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Journal articles on the topic 'Clines'

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Published: 4 June 2021

Last updated: 6 July 2024

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1

Gilchrist, A. Stuart, and Linda Partridge. "A Comparison of the Genetic Basis of Wing Size Divergence in Three Parallel Body Size Clines of Drosophila melanogaster." Genetics 153, no. 4 (December 1, 1999): 1775–87. http://dx.doi.org/10.1093/genetics/153.4.1775.

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Abstract Body size clines in Drosophila melanogaster have been documented in both Australia and South America, and may exist in Southern Africa. We crossed flies from the northern and southern ends of each of these clines to produce F1, F2, and first backcross generations. Our analysis of generation means for wing area and wing length produced estimates of the additive, dominance, epistatic, and maternal effects underlying divergence within each cline. For both females and males of all three clines, the generation means were adequately described by these parameters, indicating that linkage and higher order interactions did not contribute significantly to wing size divergence. Marked differences were apparent between the clines in the occurrence and magnitude of the significant genetic parameters. No cline was adequately described by a simple additive-dominance model, and significant epistatic and maternal effects occurred in most, but not all, of the clines. Generation variances were also analyzed. Only one cline was described sufficiently by a simple additive variance model, indicating significant epistatic, maternal, or linkage effects in the remaining two clines. The diversity in genetic architecture of the clines suggests that natural selection has produced similar phenotypic divergence by different combinations of gene action and interaction.

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2

McKenzie, Jessica L., Rashpal S. Dhillon, and Patricia M. Schulte. "Evidence for a bimodal distribution of hybrid indices in a hybrid zone with high admixture." Royal Society Open Science 2, no. 12 (December 2015): 150285. http://dx.doi.org/10.1098/rsos.150285.

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The genetic structure of a hybrid zone can provide insights into the relative roles of the various factors that maintain the zone. Here, we use a multilocus approach to characterize a hybrid zone between two subspecies of killifish ( Fundulus heteroclitus , Walbaum 1792) found along the Atlantic coast of North America. We first analysed clinal variation along the Atlantic coast using a single-nucleotide polymorphism in the mitochondrial DNA (mtDNA) displacement loop (D-loop) and a panel of nine nuclear microsatellite markers. A model constraining all clines to the same width and centre was not significantly different from a model in which the clines were allowed to vary independently. Locus-by-locus analysis indicated that the majority of nuclear clines shared the same centre as the mtDNA cline, and the widths of these clines were also narrower than that predicted by a neutral model, suggesting that selection is operating to maintain the hybrid zone. However, two of the nuclear clines had widths greater than the neutral prediction and had centres that were displaced relative to the mtDNA cline centre. We also found that a marsh located near the centre of the mtDNA cline demonstrated a bimodal distribution of nuclear hybrid index values, suggesting a deficit of first-generation hybrids and backcrossed genotypes. Thus, selection against hybrid genotypes may be playing a role in maintaining this hybrid zone and the associated steep nuclear and mtDNA clines.

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3

Potts, BM, and JB Reid. "Variation in the Eucalyptus gunnii-archeri Complex. I. Variation in the Adult Phenotype." Australian Journal of Botany 33, no. 3 (1985): 337. http://dx.doi.org/10.1071/bt9850337.

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A study of variation in the E. gunnii-archeri complex indicates continuous variation between the taxa E. gunnii Hook.f. and E. archeri Maiden & Blakely. Populations assigned to either taxon are normally allopatric but intergrade in an area of parapatry in central Tasmania. The E. gunnii-archeri complex is shown to comprise a multidimensional, clinally varying series of highly differentiated populations. In part, population differentiation appears to result from the interaction of multicharacter clines which parallel several major habitat gradients. This variation is summarized by classification of populations into five main phenetic groups. Whilst considerable differentiation occurs between disjunct stands, a large portion of the variation in the complex occurs in the more or less continuous central stands. In this area, major independent clines are associated with increasing exposure to the alpine environment and the north-south transition between subspp. gunnii and archeri. A peak in variability in geographically intermediate populations is apparent along the latter, but not the former, cline. In addition, it is shown that parallel clines in flowering time have the potential to retard gene flow along these clines. It is suggested that parallel clines which incidentally influence gene flow may be of considerable significance in parapatric differentiation and the origin of reproductive isolation.

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4

HALLAS, REBECCA, MICHELE SCHIFFER, and ARY A. HOFFMANN. "Clinal variation in Drosophila serrata for stress resistance and body size." Genetical Research 79, no. 2 (April 2002): 141–48. http://dx.doi.org/10.1017/s0016672301005523.

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Clines for size and stress resistance traits have been described for several Drosophila species and replicable clines across different species may indicate climatic selection. Here we consider clines in stress resistance traits in an Australian endemic species, D. serrata, by comparing levels of variation within and among isofemale lines initiated with flies collected from the eastern coast of Australia. We also consider clinal variation in chill coma recovery, a trait that has recently been shown to exhibit high levels of variation among Drosophila species. Patterns were compared with those in the cosmopolitan species D. melanogaster from the same area. Both desiccation and starvation resistance showed no clinal pattern despite heritable variation among isofemale lines. In contrast chill coma resistance exhibited a linear cline in the anticipated direction, resistance increasing with latitude. Body size was measured as wing length and body weight. Both traits showed geographic variation and strong non-linear clines with a sharp reduction in size in the tropics. These results are discussed in the context of climatic selection and evolutionary processes limiting species borders.

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5

Gavrilets, Sergey. "Single Locus Clines." Evolution 51, no. 3 (June 1997): 979. http://dx.doi.org/10.2307/2411171.

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6

Fujimura, Joan H., Deborah A. Bolnick, Ramya Rajagopalan, Jay S. Kaufman, Richard C. Lewontin, Troy Duster, Pilar Ossorio, and Jonathan Marks. "Clines Without Classes." Sociological Theory 32, no. 3 (September 2014): 208–27. http://dx.doi.org/10.1177/0735275114551611.

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7

Valenzuela, C. Y. "On sociogenetic clines." Ethology and Sociobiology 9, no. 5 (September 1988): 259–68. http://dx.doi.org/10.1016/0162-3095(88)90008-8.

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8

Gavrilets, Sergey. "SINGLE LOCUS CLINES." Evolution 51, no. 3 (June 1997): 979–83. http://dx.doi.org/10.1111/j.1558-5646.1997.tb03678.x.

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9

Holman, James E., Jane M. Hughes, and Roderick J. Fensham. "Origins of a morphological cline between Eucalyptus melanophloia and Eucalyptus whitei." Australian Journal of Botany 59, no. 3 (2011): 244. http://dx.doi.org/10.1071/bt10209.

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Most theories to explain the origin and maintenance of clines in Eucalyptus are based on a morphological classification system. The true relationships between putative species along clines require detailed investigation of phylogenetic relationships. A cline between Eucalyptus melanophloia and E. whitei was examined using morphological and molecular analyses to determine whether genetic structuring in nuclear and chloroplast DNA along the cline could be explained by secondary contact between independent evolutionary lineages, or whether the cline represents a single species that has undergone primary differentiation. Morphological analysis showed phenotypic variation distributed continuously across the cline and that seedlings bred true to parental type. Microsatellite analysis indicated that there was little genetic structuring across the cline, and low levels of population differentiation. This result was further reinforced by analysis of the cpDNA. The phylogeographic distribution of cpDNA haplotypes is likely to have resulted from restricted seed-mediated gene flow with isolation by distance. A cogent explanation for the cline is that it has arisen by selection on leaf types promoted by a gradient in precipitation with the short-broad, subsessile leaves of E. melanophloia favoured under higher rainfall and the long, narrow, petiolate leaves of E. whitei favoured in arid environments.

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10

Mallet, J., and N. Barton. "Inference from clines stabilized by frequency-dependent selection." Genetics 122, no. 4 (August 1, 1989): 967–76. http://dx.doi.org/10.1093/genetics/122.4.967.

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Abstract Frequency-dependent selection against rare forms can maintain clines. For weak selection, s, in simple linear models of frequency-dependence, single locus clines are stabilized with a maximum slope of between square root of s/square root of 8 sigma and square root of s/square root of 12 delta, where sigma is the dispersal distance. These clines are similar to those maintained by heterozygote disadvantage. Using computer simulations, the weak-selection analytical results are extended to higher selection pressures with up to three unlinked genes. Graphs are used to display the effect of selection, migration, dominance, and number of loci on cline widths, speeds of cline movements, two-way gametic correlations ("linkage disequilibria"), and heterozygote deficits. The effects of changing the order of reproduction, migration, and selection, are also briefly explored. Epistasis can also maintain tension zones. We show that epistatic selection is similar in its effects to frequency-dependent selection, except that the disequilibria produced in the zone will be higher for a given level of selection. If selection consists of a mixture of frequency-dependence and epistasis, as is likely in nature, the error made in estimating selection is usually less than twofold. From the graphs, selection and migration can be estimated using knowledge of the dominance and number of genes, of gene frequencies and of gametic correlations from a hybrid zone.

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11

Nagylaki, Thomas. "Clines with partial panmixia." Theoretical Population Biology 81, no. 1 (February 2012): 45–68. http://dx.doi.org/10.1016/j.tpb.2011.09.006.

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12

BARTON, N. H. "Clines in polygenic traits." Genetical Research 74, no. 3 (December 1999): 223–36. http://dx.doi.org/10.1017/s001667239900422x.

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This article outlines theoretical models of clines in additive polygenic traits, which are maintained by stabilizing selection towards a spatially varying optimum. Clines in the trait mean can be accurately predicted, given knowledge of the genetic variance. However, predicting the variance is difficult, because it depends on genetic details. Changes in genetic variance arise from changes in allele frequency, and in linkage disequilibria. Allele frequency changes dominate when selection is weak relative to recombination, and when there are a moderate number of loci. With a continuum of alleles, gene flow inflates the genetic variance in the same way as a source of mutations of small effect. The variance can be approximated by assuming a Gaussian distribution of allelic effects; with a sufficiently steep cline, this is accurate even when mutation and selection alone are better described by the ‘House of Cards’ approximation. With just two alleles at each locus, the phenotype changes in a similar way: the mean remains close to the optimum, while the variance changes more slowly, and over a wider region. However, there may be substantial cryptic divergence at the underlying loci. With strong selection and many loci, linkage disequilibria are the main cause of changes in genetic variance. Even for strong selection, the infinitesimal model can be closely approximated by assuming a Gaussian distribution of breeding values. Linkage disequilibria can generate a substantial increase in genetic variance, which is concentrated at sharp gradients in trait means.

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13

Holubar, K. "Races, Clines, and Phototypes." Archives of Dermatology 134, no. 3 (March 1, 1998): 373—a—374. http://dx.doi.org/10.1001/archderm.134.3.373-a.

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14

GÜNDÜZ, İSLAM, MARÍA JOSÉ LÓPEZ-FUSTER, JACINT VENTURA, and JEREMY B. SEARLE. "Clinal analysis of a chromosomal hybrid zone in the house mouse." Genetical Research 77, no. 1 (February 2001): 41–51. http://dx.doi.org/10.1017/s0016672300004808.

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These studies centre on the ‘Barcelona’ karyotypic race of the western house mouse (Mus musculus domesticus), first described by Adolph & Klein (1981). This is one of many races within M. m. domesticus characterized by metacentric chromosomes that have originated by repeated Robertsonian fusions, with perhaps further modification by whole-arm reciprocal translocations. Data on 111 mice from 20 sites show that the race is centred 24 km to the west of Barcelona city and has a homozygous metacentric karyotype of 2n = 28 (3·8, 4·14, 5·15, 6·10, 9·11, 12·13). The race has a small range, and mice with the standard 40-acrocentric karyotype were caught only 30 km from the race centre. Throughout the area of occurrence of metacentrics there is polymorphism (i.e. presence of acrocentrics in the population), although all six metacentrics approach fixation close to the race centre. Thus, there is a hybrid zone between the Barcelona and standard races. The centres and widths of all clines (except 3·8) were determined. Likelihood ratio tests showed that most of the cline centres differed significantly in position (i.e. the clines were staggered) and the clines for metacentrics 6·10 and 9·11 were significantly narrower than those for 4·14, 5·15 and 12·13. Overall, the clines tended to be wider the further they were from the race centre. There are various possible explanations for this hybrid zone structure and further data are needed to distinguish between them.

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15

Thompson, Ken A., Marie Renaudin, and Marc T. J. Johnson. "Urbanization drives the evolution of parallel clines in plant populations." Proceedings of the Royal Society B: Biological Sciences 283, no. 1845 (December 28, 2016): 20162180. http://dx.doi.org/10.1098/rspb.2016.2180.

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Urban ecosystems are an increasingly dominant feature of terrestrial landscapes. While evidence that species can adapt to urban environments is accumulating, the mechanisms through which urbanization imposes natural selection on populations are poorly understood. The identification of adaptive phenotypic changes (i.e. clines) along urbanization gradients would facilitate our understanding of the selective factors driving adaptation in cities. Here, we test for phenotypic clines in urban ecosystems by sampling the frequency of a Mendelian-inherited trait—cyanogenesis—in white clover ( Trifolium repens L.) populations along urbanization gradients in four cities. Cyanogenesis protects plants from herbivores, but reduces tolerance to freezing temperatures. We found that the frequency of cyanogenic plants within populations decreased towards the urban centre in three of four cities. A field experiment indicated that spatial variation in herbivory is unlikely to explain these clines. Rather, colder minimum winter ground temperatures in urban areas compared with non-urban areas, caused by reduced snow cover in cities, may select against cyanogenesis. In the city with no cline, high snow cover might protect plants from freezing damage in the city centre. Our study suggests that populations are adapting to urbanization gradients, but regional climatic patterns may ultimately determine whether adaptation occurs.

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16

Pratt, Jessica D., Andrew Datu, Thi Tran, Daniel C. Sheng, and Kailen A. Mooney. "Genetically based latitudinal clines in Artemisia californica drive parallel clines in arthropod communities." Ecology 98, no. 1 (December 9, 2016): 79–91. http://dx.doi.org/10.1002/ecy.1620.

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17

Günter, Franziska, Michaël Beaulieu, Massimo Brunetti, Lena Lange, Angela Schmitz Ornés, and Klaus Fischer. "Latitudinal and altitudinal variation in ecologically important traits in a widespread butterfly." Biological Journal of the Linnean Society 128, no. 3 (October 1, 2019): 742–55. http://dx.doi.org/10.1093/biolinnean/blz133.

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Abstract Understanding how organisms adapt to complex environments lies at the very heart of evolutionary biology and ecology, and is of particular concern in the current era of anthropogenic global change. Variation in ecologically important traits associated with environmental gradients is considered to be strong evidence for adaptive responses. Here, we study phenotypic variation along a latitudinal and an altitudinal cline in 968 field-collected males of the widespread European butterfly Pieris napi. In contrast to our expectations, body size decreased with increasing latitude and altitude, suggesting that warmer rather than cooler conditions may be more beneficial for individual development in this species. Higher altitudes but not latitudes seemed to be associated with increased flight performance, suggesting stronger challenges for flight activity in high-altitude environments (e.g. due to strong wind). Moreover, wing melanization increased while yellow reflectance decreased towards colder environments in both clines. Thus, increased melanization under thermally challenging conditions seems to compromise investment into a sexually selected trait, resulting in a trade-off. Our study, although exclusively based on field-collected males, revealed indications of adaptive patterns along geographical clines. It documents the usefulness of field-collected specimens, and the strength of comparing latitudinal and altitudinal clines to identify traits being potentially under thermal selection.

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18

van Hooft, Pim, Wayne M. Getz, Barend J. Greyling, Bas Zwaan, and Armanda D. S. Bastos. "A continent-wide high genetic load in African buffalo revealed by clines in the frequency of deleterious alleles, genetic hitchhiking and linkage disequilibrium." PLOS ONE 16, no. 12 (December 9, 2021): e0259685. http://dx.doi.org/10.1371/journal.pone.0259685.

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A high genetic load can negatively affect population viability and increase susceptibility to diseases and other environmental stressors. Prior microsatellite studies of two African buffalo (Syncerus caffer) populations in South Africa indicated substantial genome-wide genetic load due to high-frequency occurrence of deleterious alleles. The occurrence of these alleles, which negatively affect male body condition and bovine tuberculosis resistance, throughout most of the buffalo’s range were evaluated in this study. Using available microsatellite data (2–17 microsatellite loci) for 1676 animals from 34 localities (from 25°S to 5°N), we uncovered continent-wide frequency clines of microsatellite alleles associated with the aforementioned male traits. Frequencies decreased over a south-to-north latitude range (average per-locus Pearson r = -0.22). The frequency clines coincided with a multilocus-heterozygosity cline (adjusted R2 = 0.84), showing up to a 16% decrease in southern Africa compared to East Africa. Furthermore, continent-wide linkage disequilibrium (LD) at five linked locus pairs was detected, characterized by a high fraction of positive interlocus associations (0.66, 95% CI: 0.53, 0.77) between male-deleterious-trait-associated alleles. Our findings suggest continent-wide and genome-wide selection of male-deleterious alleles driven by an earlier observed sex-chromosomal meiotic drive system, resulting in frequency clines, reduced heterozygosity due to hitchhiking effects and extensive LD due to male-deleterious alleles co-occurring in haplotypes. The selection pressures involved must be high to prevent destruction of allele-frequency clines and haplotypes by LD decay. Since most buffalo populations are stable, these results indicate that natural mammal populations, depending on their genetic background, can withstand a high genetic load.

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19

Potts, BM. "Variation in the Eucalyptus gunnii-archeri Complex. III. Reciprocal Transplant Trials." Australian Journal of Botany 33, no. 6 (1985): 687. http://dx.doi.org/10.1071/bt9850687.

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Two multicharacter clines in the more or less continuous stands of Eucalyptus gunnii-archeri on the Central Plateau, Tasmania, are genetically based and appear to parallel independent habitat gradients. Results from experimental gardens established near the extremes of each cline suggest that these clines are at least partly maintained by spatially varying selective forces. Spatial variation in population fitness could be partly attributed to a differential response to drought, frost and insect predation. Most characters associated with extension growth (e.g. height, internode length, leaf size) exhibited marked phenotypic plasticity. In contrast, several characters of taxonomic importance in the complex, and which vary markedly between populations (e.g. seedling leaf shape, glaucousness), exhibited little environmental modification. The ontogenetic pattern varied between populations and, for many charac- ters, the direction of environmental modification was the same as the direction of genetic differentiation.

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20

Nuismer, Scott L., John N. Thompson, and Richard Gomulkiewicz. "COEVOLUTIONARY CLINES ACROSS SELECTION MOSAICS." Evolution 54, no. 4 (2000): 1102. http://dx.doi.org/10.1554/0014-3820(2000)054[1102:ccasm]2.0.co;2.

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21

Uljas, Sami. "Verbal Grammaticalisation Clines in Coptic." Zeitschrift für Ägyptische Sprache und Altertumskunde 146, no. 1 (May 20, 2019): 82–99. http://dx.doi.org/10.1515/zaes-2019-0010.

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Summary The present paper studies grammaticalisation of verbs in Coptic. Various (classes of) expressions found in this language can be shown to occupy different sections or ‘points’ on the continuum/cline of evolution of verbs posited in linguistics that extends from lexical items to auxiliaries, affixes, parts of other lexemes, and finally zero (nothing). The mechanisms that ‘push’ verbs along this continuum turn out to be those seen also in other languages, and the same holds for the semantic and morpho-syntactic signals thereof. Besides being of typological interest, this again emphasises the importance and necessity of studying Coptic from a more diachronic perspective.

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22

Jackson, Jeremy. "Genetic clines and climate change." Science 359, no. 6383 (March 29, 2018): 1480.5–1481. http://dx.doi.org/10.1126/science.359.6383.1480-e.

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23

Lohman, Brian K., Daniel Berner, and Daniel I. Bolnick. "Clines Arc through Multivariate Morphospace." American Naturalist 189, no. 4 (April 2017): 354–67. http://dx.doi.org/10.1086/690808.

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24

CHAPUT-BARDY, A., O. PAYS, T. LODÉ, and J. SECONDI. "Morphological clines in dendritic landscapes." Freshwater Biology 52, no. 9 (September 2007): 1677–88. http://dx.doi.org/10.1111/j.1365-2427.2007.01794.x.

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25

Nuismer, Scott L., John N. Thompson, and Richard Gomulkiewicz. "COEVOLUTIONARY CLINES ACROSS SELECTION MOSAICS." Evolution 54, no. 4 (August 2000): 1102–15. http://dx.doi.org/10.1111/j.0014-3820.2000.tb00546.x.

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26

GOMPERT, ZACHARIAH, and C. ALEX BUERKLE. "Bayesian estimation of genomic clines." Molecular Ecology 20, no. 10 (March 31, 2011): 2111–27. http://dx.doi.org/10.1111/j.1365-294x.2011.05074.x.

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27

Fitzpatrick, Benjamin M. "Alternative forms for genomic clines." Ecology and Evolution 3, no. 7 (May 23, 2013): 1951–66. http://dx.doi.org/10.1002/ece3.609.

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28

Potts, BM, and JB Reid. "Variation in the Eucalyptus gunnii-archeri Complex. II. The Origin of Variation." Australian Journal of Botany 33, no. 5 (1985): 519. http://dx.doi.org/10.1071/bt9850519.

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Previous studies of the Eucalyptus gunnii-archeri complex indicate marked differentiation of the adult phenotype. In this study, genetically based variation in the seedling phenotype is demonstrated. The five main phenetic groups in the complex are shown to be genetically defined and account for most of the genetic variation between populations. Further, the two major phenetic clines in the adult phenotype are paralleled by genetically based clines in the seedling phenotype, with greater genetic differentiation occurring along the cline between subspp. archeri and gunnii than along the cline between altitudinal extremes within subsp. gunnii. Detailed analyses of the structure of populations along the former continuum indicate no evidence for recent secondary intergradation since intermediate phenotypes are widespread and genetically stable and the various character clines appear to be independent. However, historical and biogeographical evidence is presented which suggests that a suture zone occurred between southern and northern populations during the last Pleistocene glacial. The area occupied by intermediate populations would have been amongst the last to be colonized following deglaciation. It is argued that extreme morphs differentiated in allopatry and that the continuum between the subspecies is a result of selective stabilization of a zone of secondary intergradation as opposed to primary intergradation. In contrast, the altitudinal continuum within subsp. gunnii appears to be mainly a result of primary differentiation within a population migrating up slope from a southern glacial refuge. Progeny trials indicate that the high variability and differentiation of several low-altitude, relic populations may be due to hybridization with surrounding species, whereas hybridization has little effect at the boundary of large stands. It is argued that hybridization may be important in the process of range contraction and extinction, and may be a significant evolutionary stimulus in small peripheral isolates.

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29

Mallet, J., N. Barton, G. Lamas, J. Santisteban, M. Muedas, and H. Eeley. "Estimates of selection and gene flow from measures of cline width and linkage disequilibrium in heliconius hybrid zones." Genetics 124, no. 4 (April 1, 1990): 921–36. http://dx.doi.org/10.1093/genetics/124.4.921.

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Abstract Hybrid zones can yield estimates of natural selection and gene flow. The width of a cline in gene frequency is approximately proportional to gene flow (sigma) divided by the square root of per-locus selection (square root of s). Gene flow also causes gametic correlations (linkage disequilibria) between genes that differ across hybrid zones. Correlations are stronger when the hybrid zone is narrow, and rise to a maximum roughly equal to s. Thus cline width and gametic correlations combine to give estimates of gene flow and selection. These indirect measures of sigma and s are especially useful because they can be made from collections, and require no field experiments. The method was applied to hybrid zones between color pattern races in a pair of Peruvian Heliconius butterfly species. The species are Müllerian mimics of one another, and both show the same changes in warning color pattern across their respective hybrid zones. The expectations of cline width and gametic correlation were generated using simulations of clines stabilized by strong frequency-dependent selection. In the hybrid zone in Heliconius erato, clines at three major color pattern loci were between 8.5 and 10.2 km wide, and the pairwise gametic correlations peaked at R approximately 0.35. These measures suggest that s approximately 0.23 per locus, and that sigma approximately 2.6 km. In erato, the shapes of the clines agreed with that expected on the basis of dominance. Heliconius melpomene has a nearly coincident hybrid zone. In this species, cline widths at four major color pattern loci varied between 11.7 and 13.4 km. Pairwise gametic correlations peaked near R approximately 1.00 for tightly linked genes, and at R approximately 0.40 for unlinked genes, giving s approximately 0.25 per locus and sigma approximately 3.7 km. In melpomene, cline shapes did not perfectly fit theoretical shapes based on dominance; this deviation might be explained by long-distance migration and/or strong epistasis. Compared with erato, sample sizes in melpomene are lower and the genetics of its color patterns are less well understood. In spite of these problems, selection and gene flow are clearly of the same order of magnitude in the two species. The relatively high per locus selection coefficients agree with "major gene" theories for the evolution of Müllerian mimicry, but the genetic architecture of the color patterns does not. These results show that the genetics and evolution of mimicry are still only sketchily understood.

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30

Baird, S. J. E. "A Simulation Study of Multilocus Clines." Evolution 49, no. 6 (December 1995): 1038. http://dx.doi.org/10.2307/2410429.

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31

BLACKMAN, B. K. "Connecting genetic variation to phenotypic clines." Molecular Ecology 19, no. 4 (January 25, 2010): 621–23. http://dx.doi.org/10.1111/j.1365-294x.2009.04510.x.

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32

Baird, S. J. E. "A SIMULATION STUDY OF MULTILOCUS CLINES." Evolution 49, no. 6 (December 1995): 1038–45. http://dx.doi.org/10.1111/j.1558-5646.1995.tb04431.x.

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33

Anderson, Warwick. "From Racial Types to Aboriginal Clines." Historical Studies in the Natural Sciences 50, no. 5 (November 2020): 498–524. http://dx.doi.org/10.1525/hsns.2020.50.5.498.

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The mid-twentieth century Australian fieldwork of Joseph B. Birdsell illustrates, perhaps uniquely, the transition from typological structuring in physical anthropology before World War II to human biology’s increasing interest in the geographical or clinal patterning of genes and commitment to notions of drift and selection. It also shows that some morphological inquiries lingered into the postwar period, as did an attachment to theories of racial migration and hybridization. Birdsell’s intensive and long-term fieldwork among Aboriginal Australians eventually led him to criticize the settler colonialism and white racism that had made possible his expeditions and data collection. Yet he continued to regard Aboriginal communities as “island laboratories” and to treat Aboriginal people as convenient research subjects, distancing himself from their life worlds and experiences of dispossession and exploitation. This essay is part of a special issue entitled Pacific Biologies: How Humans Become Genetic, edited by Warwick Anderson and M. Susan Lindee.

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34

McKenzie, Jessica L., Dillon J. Chung, Timothy M. Healy, Reid S. Brennan, Heather J. Bryant, Andrew Whitehead, and Patricia M. Schulte. "Mitochondrial Ecophysiology: Assessing the Evolutionary Forces That Shape Mitochondrial Variation." Integrative and Comparative Biology 59, no. 4 (July 8, 2019): 925–37. http://dx.doi.org/10.1093/icb/icz124.

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Abstract The mitonuclear species concept hypothesizes that incompatibilities between interacting gene products of the nuclear and mitochondrial genomes are a major factor establishing and maintaining species boundaries. However, most of the data available to test this concept come from studies of genetic variation in mitochondrial DNA, and clines in the mitochondrial genome across contact zones can be produced by a variety of forces. Here, we show that using a combination of population genomic analyses of the nuclear and mitochondrial genomes and studies of mitochondrial function can provide insight into the relative roles of neutral processes, adaptive evolution, and mitonuclear incompatibility in establishing and maintaining mitochondrial clines, using Atlantic killifish (Fundulus heteroclitus) as a case study. There is strong evidence for a role of secondary contact following the last glaciation in shaping a steep mitochondrial cline across a contact zone between northern and southern subspecies of killifish, but there is also evidence for a role of adaptive evolution in driving differentiation between the subspecies in a variety of traits from the level of the whole organism to the level of mitochondrial function. In addition, studies are beginning to address the potential for mitonuclear incompatibilities in admixed populations. However, population genomic studies have failed to detect evidence for a strong and pervasive influence of mitonuclear incompatibilities, and we suggest that polygenic selection may be responsible for the complex patterns observed. This case study demonstrates that multiple forces can act together in shaping mitochondrial clines, and illustrates the challenge of disentangling their relative roles.

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James, A. C., R. B. Azevedo, and L. Partridge. "Cellular basis and developmental timing in a size cline of Drosophila melanogaster." Genetics 140, no. 2 (June 1, 1995): 659–66. http://dx.doi.org/10.1093/genetics/140.2.659.

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Abstract We examined 20 Drosophila melanogaster populations collected from a 2600-km north-south transect in Australia. In laboratory culture at constant temperature and standard larval density, a genetic cline in thorax length and wing area was found, with both traits increasing with latitude. The cline in wing area was based on clines in both cell size and cell number, but was primarily determined by changes in cell number. Body size and larval development time were not associated among populations. We discuss our results in the context of selection processes operating in natural and experimental populations.

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DAVISON, PAUL J., and JEREMY FIELD. "Season length, body size, and social polymorphism: size clines but not saw tooth clines in sweat bees." Ecological Entomology 42, no. 6 (August 3, 2017): 768–76. http://dx.doi.org/10.1111/een.12448.

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Santangelo, James S., Rob W. Ness, Beata Cohan, Connor R. Fitzpatrick, Simon G. Innes, Sophie Koch, Lindsay S. Miles, et al. "Global urban environmental change drives adaptation in white clover." Science 375, no. 6586 (March 18, 2022): 1275–81. http://dx.doi.org/10.1126/science.abk0989.

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Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.

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Gilabert, A., C. A. Dedryver, S. Stoeckel, M. Plantegenest, and J. C. Simon. "Longitudinal clines in the frequency distribution of ‘super-clones’ in an aphid crop pest." Bulletin of Entomological Research 105, no. 6 (August 17, 2015): 694–703. http://dx.doi.org/10.1017/s0007485315000619.

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AbstractParthenogenesis is the main mode of reproduction of aphids. Their populations are therefore composed of clones whose frequency distribution varies in space and time. Previous population genetic studies on aphids have highlighted the existence of highly abundant clones (‘super-clones’), distributed over large geographic areas and persisting over time. Whether the abundance of ‘super-clones’ results from their ecological success or from stochastic forces, such as drift and migration, is an open question. Here, we looked for the existence of clines in clonal frequency along a climatic gradient in the cereal aphid Rhopalosiphum padi (Linnaeus, 1758) and examined the possible influence of geographical distance and environmental variables in the buildup and maintenance of such clonal clines. We investigated the spatial distribution of the commonest genotypes of R. padi by sampling populations along an east–west transect in maize fields in the northern half of France in both spring and late summer. Individual aphids were genotyped at several polymorphic loci, allowing the assessment of frequency distributions of multilocus genotypes (MLGs) across the cropping season. We found several MLGs showing longitudinal clines in their frequency distribution in both spring and summer. In particular, two dominant asexual genotypes of R. padi showed inverted geographical clines, which could suggest divergent adaptations to environmental conditions. We concluded that while the distribution of some ‘super-clones’ of R. padi seems most likely driven by the action of migration and genetic drift, selection could be also involved in the establishment of longitudinal clines of others.

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Hut, Roelof A., Silvia Paolucci, Roi Dor, Charalambos P. Kyriacou, and Serge Daan. "Latitudinal clines: an evolutionary view on biological rhythms ,." Proceedings of the Royal Society B: Biological Sciences 280, no. 1765 (August 22, 2013): 20130433. http://dx.doi.org/10.1098/rspb.2013.0433.

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Properties of the circadian and annual timing systems are expected to vary systematically with latitude on the basis of different annual light and temperature patterns at higher latitudes, creating specific selection pressures. We review literature with respect to latitudinal clines in circadian phenotypes as well as in polymorphisms of circadian clock genes and their possible association with annual timing. The use of latitudinal (and altitudinal) clines in identifying selective forces acting on biological rhythms is discussed, and we evaluate how these studies can reveal novel molecular and physiological components of these rhythms.

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Gavrilets, Sergey, and Mitchell B. Cruzan. "Neutral Gene Flow Across Single Locus Clines." Evolution 52, no. 5 (October 1998): 1277. http://dx.doi.org/10.2307/2411297.

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Stillwell, R. Craig. "Are latitudinal clines in body size adaptive?" Oikos 119, no. 9 (August 23, 2010): 1387–90. http://dx.doi.org/10.1111/j.1600-0706.2010.18670.x.

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Hare, Matthew P., Christopher Guenther, and William F. Fagan. "NONRANDOM LARVAL DISPERSAL CAN STEEPEN MARINE CLINES." Evolution 59, no. 12 (December 2005): 2509–17. http://dx.doi.org/10.1111/j.0014-3820.2005.tb00964.x.

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Gavrilets, Sergey, and Mitchell B. Cruzan. "NEUTRAL GENE FLOW ACROSS SINGLE LOCUS CLINES." Evolution 52, no. 5 (October 1998): 1277–84. http://dx.doi.org/10.1111/j.1558-5646.1998.tb02009.x.

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Hare, Matthew P., Christopher Guenther, and William F. Fagan. "NONRANDOM LARVAL DISPERSAL CAN STEEPEN MARINE CLINES." Evolution 59, no. 12 (2005): 2509. http://dx.doi.org/10.1554/05-150.1.

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Caulkins, D. Douglas. "Consensus, Clines, and Edges in Celtic Cultures." Cross-Cultural Research 35, no. 2 (May 2001): 109–26. http://dx.doi.org/10.1177/106939710103500202.

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Camacho, Juan Pedro M., Michael W. Shaw, Josefa Cabrero, Mohammed Bakkali, Mercedes Ruíz-Estévez, Francisco J. Ruíz-Ruano, Rubén Martín-Blázquez, and María Dolores López-León. "Transient Microgeographic Clines during B Chromosome Invasion." American Naturalist 186, no. 5 (November 2015): 675–81. http://dx.doi.org/10.1086/683172.

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Santangelo, James S., Marc T. J. Johnson, and Rob W. Ness. "Modern spandrels: the roles of genetic drift, gene flow and natural selection in the evolution of parallel clines." Proceedings of the Royal Society B: Biological Sciences 285, no. 1878 (May 9, 2018): 20180230. http://dx.doi.org/10.1098/rspb.2018.0230.

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Urban environments offer the opportunity to study the role of adaptive and non-adaptive evolutionary processes on an unprecedented scale. While the presence of parallel clines in heritable phenotypic traits is often considered strong evidence for the role of natural selection, non-adaptive evolutionary processes can also generate clines, and this may be more likely when traits have a non-additive genetic basis due to epistasis. In this paper, we use spatially explicit simulations modelled according to the cyanogenesis (hydrogen cyanide, HCN) polymorphism in white clover ( Trifolium repens ) to examine the formation of phenotypic clines along urbanization gradients under varying levels of drift, gene flow and selection. HCN results from an epistatic interaction between two Mendelian-inherited loci. Our results demonstrate that the genetic architecture of this trait makes natural populations susceptible to decreases in HCN frequencies via drift. Gradients in the strength of drift across a landscape resulted in phenotypic clines with lower frequencies of HCN in strongly drifting populations, giving the misleading appearance of deterministic adaptive changes in the phenotype. Studies of heritable phenotypic change in urban populations should generate null models of phenotypic evolution based on the genetic architecture underlying focal traits prior to invoking selection's role in generating adaptive differentiation.

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Koch, Paul L. "Clinal geographic variation in mammals: implications for the study of chronoclines." Paleobiology 12, no. 3 (1986): 269–81. http://dx.doi.org/10.1017/s0094837300013774.

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Mammalian species often exhibit clinal geographic variation in body size: individuals tend to be larger in areas with lower mean annual temperature. Climatic change involving increasing or decreasing mean annual temperature may cause clines to shift geographically, resulting in a phenotypic shift at all affected locales within a species' range. I assess the potential of shifting geographic clines to produce morphological trends in the fossil record. Five extant North American mammalian species (Didelphis virginiana, Mephitis mephitis, Odocoileus virginianus, Scalopus aquaticus, and Sciurus carolinensis) are examined to quantify size change along latitudinal clines and to estimate the geographic range and temperature difference commonly associated with a given difference in body size. Relative to body size, the observed size range of skeletal characters within each of these five species is comparable to that seen in a much larger sample of North American mammals. Thus patterns of variation documented for the five species may be used to assess the likelihood of dine translocation as an explanation of size change in the mammalian fossil record. As a case study, I examine three lineages from the Early Eocene of the Bighorn Basin, Wyoming. I determine that size change in these chronoclines represents evolutionary change and is not merely the result of shifting geographic clines.

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Lacocque, ANDRÉ. "The Different Versions of Esther." Biblical Interpretation 7, no. 3 (1999): 301–22. http://dx.doi.org/10.1163/156851599x00038.

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AbstractIn this article I contrast my reading of Esther as presented in The Feminine Unconventional with that proposed by David J.A. Clines in his book, The Esther Scroll: The Story of the Story. I particularly criticize his judgment on the literary genre, composition, and value of the so-called "A-Text," a Greek version of the Esther story extant in four late manuscripts, in which Clines sees an original core of the genuine story he calls the pre-Masoretic tale. The constant implication in his book is that this pre-Masoretic version is far superior in artistry and philosophical content to the later reworkings of the tale as we find them in the MT and in the LXX with its extensive Additions. To retrieve the alleged pristine meaning of the tale, Clines is led to emend all elements of the story that do not fit the conventional pattern of "the success story of the wise courtier." My reading and assessment of the A-Text are vastly different from Clines's. I explain why and present several samples of my divergent understanding. The A-Text is a most interesting piece, but, I believe, Clines has missed the real generic nature of the document and, in consequence, has drawn from it far-reaching but wrong conclusions.

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Fritz, Uwe, L. Lee Grismer, and Marika Asztalos. "Hybrid zones of Natrix helvetica and N. natrix: Phenotype data from iNaturalist and genetics reveal concordant clines and the value of species-diagnostic morphological traits." Vertebrate Zoology 73 (April 25, 2023): 383–95. http://dx.doi.org/10.3897/vz.73.e103319.

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Using georeferenced photographic records of 2944 grass snakes from Germany, Austria, and northern Italy as well as previously published mtDNA sequences (n = 1062) and microsatellite data (n = 952) for grass snakes from the same regions, we examined whether or not coloration and pattern reliably allow to differentiate between Natrix natrix and N. helvetica and if so, whether the distribution patterns revealed by phenotypes and genetics are congruent. Furthermore, we used cline analyses across hybrid zones to test whether the phenotypic transition from one species to the other parallels the steep clines unveiled by genetics. Our results suggest that the two species can be reliably differentiated using coloration and pattern. The most powerful diagnostic traits are the presence/absence of side bars on the body flanks, the number of occipital spots, and the shape of the posterior dark occipital spot. The distributions of morphologically identified N. natrix and N. helvetica match their genetically confirmed ranges. Single conflicting individuals morphologically identified as N. natrix or hybrids within the distribution range of N. helvetica either represent misidentifications or translocated snakes. For the genetic markers and phenotypes, our cline analyses revealed concordant steep clines across hybrid zones. However, the southern part of the hybrid zone in Italy, for which no sufficient genetic data are available, should be studied in more detail because the phenotypic data suggest a smooth cline in this region. The unexpected high percentage of putative hybrids with dorsal stripes in this region also calls for further research. For northwestern Germany, another region for which no genetically verified records are available, iNaturalist data suggest that the contact zone of N. natrix and N. helvetica is near the Ems River and extends from there southeastwards to the region of Höxter, North Rhine-Westphalia.

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