Галапагос аралдарындағы эволюция: Гранттардың ғылыми еңбегі

Married couple of British evolutionary biologists

Peter Raymond Grant (born October 26, 1936) and Barbara Rosemary Grant (born October 8, 1936) are a British married couple who are evolutionary biologists at Princeton University. Each currently holds the position of emeritus professor. They are known for their work with Darwin's finches on Daphne Major, one of the Galápagos Islands. Since 1973, the Grants have spent six months of every year capturing, tagging, and taking blood samples from finches on the island. They have worked to show that natural selection can be seen within a single lifetime, or even within a couple of years. Charles Darwin originally thought that natural selection was a long, drawn out process but the Grants have shown that these changes in populations can happen very quickly. In 1994, they were awarded the Leidy Award from the Academy of Natural Sciences of Philadelphia. The Grants were the subject of the book The Beak of the Finch: A Story of Evolution in Our Time by Jonathan Weiner, which won the Pulitzer Prize for General Non Fiction in 1995. In 2003, the Grants were joint recipients of the Loye and Alden Miller Research Award. They won the 2005 Balzan Prize for Population Biology. The Balzan Prize citation states:
Peter and Rosemary Grant are distinguished for their remarkable long term studies demonstrating evolution in action in Galápagos finches. They have demonstrated how very rapid changes in body and beak size in response to changes in the food supply are driven by natural selection. They have also elucidated the mechanisms by which new species arise and how genetic diversity is maintained in natural populations. The work of the Grants has had a seminal influence in the fields of population biology, evolution, and ecology.

Barbara Rosemary Grant was born in Arnside, England in 1936. In her youth, she collected plant fossils and compared them to living look alikes. At the age of 12, she read Darwin's On the Origin of Species. Despite being told by her headmistress that pursuing an education in a male dominated field of study would be foolish, in addition to contracting a serious case of mumps that temporarily stalled her academic activity, she decided to continue forth with her education. In 1960, she graduated from the University of Edinburgh with a degree in Zoology. For the next year, she studied genetics under Conrad Waddington and later devised a dissertation to study isolated populations of fish. This project was put on hold when she accepted a biology teaching job at the University of British Columbia,

Peter Raymond Grant was born in 1936 in London, but relocated to the English countryside to avoid encroaching bombings during World War II. He attended school at the Surrey Hampshire border, where he collected botanical samples, as well as insects. PhD (Evolutionary Biology), Uppsala University, 1985 On average, the birds on the islands had larger beaks. The Grants attributed these differences to what foods were available, and what was available was dependent on competitors. The bigger beaks indicated a greater range of foods present in the environment. In his article "Interspecific Competition Among Rodents", he concluded that competitive interaction for space is common among many rodent species, not just the species that have been studied in detail. The island provided the best environment to study natural selection; seasons of heavy rain switched to seasons of extended drought. With these environmental changes brought changes in the types of foods available to the birds. The Grants would study this for the next few decades of their lives. In 1973, the Grants headed out on what they thought would be a two year study on the island of Daphne Major. There they would study evolution and ultimately determine what drives the formation of new species. The lack of rain caused major food sources to become scarce, causing the need to find alternative food sources. The smaller, softer seeds ran out, leaving only the larger, tougher seeds. The finch species with smaller beaks struggled to find alternate seeds to eat. They called this bird Big Bird. It had many different characteristics than those of the native finches: a strange call, extra glossy feathers, it could eat both large and small seeds, and could also eat the nectar, pollen, and seeds of the cacti that grow on the island. Big Bird lived for thirteen years, initially interbreeding with local species. His descendants have only mated within themselves for the past thirty years, a total of seven generations. Whole genome studies have enabled scientists to trace changes in the genome as the species became distinct. Genes for beak shape (ALX1) and beak size (HMGA2) have been determined to be crucial in separating the hybridized species from local finches. Genes relating to the finches' song may also be involved. Over the course of 1982–1983, El Niño brought a steady eight months of rain. In a normal rainy season Daphne Major usually gets two months of rain. The excessive rain brought a turnover in the types of vegetation growing on the island. The seeds shifted from large, hard to crack seeds to many different types of small, softer seeds. This gave birds with smaller beaks an advantage when another drought hit the following year.

In Evolution: Making Sense of Life, the takeaway from the Grants' 40 year study can be broken down into three major lessons. The first is that natural selection is a variable, constantly changing process. The fact that they studied the island in both times of excessive rain and drought provides a better picture of what happens to populations over time. The next lesson learned is that evolution can actually be a fairly rapid process. It does not take millions of years; these processes can be seen in as little as two years. Lastly, and as the author states, most importantly, selection can change over time. During some years, selection will favour those birds with larger beaks. Other years with substantial amounts of smaller seeds, selection will favour the birds with the smaller beaks. In their 2003 paper, the Grants wrap up their decades long study by stating that selection oscillates in a direction. For this reason, neither the medium ground finch nor the cactus finch has stayed morphologically the same over the course of the experiment. The average beak and body size are not the same today for either species as they were when the study first began. The Grants also state that these changes in morphology and phenotypes could not have been predicted at the beginning. They were able to witness the evolution of the finch species as a result of the inconsistent and harsh environment of Daphne Major directly.