Darwin wanted to explain humans from bacteria. He can’t get there by just protecting what bacteria already had.The tuatara is a rare lizard that only survives on certain islands off the south island of New Zealand. It’s a ‘living fossil’ – the “Sole survivor of a once-diverse lineage,” Jones and Hutchinson write in Nature. It’s a reminder that evolution includes a strong tendency to go extinct. Somehow, this sole surviving member of Rhynchocephalia found a niche where it could survive.In the same issue of Nature, Philip Ball reviews a book that compares cities to organisms. But cities are intelligently designed; they are not subject to biological mutation and natural selection.Negative selection against deleterious alleles produced by mutation influences within-population variation as the most pervasive form of natural selection.Negative SelectionIn Science, ten authors from two consortia discuss how “Negative selection in humans and fruit flies involves synergistic epistasis.” Basically, this means that organisms work hard to rid themselves of bad mutations. Negative selection predominates, they say. We can all be thankful that our bodies try to protect us from harmful mutations, but how did bacteria climb up to humanity that route? One cannot climb Mt. Improbable by trying to stay on the same stair in a howling wind.Negative selection against deleterious alleles produced by mutation influences within-population variation as the most pervasive form of natural selection. However, it is not known whether deleterious alleles affect fitness independently, so that cumulative fitness loss depends exponentially on the number of deleterious alleles, or synergistically, so that each additional deleterious allele results in a larger decrease in relative fitness. Negative selection with synergistic epistasis should produce negative linkage disequilibrium between deleterious alleles and, therefore, an underdispersed distribution of the number of deleterious alleles in the genome. Indeed, we detected underdispersion of the number of rare loss-of-function alleles in eight independent data sets from human and fly populations. Thus, selection against rare protein-disrupting alleles is characterized by synergistic epistasis, which may explain how human and fly populations persist despite high genomic mutation rates.Genetic EntropyScience Daily‘s summary of the paper in Science, referenced above, discusses “Ongoing natural selection against damaging genetic mutations in humans.” The authors admit to an idea very similar to John Sanford’s classic, Genetic Entropy and the Mystery of the Genome. He claimed that humans pass on so many neutral mutations, the human population is more likely to go extinct than improve by rare ‘beneficial’ mutations, if there are any. This article echoes that concept:The survival of the human species in the face of high rates of genetic mutations has remained an important problem in evolutionary biology. While mutations provide a source of novelty for the species, a large fraction of these genetic changes can also be damaging. A newborn human is estimated to have ~70 new mutations that the parents did not have. In a project conducted by Brigham and Women’s Hospital research geneticist Shamil Sunyaev, PhD, and University of Michigan professor Alexey Kondrashov, PhD, scientists studied natural selection in humans. Their findings are published in a new paper in Science, where they report that, as a species, humans are able to keep the accumulation of damaging mutations in check because each additional mutation that’s added to a genome causes larger, and larger consequences, decreasing an individual’s ability to pass on genetic material.This “long-standing conundrum in evolutionary biology” is only mitigated, not overcome, by a shuffling maneuver: sex. “[S]ex had to come about in a species such as our own to allow for more effective natural selection because the mutation rate is too high to sustain otherwise.” If that constitutes an “evolutionary advantage,” it is not one poised to help an organism grow wings or eyes. “This observation is general and is not limited to the human species,” they point out. So how is Mr. Darwin supposed to coax that bacterium up Mt. Improbable, where humanity is waiting to be invented?We highly recommend Genetic Entropy by Cornell geneticist Dr. John Sanford. It will cure you of Darwinism once and for all. It will also reinforce the Biblical view that things are running down, not up, since the Creation and the Fall. (Visited 518 times, 1 visits today)FacebookTwitterPinterestSave分享0
A display of the Clivia miniatra cultivar ‘Kirstenbosch Splendour’, bred by the garden’s bulb expert Graham Duncan grows in the planted avenue of camphor trees on the Kirstenbosch premises. This image was selected as the cover photograph for the garden’s centenary publication, written by South African ecologist Professor Brian Huntley. Kirstenbosch has become an international showcase of South Africa’s natural beauty, and a leader in botanical and zoological science, research and conservation. (Images: Adam Harrower) The builders of Kirstenbosch: in 1973 Brian Rycroft presented gold watches to eight Kirstenbosch stalwarts, each with more than 25 years’ service. From left, Abraham Basson, William Basson, Frank Krieger, David Mclean, John Fredericks, Brian Rycroft, George Basson, Nicholas Josephus and James Nicholas. A photograph from the 1920s shows the slopes on which the protea and erica sections were developed in the 1960s. (Images: Sanbi) MEDIA CONTACTS • Belinda van der Merwe Random Struik +27 21 460 5400 RELATED ARTICLES • Kirstenbosch best place to picnic • Citizen science to toads’ rescue • Floral wealth in caring hands • Research output rises, papers double Wilma den HartighIn 2013 the world-famous Kirstenbosch Botanical Gardens in Cape Town celebrates its 100th anniversary. A beautiful coffee table book, written by acclaimed South African ecologist Professor Brian Huntley, has been published in honour of the garden’s centenary.Kirstenbosch: the most beautiful garden in Africa, tells the story of the garden’s establishment, its setbacks, triumphs and the remarkable people who helped to make it what it is today – an internationally renowned botanical, science and conservation facility.Through vivid photographs, art work, valuable archive material and the author’s detailed, yet accessible writing style, Huntley tells the tale of a garden that has captured the hearts of many people for centuries.The book is the first comprehensive account of the history and progress of the botanical facility since Compton’s 1965 publication, Kirstenbosch, Garden for a Nation, which went out of print many decades ago.Compton’s history only covers developments at the botanical garden until around 1963, and subsequent publications lack coverage of the important developments of the past two decades.Huntley says the approaching centenary inspired him to write an updated account of the Kirstenbosch story.“When I retired I wanted to write something that brings the history of the garden into popular media and I wanted it to be technically accurate and visually attractive,” he says.And the book achieves both objectives.A combination of beauty and scienceIn the book Huntley tells how Kirstenbosch grew to become an international showcase of South Africa’s natural beauty, and a leader in botanical and zoological science, research and conservation.Huntley believes this makes it one of the best gardens in the world.“What distinguishes a proper botanical garden of global standing is a combination of flora, landscaping and strong science and education programmes,” he says.A fascinating story, told by an expertHuntley is an internationally respected conservationist with over 45 years of field research and management experience in many African ecosystems.Since his retirement from the South African National Biodiversity Institute (Sanbi), he’s been working as a consultant to several UN agencies on conservation projects.What sets the book apart is Huntley’s personal love for the gardens. He has a long-standing relationship with Kirstenbosch spanning over 50 years. During this time he lived on the premises for 19 years, which afforded him the privilege of daily walks in the garden and the opportunity to get to know it better than just about anyone else.“Over the years, I got a good sense for the seasons in the garden,” he says.He also dedicates numerous pages to the garden’s conservation and education initiatives, and its links with the community.Ensuring that the garden can be enjoyed by people from all walks of life, and not only tourists visiting Cape Town, is a strong priority for staff at Kirstenbosch. Through its school programmes more than 20 000 underprivileged children have an opportunity to experience the beauty of Kirstenbosch every year. And by staging its popular annual series of concerts, Kirstenbosch brings in thousands of cultural and nature lovers to experience the beauty of music outdoors on a summer evening.Compiling the bookEven with so much knowledge about the gardens, Huntley says writing the book was no small feat.“A significant amount of research went into it,” he says. “I had to trawl through databases, archived photos, reports and information going back a century or two.”The book draws on information included in the annual reports published since 1914 by the National Botanic Gardens of South Africa, by its successor, the National Botanical Institute, and from Sanbi.He also included oral history accounts provided by people who have worked at Kirstenbosch for many years.“I’ve picked up many anecdotes and accounts as time went by,” he says.Huntley’s informal tone ensures that the book doesn’t read like a science journal or a history textbook, but more like a conversation about Africa’s most beautiful garden.Uncovering the unexpectedWhile looking through archive photographs, Huntley came across a few surprising facts about Kirstenbosch.“What surprised me is that in the early days of the garden, the first 10 to 30 years of its existence, it was very shabby and makeshift,” he says.Kirstenbosch wasn’t as sophisticated and pristine as it is today, yet it was very well supported.“Supporters in those days were of the highest standing in government, business and society. They were all very passionate about it and believed in the importance of the garden,” he explains.“What people don’t know is that the gardens came from very humble origins.”World-class research and scienceAn extensive range of new and ongoing research takes place at Kirstenbosch. This includes studies at global scale on topics such as climate change modelling and at continental level in specialised fields such as plant taxonomy.Scientists also undertake national research that includes biodiversity assessments, species conservation and vegetation mapping of South Africa.A molecular laboratory, established in 2000 at the Kirstenbosch Research Centre, has made it possible to pioneer research on the evolution of proteas, other fynbos plants and animal groups with special importance in South Africa, in particular reptiles and frogs.“Our national obsession with the big, hairy mammals means we have tended to overlook our lizard fauna,” Huntley says in the book.The Protea Atlas Project, which has been ongoing at Kirstenbosch since 1990, has led to the compilation of probably the biggest, most accurate, geo-referenced database of information on the distribution and abundance of any family of plants, anywhere.This unique database, put together by a small in-house team and hundreds of volunteer field workers under the leadership of scientific officer Tony Rebelo, provides researchers with information to test responses of species to changes in environmental factors.Kirstenbosch in years to comeGoing forward, Huntley believes one of the most important challenges for Kirstenbosch is to maintain the highest standards of professionalism in horticulture, visitor amenities and research.“It must retain its position as a leader in this field,” he says. “It must also remain a centre of innovation.”And is there any part of Kirstenbosch that Huntley thinks of as his favourite little nook? He can’t single out any.“There are too many good places,” he says. “If you wander around the garden, around every corner you will find something nice.”• Slideshow image courtesy of the Kirstenbosch Botanical Gardens.
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