"<p><p>Theoretical work suggests that reinforcement can cause the strengthening of prezygotic isolation in sympatry by mitigating the costs of maladaptive hybridization. However, only a handful of studies have simultaneously tested multiple predictions of this theory in natural populations. We investigated reinforcement in a mottled hybrid zone between the damselflies Ischnura elegans and I. graellsii, which are characterized by incomplete and asymmetric reproductive isolation and exhibit reproductive character displacement in mating-related structures. We tested the conditions for reinforcement by quantifying whether hybridization was costly and prezygotic isolation stronger in sympatry compared with allopatry. Additionally, we investigated two specific predictions of reinforcement: i) greater premating asymmetries in sympatry; and ii) weaker postzygotic isolation in sympatry than in allopatry. Our findings indicate the presence of maladaptive hybrids, which suggests Bateson-Dobzhansky-Müller incompatibilities in allopatry. We also found that reinforcement has strengthened mechanical isolation, at least in one direction in sympatry. We observed evidence for greater premating asymmetries in sympatry than in allopatry, which is consistent with reinforcement. However, fully testing the prediction of weaker postzygotic isolation in sympatry compared to allopatry was hindered by the highly asymmetrical levels of reproductive isolation between the two reciprocal cross directions. Our study highlights a case where reinforcement and heterospecific gene flow exert opposite effects on reproductive isolation between reciprocal crosses, where reinforcement increases reproductive isolation in one direction while gene flow weakens it in the opposite direction.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142331497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liam J Revell, Klaus P Schliep, D L Mahler, T Ingram
Many hypotheses in the field of phylogenetic comparative biology involve specific changes in the rate or process of trait evolution. This is particularly true of approaches designed to connect macroevolutionary pattern to microevolutionary process. We present a method designed to test whether the rate of evolution of a discrete character has changed in one or more clades, lineages, or time periods. This method differs from other related approaches (such as the 'covarion' model) in that the 'regimes' in which the rate or process is postulated to have changed are specified a priori by the user, rather than inferred from the data. Similarly, it differs from methods designed to model a correlation between two binary traits in that the regimes mapped onto the tree are fixed. We apply our method to investigate the rate of dewlap color and/or caudal vertebra number evolution in Caribbean and mainland clades of the diverse lizard genus Anolis. We find little evidence to support any difference in the evolutionary process between mainland and island evolution for either character. We also examine the statistical properties of the method more generally and show that it has acceptable type I error, parameter estimation, and power. Finally, we discuss some general issues of frequentist hypothesis testing and model adequacy, as well as the relationship of our method to existing models of heterogeneity in the rate of discrete character evolution on phylogenies.
系统进化比较生物学领域的许多假说都涉及性状进化速度或过程的具体变化。对于旨在将宏观进化模式与微观进化过程联系起来的方法来说,尤其如此。我们提出了一种方法,旨在检验一个或多个支系、世系或时间段内离散特征的进化速度是否发生了变化。这种方法与其他相关方法(如 "covarion "模型)的不同之处在于,假设进化速度或过程发生变化的 "体系 "是由用户先验指定的,而不是从数据中推断出来的。同样,它也不同于为两个二元性状之间的相关性建模而设计的方法,因为映射到树上的制度是固定的。我们应用我们的方法研究了加勒比海和大陆各支系中不同蜥蜴属 Anolis 的露舌颜色和/或尾椎数量的进化速度。我们发现几乎没有证据支持大陆和岛屿在这两种特征的进化过程中存在任何差异。我们还对该方法的统计特性进行了更广泛的研究,结果表明该方法具有可接受的 I 型误差、参数估计和功率。最后,我们讨论了频数假设检验和模型适当性的一些一般性问题,以及我们的方法与系统发育上离散特征进化速度异质性现有模型的关系。
{"title":"Testing for heterogeneous rates of discrete character evolution on phylogenies.","authors":"Liam J Revell, Klaus P Schliep, D L Mahler, T Ingram","doi":"10.1093/jeb/voae119","DOIUrl":"https://doi.org/10.1093/jeb/voae119","url":null,"abstract":"<p><p>Many hypotheses in the field of phylogenetic comparative biology involve specific changes in the rate or process of trait evolution. This is particularly true of approaches designed to connect macroevolutionary pattern to microevolutionary process. We present a method designed to test whether the rate of evolution of a discrete character has changed in one or more clades, lineages, or time periods. This method differs from other related approaches (such as the 'covarion' model) in that the 'regimes' in which the rate or process is postulated to have changed are specified a priori by the user, rather than inferred from the data. Similarly, it differs from methods designed to model a correlation between two binary traits in that the regimes mapped onto the tree are fixed. We apply our method to investigate the rate of dewlap color and/or caudal vertebra number evolution in Caribbean and mainland clades of the diverse lizard genus Anolis. We find little evidence to support any difference in the evolutionary process between mainland and island evolution for either character. We also examine the statistical properties of the method more generally and show that it has acceptable type I error, parameter estimation, and power. Finally, we discuss some general issues of frequentist hypothesis testing and model adequacy, as well as the relationship of our method to existing models of heterogeneity in the rate of discrete character evolution on phylogenies.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142299854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The evolution of sexual ornaments in animals is typically attributed to reproductive competition. However, sexual ornaments also arise in contexts where the ornamented sex is neither mate nor gamete limited, and explanations for ornamentation in these cases remains incomplete. In many species, particularly those with slow life histories, lifetime reproductive success depends more strongly on adult survival than fecundity, and survival can depend on intersexual interactions. We develop a population genetic model to investigate how the effect of intersexual interactions on survival may contribute to ornament evolution in the absence of competition for mates. Using female ornamentation in polygynous mating systems as a case study, we show that, indeed, ornaments can evolve when the ornament functions to modify interactions with males in ways that enhance a female's own survival. The evolutionary dynamics depend on qualitatively on the specific behavioral mechanism by which the ornament modifies social interactions. In all cases, the ornament's long-term persistence is ultimately determined by the coevolution of the male locus that determines how males affect female survival. We outline the scenarios that are most likely to favor the evolution of female ornaments through effects of intersexual interactions on survival, and we urge empirical researchers to consider the potential for this social selection mechanism to shape traits of interest across taxa.
{"title":"The effects of intersexual interactions on survival can drive the evolution of female ornaments in the absence of mate limitation.","authors":"J Colton Watts, Courtney L Fitzpatrick","doi":"10.1093/jeb/voae121","DOIUrl":"https://doi.org/10.1093/jeb/voae121","url":null,"abstract":"<p><p>The evolution of sexual ornaments in animals is typically attributed to reproductive competition. However, sexual ornaments also arise in contexts where the ornamented sex is neither mate nor gamete limited, and explanations for ornamentation in these cases remains incomplete. In many species, particularly those with slow life histories, lifetime reproductive success depends more strongly on adult survival than fecundity, and survival can depend on intersexual interactions. We develop a population genetic model to investigate how the effect of intersexual interactions on survival may contribute to ornament evolution in the absence of competition for mates. Using female ornamentation in polygynous mating systems as a case study, we show that, indeed, ornaments can evolve when the ornament functions to modify interactions with males in ways that enhance a female's own survival. The evolutionary dynamics depend on qualitatively on the specific behavioral mechanism by which the ornament modifies social interactions. In all cases, the ornament's long-term persistence is ultimately determined by the coevolution of the male locus that determines how males affect female survival. We outline the scenarios that are most likely to favor the evolution of female ornaments through effects of intersexual interactions on survival, and we urge empirical researchers to consider the potential for this social selection mechanism to shape traits of interest across taxa.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142299855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When mating is promiscuous, the ejaculate volume allocated to each female is expected (intuitively) to be linked with the presence and number of rival males. Previous theories have indicated that, in the absence of rival males, males will allocate the minimum ejaculate volume sufficient for fertilization of all available oocytes. However, it is unclear if this ejaculation strategy is still effective where females have a mechanism to remove sperm after copulation ('female sperm rejection'). In the Japanese pygmy squid, Idiosepius paradoxus, female sperm rejection was observed to occur frequently, but males were able to increase the remaining sperm volume available for fertilization, suggesting that there is no significant impact of female sperm rejection on male ejaculation strategy. However, males decreased ejaculate volume in the presence of rival males and increased it in their absence, a pattern counterintuitive to predictions from previous theories. Females reject sperm at every copulation, so, after copulation, the amount of a given male's sperm remaining with the female may decrease after each subsequent rival copulates with the female. Perhaps in this species the presence of rivals signals the risk of further sperm rejection, so males choose to conserve their resources and move on.
{"title":"In the presence of rivals, males allocate less ejaculate per mating in Japanese pygmy squid with female sperm rejection.","authors":"Ryohei Tanabe, Nobuhiko Akiyama, Noriyosi Sato","doi":"10.1093/jeb/voae120","DOIUrl":"https://doi.org/10.1093/jeb/voae120","url":null,"abstract":"<p><p>When mating is promiscuous, the ejaculate volume allocated to each female is expected (intuitively) to be linked with the presence and number of rival males. Previous theories have indicated that, in the absence of rival males, males will allocate the minimum ejaculate volume sufficient for fertilization of all available oocytes. However, it is unclear if this ejaculation strategy is still effective where females have a mechanism to remove sperm after copulation ('female sperm rejection'). In the Japanese pygmy squid, Idiosepius paradoxus, female sperm rejection was observed to occur frequently, but males were able to increase the remaining sperm volume available for fertilization, suggesting that there is no significant impact of female sperm rejection on male ejaculation strategy. However, males decreased ejaculate volume in the presence of rival males and increased it in their absence, a pattern counterintuitive to predictions from previous theories. Females reject sperm at every copulation, so, after copulation, the amount of a given male's sperm remaining with the female may decrease after each subsequent rival copulates with the female. Perhaps in this species the presence of rivals signals the risk of further sperm rejection, so males choose to conserve their resources and move on.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142299853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Elizabeth A Mittell, Priyam Mandaliya, Josephine M Pemberton, Alison Morris, Sean Morris, Susan E Johnston, Loeske E B Kruuk
While senescence is a common occurrence in wild populations, not all traits decline with age simultaneously and some do not show any senes- cence. A lack of senescence in secondary sexual traits is thought to be due to their importance for reproductive success. However, if reproduc- tive success senesces, why would secondary sexual traits apparently not senesce? Here we explored this question in a wild population of red deer (Cervus elaphus) using antler form (number of points), a secondary sexual trait which shows little senescence, despite the occurrence of reproductive senescence. In line with expectations for traits that senesce, genetic vari- ance in antler form increased with age and selection weakened with age. Therefore, there was no indication that stronger selection on individu- als that survived to older ages was countering the dilution of selection due to fewer individuals being alive. Furthermore, the effect of selec- tive disappearance masking a slight decline in antler form in the oldest years was small. Interestingly, although genetic variance and positive se- lection of antler form were found, there was no evidence of a response to selection, supporting a genetic decoupling of antler senescence and re- productive senescence. Finally, a positive genetic covariance in antler form among age classes provides a possible explanation for the the lack of senescence. These findings suggest that antler form is under a genetic constraint that prevents it from senescing, providing an interesting evolu- tionary explanation for negligible senescence in a secondary sexual trait, and consequently, the existence of asynchrony in senescence among traits within populations.
{"title":"Antler size in red deer: declining selection and increasing genetic variance with age, but little senescence.","authors":"Elizabeth A Mittell, Priyam Mandaliya, Josephine M Pemberton, Alison Morris, Sean Morris, Susan E Johnston, Loeske E B Kruuk","doi":"10.1093/jeb/voae112","DOIUrl":"https://doi.org/10.1093/jeb/voae112","url":null,"abstract":"<p><p>While senescence is a common occurrence in wild populations, not all traits decline with age simultaneously and some do not show any senes- cence. A lack of senescence in secondary sexual traits is thought to be due to their importance for reproductive success. However, if reproduc- tive success senesces, why would secondary sexual traits apparently not senesce? Here we explored this question in a wild population of red deer (Cervus elaphus) using antler form (number of points), a secondary sexual trait which shows little senescence, despite the occurrence of reproductive senescence. In line with expectations for traits that senesce, genetic vari- ance in antler form increased with age and selection weakened with age. Therefore, there was no indication that stronger selection on individu- als that survived to older ages was countering the dilution of selection due to fewer individuals being alive. Furthermore, the effect of selec- tive disappearance masking a slight decline in antler form in the oldest years was small. Interestingly, although genetic variance and positive se- lection of antler form were found, there was no evidence of a response to selection, supporting a genetic decoupling of antler senescence and re- productive senescence. Finally, a positive genetic covariance in antler form among age classes provides a possible explanation for the the lack of senescence. These findings suggest that antler form is under a genetic constraint that prevents it from senescing, providing an interesting evolu- tionary explanation for negligible senescence in a secondary sexual trait, and consequently, the existence of asynchrony in senescence among traits within populations.</p>","PeriodicalId":50198,"journal":{"name":"Journal of Evolutionary Biology","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142299851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}