Hypothesis: Natural and sexual selection should be stronger on whole-organism functional performance traits (sprinting, biting) than on correlated morphological variables. Organisms: Lizards, snakes, turtles, frogs, and fish (review of past field and laboratory studies). Field sites: Various (review of past field and laboratory studies). Methods: We reviewed existing literature on the nature and intensity of natural and sexual selection on whole-organism performance traits. We answer some key questions in regards to how selection operates on performance, and whether selection is stronger on performance compared with morphological traits. Results: We identified 23 studies that have quantified selection on performance. Natural and sexual selection were typically directional in nature, with a distinct preference for high rather than low values of performance. However, some studies uncovered no significant selection on performance, and there was also no evidence that selection was stronger on performance traits than morphological traits.
{"title":"How does selection operate on whole-organism functional performance capacities? A review and synthesis","authors":"D. Irschick, J. Meyers, J. Husak, J. Galliard","doi":"10.7275/R58G8HX6","DOIUrl":"https://doi.org/10.7275/R58G8HX6","url":null,"abstract":"Hypothesis: Natural and sexual selection should be stronger on whole-organism functional performance traits (sprinting, biting) than on correlated morphological variables. Organisms: Lizards, snakes, turtles, frogs, and fish (review of past field and laboratory studies). Field sites: Various (review of past field and laboratory studies). Methods: We reviewed existing literature on the nature and intensity of natural and sexual selection on whole-organism performance traits. We answer some key questions in regards to how selection operates on performance, and whether selection is stronger on performance compared with morphological traits. Results: We identified 23 studies that have quantified selection on performance. Natural and sexual selection were typically directional in nature, with a distinct preference for high rather than low values of performance. However, some studies uncovered no significant selection on performance, and there was also no evidence that selection was stronger on performance traits than morphological traits.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"10 1","pages":"177-196"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71384069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
474–498; Endler, J., 1986, Natural Selection in the Wild. Princeton, NJ: Princeton University Press; Kingsolver et al., 2001, Am. Nat., 157: 245–261). While we agree that such attention is warranted, we aim to divert your attention towards another topic, namely the microevolution of whole-organism performance capacity. The articles in this special collection present more detail on definitions of performance capacity, but we define it here as the quantitative measure of the ability of an organism to conduct an ecologically relevant task. Classic examples include sprint speed, bite force, and locomotor endurance, among other measures (Irschick, D.J., and Garland, T., Jr., 2001, Annu. Rev. Ecol. Syst., 32: 367–396). The most burning issue that motivated this special collection was how the forces of natural and sexual selection operate on performance traits, in contrast to morphology. Because performance as defined here is measured at the whole-organism level, variation in performance arises from variation from many other traits, such as aspects of physiology and morphological shape. Therefore, visualizing selection on performance is potentially trickier than for morphology because one is immediately drawn to the potential for interrelationships: does selection favour high performance, good morphological attributes, or both? Some of the papers in this special collection address this topic head-on, and suggest a high degree of interrcorrelation between morphology and performance, as well as with behaviour (Le Galliard and Ferriere, this issue). Another paper shows that the strength of selection appears not to differ between morphological and performance traits (Irschick, Meyers, Husak, and Le Galliard, this issue). These findings remind the reader of the complex nature of co-evolved aspects of the phenotype and genotype (Cheverud, J., 1982, Evolution, 36: 499–516), and also imply that selection studies should aim to move towards more comprehensive measures of the entire phenotype and emergent functional and behavioural properties. A review of selection studies (Irschick et al., this issue) reveals another interesting finding – selection on performance, much like morphology, is rarely stabilizing or disruptive. Nearly half of the 23 selection studies reviewed were directional, with a distinct favouring of high performance. One intriguing possibility is that selection may favour different combinations of morphology and performance in different years, as environmental conditions change (Calsbeek, this issue), leading to directional selection within a season and a more static pattern of evolution over ecological time. Sadly, as this special collection highlights, we lack the long-term studies of performance to test this intriguing possibility. One of the most exciting developments over the past 10 years has been an increased appreciation for the dual and potentially conflicting role of sexual and natural selection (Le Galliard and Ferriere, this issue). I
474 - 498;Endler, J.， 1986，《野外自然选择》。普林斯顿，新泽西州:普林斯顿大学出版社;Kingsolver et al.， 2001, Am。《自然》，157:245-261)。虽然我们同意这种关注是必要的，但我们的目标是将您的注意力转移到另一个主题，即整个生物体性能能力的微观进化。本特辑中的文章对性能能力的定义进行了更详细的介绍，但我们在这里将其定义为生物体执行生态相关任务的能力的定量度量。经典的例子包括冲刺速度，咬合力和运动耐力，以及其他测量(Irschick, d.j.， and Garland, T.， Jr.， 2001, Annu。启生态。系统。科学通报，32:367-396)。激发这一特别收藏的最紧迫的问题是，与形态学相反，自然和性选择的力量是如何作用于性能特征的。因为这里定义的表现是在整个有机体水平上衡量的，所以表现的变化源于许多其他特征的变化，例如生理和形态形状方面。因此，可视化性能上的选择可能比形态学上的选择更棘手，因为人们会立即被潜在的相互关系所吸引:选择是倾向于高性能、良好的形态学属性，还是两者兼而有之?本特辑中的一些论文正面讨论了这一主题，并提出形态和性能以及行为之间存在高度的相互关系(Le Galliard和Ferriere，本期)。另一篇论文表明，选择的强度似乎在形态特征和性能特征之间没有差异(Irschick, Meyers, Husak, and Le Galliard，本期)。这些发现提醒读者注意表型和基因型共同进化方面的复杂性(Cheverud, J.， 1982, Evolution, 36: 499-516)，也暗示选择研究应该朝着更全面地测量整个表型和突现功能和行为特性的方向发展。对选择研究的回顾(Irschick et al.，本期)揭示了另一个有趣的发现——对表现的选择，就像形态学一样，很少是稳定的或破坏性的。在23项选择研究中，近一半是定向的，明显倾向于高绩效。一种有趣的可能性是，随着环境条件的变化，在不同的年份，选择可能倾向于形态和性能的不同组合(calsheek，本期)，导致在一个季节内的定向选择和在生态时间内更静态的进化模式。可悲的是，正如这个特别的收藏所强调的那样，我们缺乏对性能的长期研究来测试这种有趣的可能性。在过去10年里，最令人兴奋的发展之一是人们越来越认识到性选择和自然选择的双重作用和潜在的冲突(Le Galliard和Ferriere，本期)。在本特辑的一些论文中，有证据表明这两种力量是一致的，这意味着高质量的男性(至少在英国)
{"title":"Studying the evolution of whole-organism performance capacity: sex, selection, and haiku - an introduction","authors":"D. Irschick, J. L. Galliard","doi":"10.7275/R5D798NX","DOIUrl":"https://doi.org/10.7275/R5D798NX","url":null,"abstract":"474–498; Endler, J., 1986, Natural Selection in the Wild. Princeton, NJ: Princeton University Press; Kingsolver et al., 2001, Am. Nat., 157: 245–261). While we agree that such attention is warranted, we aim to divert your attention towards another topic, namely the microevolution of whole-organism performance capacity. The articles in this special collection present more detail on definitions of performance capacity, but we define it here as the quantitative measure of the ability of an organism to conduct an ecologically relevant task. Classic examples include sprint speed, bite force, and locomotor endurance, among other measures (Irschick, D.J., and Garland, T., Jr., 2001, Annu. Rev. Ecol. Syst., 32: 367–396). The most burning issue that motivated this special collection was how the forces of natural and sexual selection operate on performance traits, in contrast to morphology. Because performance as defined here is measured at the whole-organism level, variation in performance arises from variation from many other traits, such as aspects of physiology and morphological shape. Therefore, visualizing selection on performance is potentially trickier than for morphology because one is immediately drawn to the potential for interrelationships: does selection favour high performance, good morphological attributes, or both? Some of the papers in this special collection address this topic head-on, and suggest a high degree of interrcorrelation between morphology and performance, as well as with behaviour (Le Galliard and Ferriere, this issue). Another paper shows that the strength of selection appears not to differ between morphological and performance traits (Irschick, Meyers, Husak, and Le Galliard, this issue). These findings remind the reader of the complex nature of co-evolved aspects of the phenotype and genotype (Cheverud, J., 1982, Evolution, 36: 499–516), and also imply that selection studies should aim to move towards more comprehensive measures of the entire phenotype and emergent functional and behavioural properties. A review of selection studies (Irschick et al., this issue) reveals another interesting finding – selection on performance, much like morphology, is rarely stabilizing or disruptive. Nearly half of the 23 selection studies reviewed were directional, with a distinct favouring of high performance. One intriguing possibility is that selection may favour different combinations of morphology and performance in different years, as environmental conditions change (Calsbeek, this issue), leading to directional selection within a season and a more static pattern of evolution over ecological time. Sadly, as this special collection highlights, we lack the long-term studies of performance to test this intriguing possibility. One of the most exciting developments over the past 10 years has been an increased appreciation for the dual and potentially conflicting role of sexual and natural selection (Le Galliard and Ferriere, this issue). I","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71383686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
.This has been interpreted to be a consequence of large mammals (mostly herbivores)harbouring symbiotic bacteria in their gastrointestinal tract and therefore (a) they arehardly ever in a ‘post-absorptive’ state and (b) the metabolism of these symbionts isincluded in any measurement on the host organism. The only way to address this problemis to exclude larger species from regressions. Using the
{"title":"Mammalian metabolic rate scaling to 2/3 or 3/4 depends on the presence of gut contents","authors":"M. Clauss, J. Hummel, W. Streich, K. Südekum","doi":"10.5167/UZH-3488","DOIUrl":"https://doi.org/10.5167/UZH-3488","url":null,"abstract":".This has been interpreted to be a consequence of large mammals (mostly herbivores)harbouring symbiotic bacteria in their gastrointestinal tract and therefore (a) they arehardly ever in a ‘post-absorptive’ state and (b) the metabolism of these symbionts isincluded in any measurement on the host organism. The only way to address this problemis to exclude larger species from regressions. Using the","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"12 1","pages":"153-154"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70649533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Question: Does testosterone suppress the immune system of males in a strongly sexually dimorphic and long-lived ungulate?Immunocompetence handicap hypothesis: Testosterone promotes the development of secondary sexual characteristics and simultaneously suppresses immunological defence.Organisms: Free-ranging and individually identifiable male Alpine ibex (Capra ibex).Methods: In faecal samples, measure testosterone levels (ng · g−1) and the number of parasite eggs per gram of faeces (faecal egg counts). Determine social dominance by observing the outcomes of agonistic interactions in the field. Weigh males at a salt-lick scale.Data analysis: Path analysis to examine the relationships between testosterone levels, dominance, body mass, age, and faecal egg counts.Conclusions: We found a strong positive effect of testosterone on the amount of parasite eggs in the faeces of males. The level of parasite infection did not depend on any other tested variable. Testosterone therefore has an immunosuppressive effect in male Alpine ibex, assuggested by the immunocompetence handicap hypothesis.
{"title":"Testosterone is positively related to the output of nematode eggs in male Alpine ibex (Capra ibex) faeces","authors":"P. Decristophoris, A. Hardenberg, A. McElligott","doi":"10.5167/UZH-714","DOIUrl":"https://doi.org/10.5167/UZH-714","url":null,"abstract":"Question: Does testosterone suppress the immune system of males in a strongly sexually dimorphic and long-lived ungulate?Immunocompetence handicap hypothesis: Testosterone promotes the development of secondary sexual characteristics and simultaneously suppresses immunological defence.Organisms: Free-ranging and individually identifiable male Alpine ibex (Capra ibex).Methods: In faecal samples, measure testosterone levels (ng · g−1) and the number of parasite eggs per gram of faeces (faecal egg counts). Determine social dominance by observing the outcomes of agonistic interactions in the field. Weigh males at a salt-lick scale.Data analysis: Path analysis to examine the relationships between testosterone levels, dominance, body mass, age, and faecal egg counts.Conclusions: We found a strong positive effect of testosterone on the amount of parasite eggs in the faeces of males. The level of parasite infection did not depend on any other tested variable. Testosterone therefore has an immunosuppressive effect in male Alpine ibex, assuggested by the immunocompetence handicap hypothesis.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"9 1","pages":"1277-1292"},"PeriodicalIF":0.0,"publicationDate":"2007-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70660698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
QUESTIONS: Whether or not cooperation can be enhanced if players with a performance higher than the mean are forced to pay an additional cost in each generation? MATHEMATICAL METHODS: Analysis of replicator dynamics with mutation. The ESS distribution of cooperation level is obtained. KEY ASSUMPTIONS: Players engage in cooperative dilemma game, and at the end of each generation, those with higher performance than the mean are forced to pay additional cost. CONCLUSIONS: Without mutation, the entire population eventually conforms to a single cooperation level determined by the initial composition of the population. With mutation, there is an equilibrium distribution of cooperation level, which has a peak at an intermediate level of cooperation. Whether it is institutionalized such as tax or just a social custom, fitness adjustment based ultimately on people's emtion of "envy" is able to maintain cooperation.
{"title":"COOPERATION MAINTAINED BY FITNESS ADJUSTMENT.","authors":"Christine Taylor, Janet Chen, Yoh Iwasa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>QUESTIONS: Whether or not cooperation can be enhanced if players with a performance higher than the mean are forced to pay an additional cost in each generation? MATHEMATICAL METHODS: Analysis of replicator dynamics with mutation. The ESS distribution of cooperation level is obtained. KEY ASSUMPTIONS: Players engage in cooperative dilemma game, and at the end of each generation, those with higher performance than the mean are forced to pay additional cost. CONCLUSIONS: Without mutation, the entire population eventually conforms to a single cooperation level determined by the initial composition of the population. With mutation, there is an equilibrium distribution of cooperation level, which has a peak at an intermediate level of cooperation. Whether it is institutionalized such as tax or just a social custom, fitness adjustment based ultimately on people's emtion of \"envy\" is able to maintain cooperation.</p>","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"9 6","pages":"1023-1041"},"PeriodicalIF":0.0,"publicationDate":"2007-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2600810/pdf/nihms49941.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"27897061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Questions: What was the distribution of fossil mammal taxa in the Miocene German Molasse Basin? Were there changes in community structure during the terrestrial development of the Molasse Basin? Were community dynamics similar in the Molasse Basin to those in the rest of Europe? Data: We gathered the available Miocene large mammal herbivore occurrences from the southern German Molasse Basin [museum data mainly from Munich (Germany), with additional data from museums in Stuttgart (Germany) and Vienna (Austria)]. We used public data from NOW (Neogene of the Old World database, http://www.helsinki.fi/science/now) for comparison and as the source of ecological data for the species. Methods: We combined ecological data from the NOW database with distributions of herbivorous mammals within the Molasse Basin. We plotted the occurrences of taxa on a base map, and used the associated body size and dietary categories to plot these data on the map. We investigated the differences in the structure of communities in different time periods. We compared different time periods and differences among areas. We also compared the Molasse Basin and NOW data. Conclusions: The evolution of large-mammal communities in the Molasse Basin occurred in two phases: build up and decline. The build-up phase was characterized especially by a high abundance of small-sized browsers and mixed feeders. The diversity was especially high during the built-up phase, indicating a highly differentiated wetland habitat. The decline phase saw a very different community structure with fewer mixed feeders and with larger sized mammals dominating. The difference between these phases was largely the consequence of regional extinctions of species and genera. The Molasse Basin community dynamics also differ from those of the rest of Europe (NOW data).
{"title":"Wetland paradise lost: Miocene community dynamics in large herbivorous mammals from the German Molasse Basin","authors":"J. Eronen, Gertrud E. Rössner","doi":"10.5282/UBM/EPUB.11444","DOIUrl":"https://doi.org/10.5282/UBM/EPUB.11444","url":null,"abstract":"Questions: What was the distribution of fossil mammal taxa in the Miocene German Molasse Basin? Were there changes in community structure during the terrestrial development of the Molasse Basin? Were community dynamics similar in the Molasse Basin to those in the rest of Europe? Data: We gathered the available Miocene large mammal herbivore occurrences from the southern German Molasse Basin [museum data mainly from Munich (Germany), with additional data from museums in Stuttgart (Germany) and Vienna (Austria)]. We used public data from NOW (Neogene of the Old World database, http://www.helsinki.fi/science/now) for comparison and as the source of ecological data for the species. Methods: We combined ecological data from the NOW database with distributions of herbivorous mammals within the Molasse Basin. We plotted the occurrences of taxa on a base map, and used the associated body size and dietary categories to plot these data on the map. We investigated the differences in the structure of communities in different time periods. We compared different time periods and differences among areas. We also compared the Molasse Basin and NOW data. Conclusions: The evolution of large-mammal communities in the Molasse Basin occurred in two phases: build up and decline. The build-up phase was characterized especially by a high abundance of small-sized browsers and mixed feeders. The diversity was especially high during the built-up phase, indicating a highly differentiated wetland habitat. The decline phase saw a very different community structure with fewer mixed feeders and with larger sized mammals dominating. The difference between these phases was largely the consequence of regional extinctions of species and genera. The Molasse Basin community dynamics also differ from those of the rest of Europe (NOW data).","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"9 1","pages":"471-494"},"PeriodicalIF":0.0,"publicationDate":"2007-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71095090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Competing hypotheses: (1) Large body size confers more efficient energy use (relative efficiency hypothesis). (2) Large body size requires more energy to be sustained, a disadvantage when food is limited (absolute energy demand hypothesis). Organism: Yellow dung flies, Scathophaga stercoraria (Diptera: Scathophagidae), artificially selected for large and small body size in the laboratory for 11 (24) generations. Methods: Flies were reared in limited and unlimited larval food conditions and low and stressfully high temperatures, and after adult emergence they were held on water only to study the relationship between energy content (lipids, glucose, glycogen) and (physiological) adult life span under complete starvation (starvation resistance) in the laboratory. Conclusions: Limited larval food and high temperature decreased life span. Life span increased markedly with body size due to the greater energy content of larger flies. Small selection line flies had relatively more energy and longer life spans under complete starvation, indicating a compensatory correlated genetic response to body size selection. The larger males suffered most under multiple stresses. Our results support the relative efficiency hypothesis, which more than compensates for the greater absolute energy demand of larger individuals.
{"title":"Size-dependent effects of temperature and food stress on energy reserves and starvation resistance in yellow dung flies","authors":"C. Reim, Y. Teuschl, W. Blanckenhorn","doi":"10.5167/UZH-76182","DOIUrl":"https://doi.org/10.5167/UZH-76182","url":null,"abstract":"Competing hypotheses: (1) Large body size confers more efficient energy use (relative efficiency hypothesis). (2) Large body size requires more energy to be sustained, a disadvantage when food is limited (absolute energy demand hypothesis). Organism: Yellow dung flies, Scathophaga stercoraria (Diptera: Scathophagidae), artificially selected for large and small body size in the laboratory for 11 (24) generations. Methods: Flies were reared in limited and unlimited larval food conditions and low and stressfully high temperatures, and after adult emergence they were held on water only to study the relationship between energy content (lipids, glucose, glycogen) and (physiological) adult life span under complete starvation (starvation resistance) in the laboratory. Conclusions: Limited larval food and high temperature decreased life span. Life span increased markedly with body size due to the greater energy content of larger flies. Small selection line flies had relatively more energy and longer life spans under complete starvation, indicating a compensatory correlated genetic response to body size selection. The larger males suffered most under multiple stresses. Our results support the relative efficiency hypothesis, which more than compensates for the greater absolute energy demand of larger individuals.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"8 1","pages":"1215-1234"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70661510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ability to create shelters that provide protection from the environment is widespread among animals. However, in spite of the central role roosts play in the life of bats (Chiroptera), only a few species have developed the ability to make their own refuges, one of them being the Neotropical Lophostoma silvicolum. This bat creates and inhabits cavities in active arboreal nests of the termite Nasutitermes corniger. We measured temperature in cavities inside active and dead termite nests, and in tree holes occupied by closely related bats, to determine whether energetic benefits compensate for the cost of excavating the hard nests. The inside temperatures of active termite nests were very stable and 2.1–2.8 °C warmer than those of the other two potential roost types. The observed temperature difference is estimated to allow euthermic L. silvicolum to save about 5% of their daily energy expenditure when roosting in active termite nests instead of dead nests or tree holes. Suitable roosting conditions result from the presence of termites and are independent of nest architecture. Our results indicate that the benefits of higher temperatures may be one of the driving forces promoting the evolution of active roost making in bats.
{"title":"Ecology of an exceptional roost: Energetic benefits could explain why the bat Lophostoma silvicolum roosts in active termite nests","authors":"D. Dechmann, E. Kalko, G. Kerth","doi":"10.5167/UZH-584","DOIUrl":"https://doi.org/10.5167/UZH-584","url":null,"abstract":"The ability to create shelters that provide protection from the environment is widespread among animals. However, in spite of the central role roosts play in the life of bats (Chiroptera), only a few species have developed the ability to make their own refuges, one of them being the Neotropical Lophostoma silvicolum. This bat creates and inhabits cavities in active arboreal nests of the termite Nasutitermes corniger. We measured temperature in cavities inside active and dead termite nests, and in tree holes occupied by closely related bats, to determine whether energetic benefits compensate for the cost of excavating the hard nests. The inside temperatures of active termite nests were very stable and 2.1–2.8 °C warmer than those of the other two potential roost types. The observed temperature difference is estimated to allow euthermic L. silvicolum to save about 5% of their daily energy expenditure when roosting in active termite nests instead of dead nests or tree holes. Suitable roosting conditions result from the presence of termites and are independent of nest architecture. Our results indicate that the benefits of higher temperatures may be one of the driving forces promoting the evolution of active roost making in bats.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"6 1","pages":"1037-1050"},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70656525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. McElligott, F. Naulty, William V. Clarke, T. Hayden
The somatic costs of reproduction are important for understanding the relationship between sexual selection and life-history evolution, and there are two main hypotheses used to explain the pattern of reproductive effort in ungulates. The terminal investment hypothesis predicts that reproductive effort should increase with age, because the value of each offspring increases as the number of future potential offspring decreases over the lifetime of an individual. In contrast, the mating strategy-effort hypothesis predicts that reproductive effort should be highest in prime-aged males, and lower in both younger and older males, since prime-aged males are most active in trying to gain matings. We examined reproductive effort among prime-aged (5–8 years old) fallow bucks (Dama dama) by comparing mass loss during the breeding season with mating success and activities associated with mating. Males lost about 26% of their body mass during the breeding season and mating success was strongly positively related to the time spent moving and in vocal display. However, mass loss was not related to either mating success or the behaviours associated with mating success. This indicates that males of higher quality were more efficient at converting energy into reproductive success, and is consistent with our earlier results showing phenotypic quality differences between males in our study population. Mass loss was positively correlated with initial mass. Therefore, body condition at the start of the breeding season was the most important determinant of reproductive effort. Mass loss was not related to age, in that it neither increased with age nor peaked in males that are usually the most reproductively active (ages 6 and 7). Thus, for reproductive effort in prime-aged males, our results do not support either the terminal investment hypothesis or the mating strategy-effort hypothesis.
{"title":"The somatic cost of reproduction: what determines reproductive effort in prime-aged fallow bucks?","authors":"A. McElligott, F. Naulty, William V. Clarke, T. Hayden","doi":"10.5167/UZH-402","DOIUrl":"https://doi.org/10.5167/UZH-402","url":null,"abstract":"The somatic costs of reproduction are important for understanding the relationship between sexual selection and life-history evolution, and there are two main hypotheses used to explain the pattern of reproductive effort in ungulates. The terminal investment hypothesis predicts that reproductive effort should increase with age, because the value of each offspring increases as the number of future potential offspring decreases over the lifetime of an individual. In contrast, the mating strategy-effort hypothesis predicts that reproductive effort should be highest in prime-aged males, and lower in both younger and older males, since prime-aged males are most active in trying to gain matings. We examined reproductive effort among prime-aged (5–8 years old) fallow bucks (Dama dama) by comparing mass loss during the breeding season with mating success and activities associated with mating. Males lost about 26% of their body mass during the breeding season and mating success was strongly positively related to the time spent moving and in vocal display. However, mass loss was not related to either mating success or the behaviours associated with mating success. This indicates that males of higher quality were more efficient at converting energy into reproductive success, and is consistent with our earlier results showing phenotypic quality differences between males in our study population. Mass loss was positively correlated with initial mass. Therefore, body condition at the start of the breeding season was the most important determinant of reproductive effort. Mass loss was not related to age, in that it neither increased with age nor peaked in males that are usually the most reproductively active (ages 6 and 7). Thus, for reproductive effort in prime-aged males, our results do not support either the terminal investment hypothesis or the mating strategy-effort hypothesis.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"5 1","pages":"1239-1250"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70652859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most animals actively avoid predators. If such a reaction reduces competitive ability, for example by reducing food intake, predator presence can lead to trait-mediated indirect effects. Because predator avoidance typically leads to reduced growth rather than reduced survival, its effect on population processes is difficult to assess. This is especially true for organisms with complex life-cycles, where predator avoidance during one stage is expected to lead to traitmediated indirect effects if it has effects reaching into the following life stages. I experimentally investigated the effect of caged (thus non-lethal) dragonfly larvae on the competition between tadpoles of two frog species (Rana lessonae and R. esculenta) and on juvenile frog survival during the subsequent terrestrial stage. In response to caged predators, R. lessonae delayed metamorphosis more than R. esculenta, but they both metamorphosed heavier. These differences suggest the possibility of a competitive disadvantage for R. lessonae in the presence of predators, which could lead to trait-mediated indirect effects. However, the presence of predators did not modify competitive effects and had no measurable consequences on terrestrial survival. Regardless of the presence of predators, competition during the larval stage had large effects on metamorphosis and led to strongly decreased survival in the subsequent terrestrial stage. These results suggest that trait-mediated indirect effects are not important in this system, because the predator reaction of the tadpoles in both species had no measurable effect on the following life stage and, therefore, probably no strong effect on community dynamics.
{"title":"Trait-mediated indirect effects and complex life-cycles in two European frogs","authors":"R. Altwegg","doi":"10.5167/UZH-503","DOIUrl":"https://doi.org/10.5167/UZH-503","url":null,"abstract":"Most animals actively avoid predators. If such a reaction reduces competitive ability, for example by reducing food intake, predator presence can lead to trait-mediated indirect effects. Because predator avoidance typically leads to reduced growth rather than reduced survival, its effect on population processes is difficult to assess. This is especially true for organisms with complex life-cycles, where predator avoidance during one stage is expected to lead to traitmediated indirect effects if it has effects reaching into the following life stages. I experimentally investigated the effect of caged (thus non-lethal) dragonfly larvae on the competition between tadpoles of two frog species (Rana lessonae and R. esculenta) and on juvenile frog survival during the subsequent terrestrial stage. In response to caged predators, R. lessonae delayed metamorphosis more than R. esculenta, but they both metamorphosed heavier. These differences suggest the possibility of a competitive disadvantage for R. lessonae in the presence of predators, which could lead to trait-mediated indirect effects. However, the presence of predators did not modify competitive effects and had no measurable consequences on terrestrial survival. Regardless of the presence of predators, competition during the larval stage had large effects on metamorphosis and led to strongly decreased survival in the subsequent terrestrial stage. These results suggest that trait-mediated indirect effects are not important in this system, because the predator reaction of the tadpoles in both species had no measurable effect on the following life stage and, therefore, probably no strong effect on community dynamics.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"4 1","pages":"519-536"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70654661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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