Quantitative genetics of body size and development time in the parasitoid wasp Aphidius ervi (Hymenoptera: Aphidiidae)

1992 ◽  
Vol 70 (6) ◽  
pp. 1102-1108 ◽  
Author(s):  
R. Sequeira ◽  
M. Mackauer
Keyword(s):  
Body Size ◽  
Development Time ◽  
Phenotypic Variability ◽  
Rapid Development ◽  
Phenotypic Expression ◽  
Natural Populations ◽  
Host Size ◽  
Life History Strategies ◽  
Aphidius Ervi ◽  
Aphid Parasitoids

Body size and development time are key components of life-history strategies and fitness in parasitoid wasps. To assess the relative importance of phenotypic variability for fitness, we determined the heritabilities and reaction norms of body size (= dry mass) and development time in Aphidius ervi, a solitary parasitoid of the pea aphid. We estimated the variance components for body size from an ANOVA model for haplodiploidy, using a half-sib design, with each of 18 sires mated to 2 or 3 dams. Phenotypic expression of body size was strongly influenced by host size (= instar) at the time of parasitization. Heritability for body size in female A. ervi, averaged over sire and dam components, was 0.38. Although the heritability for development time could not be estimated precisely, a larger dam than sire component suggests that development time has lower heritability than body size. Differences between the heritability estimates for body size in males and females indicate that the mode of inheritance and phenotypic expression may be asymmetrical. These results suggest that, in a stochastic environment, aphid parasitoids experience strong selection for rapid development; however, host-size effects are likely to mask differences in genetically determined body size. Genotype–environment interactions may play an important role in maintaining genetic variability in body size in natural populations of A. ervi.

scholarly journals Allelic polymorphism at foxo contributes to local adaptation in Drosophila melanogaster

2018 ◽  
Author(s):  
Nicolas J. Betancourt ◽  
Subhash Rajpurohit ◽  
Esra Durmaz ◽  
Daniel K. Fabian ◽  
Martin Kapun ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Life History ◽  
Body Size ◽  
Local Adaptation ◽  
Development Time ◽  
Genetic Variance ◽  
Allelic Variation ◽  
Natural Populations ◽  
Life History Variation ◽  
Starvation Tolerance

AbstractThe insulin insulin-like growth factor signaling pathway has been hypothesized as a major determinant of life history profiles that vary adaptively in natural populations. In Drosophila melanogaster, multiple components of this pathway vary predictably with latitude; this includes foxo, a conserved gene that regulates insulin signaling and has pleiotropic effects on a variety of fitness-associated traits. We hypothesized that allelic variation at foxo underlies genetic variance for traits that vary with latitude and reflect local adaptation. To evaluate this, we generated recombinant outbred populations in which the focal foxo allele was homozygous and fixed for either the allele common at high latitude or low latitude and the genomic background was randomized across 20 inbred lines. After eight generations of recombination, experimental populations were phenotyped for a series of traits related to gene function. Our results demonstrate that natural allelic variation at foxo has major and predictable effects on body size and starvation tolerance, but not on development time. These patterns mirror those observed in natural populations collected across the latitudinal gradient in the eastern U.S.: clines were observed for starvation tolerance and body size, but development time exhibited no association with latitude. Furthermore, differences in size between foxo genotypes were equivalent to those observed between populations sampled from the latitudinal extremes, although contribution to the genetic variance for starvation tolerance was less pronounced. These results suggest that allelic variation at foxo is a major contributor to adaptive patterns of life history variation in natural populations of this genetic model.

scholarly journals Independent evolution towards larger body size in the distinctive Faroe Island mice

2021 ◽  
Author(s):  
Ricardo Wilches ◽  
William H Beluch ◽  
Ellen McConnell ◽  
Diethard Tautz ◽  
Yingguang Frank Chan
Keyword(s):  
Body Size ◽  
Meta Analysis ◽  
Small Body ◽  
Laboratory Mouse ◽  
Large Body ◽  
Natural Populations ◽  
Size Variation ◽  
Phenotypic Traits ◽  
Island Population ◽  
Multiple Loci

Abstract Most phenotypic traits in nature involve the collective action of many genes. Traits that evolve repeatedly are particularly useful for understanding how selection may act on changing trait values. In mice, large body size has evolved repeatedly on islands and under artificial selection in the laboratory. Identifying the loci and genes involved in this process may shed light on the evolution of complex, polygenic traits. Here, we have mapped the genetic basis of body size variation by making a genetic cross between mice from the Faroe Islands, which are among the largest and most distinctive natural populations of mice in the world, and a laboratory mouse strain selected for small body size, SM/J. Using this F2 intercross of 841 animals, we have identified 111 loci controlling various aspects of body size, weight and growth hormone levels. By comparing against other studies, including the use of a joint meta-analysis, we found that the loci involved in the evolution of large size in the Faroese mice were largely independent from those of a different island population or other laboratory strains. We hypothesize that colonization bottleneck, historical hybridization, or the redundancy between multiple loci have resulted in the Faroese mice achieving an outwardly similar phenotype through a distinct evolutionary path.

An ecological explanation for hyperallometric scaling of reproduction

2021 ◽  
Author(s):  
Tomos Potter ◽  
Anja Felmy
Keyword(s):  
Body Size ◽  
Reproductive Output ◽  
Resource Competition ◽  
Natural Populations ◽  
Scaling Exponent ◽  
Wild Populations ◽  
Wet Season ◽  
Size Dependent ◽  
In The Wild ◽  
The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

scholarly journals Genetic correlations across genetically determined and developmentally plastic alternative reproductive tactics

2019 ◽  
Author(s):  
Jessica K. Abbott ◽  
Oscar Rios-Cardenas ◽  
Molly Morris
Keyword(s):  
Body Size ◽  
Genetic Correlation ◽  
Genetic Correlations ◽  
Phenotypic Expression ◽  
Alternative Reproductive Tactics ◽  
Phenotypic Trait ◽  
Sexual Antagonism ◽  
Reproductive Tactics ◽  
Genetic Conflict ◽  
Genetically Determined

AbstractAlternative reproductive tactics occur when individuals of the same sex have a suite of morphological and/or behavioural traits that allow them to pursue different reproductive strategies. A common pattern is e.g. the existence of “courter” and “sneaker” tactics within males. We have previously argued that alternative reproductive tactics should be subject to genetic conflict over the phenotypic expression of traits, similar to sexual antagonism. In this process, which we called intra-locus tactical conflict, genetically determined tactics experience conflicting selection on a shared phenotypic trait, such as body size, but a positive genetic correlation between tactics in body size prevents either tactic from reaching its optimum. Recently, other authors have attempted to extend this idea to developmentally plastic alternative reproductive tactics, with mixed results. However, it is not clear whether we should expect intra-locus tactical conflict in developmentally plastic tactics or not. We have therefore run a series of simulation models investigating under what conditions we should expect to see positive estimates of the inter-tactical genetic correlation, since a positive genetic correlation is a prerequisite for the existence of intra-locus tactical conflict. We found that for autosomal, X-linked, and Y-linked genetically-determined tactics, estimated inter-tactical genetic correlations were generally high. However, for developmentally plastic tactics, the genetic correlation depends on the properties of the switching threshold between tactics. If it is fixed, then estimated genetic correlations are positive, but if there is genetic variation in the switch-point, then any sign and magnitude of estimated genetic correlation is possible, even for highly heritable traits where the true underlying correlation is perfect. This means that caution should be used when investigating genetic constraints in plastic phenotypes.

scholarly journals Altered trait variability in response to size-selective mortality

2016 ◽  
Vol 12 (9) ◽  
pp. 20160584 ◽  
Author(s):  
Silva Uusi-Heikkilä ◽  
Kai Lindström ◽  
Noora Parre ◽  
Robert Arlinghaus ◽  
Josep Alós ◽  
...  
Keyword(s):  
Body Size ◽  
Phenotypic Variability ◽  
Large Body ◽  
Size Variation ◽  
Directional Selection ◽  
Fish Stocks ◽  
Alternative Feeding ◽  
Stability And Resilience ◽  
Feeding Environments ◽  
Trait Variability

Changes in trait variability owing to size-selective harvesting have received little attention in comparison with changes in mean trait values, perhaps because of the expectation that phenotypic variability should generally be eroded by directional selection typical for fishing and hunting. We show, however, that directional selection, in particular for large body size, leads to increased body-size variation in experimentally harvested zebrafish ( Danio rerio ) populations exposed to two alternative feeding environments: ad libitum and temporarily restricted food availability. Trait variation may influence population adaptivity, stability and resilience. Therefore, rather than exerting selection pressures that favour small individuals, our results stress the importance of protecting large ones, as they can harbour a great amount of variation within a population, to manage fish stocks sustainably.

scholarly journals The costs of being male: are there sex-specific effects of uniparental mitochondrial inheritance?

2014 ◽  
Vol 369 (1646) ◽  
pp. 20130440 ◽  
Author(s):  
Madeleine Beekman ◽  
Damian K. Dowling ◽  
Duur K. Aanen
Keyword(s):  
Maternal Inheritance ◽  
Phenotypic Expression ◽  
Natural Populations ◽  
Mtdna Mutations ◽  
Specific Effects ◽  
Mtdna Sequence ◽  
Multiple Copies ◽  
The One ◽  
Mtdna Variants ◽  
Male Expression

Eukaryotic cells typically contain numerous mitochondria, each with multiple copies of their own genome, the mtDNA. Uniparental transmission of mitochondria, usually via the mother, prevents the mixing of mtDNA from different individuals. While on the one hand, this should resolve the potential for selection for fast-replicating mtDNA variants that reduce organismal fitness, maternal inheritance will, in theory, come with another set of problems that are specifically relevant to males. Maternal inheritance implies that the mitochondrial genome is never transmitted through males, and thus selection can target only the mtDNA sequence when carried by females. A consequence is that mtDNA mutations that confer male-biased phenotypic expression will be prone to evade selection, and accumulate. Here, we review the evidence from the ecological, evolutionary and medical literature for male specificity of mtDNA mutations affecting fertility, health and ageing. While such effects have been discovered experimentally in the laboratory, their relevance to natural populations—including the human population—remains unclear. We suggest that the existence of male expression-biased mtDNA mutations is likely to be a broad phenomenon, but that these mutations remain cryptic owing to the presence of counter-adapted nuclear compensatory modifier mutations, which offset their deleterious effects.

scholarly journals SEASONALLY VARYING DIET QUALITY AND THE QUANTITATIVE GENETICS OF DEVELOPMENT TIME AND BODY SIZE IN BIRCH FEEDING INSECTS

Evolution ◽  
2001 ◽  
Vol 55 (10) ◽  
pp. 1992-2001 ◽  
Author(s):  
Antti Kause ◽  
Irma Saloniemi ◽  
Jean-Philippe Morin ◽  
Erkki Haukioja ◽  
Sinikka Hanhimäki ◽  
...  
Keyword(s):  
Body Size ◽  
Quantitative Genetics ◽  
Diet Quality ◽  
Development Time

scholarly journals Big-brained birds survive better in nature

2007 ◽  
Vol 274 (1611) ◽  
pp. 763-769 ◽  
Author(s):  
Daniel Sol ◽  
Tamás Székely ◽  
András Liker ◽  
Louis Lefebvre
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Natural Populations ◽  
Adult Mortality ◽  
Environmental Stresses ◽  
Cognitive Responses ◽  
Partial Support ◽  
General Importance ◽  
Extensive Information ◽  
Size Limits

Big brains are hypothesized to enhance survival of animals by facilitating flexible cognitive responses that buffer individuals against environmental stresses. Although this theory receives partial support from the finding that brain size limits the capacity of animals to behaviourally respond to environmental challenges, the hypothesis that large brains are associated with reduced mortality has never been empirically tested. Using extensive information on avian adult mortality from natural populations, we show here that species with larger brains, relative to their body size, experience lower mortality than species with smaller brains, supporting the general importance of the cognitive buffer hypothesis in the evolution of large brains.

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