Testing Evolutionary Theories Research Articles

Taxonomic resurrection of Saxifraga lancangensis (Saxifragaceae)

BackgroundAccurate species delimitation is fundamental for testing evolutionary theory and provides essential implications for conservation management. The arctic-alpine genus Saxifraga L. (Saxifragaceae) is taxonomically complex and many species have not been critically assessed. The taxonomic and phylogenetic status of Saxifraga lancangensis Y.Y.Qian, considered as a synonym of Saxifraga mengtzeana Engl. & Irmsch. in previous studies, is re-evaluated in light of new evidence presented here.ResultsEvidence from morphological comparison and sequencing of plastid genome indicate that S. lancangensis belongs to Saxifraga sect. Irregulares Haw., and is closely related to Saxifraga geifolia Balf.f., and S. mengtzeana. However, S. lancangensis can be diagnosed by its petals with red and clawless base, leaf blade orbicular and leaf margin shallowly dentate.ConclusionsThe morphological and molecular evidence support the resurrection of S. lancangensis as a distinct species. An updated morphological description based on protologue and fresh material, diagnostic characters, and original photographs of the resurrected species are presented.

On the origin of schizophrenia: Testing evolutionary theories in the post-genomic era.

Considering the relatively high heritability of schizophrenia and the fact that it significantly reduces the reproductive fitness of affected individuals, it is not clear how the disorder is still maintained in human populations at a disproportionally high prevalence. Many theories propose that the disorder is a result of a trade-off between costs and benefits of the evolution of exclusively human adaptations. There have also been suggestions that schizophrenia risk alleles are accompanied with increase in fitness of affected persons or their relatives in both past and current social contexts. The discoveries of novel schizophrenia-related genes and the advancements in comparative genomics (especially comparisons of the human genome and the genomes of related species, such as chimpanzees and extinct hominids) have finally made certain evolutionary theories testable. In this paper, we review the current understanding of the genetics of schizophrenia, the basic principles of evolution that complement our understanding of the subject, and the latest genetic studies that examine long-standing evolutionary theories of schizophrenia using novel methodologies and data. We find that the origin of schizophrenia is complex and likely governed by different evolutionary mechanisms that are not mutually exclusive. Furthermore, the most recent evidence implies that schizophrenia cannot be comprehended as a trait that has elevated fitness in human evolutionary lineage, but has been a mildly deleterious by-product of specific patterns of the evolution of the human brain. In other words, novel findings do not support previous hypotheses stating that schizophrenia risk genes have an evolutionary advantage.

On the origin of obesity: identifying the biological, environmental and cultural drivers of genetic risk among human populations.

Genetic predisposition to obesity presents a paradox: how do genetic variants with a detrimental impact on human health persist through evolutionary time? Numerous hypotheses, such as the thrifty genotype hypothesis, attempt to explain this phenomenon yet fail to provide a justification for the modern obesity epidemic. In this critical review, we appraise existing theories explaining the evolutionary origins of obesity and explore novel biological and sociocultural agents of evolutionary change to help explain the modern-day distribution of obesity-predisposing variants. Genetic drift, acting as a form of 'blind justice,' may randomly affect allele frequencies across generations while gene pleiotropy and adaptations to diverse environments may explain the rise and subsequent selection of obesity risk alleles. As an adaptive response, epigenetic regulation of gene expression may impact the manifestation of genetic predisposition to obesity. Finally, exposure to malnutrition and disease epidemics in the wake of oppressive social systems, culturally mediated notions of attractiveness and desirability, and diverse mating systems may play a role in shaping the human genome. As an important first step towards the identification of important drivers of obesity gene evolution, this review may inform empirical research focused on testing evolutionary theories by way of population genetics and mathematical modelling.

Testing evolutionary theory of household consumption behavior in the case of novelty - a product characteristics approach

This article tests and extends the evolutionary theory of household consumption behavior, which is an alternative to neoclassical theory. Evolutionary economists offer novel approaches to the analysis of consumption behavior that emphasize the major role of learning in the evolution of consumer preferences and wants. As a possible inspiration for further progress in evolutionary thought, this paper examines the idea of consumer learning by studying the nature of what consumers should learn in the context of ‘novelty’. Our empirical results regarding novelty during the learning process show that consumers learn the ‘new characteristics’ of consumer goods, contrary to the Lancasterian approach, which suggests that the characteristics space of goods is fixed. We show that during the process of consumption, ‘consumer learning’ extends the characteristics space of consumer goods; this phenomenon is far from negligible and differs across product types. Moreover, our results show that the emergence of new characteristics cannot be modeled as a Poisson process because these new characteristics exhibit clear interdependence over time.

Mate competition and evolutionary outcomes in genetically modified zebrafish (Danio rerio).

Demonstrating relationships between sexual selection mechanisms and trait evolution is central to testing evolutionary theory. Using zebrafish, we found that wild-type males possessed a significant advantage in mate competition over transgenic RFP Glofish® males. In mating trials, wild-type males were aggressively superior to transgenic males in male-male chases and male-female chases; as a result, wild-type males sired 2.5× as many young as did transgenic males. In contrast, an earlier study demonstrated that female zebrafish preferred transgenic males as mates when mate competition was excluded experimentally. We tested the evolutionary consequence of this conflict between sexual selection mechanisms in a long-term study. The predicted loss of the transgenic phenotype was confirmed. More than 18,500 adults collected from 18 populations across 15 generations revealed that the frequency of the transgenic phenotype declined rapidly and was eliminated entirely in all but one population. Fitness component data for both sexes indicated that only male mating success differed between wild-type and transgenic individuals. Our predictive demographic model based on fitness components closely matched the rate of transgenic phenotype loss observed in the long-term study, thereby supporting its utility for studies assessing evolutionary outcomes of escaped or released genetically modified animals.

Seasonal male plumage as a multi-component sexual signal: insights and opportunities

Seasonal breeding plumage of male fairy-wrens (Malurus spp.) shows significant inter-and intra-specific variation in several potential signalling components that we systematically review here. There is extensive colour variation in the genus, possibly related to variation in visual sensitivity. In many species, males can delay development of their first complete breeding plumage for one or more years, although males in more complete breeding plumage appear to be reproductively more successful. An additional sexual signal, and an evolutionary innovation, is the timing of the pre-breeding moult. A mechanism regulating this moult is testosterone, which can stimulate initiation of moult and development of male breeding colouration and is presumably required for maintenance of the breeding plumage. Males undertake pre-breeding moult earlier as they age, and early pre-breeding moult appears selected by female choice for extra-pair mates. Few studies have addressed variation in colour quality or the role of plumage in aggressive interactions. Condition-dependence of moult or breeding plumage has not been experimentally investigated. We argue that the genus is particularly suited to comparative analyses, as it provides informative contrasts in colour, plumage development, patterns of moult, colour vision and mating system, offering many exciting opportunities for testing evolutionary theories on function and maintenance of sexual signals.

A TEST AND REVIEW OF THE ROLE OF EFFECTIVE POPULATION SIZE ON EXPERIMENTAL SEXUAL SELECTION PATTERNS

Experimental evolution, particularly experimental sexual selection in which sexual selection strength is manipulated by altering the mating system, is an increasingly popular method for testing evolutionary theory. Concerns have arisen regarding genetic diversity variation across experimental treatments: differences in the number and sex ratio of breeders (effective population size; N(e)) and the potential for genetic hitchhiking, both of which may cause different levels of genetic variation between treatments. Such differences may affect the selection response and confound interpretation of results. Here we use both census-based estimators and molecular marker-based estimates to empirically test how experimental evolution of sexual selection in Drosophila pseudoobscura impacts N(e) and autosomal genetic diversity. We also consider effects of treatment on X-linked N(e)s, which have previously been ignored. Molecular autosomal marker-based estimators indicate that neither N(e) nor genetic diversity differs between treatments experiencing different sexual selection intensities; thus observed evolutionary responses reflect selection rather than any confounding effects of experimental design. Given the increasing number of studies on experimental sexual selection, we also review the census N(e)s of other experimental systems, calculate X-linked N(e), and compare how different studies have dealt with the issues of inbreeding, genetic drift, and genetic hitchhiking to help inform future designs.

Insect thermal tolerance: what is the role of ontogeny, ageing and senescence?

Temperature has dramatic evolutionary fitness consequences and is therefore a major factor determining the geographic distribution and abundance of ectotherms. However, the role that age might have on insect thermal tolerance is often overlooked in studies of behaviour, ecology, physiology and evolutionary biology. Here, we review the evidence for ontogenetic and ageing effects on traits of high- and low-temperature tolerance in insects and show that these effects are typically pronounced for most taxa in which data are available. We therefore argue that basal thermal tolerance and acclimation responses (i.e. phenotypic plasticity) are strongly influenced by age and/or ontogeny and may confound studies of temperature responses if unaccounted for. We outline three alternative hypotheses which can be distinguished to propose why development affects thermal tolerance in insects. At present no studies have been undertaken to directly address these options. The implications of these age-related changes in thermal biology are discussed and, most significantly, suggest that the temperature tolerance of insects should be defined within the age-demographics of a particular population or species. Although we conclude that age is a source of variation that should be carefully controlled for in thermal biology, we also suggest that it can be used as a valuable tool for testing evolutionary theories of ageing and the cellular and genetic basis of thermal tolerance.

Testing evolutionary theories of menopause.

Why do women cease fertility rather abruptly through menopause at an age well before generalized senescence renders child rearing biologically impossible? The two main evolutionary hypotheses are that menopause serves either (i) to protect mothers from rising age-specific maternal mortality risks, thereby protecting their highly dependent younger children from death if the mother dies or (ii) to provide post-reproductive grandmothers who enhance their inclusive fitness by helping to care and provide for their daughters' children. Recent theoretical work indicates that both factors together are necessary if menopause is to provide an evolutionary advantage. However, these ideas need to be tested using detailed data from actual human life histories lived under reasonably 'natural' conditions; for obvious reasons, such data are extremely scarce. We here describe a study based on a remarkably complete dataset from The Gambia. The data provided quantitative estimates for key parameters for the theoretical model, which were then used to assess the actual effects on fitness. Empirically based numerical analysis of this nature is essential if the enigma of menopause is to be explained satisfactorily in evolutionary terms. Our results point to the distinctive (and perhaps unique) role of menopause in human evolution and provide important support for the hypothesized evolutionary significance of grandmothers.

Complex Genetic Changes in Strains of Saccharomyces cerevisiae Derived by Selection in the Laboratory

Selection of model organisms in the laboratory has the potential to generate useful substrates for testing evolutionary theories. These studies generally employ relatively long-term selections with weak selective pressures to allow the accumulation of multiple adaptations. In contrast to this approach, we analyzed two strains of Saccharomyces cerevisiae that were selected for resistance to multiple stress challenges by a rapid selection scheme to test whether the variation between rapidly selected strains might also be useful in evolutionary studies. We found that resistance to oxidative stress is a multigene trait in these strains. Both derived strains possess the same major-effect adaptations to oxidative stress, but have distinct modifiers of the phenotype. Similarly, both derived strains have altered their global transcriptional responses to oxidative stress in similar ways, but do have at least some distinct differences in transcriptional regulation. We conclude that short-term laboratory selections can generate complex genetic variation that may be a useful substrate for testing evolutionary theories.

Reduced Mating Vigor in Selection Lines of the Butterfly Bicyclus anynana

Despite its acknowledged value for testing evolutionary theory, artificial selection is vulnerable to artifacts that are difficult to control. Here, we show that lines of the butterfly Bicyclus anynana, being artificially selected for differences in egg size, show considerably reduced mating vigor and male mating success than control lines, which is attributed to presumed differences in the levels of inbreeding. Besides selection line, neither forewing length, body dry mass or fat content of males had a detectable impact on male mating performance. Because artificial selection may (e.g. due to inbreeding) yield inadvertent effects even on traits that seem not to be related to the target trait, their results should be interpreted with caution.

Testing evolutionary theories of aging in wild populations

Classic theories for the evolution of senescence predict that rates of aging should be highest in populations in which extrinsic mortality is high. This predication is called into question in new work by David Reznick and co-workers, who found that guppies Poecilia reticulata derived from natural populations with high levels of predation live the longest in the laboratory. This study illustrates that the effect of mortality on aging might depend on how we define aging, and on the particular cause of increased mortality.

The discrimination of alternative male morphologies

Male dimorphisms represent alternative selective regimes within a sex. As such, they can be used as a powerful tool in testing evolutionary theory. However, to realize this potential, we need to be able to accurately discriminate individuals into two separate morphs. In this article we discuss the existing methods and propose a new one. We test our method with data from three dimorphic species and compare these results to results with existing methods. We conclude that existing methods often misclassify a large proportion of individuals, but applying our method notably reduces these errors.

The Effects of Sex and Temporal Context on Feelings of Romantic Desire: An Experimental Evaluation of Sexual Strategies Theory

According to evolutionary theories of human mating, people should feel the most romantic desire toward potential mates who possess reproductively adaptive attributes. Across five person-perception experiments involving staged interviews, we found that men’s and women’s feelings of romantic desire can be manipulated by varying adaptive attributes in a target person. For example, during some interviews, participants were exposed to an experimental confederate exhibiting cues to easy sexual access. Because men’s short-term sexual strategy is based on obtaining high numbers of partners, it was predicted that exposure to a target person suggesting easy sexual access would especially intensify men’s short-term romantic desires. The authors found evidence that targets who exhibited cues to easy sexual access were rated the most desirable by men in the context of short-term mating. Discussion focused on limitations of the current studies and on the importance of invoking methodological pluralism when testing evolutionary theories of romantic desire.

Testing evolutionary theories of aging.

Annals of the New York Academy of SciencesVolume 908, Issue 1 p. 319-320 Testing Evolutionary Theories of Aging GAWAIN McCOLL, Corresponding Author GAWAIN McCOLL School of Biological Sciences, University of Manchester, Oxford Road, United KingdomAddress for correspondence: Gawain McColl, School of Biological Sciences, University of Manchester, 3.239 Stopford Building, Oxford Road, Manchester M13 9PT, United Kingdom.Search for more papers by this authorNICOLE L. JENKINS, NICOLE L. JENKINS School of Biological Sciences, University of Manchester, Oxford Road, United KingdomSearch for more papers by this authorDAVID W. WALKER, DAVID W. WALKER School of Biological Sciences, University of Manchester, Oxford Road, United KingdomSearch for more papers by this authorGORDON J. LITHGOW, GORDON J. LITHGOW School of Biological Sciences, University of Manchester, Oxford Road, United KingdomSearch for more papers by this author GAWAIN McCOLL, Corresponding Author GAWAIN McCOLL School of Biological Sciences, University of Manchester, Oxford Road, United KingdomAddress for correspondence: Gawain McColl, School of Biological Sciences, University of Manchester, 3.239 Stopford Building, Oxford Road, Manchester M13 9PT, United Kingdom.Search for more papers by this authorNICOLE L. JENKINS, NICOLE L. JENKINS School of Biological Sciences, University of Manchester, Oxford Road, United KingdomSearch for more papers by this authorDAVID W. WALKER, DAVID W. WALKER School of Biological Sciences, University of Manchester, Oxford Road, United KingdomSearch for more papers by this authorGORDON J. LITHGOW, GORDON J. LITHGOW School of Biological Sciences, University of Manchester, Oxford Road, United KingdomSearch for more papers by this author First published: 25 January 2006 https://doi.org/10.1111/j.1749-6632.2000.tb06663.xCitations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume908, Issue1MOLECULAR AND CELLULAR GERONTOLOGYJune 2000Pages 319-320 RelatedInformation

First Estimates of Heritability in the Age of Menopause

Previous articleNext article No AccessReportFirst Estimates of Heritability in the Age of Menopause1Jocelyn Scott PecceiJocelyn Scott PecceiDepartment of Anthropology, University of California, Los Angeles, 341 Haines Hall, 405 Hilgard Ave., Los Angeles, Calif. 90095‐1553, U.S.A. ([email protected]). Search for more articles by this author Department of Anthropology, University of California, Los Angeles, 341 Haines Hall, 405 Hilgard Ave., Los Angeles, Calif. 90095‐1553, U.S.A. ([email protected]).PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Current Anthropology Volume 40, Number 4August/October 1999 Sponsored by the Wenner-Gren Foundation for Anthropological Research Article DOIhttps://doi.org/10.1086/200053 Views: 31Total views on this site Citations: 9Citations are reported from Crossref History © 1999 by The Wenner‐Gren Foundation for Anthropological Research. All rights reservedPDF download Crossref reports the following articles citing this article:A. Friederike Kachel, L. S. Premo Disentangling the Evolution of Early and Late Life History Traits in Humans, Evolutionary Biology 39, no.44 (Mar 2012): 638–649.https://doi.org/10.1007/s11692-012-9169-4Daryl P Shanley, Rebecca Sear, Ruth Mace, Thomas B.L Kirkwood Testing evolutionary theories of menopause, Proceedings of the Royal Society B: Biological Sciences 274, no.16281628 (Sep 2007): 2943–2949.https://doi.org/10.1098/rspb.2007.1028Barry X. Kuhle An evolutionary perspective on the origin and ontogeny of menopause, Maturitas 57, no.44 (Aug 2007): 329–337.https://doi.org/10.1016/j.maturitas.2007.04.004Gillian R. Bentley, Shanthi Muttukrishna Potential use of biomarkers for analyzing interpopulation and cross-cultural variability in reproductive aging, Menopause 14, no.44 (Jul 2007): 668–679.https://doi.org/10.1097/gme.0b013e318093df43Lynnette Leidy Sievert Recalling age at menopause, Menopause 12, no.33 (May 2005): 248–249.https://doi.org/10.1097/01.GME.0000163191.19167.5BCheryl Sorenson Jamison, Laurel L. Cornell, Paul L. Jamison, Hideki Nakazato Are all grandmothers equal? A review and a preliminary test of the ?grandmother hypothesis? in Tokugawa Japan, American Journal of Physical Anthropology 119, no.11 (Aug 2002): 67–76.https://doi.org/10.1002/ajpa.10070Jocelyn Scott Peccei A critique of the grandmother hypotheses: Old and new, American Journal of Human Biology 13, no.44 (Jan 2001): 434–452.https://doi.org/10.1002/ajhb.1076Jocelyn Scott Peccei Menopause: Adaptation or epiphenomenon?, Evolutionary Anthropology: Issues, News, and Reviews 10, no.22 (Apr 2001): 43–57.https://doi.org/10.1002/evan.1013Jocelyn Scott Peccei Genetic correlation between the ages of menarche and menopause, Human Nature 11, no.11 (Mar 2000): 43–63.https://doi.org/10.1007/s12110-000-1002-6

Self-fertilization in brooding hermaphroditic Caribbean corals: Evidence from molecular markers

The occurrence of self-fertilization in natural populations of hermaphroditic marine invertebrates has seldom been documented. This is in contrast to plant systems where studies of self-fertilization dominate plant mating system literature. Randomly amplified polymorphic DNA markers were used to assess rates of natural self-fertilization in two common hermaphroditic Caribbean corals from the Florida Keys, Favia fragum and Porites astreoides. Rates of self-fertilization in the field were found to be high (34% for P. astreoides and 49% for F. fragum) indicating that selfing is an important mode of reproduction for both species. Furthermore, rates of selfing were found to be significantly heterogeneous among individuals for both species and between sites for P. astreoides; thus, both species exhibit a mixed mode of mating ranging from complete outcrossing to nearly complete selfing. These results suggest that corals and other marine invertebrates may provide a rich source of comparative data for testing evolutionary theories of selfing that have primarily been developed through studies of plant mating systems.