scholarly journals Insights from Fisher’s geometric model on the likelihood of speciation under different histories of environmental change

2019 ◽  
Author(s):  
Ryo Yamaguchi ◽  
Sarah P. Otto
Keyword(s):  
Environmental Change ◽  
Geometric Model ◽  
Ecological Speciation ◽  
Hybrid Speciation ◽  
Multiple Traits ◽  
Isolated Populations ◽  
Genetic Changes ◽  
Divergent Natural Selection ◽  
Species Formation ◽  
Evolutionary Trajectories

AbstractThe formation of new species via the accumulation of incompatible genetic changes is thought to result either from ecologically-based divergent natural selection or the order by which mutations happen to arise, leading to different evolutionary trajectories even under similar selection pressures. There is growing evidence in support of both ecological speciation and mutation-order speciation, but how different environmental scenarios affect the rate of species formation remains underexplored. We use a simple model of optimizing selection on multiple traits (“Fisher’s geometric model”) to determine the conditions that generate genetic incompatibilities in a changing environment. We find that incompatibilities are likely to accumulate in isolated populations adapting to different environments, consistent with ecological speciation. Incompatibilities also arise when isolated populations face a similar novel environment; these cases of mutation-order speciation are particularly likely when the environment changes rapidly and favors the accumulation of large-effect mutations. In addition, we find that homoploid hybrid speciation is likely to occur either when new environments arise in between the parental environments or when parental populations have accumulated large-effect mutations following a period of rapid adaptation. Our results indicate that periods of rapid environmental change are particularly conducive to speciation, especially mutation-order or hybrid speciation.

scholarly journals Parallel genomic evolution of parasite tolerance in wild honey bee populations

2018 ◽  
Author(s):  
Katarzyna Bozek ◽  
Juliana Rangel ◽  
Jatin Arora ◽  
Mandy Tin ◽  
Emily Crotteau ◽  
...  
Keyword(s):  
Honey Bee ◽  
The United States ◽  
Natural Environments ◽  
Data Sets ◽  
Strongly Correlated ◽  
Isolated Populations ◽  
Genetic Changes ◽  
Evolutionary Response ◽  
Evolutionary Trajectories ◽  
Metabolic Protein

Sudden biotic pressures, such as those from novel diseases and pathogens, require populations to respond rapidly or face potential extinction. How this response process takes place remains poorly understood, particularly in natural environments. In this study we take advantage of unique decade-long data sets of two wild honey bee (Apis mellifera) populations in the United States to reconstruct the evolution of tolerance to a novel parasite, the ectoparasitic mite Varroa destructor. Upon the arrival of Varroa, the two geographically isolated populations simultaneously suffered massive Varroa-induced mortality, but stabilized within two years. Here we sequenced and phased genomes of 465 bees sampled from both populations annually over the decade that spanned Varroa's arrival. Remarkably, we found that genetic changes were strongly correlated between the populations, suggesting parallel selective responses to Varroa parasitization. The arrival of Varroa was also correlated with an influx of genes of African origin into both populations, though surprisingly it did not substantially contribute to the overall similarity of the evolutionary response between them. Genes involved in metabolic, protein processing and developmental pathways were under particularly strong selection. It is possible that interactions among highly connected gene groups in these pathways may help channelize selective responses to novel parasites, causing completely unrelated populations to exhibit parallel evolutionary trajectories when faced with the same biotic pressure. Our analyses illustrate that ecologically relevant traits emerge from highly polygenic selection involving thousands of genes contributing to complex patterns of evolutionary change.

scholarly journals Ecological Divergence and the Origins of Intrinsic Postmating Isolation with Gene Flow

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Aneil F. Agrawal ◽  
Jeffrey L. Feder ◽  
Patrik Nosil
Keyword(s):  
Linkage Disequilibrium ◽  
Gene Flow ◽  
Natural Selection ◽  
Theoretical Models ◽  
Ecological Speciation ◽  
Divergent Selection ◽  
Postmating Isolation ◽  
Divergent Natural Selection ◽  
Mathematical Exploration ◽  
Neutral Gene

The evolution of intrinsic postmating isolation has received much attention, both historically and in recent studies of speciation genes. Intrinsic isolation often stems from between-locus genetic incompatibilities, where alleles that function well within species are incompatible with one another when brought together in the genome of a hybrid. It can be difficult for such incompatibilities to originate when populations diverge with gene flow, because deleterious genotypic combinations will be created and then purged by selection. However, it has been argued that if genes underlying incompatibilities are themselves subject to divergent selection, then they might overcome gene flow to diverge between populations, resulting in the origin of incompatibilities. Nonetheless, there has been little explicit mathematical exploration of such scenarios for the origin of intrinsic incompatibilities during ecological speciation with gene flow. Here we explore theoretical models for the origin of intrinsic isolation where genes subject to divergent natural selection also affect intrinsic isolation, either directly or via linkage disequilibrium with other loci. Such genes indeed overcome gene flow, diverge between populations, and thus result in the evolution of intrinsic isolation. We also examine barriers to neutral gene flow. Surprisingly, we find that intrinsic isolation sometimes weakens this barrier, by impeding differentiation via ecologically based divergent selection.

scholarly journals Evolutionary Highways to Persistent Bacterial Infection

2018 ◽  
Author(s):  
Jennifer A Bartell ◽  
Lea M Sommer ◽  
Janus A J Haagensen ◽  
Anne Loch ◽  
Rocio Espinosa ◽  
...  
Keyword(s):  
Complex Trait ◽  
Host Finding ◽  
Patient Specific ◽  
Rapid Adaptation ◽  
Multiple Traits ◽  
New Associations ◽  
Persistent Infections ◽  
Evolutionary Trajectories ◽  
Pathoadaptive Mutations ◽  
Trait Correlations

ABSTRACTPersistent infections require bacteria to evolve from their naïve colonization state by optimizing fitness in the host. This optimization involves coordinated adaptation of multiple traits, obscuring evolutionary trends and complicating infection management. Accordingly, we screen 8 infection-relevant phenotypes of 443 longitudinal Pseudomonas aeruginosa isolates from 39 young cystic fibrosis patients over 10 years. Using statistical modeling, we map evolutionary trajectories and identify trait correlations accounting for patient-specific influences. By integrating previous genetic analyses of 474 isolates, we provide a window into early adaptation to the host, finding: 1) a 2-3 year timeline of rapid adaptation after colonization, 2) variant “naïve” and “adapted” states reflecting discordance between phenotypic and genetic adaptation, 3) adaptive trajectories leading to persistent infection via 3 distinct evolutionary modes, and 4) new associations between phenotypes and pathoadaptive mutations. Ultimately, we effectively deconvolute complex trait adaptation, offering a framework for evolutionary studies and precision medicine in clinical microbiology.

scholarly journals Homoploid hybrid speciation and genome evolution via chromosome sorting

2015 ◽  
Vol 282 (1807) ◽  
pp. 20150157 ◽  
Author(s):  
Vladimir A. Lukhtanov ◽  
Nazar A. Shapoval ◽  
Boris A. Anokhin ◽  
Alsu F. Saifitdinova ◽  
Valentina G. Kuznetsova
Keyword(s):  
Reproductive Isolation ◽  
Direct Consequence ◽  
Convincing Evidence ◽  
Interspecific Crosses ◽  
Parental Origin ◽  
Hybrid Speciation ◽  
Species Formation ◽  
Homoploid Hybrid ◽  
Creative Role

Genomes of numerous diploid plant and animal species possess traces of interspecific crosses, and many researches consider them as support for homoploid hybrid speciation (HHS), a process by which a new reproductively isolated species arises through hybridization and combination of parts of the parental genomes, but without an increase in ploidy. However, convincing evidence for a creative role of hybridization in the origin of reproductive isolation between hybrid and parental forms is extremely limited. Here, through studying Agrodiaetus butterflies, we provide proof of a previously unknown mode of HHS based on the formation of post-zygotic reproductive isolation via hybridization of chromosomally divergent parental species and subsequent fixation of a novel combination of chromosome fusions/fissions in hybrid descendants. We show that meiotic segregation, operating in the hybrid lineage, resulted in the formation of a new diploid genome, drastically rearranged in terms of chromosome number. We also demonstrate that during the heterozygous stage of the hybrid species formation, recombination was limited between rearranged chromosomes of different parental origin, representing evidence that the reproductive isolation was a direct consequence of hybridization.

scholarly journals Assortative flocking in crossbills and implications for ecological speciation

2012 ◽  
Vol 279 (1745) ◽  
pp. 4223-4229 ◽  
Author(s):  
Julie W. Smith ◽  
Stephanie M. Sjoberg ◽  
Matthew C. Mueller ◽  
Craig W. Benkman
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Assortative Mating ◽  
Ecological Speciation ◽  
Central Question ◽  
Loxia Curvirostra ◽  
Call Type ◽  
Divergent Natural Selection ◽  
Contact Calls ◽  
Red Crossbills

How reproductive isolation is related to divergent natural selection is a central question in speciation. Here, we focus on several ecologically specialized taxa or ‘call types’ of red crossbills ( Loxia curvirostra complex), one of the few groups of birds providing much evidence for ecological speciation. Call types differ in bill sizes and feeding capabilities, and also differ in vocalizations, such that contact calls provide information on crossbill phenotype. We found that two call types of red crossbills were more likely to approach playbacks of their own call type than those of heterotypics, and that their propensity to approach heterotypics decreased with increasing divergence in bill size. Although call similarity also decreased with increasing divergence in bill size, comparisons of responses to familiar versus unfamiliar call types indicate that the decrease in the propensity to approach heterotypics with increasing divergence in bill size was a learned response, and not a by-product of calls diverging pleiotropically as bill size diverged. Because crossbills choose mates while in flocks, assortative flocking could lead indirectly to assortative mating as a by-product. These patterns of association therefore provide a mechanism by which increasing divergent selection can lead to increasing reproductive isolation.

scholarly journals Divergent evolutionary trajectories shape the postmating transcriptional profiles of conspecific and heterospecifically mated females

2021 ◽  
Author(s):  
Fernando Diaz ◽  
Allan W. Carson ◽  
Xingsen Chen ◽  
Joshua M. Coleman ◽  
Jeremy M. Bono ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Genetic Basis ◽  
Intron Retention ◽  
Transcriptional Response ◽  
Isolated Populations ◽  
Closely Related Species ◽  
Transcriptional Profiles ◽  
Future Studies ◽  
Evolutionary Forces ◽  
Evolutionary Trajectories

Postmating-prezygotic (PMPZ) reproductive isolation is hypothesized to result from divergent coevolutionary trajectories of sexual selection and/or sexual conflict in isolated populations (coevolutionary divergence model). However, the genetic basis of PMPZ incompatibilities between species is poorly understood. Here, we use a comparative framework to test predictions of the coevolutionary divergence model using a large transcriptomic dataset generated from con- and heterospecifically mated Drosophila mojavensis and D. arizonae female reproductive tracts. We found striking divergence between the species in the female postmating transcriptional response to conspecific mating, including differences in differential expression (DE), alternative splicing (AS), and intron retention (IR). As predicted, heterospecific matings produced disrupted transcriptional profiles, but the overall patterns of misregulation were different between the reciprocal crosses. Moreover, we found a positive correlation between postmating transcriptional divergence between species and levels of transcriptional disruption in heterospecific crosses, indicating that mating-responsive genes that have diverged more in expression also have more disrupted transcriptional profiles in heterospecifically mated females. Overall, our results are consistent with predictions of the coevolutionary divergence model and lay the foundation for future studies aimed at identifying specific genes involved in PMPZ incompatibilities and the evolutionary forces that have contributed to their divergence in closely related species.

scholarly journals Rapid experimental evolution of reproductive isolation from a single natural population

2019 ◽  
Vol 116 (27) ◽  
pp. 13440-13445 ◽  
Author(s):  
Scott M. Villa ◽  
Juan C. Altuna ◽  
James S. Ruff ◽  
Andrew B. Beach ◽  
Lane I. Mulvey ◽  
...  
Keyword(s):  
Body Size ◽  
Natural Selection ◽  
Reproductive Isolation ◽  
Natural Population ◽  
Experimental Evolution ◽  
Natural Populations ◽  
Ecological Speciation ◽  
Phenotypic Trait ◽  
Divergent Natural Selection ◽  
Feather Lice

Ecological speciation occurs when local adaptation generates reproductive isolation as a by-product of natural selection. Although ecological speciation is a fundamental source of diversification, the mechanistic link between natural selection and reproductive isolation remains poorly understood, especially in natural populations. Here, we show that experimental evolution of parasite body size over 4 y (approximately 60 generations) leads to reproductive isolation in natural populations of feather lice on birds. When lice are transferred to pigeons of different sizes, they rapidly evolve differences in body size that are correlated with host size. These differences in size trigger mechanical mating isolation between lice that are locally adapted to the different sized hosts. Size differences among lice also influence the outcome of competition between males for access to females. Thus, body size directly mediates reproductive isolation through its influence on both intersexual compatibility and intrasexual competition. Our results confirm that divergent natural selection acting on a single phenotypic trait can cause reproductive isolation to emerge from a single natural population in real time.

scholarly journals Evolution in leaps: The punctuated accumulation and loss of cultural innovations

2015 ◽  
Vol 112 (49) ◽  
pp. E6762-E6769 ◽  
Author(s):  
Oren Kolodny ◽  
Nicole Creanza ◽  
Marcus W. Feldman
Keyword(s):  
Environmental Change ◽  
Cultural Change ◽  
Cultural Evolution ◽  
Large Scale ◽  
Multiple Traits ◽  
Differential Distribution ◽  
Sudden Gains ◽  
Cultural Innovation ◽  
The Impact ◽  
Increased Susceptibility

Archaeological accounts of cultural change reveal a fundamental conflict: Some suggest that change is gradual, accelerating over time, whereas others indicate that it is punctuated, with long periods of stasis interspersed by sudden gains or losses of multiple traits. Existing models of cultural evolution, inspired by models of genetic evolution, lend support to the former and do not generate trajectories that include large-scale punctuated change. We propose a simple model that can give rise to both exponential and punctuated patterns of gain and loss of cultural traits. In it, cultural innovation comprises several realistic interdependent processes that occur at different rates. The model also takes into account two properties intrinsic to cultural evolution: the differential distribution of traits among social groups and the impact of environmental change. In our model, a population may be subdivided into groups with different cultural repertoires leading to increased susceptibility to cultural loss, whereas environmental change may lead to rapid loss of traits that are not useful in a new environment. Taken together, our results suggest the usefulness of a concept of an effective cultural population size.

scholarly journals Floral signals evolve in a predictable way under artificial and pollinator selection in Brassica rapa using a G-matrix

2019 ◽  
Author(s):  
Pengjuan Zu ◽  
Florian P. Schiestl ◽  
Daniel Gervasi ◽  
Xin Li ◽  
Daniel Runcie ◽  
...  
Keyword(s):  
Brassica Rapa ◽  
Resource Limitation ◽  
Floral Traits ◽  
Selection Experiment ◽  
Response To Selection ◽  
Multiple Traits ◽  
Floral Trait ◽  
Genetic Covariance ◽  
Evolutionary Changes ◽  
Evolutionary Trajectories

AbstractBackgroundAngiosperms employ an astonishing variety of visual and olfactory floral signals that are generally thought to evolve under natural selection. Those morphological and chemical traits can form highly correlated sets of traits. It is not always clear which of these are used by pollinators as primary targets of selection and which would be indirectly selected by being linked to those primary targets. Quantitative genetics tools for predicting multiple traits response to selection have been developed since long and have advanced our understanding of evolution of genetically correlated traits in various biological systems. We use these tools to predict the evolutionary trajectories of floral traits and understand the selection pressures acting on them.ResultsWe used data from an artificial and a pollinator (bumblebee, hoverfly) selection experiment with fast cycling Brassica rapa plants to predict evolutionary changes of 12 floral volatiles and 4 morphological floral traits in response to selection. Using the observed selection gradients and the genetic variance-covariance matrix (G-matrix) of the traits, we showed that the responses of most floral traits including volatiles were predicted in the right direction in artificial- and bumblebee-selection experiment, revealing direct and indirect targets of bumblebee selection. Genetic covariance had a mix of constraining and facilitating effects on evolutionary responses. We further revealed how G-matrices evolved in the selection processes.ConclusionsOverall, our integrative study shows that floral signals, and especially volatiles, evolve under selection in a mostly predictable way, at least during short term evolution. Evolutionary constraints stemming from genetic covariance affected traits evolutionary trajectories and thus it is important to include genetic covariance for predicting the evolutionary changes of a comprehensive suite of traits. Other processes such as resource limitation and selfing also needs to be considered for a better understanding of floral trait evolution.

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