scholarly journals The evolutionary origins of modularity

2013 ◽  
Vol 280 (1755) ◽  
pp. 20122863 ◽  
Author(s):  
Jeff Clune ◽  
Jean-Baptiste Mouret ◽  
Hod Lipson
Keyword(s):  
Biological Networks ◽  
Network Performance ◽  
Indirect Selection ◽  
Direct Selection ◽  
Network Nodes ◽  
Evolutionary Origins ◽  
Modular Networks ◽  
Key Driver ◽  
Selection For ◽  
The Cost

A central biological question is how natural organisms are so evolvable (capable of quickly adapting to new environments). A key driver of evolvability is the widespread modularity of biological networks—their organization as functional, sparsely connected subunits—but there is no consensus regarding why modularity itself evolved. Although most hypotheses assume indirect selection for evolvability, here we demonstrate that the ubiquitous, direct selection pressure to reduce the cost of connections between network nodes causes the emergence of modular networks. Computational evolution experiments with selection pressures to maximize network performance and minimize connection costs yield networks that are significantly more modular and more evolvable than control experiments that only select for performance. These results will catalyse research in numerous disciplines, such as neuroscience and genetics, and enhance our ability to harness evolution for engineering purposes.

scholarly journals Early generation selection strategy for yield and yield components in white oat

2005 ◽  
Vol 62 (4) ◽  
pp. 357-365 ◽  
Author(s):  
Giovani Benin ◽  
Fernando Irajá Félix de Carvalho ◽  
Antônio Costa de Oliveira ◽  
Claudir Lorencetti ◽  
Igor Pires Valério ◽  
...  
Keyword(s):  
Grain Yield ◽  
Indirect Selection ◽  
Grain Weight ◽  
Yield Potential ◽  
High Yield ◽  
Direct Selection ◽  
Selection Strategy ◽  
Breeding Method ◽  
Growing Seasons ◽  
Selection For

Several studies have searched for higher efficiency on plant selection in generations bearing high frequency of heterozygotes. This work aims to compare the response of direct selection for grain yield, indirect selection through average grain weight and combined selection for higher yield potential and average grain weight of oat plants (Avena sativa L.), using the honeycomb breeding method. These strategies were applied in the growing seasons of 2001 and 2002 in F3 and F4 populations, respectively, in the crosses UPF 18 CTC 5, OR 2 <FONT FACE=Symbol>´</FONT> UPF 7 and OR 2 <FONT FACE=Symbol>´</FONT> UPF 18. The ten best genetic combinations obtained for each cross and selection strategy were evaluated in greenhouse yield trials. Selection of plants with higher yield and average grain weight might be performed on early generations with high levels of heterozygosis. The direct selection for grain yield and indirect selection for average grain weight enabled to increase the average of characters under selection. However, genotypes obtained through direct selection presented lower average grain weight and those obtained through the indirect selection presented lower yield potential. Selection strategies must be run simultaneously to combine in only one genotype high yield potential and large grain weight, enabling maximum genetic gain for both characters.

Selection on ram 18-month weight to improve lamb growth rate

1983 ◽  
Vol 36 (2) ◽  
pp. 159-164
Author(s):  
D. Croston ◽  
J. L. Read ◽  
D. W. Jones ◽  
D. E. Steane ◽  
C. Smith
Keyword(s):  
Growth Rate ◽  
Live Weight ◽  
Indirect Selection ◽  
Direct Selection ◽  
Selection For ◽  
The Relationship ◽  
Lamb Growth

ABSTRACTThirteen pairs of Suffolk rams were selected on high and low 18-month adjusted live weight from six farms over 2 years, to establish the relationship between 18-month weight and early lamb growth. Progeny were first produced in recorded crossbred flocks (618 lambs) and then in an experimental flock of crossbred ewes (1083 lambs). Different results were obtained from the recorded and experimental flocks. The regressions of lamb 12- to 13-week weight on ram 18-month weight (within farm deviation) were 0·053 ± 0·022 kg and –0·004 ± 0·020 kg, respectively. These regressions for indirect selection correspond to ‘effective’ heritabilities for direct selection for lamb growth of 0·18 ± 0·07 and 0·02 ± 0·06 respectively. Improvement of early Iamb growth is discussed and it is concluded that selection for 18-month weight is unlikely to be a useful method.

scholarly journals Same-sex sexual behavior and selection for indiscriminate mating

2020 ◽  
Author(s):  
Brian A Lerch ◽  
Maria R Servedio
Keyword(s):  
Sexual Behavior ◽  
Sexual Reproduction ◽  
Optimal Strategy ◽  
Strong Support ◽  
Same Sex ◽  
Evolutionary Origins ◽  
Wide Range ◽  
Selection For ◽  
The Cost ◽  
Time And Energy

The widespread presence of same-sex sexual behavior (SSB) has long been thought to pose an evolutionary conundrum1-3, as participants in SSB suffer the cost of failing to reproduce after expending the time and energy to find a mate. The potential for SSB to occur as part of an optimal strategy has received almost no attention, although indiscriminate sexual behavior may be the ancestral mode of sexual reproduction4. Here, we build a simple model of sexual reproduction and create a theoretical framework for the evolution of indiscriminate sexual behavior. We provide strong support for the hypothesis that SSB is likely maintained by selection for indiscriminate sexual behavior, by showing that indiscriminate mating is the optimal strategy under a wide range of conditions. Further, our model suggests that the conditions that most strongly favor indiscriminate mating were likely present at the origin of sexual behavior. These findings have implications not only for the evolutionary origins of SSB, but also for the evolution of discriminate sexual behavior across the animal kingdom.

Usefulness of some components of the lactation curve for selection in Murrah buffaloes

1983 ◽  
Vol 36 (2) ◽  
pp. 277-283
Author(s):  
J. S. Cheema ◽  
S. B. Basu
Keyword(s):  
Milk Yield ◽  
Genetic Correlations ◽  
Indirect Selection ◽  
Direct Selection ◽  
Single Factor ◽  
Daily Production ◽  
Murrah Buffaloes ◽  
Lactation Curve ◽  
Selection For ◽  
Initial Peak

ABSTRACTThe study was based on 1156 lactation records of 545 Murrah buffaloes. Initial milk yield, peak yield, ascending phase milk yield and days to attain peak daily production, the means of which were 26·7 kg, 10·3 kg, 407 kg and 58·9 days respectively, were all affected by period, season and parity of calving. Heifers recorded the least initial milk yield and peak yield and took the longest time to reach peak production. Peak yield was the most important single factor (R2 = 0·41) in causing variation in 43-week milk yield. The heritability estimates for initial, peak and ascending phase milk yields and days to attain peak yield were 0·35, 0·51, 0·27 and 0·13 respectively, whilst that for 43-week milk yield was 0·18. Peak yield had the highest phenotypic (rP = 0·64) and genetic correlations (ra = 0·68 ± 0·19) with the 43-week milk yield. Other genetic correlations with the 43-week milk yield were low and non-significant. The results indicated that indirect selection for peak yield would be more effective than direct selection for improving the 43-week milk yield in buffaloes.

scholarly journals Conspecific sperm precedence is reinforced but sexual selection weakened in sympatric populations ofDrosophila

2016 ◽  
Author(s):  
Dean M. Castillo ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Sperm Competition ◽  
Competitive Ability ◽  
Genetic Basis ◽  
Direct Selection ◽  
Sperm Precedence ◽  
Sympatric Populations ◽  
Selection For ◽  
The Cost

SUMMARYSexual selection is well recognized as a driver of reproductive isolation between lineages. However, selection for increased reproductive isolation could reciprocally change the outcomes of sexual selection, when these processes share a genetic basis. Direct selection for reproductive isolation occurs in the context of ‘reinforcement’, where selection acts to increase prezygotic barriers to reduce the cost of heterospecific matings. Many studies of reinforcement focus on premating reproductive barriers, however postmating traits-such as conspecific sperm precedence (CSP)-can also respond to reinforcing selection. We tested whether i) CSP responded to reinforcing selection, and ii) this response in sympatric populations altered intraspecific sperm competition (ISC) and the strength of sexual selection, with the sister speciesDrosophila pseudoobscuraandD. persimilis. We used sperm competition experiments to evaluate differences in CSP and ISC between two sympatric and two allopatric populations ofD. pseudoobscura. Using multiple genotypes for each population allowed us to estimate not only patterns of phenotype divergence, but also the opportunity for sexual selection within each population. Consistent with a pattern of reinforcement, the sympatric populations had higher mean CSP. Moreover, ISC was altered in sympatric populations, where we observed decreased average offensive sperm competitive ability against conspecific males, allowing less opportunity for sexual selection to operate within these populations. These data demonstrate that strong reinforcing selection for reproductive isolation can have consequences for sexual selection and sexual interactions within species, in these important postmating sperm competition traits.

Estimates of selection parameters associated with protein and oil content of soybean seeds (Glycine max (L.) Merr.)

1977 ◽  
Vol 28 (2) ◽  
pp. 211 ◽  
Author(s):  
R Shorter ◽  
DE Byth ◽  
VE Mungomery
Keyword(s):  
Seed Yield ◽  
Variance Component ◽  
Selection Index ◽  
Chemical Yield ◽  
Indirect Selection ◽  
Direct Selection ◽  
Yield Traits ◽  
Oil Percentage ◽  
Selection For ◽  
Location Interaction

Three crosses of soybean involving United States and other germplasm were examined in the F3 and F4 generations at two locations, one near the coast, the other on the Darling Downs. Line and line x location interaction variances within crosses for most traits were almost all significant, except for protein, oil, and protein plus oil yield where line variances were non-significant when data were combined over locations. Line variances were considerably smaller for all traits when estimated across, rather than within, locations. For protein, oil, and protein plus oil percentage, the line x location interaction variance component generally was smaller than the line variance component in two crosses, but larger in a third even though the latter cross had the largest line variance for these traits. The line x location interactions may have been related in some cases to lower protein and oil percentages of late-maturing lines in that location where cold conditions prevailed late in the season. Heritability percentages computed from F4 variance components ranged from 49 to 89% and were largest for the chemical pexentage traits within locations. Standard unit heritability percentages estimated from F3–F4 generations were lower than those computed via the variance component method, and approached zero for oil percentage, protein plus oil percentage, and the chemical yield traits in some crosses if the generations were grown in different locations. Genotypic correlations between protein percentage and seed yield ranged from –0.50 to 0.16 across crosses and were opposite in sign to those between oil percentage and seed yield. Genotypic and phenotypic correlations between protein and oil percentage were highly negative in two crosses (–0.62 to –0.96) but much less negative in the third cross (–0.24 to –0.35). Predicted genetic advance (percentage of population mean) ranged from 5.9 to 26.1% for the chemical yield traits and from 1.5 to 6.3% for protein or oil percentage. Indirect selection for chemical yield through seed yield was 90–109% as efficient as direct selection, and a selection index that combined seed yield and either protein, oil, or protein plus oil percentage generally was no more efficient than direct selection for the corresponding chemical yield trait. Indirect selection for chemical yield through chemical percentage was much less efficient than direct selection for chemical yield.

scholarly journals Conspecific sperm precedence is reinforced, but postcopulatory sexual selection weakened, in sympatric populations of Drosophila

2019 ◽  
Vol 286 (1899) ◽  
pp. 20182535 ◽  
Author(s):  
Dean M. Castillo ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Isolation ◽  
Competitive Ability ◽  
Reproductive Traits ◽  
Sister Species ◽  
Direct Selection ◽  
Sympatric Populations ◽  
Collateral Effect ◽  
Selection For ◽  
The Cost

Sexual selection can accelerate speciation by driving the evolution of reproductive isolation, but forces driving speciation could also reciprocally feedback on sexual selection. This might be particularly important in the context of ‘reinforcement’, where selection acts directly to increase prezygotic barriers to reduce the cost of heterospecific matings. Using assays of sperm competition within and between two sister species, we show a signature of reinforcement where these species interact: populations of Drosophila pseudoobscura that co-occur with sister species D. persimilis have an elevated ability to outcompete heterospecific sperm, consistent with selection for increased postcopulatory isolation. We also find these D. pseudoobscura populations have decreased sperm competitive ability against conspecifics, reducing the opportunity for sexual selection within these populations. Our findings demonstrate that direct selection to increase reproductive isolation against other species can compromise the efficacy of sexual selection within species, a collateral effect of reproductive traits responding to heterospecific interactions.

Inheritance of Cowpea Yields under Different Soil Conditions in Papua New Guinea

1978 ◽  
Vol 14 (1) ◽  
pp. 23-28 ◽  
Author(s):  
W. Erskine ◽  
T. N. Khan
Keyword(s):  
Soil Fertility ◽  
Grain Yield ◽  
Papua New Guinea ◽  
Seed Weight ◽  
New Guinea ◽  
Indirect Selection ◽  
Direct Selection ◽  
Soil Conditions ◽  
Selection For ◽  
Broadsense Heritability

SUMMARYBroadsense heritability, and correlations of grain yield and related characters, were estimated in three crosses under two levels of soil fertility, which profoundly affected heritability of height and seed weight. Grain yield exhibited heritability of 51–81%, and in one cross significant heterosis in F2. Amongst yield-related characters only pods/plant and seeds/pod were both correlated to yield, and also lacked negative genotypic correlations with other economic characters. However, direct selection for grain yield was considered more efficient than indirect selection using yield-related characters.

RELATIVE MERIT OF SIB VERSUS OWN PERFORMANCE IN SELECTION FOR LEAN MEAT PRODUCTION IN SWINE

1967 ◽  
Vol 47 (3) ◽  
pp. 171-179 ◽  
Author(s):  
A. H. Martin ◽  
H. T. Fredeen
Keyword(s):  
Genetic Correlation ◽  
Population Size ◽  
Genetic Parameters ◽  
Selection Procedure ◽  
Indirect Selection ◽  
Direct Selection ◽  
Meat Production ◽  
Population Sizes ◽  
Selection For ◽  
Selection Intensities

The relative selection efficiency (RSE) of direct selection for a trait of basic interest and indirect selection on an alternate trait was examined with consideration given to several population sizes, selection intensities and genetic parameters. Slaughter of litter samples resulting in a reduction of the population available for selection was associated with the direct but not the indirect selection procedure. Values of RSE increased with increasing values of the genetic correlation, but for any given value of the genetic correlation, RSE was inversely related to the heritability of the basic trait. Population size was important only for herds comprising fewer than 10 breeding females.Using predicted percent yield of lean cuts, (A), as the trait for direct selection with [Formula: see text] of 0.2, 0.3 and 0.4 and the live back fat probe, (B), as the trait for indirect selection, with [Formula: see text] and assuming a genetic correlaton between A and B of 0.6, it was demonstrated that, respectively 38, 19 and 9% faster genetic gains in the basic trait accrued from indirect as compared with direct selection. It is suggested that the inherent reduction in population size, coupled with other practical aspects associated with carcass testing, might make the indirect selection method preferable even when RSE is less than unity.

scholarly journals A novel SNP of Lysozyme Gene and Its Association with Mastitis Trait in Chinese Holstein

2013 ◽  
Vol 56 (1) ◽  
pp. 589-592
Author(s):  
R. Chen ◽  
Z. Wang ◽  
Z. Yang ◽  
Y. Mao ◽  
D. Ji ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Dairy Industry ◽  
Clinical Mastitis ◽  
Indirect Selection ◽  
Economic Losses ◽  
Direct Selection ◽  
Selection For ◽  
Herd Milk ◽  
Important Disease ◽  
Novel Snp

Abstract. Mastitis is the most frequent and important disease in the dairy industry worldwide, which leads to great economic losses in the dairy industry (Nash et al. 2003). Direct selection for resistance to clinical mastitis may be very difficult and indirect selection has been practiced widely. The recommended measure is to record herd milk somatic cell scores (SCS) based on the positive correlation between clinical mastitis and milk SCS (Rupp et al. 1999).

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