Separation Of Different Populations Research Articles

Phylogeny and genetic diversity reveal the influence of Qinghai-Tibet Plateau uplift on the divergence and distribution of Gymnocypris species

The complex environments and climatic conditions of the Qinghai-Tibet Plateau (QTP) create unique patterns of species diversity. However, the effect of uplift of the QTP on the distribution of Gymnocypris species (Gymnocypris) remain unclear. We found that the Qilian Mountain (QL) population has the highest genetic diversity by mitochondrial DNA hypervariable region of Gymnocypris species, the Tibetan (T) population has the lowest genetic diversity. The T population differs significantly from the Qinghai Lake (QH) and QL populations based on single nucleotide polymorphisms. A phylogeny and network distribution of this species on the QTP reveal differences in its genetic structure and support its taxonomic status. Neutrality tests reveal that Gymnocypris species has experienced different degrees of expansion, even secondary expansion. A divergence timetree estimates that the time of separation of different populations is possible related to uplift of the QTP and is consistent with the time of corresponding geological events. The QL population was separated from the other populations during the third uplift of the QTP (approximately 0.14 million years ago), and the QH and T populations were separated in the late Pleistocene to the Holocene (approximately 0.03 million years ago). In conclusion, this study provides different insights into the distribution of Gymnocypris species due to uplift of the QTP. Gymnocypris species was separated into different populations by this uplift, and each population exhibits unique characteristics, especially in terms of genetic structure and the degree of expansion. Moreover, the divergence time is consistent with the time of uplift of the QTP.

DNA methylation patterns of behavior-related gene promoter regions dissect the gray wolf from domestic dog breeds.

A growing body of evidence highlights the relationship between epigenetics, especially DNA methylation, and population divergence as well as speciation. However, little is known about how general the phenomenon of epigenetics-wise separation of different populations is, or whether population assignment is, possible based on solely epigenetic marks. In the present study, we compared DNA methylation profiles between four different canine populations: three domestic dog breeds and their ancestor the gray wolf. Altogether, 79 CpG sites constituting the 65 so-called CpG units located in the promoter regions of genes affecting behavioral and temperamental traits (COMT, HTR1A, MAOA, OXTR, SLC6A4, TPH1, WFS1)-regions putatively targeted during domestication and breed selection. Methylation status of buccal cells was assessed using EpiTYPER technology. Significant inter-population methylation differences were found in 52.3% of all CpG units investigated. DNA methylation profile-based hierarchical cluster analysis indicated an unambiguous segregation of wolf from domestic dog. In addition, one of the three dog breeds (Golden Retriever) investigated also formed a separate, autonomous group. The findings support that population segregation is interrelated with shifts in DNA methylation patterns, at least in putative selection target regions, and also imply that epigenetic profiles could provide a sufficient basis for population assignment of individuals.

SOLITARY PHILLIPSASTREIDAE (RUGOSA) FROM THE LATE DEVONIAN OF EUROPE AND NORTHERN AFRICA

Macgeea is a cosmopolitan genus of Devonian rugose corals that includes numerous, generally highly variable, species. Because of its wide skeletal variation and additional trabecular dilation it is difficult to recognize taxonomically relevant characters and to separate those from ecologically induced modifications. The high variability is probably related to radiations following phases of sea level rise and is connected to bioevents. Length of major septa in ontogenetic stages allows a separation of different populations within the Macgeea dubia species group. However, it remains questionable if septal length is a reliable taxonomic character, indicating a phylogenetic trend, or if it is subject to large individual variability. By revising Macgeea dubia, we reveal its synonymy with Macgeea heterophylloides sensu Birenheide. In addition, Macgeea recta (type species of Pexiphyllum Walther, 1929) is discussed as an insufficiently defined taxon of problematic status. Macgeea crassiseptata n. sp. is also described from the Late Givetian of Morocco.The erection of the new pseudocolumellate genus Baculophyllum with type species Pexiphyllum ultimum Walther, 1929 requires a comparison with Protomacgeea from Poland and Australia as well as a phylogenetic discussion of the solitary Phillipsastreidae. The new genus most probably belongs to a separate lineage of the Upper Devonian Macgeea group but could also be considered as a descendant of the Australian Lower Devonian columellate solitary phillipsastreid species group, that has not yet been recorded from the Middle Devonian. Because of large stratigraphic gaps between the occurrences of both genera, preference is given to the interpretation of a development of polycronomorph taxa (homeomorphic taxa living at a different time) not belonging to a single lineage. This shows again the significance of stratigraphic age when comparing similar-looking taxa, which should be considered in any phylogenetic reconstruction.

Allocation and discrimination based on human odontometric data.

This study contrasts the confidence with which individuals may be grouped and then re-allocated on the basis of odontometric data. These data are derived from the mesiodistal and buccolingual diameters of 202 Lengua Indians of Paraguay (100 males, 102 females), 125 Caucasoid schoolchildren (59 male, 66 female), and 206 Negroes (106 male, 100 female). Multivariate intergroup discrimination is effected by means of canonical and stepwise discriminant analysis, whilst allocation is evaluated by means of posterior and typicality probabilities. Bias is reduced by means of a jackknifing procedure. High levels of discriminatory confidence (each Wilk's Lambda, P less than 0.01) are matched by high percentage correct classification (Caucasoid, 67.4-75.0%; Negro, 71.0-77.3%; Amerindian, 65.2-78.1%). However, these results are not matched by allocatory procedures: only 21.7% of caucasoids, 21.4% of Negroes, and 28.8% of Amerindians could be re-allocated with probabilities in excess of 80%. It is concluded that while multivariate discriminant techniques may be usefully employed in the separation of different populations, individuals may not be assigned with the same degree of confidence, even with an a priori knowledge of their group membership.

Adaptive diversity in subfossil Malagasy prosimians

The island of Madagascar exhibits an exceptional degree of topographical, climatic, and ecological diversity. This great internal complexity has been characterized by Martin (1972) as similar to closed group of (somewhat elastic) islands. The evolutionary implications of such a situation are readily apparent; the colonizing prosimian fauna no doubt encountered numerous op portunities for geographical separation of different populations, allopatric speciation, and subsequent competition leading to niche specializations. The considerable diversity in behavioral and morphological adaptations among living Malagasy prosimians strongly supports such an adaptive radiation scenario (Petter et al., 1977). Moreover, if recently extinct (subfossil) forms are taken into account, the entire remainder of the primate order strains to find suitable morphological and eco-ethological analogies to the Malagasy prosimians (Tatter sall, 1973 a; Walker, 1974). It is possible to demonstrate quite close taxonomic relationships among various subf ossil and extant Malagasy lemurs (Table 1). All recognized families except the Cheirogaleidae possess both living and extinct representatives. Pachylemur is the lone subf ossil member of the Lemuridae; similary, Megaladapis (three species) is the only extinct representative of the Lepilemuridae. Daubentonia robustus is little more than a larger, more robust form of the living aye-aye. Only within the Indriidae are there more known subfossil than living genera. Several of the subfossil deposits have yielded extinct specimens in association with living species (e. g., Lemur catta and Propithecus verreauxi at Andrahomana in association with Archaeolemur and Megaladapis), and radiocarbon dating of the various localities spans a narrow period of approximately 1,000?3,000 years B. P. (Tattersall, 1973 b). One of the most consistent differences between the living and the subfossil members of each family is that of size; the extinct forms tend to be larger than