Unidirectional response to bidirectional selection on body size II Quantitative genetics

AbstractAnticipating the genetic and phenotypic changes induced by natural or artificial selection requires reliable estimates of trait evolvabilities (genetic variances and covariances). However, whether or not multivariate quantitative genetics models are able to predict precisely the evolution of traits of interest, especially fitness-related, life-history traits, remains an open empirical question. Here, we assessed to what extent the response to bivariate artificial selection on both body size and maturity in the medaka Oryzias latipes, a model fish species, fits the theoretical predictions. Three lines (Large, Small, and Control lines) were differentially selected for body length at 75 days of age, conditional on maturity. As maturity and body size were phenotypically correlated, this selection procedure generated a bi-dimensional selection pattern on two life history traits. After removal of non-heritable trends and noise with a random effect (’animal’) model, the observed selection response did not match the expected bidirectional response. For body size, Large and Control lines responded along selection gradients (larger body size and stasis, respectively), but, surprisingly, the Small did not evolve a smaller body length, and remained identical to the Control line throughout the experiment. The magnitude of the empirical response was smaller than the theoretical prediction in both selected directions. For maturity, the response was opposite to the expectation (the Large line evolved late maturity compared to the Control line, while the Small line evolved early maturity, while the opposite pattern was predicted due to the strong positive genetic correlation between both traits). The mismatch between predicted and observed response was substantial and could not be explained by usual sources of uncertainties (including sampling effects, genetic drift, and error in G matrix estimates).

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Artificial selection on male size depletes genetic variance but not covariance of life history traits in the yellow dung fly

10.1101/664326 ◽

2019 ◽

Author(s):

WU Blanckenhorn ◽

V Llaurens ◽

C Reim ◽

Y Teuschl ◽

E Postma

Keyword(s):

Genetic Variation ◽

Life History ◽

Body Size ◽

Artificial Selection ◽

Development Time ◽

Life History Traits ◽

Genetic Variance ◽

Genetic Correlations ◽

Male Size ◽

First Clutch

SUMMARYThe evolutionary potential of organisms depends on the presence of sufficient genetic variation for traits subject to selection, as well as on the genetic covariances among them. While genetic variation ultimately derives from mutation, theory predicts the depletion of genetic (co)variation under consistent directional or stabilizing selection in natural populations. We estimated and compared additive genetic (co)variances for several standard life history traits, including some for which this has never been assessed, before and after 24 generations of artificial selection on male size in the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae) using a series of standard half-sib breeding experiments. As predicted, genetic variances (VA), heritabilities (h2) and evolvabilities (IA) of body size, development time, first clutch size, and female age at first clutch were lower after selection. As independent selection lines were crossed prior to testing, we can rule out that this reduction is due to genetic drift. In contrast to the variances, and against expectation, the additive genetic correlations between the sexes for development time and body size remained strong and positive (rA = 0.8–0.9), while the genetic correlation between these traits within the sexes tended to strengthen (but not significantly so). Our study documents that the effect of selection on genetic variance is predictable, whereas that on genetic correlations is not.

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PSVIII-17 Assessment of conformational changes across three parities in sows

Journal of Animal Science ◽

10.1093/jas/skaa054.386 ◽

2020 ◽

Vol 98 (Supplement_3) ◽

pp. 221-222

Author(s):

Melanie D Trenhaile-Grannemann ◽

Ronald M Lewis ◽

Stephen D Kachman ◽

Kenneth J Stalder ◽

Benny E Mote

Keyword(s):

Body Size ◽

Body Length ◽

Conformational Changes ◽

Repeated Measures ◽

Fixed Effects ◽

Random Effect ◽

Joint Angles ◽

Body Depth ◽

Conformation Changes ◽

Over Time

Abstract Conformation-based sow selection is performed prior to reaching mature size, yet little is known about how conformation changes as growth continues. To assess conformation changes, 9 conformational traits were objectively measured at 12 discrete time points between 112 d of age and parity 3 weaning on 622 sows in 5 cohorts. The 9 traits included 5 body size traits (body length, body depth at the shoulder and flank, and height at the shoulder and flank) and 4 joint angles (knee, hock, and front and rear pastern). Data were analyzed with a repeated measures model (SAS V 9.4) including cohort and time point as fixed effects, sire as a random effect, and heterogeneous compound symmetry as the covariance structure. Sire variance ranged from 0.16 (body depth shoulder) to 2.00 (body length) cm2 for body size traits and 2.28 (rear pastern) to 4.22 (front pastern) degrees2 for joint angles. Cohort had an effect on all traits (P < 0.05). All traits displayed changes over time (P < 0.001). Size traits increased between 112 d of age and parity 3 weaning (64.16 vs. 107.57 cm, 26.62 vs. 44.14 cm, 23.32 vs. 36.92 cm, 46.10 vs. 73.55 cm, 49.36 vs. 77.47 cm for body length, body depth shoulder and flank, and height shoulder and flank, respectively); however, they fluctuated within parity by increasing during gestation and decreasing at weaning. Knee angle decreased (164.12 vs. 150.72 degrees) while fluctuating within parity by decreasing in the second half of gestation and increasing after weaning. Front and rear pastern angles decreased over time (60.89 vs. 53.74 degrees and 64.64 vs. 55.50 degrees for front and rear pastern, respectively), while biologically negligible change was observed in hock angle (148.63 vs. 147.48 degrees). Sow conformation changes throughout life, and these changes may require consideration when making selection decisions.

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Differential effects on life history traits and body size of two anuran species inhabiting an environment related to fluorite mine

Ecological Indicators ◽

10.1016/j.ecolind.2018.04.065 ◽

2018 ◽

Vol 93 ◽

pp. 36-44 ◽

Cited By ~ 6

Author(s):

Manuel A. Otero ◽

Favio E. Pollo ◽

Pablo R. Grenat ◽

Nancy E. Salas ◽

Adolfo L. Martino

Keyword(s):

Life History ◽

Body Size ◽

Life History Traits ◽

Differential Effects ◽

Anuran Species

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Life history and habitat do not mediate temporal changes in body size due to climate warming in rodents

PeerJ ◽

10.7717/peerj.9792 ◽

2020 ◽

Vol 8 ◽

pp. e9792

Author(s):

Aluwani Nengovhela ◽

Christiane Denys ◽

Peter J. Taylor

Keyword(s):

Life History ◽

Body Size ◽

Climate Warming ◽

Life History Traits ◽

Vegetation Type ◽

Reproductive Rate ◽

Temporal Changes ◽

Temporal Response ◽

Extrinsic Factors ◽

African Species

Temporal changes in body size have been documented in a number of vertebrate species, with different contested drivers being suggested to explain these changes. Among these are climate warming, resource availability, competition, predation risk, human population density, island effects and others. Both life history traits (intrinsic factors such as lifespan and reproductive rate) and habitat (extrinsic factors such as vegetation type, latitude and elevation) are expected to mediate the existence of a significant temporal response of body size to climate warming but neither have been widely investigated. Using examples of rodents, we predicted that both life history traits and habitat might explain the probability of temporal response using two tests of this hypothesis. Firstly, taking advantage of new data from museum collections spanning the last 106 years, we investigated geographical and temporal variation in cranial size (a proxy for body size) in six African rodent species of two murid subfamilies (Murinae and Gerbillinae) of varying life history, degree of commensality, range size, and habitat. Two species, the commensal Mastomys natalensis, and the non-commensal Otomys unisulcatus showed significant temporal changes in body size, with the former increasing and the latter decreasing, in relation with climate warming. Commensalism could explain the increase in size with time due to steadily increasing food availability through increased agricultural production. Apart from this, we found no general life history or habitat predictors of a temporal response in African rodents. Secondly, in order to further test this hypothesis, we incorporated our data into a meta-analysis based on published literature on temporal responses in rodents, resulting in a combined dataset for 50 species from seven families worldwide; among these, 29 species showed no significant change, eight showed a significant increase in size, and 13 showed a decline in size. Using a binomial logistic regression model for these metadata, we found that none of our chosen life history or habitat predictors could significantly explain the probability of a temporal response to climate warming, reinforcing our conclusion based on the more detailed data from the six African species.

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Sexual dimorphism in body size and life‐history traits in a population ofTriturus alpestris alpestris

Italian Journal of Zoology ◽

10.1080/11250000409356620 ◽

2004 ◽

Vol 71 (sup2) ◽

pp. 117-120 ◽

Cited By ~ 3

Author(s):

Elena Marzona ◽

Daniele Seglie ◽

Cristina Giacoma

Keyword(s):

Life History ◽

Body Size ◽

Sexual Dimorphism ◽

Life History Traits

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Do females preferentially associate with males given a better start in life?

Biology Letters ◽

10.1098/rsbl.2011.1106 ◽

2012 ◽

Vol 8 (3) ◽

pp. 362-364 ◽

Cited By ~ 20

Author(s):

Andrew T. Kahn ◽

Julianne D. Livingston ◽

Michael D. Jennions

Keyword(s):

Life History ◽

Body Size ◽

Food Intake ◽

Compensatory Growth ◽

Life History Traits ◽

Adult Life ◽

Gambusia Holbrooki ◽

Developmental History ◽

Restricted Diet ◽

Adult Body

A poor start in life owing to a restricted diet can have readily detectable detrimental consequences for many adult life-history traits. However, some costs such as smaller adult body size are potentially eliminated when individuals modify their development. For example, male mosquitofish ( Gambusia holbrooki ) that have reduced early food intake undergo compensatory growth and delay maturation so that they eventually mature at the same size as males that develop normally. But do subtle effects of a poor start persist? Specifically, does a male's developmental history affect his subsequent attractiveness to females? Females prefer to associate with larger males but, controlling for body length, we show that females spent less time in association with males that underwent compensatory growth than with males that developed normally.

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Determinants of life-history traits in a fish ectoparasite: a hierarchical analysis

Parasitology ◽

10.1017/s003118201100014x ◽

2011 ◽

Vol 138 (7) ◽

pp. 848-857 ◽

Cited By ~ 10

Author(s):

G. LOOT ◽

N. POULET ◽

S. BROSSE ◽

L. TUDESQUE ◽

F. THOMAS ◽

...

Keyword(s):

Life History ◽

Body Size ◽

Egg Size ◽

Life History Traits ◽

Abiotic Factors ◽

Individual Characteristics ◽

Trade Off ◽

Individual Fitness ◽

Parasite Number ◽

Egg Number

SUMMARYObjective. Unravelling the determinants of parasite life-history traits in natural settings is complex. Here, we deciphered the relationships between biotic, abiotic factors and the variation in 4 life-history traits (body size, egg presence, egg number and egg size) in the fish ectoparasite Tracheliastes polycolpus. We then determined the factors affecting the strength of the trade-off between egg number and egg size. Methods. To do so, we used 4-level (parasite, microhabitat, host and environment) hierarchical models coupled to a field database. Results. Variation in life-history traits was mostly due to individual characteristics measured at the parasite level. At the microhabitat level (fins of fish hosts), parasite number was positively related to body size, egg presence and egg number. Higher parasite number on fins was positively associated with individual parasite fitness. At the host level, host body size was positively related to the individual fitness of the parasite; parasites were bigger and more fecund on bigger hosts. In contrast, factors measured at the environmental level had a weak influence on life-history traits. Finally, a site-dependent trade-off between egg number and egg size existed in this population. Conclusion. Our study illustrates the importance of considering parasite life-history traits in a hierarchical framework to decipher complex links between biotic, abiotic factors and parasite life-history traits.

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