Humans do not have tails, but do we have “what it takes” for a tail? Hens don’t have teeth, but they have the genes for it. With atavism, it is as if our genomes serve as archives of our evolutionary past.
Posts tagged Genetics.
Oldest Hominin DNA Sequenced: Mitochondrial Genome of a 400,000-Year-Old Hominin from Spain Decoded
Dec. 4, 2013 — Using novel techniques to extract and study ancient DNA researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have determined an almost complete mitochondrial genome sequence of a 400,000-year-old representative of the genus Homo from Sima de los Huesos, a unique cave site in Northern Spain, and found that it is related to the mitochondrial genome of Denisovans, extinct relatives of Neandertals in Asia. DNA this old has until recently been retrieved only from the permafrost.
Chromosome 2 - What separates chimps from humans?
At the genetic level chimpanzees are almost indistinguishable from humans, so how did the formation of human chromosome 2 lead to our divergence from our primate relatives?
Geneticist Aoife McLysaght heads to Dublin Zoo to explain more…
How whales made the dramatic evolutionary shift from land to the sea
All whales and dolphins are descended from terrestrial mammals, ancient creatures that were very similar to the modern hippopotamus. Now, a fascinating new genetics study shows the incredible evolutionary changes these animals had to experience to become the perfectly adapted marine animals we see today.
Biologists aren’t entirely sure which creature modern cetaceans (dolphins, whales, and porpoises) are descended from. The traditional theory suggests mesonychids, an extinct order of carnivorous ungulates (hoofed animals) which resembled wolves. But more recent genetic analysis points to artiodactyls, a hippo-like creature. Regardless, all cetaceans were land mammals at one point in their evolutionary history — and they had to undergo some rather remarkable changes to adapt to underwater life.
Biologists Find an Evolutionary Facebook for Monkeys and Apes
Nov. 18, 2013 — Why do the faces of some primates contain so many different colors — black, blue, red, orange and white — that are mixed in all kinds of combinations and often striking patterns while other primate faces are quite plain?
UCLA biologists reported last year on the evolution of 129 primate faces in species from Central and South America. This research team now reports on the faces of 139 Old World African and Asian primate species that have been diversifying over some 25 million years.
500,000-Year-Old Neanderthal Viruses Found in Modern Human DNA —(Did We Interbreed?)
Neanderthal viruses dating back 500,000 years has been discovered in modern human DNA when scientists studied links between ‘endogenous retroviruses’, which are hard-wired into DNA, and modern diseases such as AIDs and cancer. The researchers compared DNA from Neanderthals and another group of ancient humans called Denisovans with that obtained from cancer patients and found evidence of Neanderthal and Denisovan viruses in modern DNA, suggesting they shared a common ancestor more than 500,000 years ago. Neanderthals co-existed and possibly interbred with our ancestors in Europe for thousands of years, but belonged to a different sub-species, eventually becoming extinct around 30,000 years ago.
Approximately 8% of human DNA is made up of endogenous retroviruses, or ERVs, which are DNA sequences left by viruses which pass from generation to generation, forming part of the 90 per cent of the genome, sometimes called ‘junk’ DNA, that contains no instruction codes for making proteins.
"Primates, the mammalian order including our own species, comprise 480 species in 78 genera. Thus, they represent the third largest of the 18 orders of eutherian mammals. Although recent phylogenetic studies on primates are increasingly built on molecular datasets, most of these studies have focused on taxonomic subgroups within the order. Complete mitochondrial (mt) genomes have proven to be extremely useful in deciphering within-order relationships even up to deep nodes. Using 454 sequencing, we sequenced 32 new complete mt genomes adding 20 previously not represented genera to the phylogenetic reconstruction of the primate tree. With 13 new sequences, the number of complete mt genomes within the parvorder Platyrrhini was widely extended, resulting in a largely resolved branching pattern among New World monkey families. We added 10 new Strepsirrhini mt genomes to the 15 previously available ones, thus almost doubling the number of mt genomes within this clade. Our data allow precise date estimates of all nodes and offer new insights into primate evolution. One major result is a relatively young date for the most recent common ancestor of all living primates which was estimated to 66-69 million years ago, suggesting that the divergence of extant primates started close to the K/T-boundary. Although some relationships remain unclear, the large number of mt genomes used allowed us to reconstruct a robust primate phylogeny which is largely in agreement with previous publications. Finally, we show that mt genomes are a useful tool for resolving primate phylogenetic relationships on various taxonomic levels” (read more/open access).
Evolution of new species requires few genetic changes
Only a few genetic changes are needed to spur the evolution of new species—even if the original populations are still in contact and exchanging genes. Once started, however, evolutionary divergence evolves rapidly, ultimately leading to fully genetically isolated species, report scientists from the University of Chicago in the Oct 31 Cell Reports.
"Speciation is one of the most fundamental evolutionary processes, but there are still aspects that we do not fully understand, such as how the genome changes as one species splits into two,” said Marcus Kronforst, Ph.D., Neubauer Family assistant professor of ecology and evolution, and lead author of the study.
Genome-wide signatures of convergent evolution in echolocating mammals
Evolution is typically thought to proceed through divergence of genes, proteins and ultimately phenotypes. However, similar traits might also evolve convergently in unrelated taxa owing to similar selection pressures. Adaptive phenotypic convergence is widespread in nature, and recent results from several genes have suggested that this phenomenon is powerful enough to also drive recurrent evolution at the sequence level. Where homoplasious substitutions do occur these have long been considered the result of neutral processes. However, recent studies have demonstrated that adaptive convergent sequence evolution can be detected in vertebrates using statistical methods that model parallel evolution9, 10, although the extent to which sequence convergence between genera occurs across genomes is unknown. Here we analyse genomic sequence data in mammals that have independently evolved echolocation and show that convergence is not a rare process restricted to several loci but is instead widespread, continuously distributed and commonly driven by natural selection acting on a small number of sites per locus. Systematic analyses of convergent sequence evolution in 805,053 amino acids within 2,326 orthologous coding gene sequences compared across 22 mammals (including four newly sequenced bat genomes) revealed signatures consistent with convergence in nearly 200 loci. Strong and significant support for convergence among bats and the bottlenose dolphin was seen in numerous genes linked to hearing or deafness, consistent with an involvement in echolocation. Unexpectedly, we also found convergence in many genes linked to vision: the convergent signal of many sensory genes was robustly correlated with the strength of natural selection. This first attempt to detect genome-wide convergent sequence evolution across divergent taxa reveals the phenomenon to be much more pervasive than previously recognized.
Humans May Be Most Adaptive Species
Constant climate change may have given Homo sapiens our flexibility
In the 5 million years since early hominids first emerged from east Africa’s Rift Valley, the Earth’s climate has grown increasingly erratic. Over cycles lasting hundreds of thousands of years, arid regions of central Africa were overrun by forests, forests gave way to grasslands and contiguous landscapes were fractured by deep lakes.
It was within the context of this swiftly changing landscape that humans evolved their sizable brains and capacity for adaptive behavior, said Rick Potts, director of the Human Origins Program at the Smithsonian Institution National Museum of Natural History. In such a world, the ability to think creatively, to imagine novel solutions to survival threats, proved to be a major asset, he said.