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Evolution; International Journal of Organic Evolution

Marisol Sánchez-García, P Brandon Matheny
Although fungi are one of the most diverse groups of organisms, little is known about the processes that shape their high taxonomic diversity. This study focuses on evolution of ectomycorrhizal (ECM) mushroom-forming fungi, symbiotic associates of many trees and shrubs, in the suborder Tricholomatineae of the Agaricales. We used the BiSSE model and BAMM to test the hypothesis that the ECM habit represents an evolutionary key innovation that allowed the colonization of new niches followed by an increase in diversification rate...
October 21, 2016: Evolution; International Journal of Organic Evolution
Michael A Grillo, Stephane De Mita, Patricia V Burke, Kathryn L S Solórzano-Lowell, Katy D Heath
Bottom-up evolutionary approaches, including geographically-explicit population genomic analyses, have the power to reveal the mechanistic basis of adaptation. Here we conduct a population genomic analysis in the model legume, Medicago truncatula, in order to characterize population genetic structure and identify symbiosis-related genes showing evidence of spatially-variable selection. Using RAD-seq, we generated over 26,000 SNPs from 191 accessions from within three regions of the native range in Europe. Results from STRUCTURE analysis identify 5 distinct genetic clusters with divisions that separate east and west regions in the Mediterranean basin...
October 19, 2016: Evolution; International Journal of Organic Evolution
A M S Tocts, D W Johnson, A J R Carter
Theoretical links between fluctuating asymmetry (FA) and fitness have led many to use FA as a proxy for average fitness. However, studies examining whether asymmetry actually correlates with individual fitness in wild populations are relatively rare and often use simple measures of association (e.g., correlation coefficients). Consequently, the pattern of selection on asymmetry in the wild is seldom clear. We examined selection on FA of pectoral fin morphology in two wild populations of a marine fish (the kelp perch; Brachyistius frenatus)...
October 19, 2016: Evolution; International Journal of Organic Evolution
Lesley A Alton, Catriona Condon, Craig R White, Michael J Angilletta
The effect of temperature on the evolution of metabolism has been the subject of debate for a century; however, no consistent patterns have emerged from comparisons of metabolic rate within and among species living at different temperatures. We used experimental evolution to determine how metabolism evolves in populations of Drosophila melanogaster exposed to one of three selective treatments: a constant 16°C, a constant 25°C, or temporal fluctuations between 16 and 25°C. We tested August Krogh's controversial hypothesis that colder environments select for a faster metabolism...
October 19, 2016: Evolution; International Journal of Organic Evolution
Russell A Ligon, Richard K Simpson, Nicholas A Mason, Geoffrey E Hill, Kevin J McGraw
The ornaments used by animals to mediate social interactions are diverse, and by reconstructing their evolutionary pathways we can gain new insights into the mechanisms underlying ornamental innovation and variability. Here, we examine variation in plumage carotenoids among the true finches (Aves: Fringillidae) using biochemical and comparative phylogenetic analyses to reconstruct the evolutionary history of carotenoid states and evaluate competing models of carotenoid evolution. Our comparative analyses reveal that the most likely ancestor of finches used dietary carotenoids as yellow plumage colorants, and that the ability to metabolically modify dietary carotenoids into more complex pigments arose secondarily once finches began to use modified carotenoids to create red plumage...
October 19, 2016: Evolution; International Journal of Organic Evolution
Shaghayegh Soudi, Klaus Reinhold, Leif Engqvist
One of the major goals in speciation research is to understand which isolation mechanisms form the first barriers to gene flow. This requires examining lineages which are still in the process of divergence or incipient species. Here, we investigate the presence of behavioural and several cryptic barriers between the sympatric willow and birch host races of Lochmaea capreae. Behavioural isolation did not have any profound effect on preventing gene flow. Yet despite pairs mating indiscriminately, no offspring were produced from the heterospecific matings between birch females and willow males due to the inability of males to transfer sperm to females...
October 17, 2016: Evolution; International Journal of Organic Evolution
Kjetil Lysne Voje
The dominating view of evolution based on the fossil record is that established species remain more or less unaltered during their existence. Substantial evolution is on the other hand routinely reported for contemporary populations, and most quantitative traits show high potential for evolution. These contrasting observations on long and short time scales are often referred to as the paradox of stasis, which rests on the fundamental assumption that periods of morphological stasis in the fossil record represent minimal evolutionary change...
October 17, 2016: Evolution; International Journal of Organic Evolution
Janette W Boughman, Richard Svanbäck
The ecological niche and mate preferences have independently been shown to be important for the process of speciation. Here we articulate a novel mechanism by which ecological niche use and mate preference can be linked to promote speciation. The degree to which individual niches are narrow and clustered affects the strength of divergent natural selection and population splitting. Similarly, the degree to which individual mate preferences are narrow and clustered affects the strength of divergent sexual selection and assortative mating between diverging forms...
October 17, 2016: Evolution; International Journal of Organic Evolution
M L Head, R J Fox, I Barber
Sexual cues, including extended phenotypes, are expected to be reliable indicators of male genetic quality and/or provide information on parental quality. However, the reliability of these cues may be dependent on stability of the environment, with heterogeneity affecting how selection acts on such traits. Here we test how environmental change mediates mate choice for multiple sexual traits, including an extended phenotype - the structure of male-built nests - in stickleback fish. First, we manipulated the dissolved oxygen (DO) content of water to create high or low DO environments in which male fish built nests...
October 17, 2016: Evolution; International Journal of Organic Evolution
Ana Cristina R Gomes, Michael D Sorenson, Gonçalo C Cardoso
Although sexual ornamentation mediates reproductive isolation, comparative evidence does not support the hypothesis that stronger sexual selection promotes speciation. Prior analyses have neglected the possibility that decreases in ornamentation may also promote speciation, such that both increases and decreases in the strength of sexual selection and associated changes in ornamentation promote speciation. To test this hypothesis, we studied color ornamentation in one of the largest and fastest avian radiations, the estrildid finches...
October 8, 2016: Evolution; International Journal of Organic Evolution
Ryan Greenway, Shannon Drexler, Lenin Arias-Rodriguez, Michael Tobler
Assortative mating is critical for reproductive isolation during speciation, however, the mechanisms underlying mating preferences are often unknown. Assortative mating can be mediated through preferences for condition-dependent and adaptive ("magic") traits, but rigorously testing these hypotheses has been impeded by trait covariation in living organisms. We used computer-generated models to examine the role of body shape in producing association preferences between fish populations undergoing ecological speciation in different habitat types...
October 8, 2016: Evolution; International Journal of Organic Evolution
Ronald D Bassar, Troy Simon, William Roberts, Joseph Travis, David N Reznick
Species coexistence may result by chance when co-occurring species do not strongly interact or it may be an evolutionary outcome of strongly interacting species adapting to each other. While patterns like character displacement indicate that coexistence has often been an evolutionary outcome, it is unclear how often the evolution of coexistence represents adaptation in only one species or reciprocal adaptation among all interacting species. Here we demonstrate a strong role for evolution in the coexistence of guppies and killifish in Trinidadian streams...
October 8, 2016: Evolution; International Journal of Organic Evolution
Thomas D Brekke, Lindy A Henry, Jeffrey M Good
The importance of regulatory incompatibilities to the early stages of speciation remains unclear. Hybrid mammals often show extreme parent-of-origin growth effects that are thought to be a consequence of disrupted genetic imprinting (parent-specific epigenetic gene silencing) during early development. Here we test the long-standing hypothesis that abnormal hybrid growth reflects disrupted gene expression due to loss of imprinting (LOI) in hybrid placentas, resulting in dosage imbalances between paternal growth factors and maternal growth repressors...
October 7, 2016: Evolution; International Journal of Organic Evolution
Joana Costa, Sílvia Castro, João Loureiro, Spencer Ch Barrett
Most heterostylous plants possess a reciprocal arrangement of stigmas and anthers (reciprocal herkogamy), heteromorphic self-incompatibility and ancillary polymorphisms of pollen and stigmas. The topographical complementarity hypothesis proposes that ancillary polymorphisms function in the rejection of incompatible pollen thus promoting disassortative pollination. Here, we test this hypothesis by investigating patterns of pollen transfer and capture in populations of dimorphic Armeria maritima and A. pubigera and distylous Limonium vulgare (Plumbaginaceae), and by studying pollen adherence and germination patterns in A...
October 7, 2016: Evolution; International Journal of Organic Evolution
Erik R Mohlhenrich, Rachel Lockridge Mueller
Salamanders have the largest nuclear genomes among tetrapods and, excepting lungfishes, among vertebrates as a whole. Lynch and Conery (2003) have proposed the mutational-hazard hypothesis to explain variation in genome size and complexity. Under this hypothesis, non-coding DNA imposes a selective cost by increasing the target for degenerative mutations, i.e. the mutational hazard. Expansion of non-coding DNA, and thus genome size, is driven by increased levels of genetic drift and/or decreased mutation rates; the former determines the efficiency with which purifying selection can remove excess DNA, while the latter determines the level of mutational hazard...
October 7, 2016: Evolution; International Journal of Organic Evolution
Anna M F Harts, Isobel Booksmythe, Michael D Jennions
In many birds males are presumed to protect their paternity by closely guarding their mate or copulating frequently with her. Both these costly behaviours are assumed to reduce the risk and/or intensity of sperm competition. However, despite many studies on avian extra-pair paternity, it remains unclear how strongly these behaviours are related to fitness and other key life-history traits. Here we conduct meta-analyses to address two questions. First, are mate guarding and/or frequent copulation positively correlated with a male's share of paternity at his nest? We find a significant positive correlation between both presumed paternity protection behaviours and paternity share...
October 7, 2016: Evolution; International Journal of Organic Evolution
Jonathan D Kennedy, Michael K Borregaard, Knud A Jønsson, Ben Holt, Jon Fjeldså, Carsten Rahbek
Regional variation in clade richness can be vast, reflecting differences in the dynamics of historical dispersal and diversification among lineages. Although it has been proposed that dispersal into new biogeographic regions may facilitate diversification, to date there has been limited assessment of the importance of this process in the generation, and maintenance, of broad-scale biodiversity gradients. To address this issue, we analytically derive biogeographic regions for a global radiation of passerine birds (the Corvides, c...
October 6, 2016: Evolution; International Journal of Organic Evolution
Sjouke A Kingma, Kat Bebbington, Martijn Hammers, David S Richardson, Jan Komdeur
Why sexually mature individuals stay in groups as nonreproductive subordinates is central to the evolution of sociality and cooperative breeding. To understand such delayed dispersal, its costs and benefits need to be compared with those of permanently leaving to float through the population. However, comprehensive comparisons, especially regarding differences in future breeding opportunities, are rare. Moreover, extraterritorial prospecting by philopatric individuals has generally been ignored, even though the factors underlying this route to independent breeding may differ from those of strict philopatry or floating...
October 6, 2016: Evolution; International Journal of Organic Evolution
C Lindstedt, E Schroderus, L Lindström, T Mappes, J Mappes
To predict evolutionary responses of warning signals under selection, we need to determine the inheritance pattern of the signals, and how they are genetically correlated with other traits contributing to fitness. Furthermore, protective coloration often undergoes remarkable changes within an individual's lifecycle, requiring us to quantify the genetic constraints of adaptive coloration across all the relevant life stages. Based on a 12 generation pedigree with > 11,000 individuals of the wood tiger moth (Arctia plantaginis), we show that high primary defense as a larva (large warning signal) results in weaker defenses as adult (less efficient warning color), due to the negative genetic correlation between the efficacy of larval and adult warning coloration...
October 6, 2016: Evolution; International Journal of Organic Evolution
Samuel L Díaz-Muñoz, Amy Boddy, Gautam Dantas, Christopher M Waters, Judith L Bronstein
Biologists have taken the concept of organism largely for granted. However, advances in the study of chimerism, symbiosis, bacterial-eukaryote associations, and microbial behavior have prompted a redefinition of organisms as biological entities exhibiting low conflict and high cooperation among their parts. This expanded view identifies organisms in evolutionary time. However, the ecological processes, mechanisms, and traits that drive the formation of organisms remain poorly understood. Recognizing that organismality can be context-dependent, we advocate elucidating the ecological contexts under which entities do or do not act as organisms...
October 5, 2016: Evolution; International Journal of Organic Evolution
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