Classification and Systematics
Jacques Derek Charlwood in The Ecology of Malaria Vectors, 2019
In South America the picture is, if anything, more complicated (Conn et al., 2013). Thus, in a recent study examining Anophelinae species diversity from settler communities in the Amazonas region of Brazil, 23 species were collected, of which up to 13 appeared to be new. The contraction of the Amazon rainforest into isolated patches, so-called forest refugia (Haffer, 1974), during the Pleistocene (0.01–2.6 mya), with secondary intergradiation when rainfall increased is considered to be the primary driver for divergence in these mosquitoes (as well as butterflies, Drosophila and lizards). Isolation by distance is also likely to be important because most species do not have continuously distributed populations and gene flow between clumped demes is generally leptokurtic (because more individuals move smaller distances than they would if they moved at random). Hence, species with broad ranges are more likely to be divided by changes in geomorphology and climate than species with limited ranges. They are also more likely to have greater habitat diversity and so may develop clines and subspecies.
Race and the Role of Sociocultural Context in Forensic Anthropological Ancestry Assessment
Heather M. Garvin, Natalie R. Langley in Case Studies in Forensic Anthropology, 2019
Furthermore, while race is socially defined, there does exist observable phenotypic, or physically expressed, variation among human groups that is biological in nature. However, patterned variation in human variation does not equate to race; race is typically conceived of as discrete bins, whereas biological variation is clinal – that is, much of human physical variation occurs along gradients (typically geographic in nature) with no well-defined or distinct boundaries. The systematic nature of human variation means that more closely related populations of individuals tend to share greater similarity in their phenotypic expression – including skeletal traits – than do more distantly related groups, even though expression of those traits is not homogenous within any group (i.e., there is significant variation within groups) and any given expression of a trait is not unique to any one group (Hefner, 2009: Tables 3–13). Perhaps the simplest clinal or geographically patterned phenotypic trait to appreciate in humans is skin color (Relethford, 2002). Yet, when it comes to race, an individual’s skin color does not obligate them to self-identify by others’ external categories; for example, individuals who self-identify as “Black” can have less melanin (i.e., lighter skin tone) than those who self-identify as “White.”
Plant DNA: Contents and Systematics
S. K. Dutta in DNA Systematics, 2019
That the geographical ranges are determined by the amount of nuclear DNA content has also been comprehensively demonstrated in the case of crop plants. A DNA amount-latitude cline has been shown for cereal grain crops, cultivated pasture grasses, and pulses.20 Furthermore, a clear correlation exists between the latitude of supposed sites of domestication, thereby implying the natural distribution of wild progenitors and DNA amount. This shows that the cline is a natural phenomenon and crop species with increasingly low DNA amounts were selected at successively lower latitudes. This cline has evidently been modified and exaggerated in agriculture later on.
An evaluation of inter and intra population structure of Uttar Pradesh, inferred from 24 autosomal STRs
Published in Annals of Human Biology, 2022
Ikramul Haque, Shivani Dixit, Akash Kumar, Akshay Kumar, Sunita Verma, Devinder Kumar, Ankit Srivastava, R. K. Kumawat, Divya Shrivastava, Gyaneshwer Chaubey, Pankaj Shrivastava
East and south-east Asian populations, Pakistani populations, and Indian populations (Sultana et al. 2015) were evaluated for the structure analysis using a Bayesian-based method to estimate the delta K for the number of cluster K = 2 to K = 10. Cluster 5 (K = 5) was found to be most informative (Figure 6) for showing the ancestry component distribution among the compared populations (Figure 7). The light green coloured ancestry component was observed as most dominant in the South Indian population, whereas the dark green and light green coloured ancestry components jointly showed the ancestry components of the ancestral North Indian populations. The light blue coloured ancestry component was most dominant in the East Asian populations. The orange coloured ancestry component showed an ancestry gradient towards East to West geography. The overall structure revealed an ancestry cline in the East to West direction..
How have our clocks evolved? Adaptive and demographic history of the out-of-African dispersal told by polymorphic loci in circadian genes
Published in Chronobiology International, 2018
Arcady A. Putilov, Vladimir B. Dorokhov, Michael G. Poluektov
The intrinsic molecular clocks coordinate our physiology and behavior into circadian rhythms entrained to the 24-hour solar day. In human and other mammal species the mechanism of these clocks is currently understood as a transcription/translation feedback loop involving more than ten genes (Partch et al. 2014; Takahashi 2015). The genetic variation at some of particular loci in these genes was shaped by environmental factors. The most evident examples of such adaptation are latitudinal clines in allele frequency (Hut and Beersma 2011; Hut et al. 2013; Kyriacou et al. 2008). They were documented for the genes of circadian family in several animal species including birds (Johnsen et al. 2007; Liedvogel et al. 2009), fishes (Lemay and Russello 2014; O’Malley and Banks 2008), and flies (Costa et al. 1992; Rosato et al. 1997; Sawyer et al. 2006). However, a set of rather contradictive conclusions was drawn from the results of rare human studies. Their authors generalized that the latitude-driven changes in allele frequency were either absent (e.g., Ciarleglio et al., 2008) or rare (e.g., Dall’Ara et al., 2016) or common (e.g., Forni et al. 2014).
Genome-wide analysis of unrecognised ethnic group Chuanqing people revealing a close affinity with Southern Han Chinese
Published in Annals of Human Biology, 2020
Jiani Lu, Hongling Zhang, Zheng Ren, Qiyan Wang, Yubo Liu, Yingxiang Li, Guanglin He, Jianxin Guo, Jing Zhao, Rong Hu, Lan-Hai Wei, Gang Chen, Jiang Huang, Chuan‑Chao Wang
First, we carried out a qualitative PCA on East Asian populations from the Human Origin Dataset. We observed a clear north-south genetic cline in the visualising plot of PC1 and PC2 (Figure 2, Supplementary Figure S1). The populations from northern China and Northeast Asia speaking Tungusic, Mongolic, and Turkic languages occupy the northern pole of the plot, while indigenous populations from southern China and Southeast Asia speaking Tai-Kadai, Austronesian, and Austroasiatic languages form a cluster in the south-end of the cline. The Han Chinese are in an intermediate position in the plot with a cline from northern Han to southern Han. CHB (Han Chinese in Beijing) samples are closer to northern populations in East Asia, while CHS (Han Chinese South) samples are closer to southern groups. The Chuanqing samples cluster closely with southern Han Chinese, Tujia, and Hmong-Mien speaking Miao and She, showing a distinct genetic profile with indigenous populations in southern China and Southeast Asia. The Tibeto-Burman speaking populations such as Tibetan, Yi, Burmese, Lahu, Sherpa and Naxi are scattered in the plot, but the Chuanqing people are genetically close to none of them. We also plotted PC3 and PC4 as Supplementary Figure S2, in which Chuanqing samples are generally close to mainland East Asians. We also restricted the populations to Chuanqing, Tujia, Miao, She, and southern Han Chinese to rerun PCA. We found Chuanqing samples cluster closely with the Miao samples (Supplementary Figure S3).
Related Knowledge Centers
- Adaptation
- Allele Frequency
- Gene Flow
- Subspecies
- Species Distribution
- Blood Type
- Species
- Natural Selection
- Speciation
- Genetic Admixture