Search results for "evolutionary"

Data Evaluation in Population Genetics and Evolution

1994

Isozymes maybe generated by different enzyme loci (a) (isoenzymes), (b) alleles of a locus (allozymes) or (c) post-translational modifications (secondary isozymes). Differences in isozyme numbers and isoenzyme properties can be used for evolutionary studies. But quantitations of genetic variation among or within populations are obtainable only from allozyme frequencies.

Investigations on the geographical variability of the human transferrins.

1971

On the basis of own and from the widely scattered literature compiled materials the geographical distribution of the transferrin alleles is discussed. They reveal a characteristic distribution pattern, as the slow Tf variants produced by TfD alleles are obviously more frequent in tropical than in non-tropical populations. Considering similar results in cattle and its interpretation by Ashton (1958, 1965), it is hypothesized, that the relatively high TfΓ frequencies in tropical biotops might be a selective adaptation to their special climatic conditions. In this connection an association between slowly moving transferrin proteins in man and tolerance to hotter climates — as could be found in…

A novel and ancient group of type I keratins with members in bichir, sturgeon and gar

2006

Abstract 1. Background Vertebrate epithelial cells typically express a specific set of keratins. In teleosts, keratins are also present in a variety of mesenchymal cells, which usually express vimentin. Significantly, our previous studies revealed that virtually all known teleost keratins evolved independently from those present in terrestrial vertebrates. To further elucidate the evolutionary scenario that led to the large variety of keratins and their complex expression patterns in present day teleosts, we have investigated their presence in bichir, sturgeon and gar. 2. Results We have discovered a novel group of type I keratins with members in all three of these ancient ray-finned fish, …

Regulatory Changes in Pterin and Carotenoid Genes Underlie Balanced Color Polymorphisms in the Wall Lizard

2018

ABSTRACTReptiles use pterin and carotenoid pigments to produce yellow, orange, and red colors. These conspicuous colors serve a diversity of signaling functions, but their molecular basis remains unresolved. Here, we show that the genomes of sympatric color morphs of the European common wall lizard, which differ in orange and yellow pigmentation and in their ecology and behavior, are virtually undifferentiated. Genetic differences are restricted to two small regulatory regions, near genes associated with pterin (SPR) and carotenoid metabolism (BCO2), demonstrating that a core gene in the housekeeping pathway of pterin biosynthesis has been co-opted for bright coloration in reptiles and indi…

Adult Lactose Tolerance Is Not an Advantageous Evolutionary Trait

2004

To the Editor. I read with great interest the recent article from Fomon1 in which he refers to the well-known hypothesis that views the variable frequencies of lactase persistence in different human populations and, consequently, the possibility for some adults to feed on milk (lactose tolerance) as an advantageous evolutionary trait that has been genetically determined and brought about through centuries of natural selection. This notion stands as a common statement in current medical literature, and most authors have accepted its validity since the 1970s.2,3 Because adult mammals are lactose-intolerant, this hypothesis is, moreover, based on the low percentage of lactose malabsorption and…

Paternity testing of endangered species of birds by DNA fingerprinting and random amplified polymorphic DNA fingerprinting

1994

Since 1985 DNA fingerprinting is the method of choice to solve forensic problems such as paternity testing (Jeffreys et al., 1986) or identification of immigration cases (Jeffreys et al., 1985 a, b). Its applicability became evident not only in man but also in many biological problems. Jeffreys’probes 33.15 and 33.6 or Epplen’s oligonucleotide probes were used in DNA fingerprinting of dogs and cats (Jeffreys & Morton, 1987), non-human primates (Weiss, 1989), birds (Longmire et al., 1991, Miyaki et al., 1993), fishes (Schartl et al., 1993) or even plants (Weising et al., 1991). Especially its application in paternity testing turned to account in many species of animals (Lubjuhn et al., 1991,…

Evolutionary site-number changes of ribosomal DNA loci during speciation: complex scenarios of ancestral and more recent polyploid events.

2015

Genes encoding ribosomal RNA are universal key constituents of eukaryotic genomes, but the number of loci varies between species. We assessed the evolutionary trends in site-number changes of rDNA loci during speciation in a lineage of the cabbage family, characterized by complex scenarios of polyploidy. Our results suggest the existence of constrictions to burst loci amplification in the 5S rDNA family in polyploids and an overall trend to further reduce their number. The 45S rDNA site change in polyploids tells a different story, implying loci amplification in most of the polyploid entities.

Multiscale variation in drought controlled historical forest fire activity in the boreal forests of eastern Fennoscandia

2017

Forest fires are a key disturbance in boreal forests, and characteristics of fire regimes are among the most important factors explaining the variation in forest structure and species composition. The occurrence of fire is connected with climate, but earlier, mostly local-scale studies in the northern European boreal forests have provided little insight into fire-climate relationship before the modern fire suppression period. Here, we compiled annually resolved fire history, temperature, and precipitation reconstructions from eastern Fennoscandia from the mid-16th century to the end of the 19th century, a period of strong human influence on fires. We used synchrony of fires over the network…

Coronavirus Disease (COVID-19) and Its Psychobehavioral Consequences

2021

Simulated eutrophication and browning alters zooplankton nutritional quality and determines juvenile fish growth and survival

2018

Source at https://doi.org/10.1002/ece3.3832. The first few months of life is the most vulnerable period for fish and their optimal hatching time with zooplankton prey is favored by natural selection. Traditionally, however, prey abundance (i.e., zooplankton density) has been considered important, whereas prey nutritional composition has been largely neglected in natural settings. High‐quality zooplankton, rich in both essential amino acids (EAAs) and fatty acids (FAs), are required as starting prey to initiate development and fast juvenile growth. Prey quality is dependent on environmental conditions, and, for example, eutrophication and browning are two major factors defining primary produ…