January 18, 2023
Evolution and Darwin’s Finches of the Galapagos Islands
Rosemary and Peter Grant
Evolutionary Biologists
Peter and Rosemary Grant (speakers)
Christine Danser (introducer)
Minutes of the 15th Meeting of the 81st Year
President John Cotton called the meeting to order at 10:15 a.m. Minutes of the last meeting were read by Lincoln Hollister. Christine Danser presented guests Jeff Lipkowitz, Jack Danser-Anger, and Andrea Danser-Anger; Marsha Levin-Rojer introduced her guest, Ann Sobel; Nancy Beck’s guest was Gail Ivers; Ralph Widner’s guests were Anton and Alison Lahnston An additional membership applicant was introduced, bringing the number of candidates to seven: William Clayton, Lynne Durkee, Michael Lapp, Jeff Lipkowitz, Bill Katen-Narvell, Leighton Newlin, and John van Raalte. Voting will be held at the January 25, 2023, meeting. The president stated that further consideration of the proposed amendments to the bylaws will be postponed until March when we resume in-person meetings.
Christine Danser introduced our speakers, Peter and Rosemary Grant, Professors in the Department of Ecology and Evolutionary Biology at Princeton University. Their body of work has received many prestigious awards and the research supporting today's topic inspired a Pulitzer Prize-winning book by Jonathan Weiner.
The topic of their talk was The Evolution of Darwin's Finches of The Galapagos Islands. Their 40 year-long work with the finches illuminated the route by which a single ancestral species can, over time, evolve into many species.
Professor Peter Grant began by telling us how they began their work on the uninhabited, pristine volcanic islands of Genovesa and Daphne Major. He showed images of their research camp, which was necessarily rustic with a cave for a kitchen. Care was taken to avoid importing insects, bacteria, or foreign vegetation. He briefly discussed how the birds were captured, weighed, measured, colorfully banded with identifying information, and how a drop of blood was collected for DNA analysis.
A chart showing ten different varieties of finches was displayed. The audience was invited to note the variation in the sizes and shapes of the beaks and reminded that the beaks are primarily tools for dealing with food.
We were shown an image from afar of the rocky island, Daphne Major, with a crater in its midst, emphasizing its volcanic state. Another image showed arid terrain with a type of cactus as the prominent vegetation. Other images showed the island after a period of intense and prolonged rainfall. An abundance of green foliage and vines almost obscured the cacti.
A diagram inspired by Darwin showed the divergence of one finch group into two, changing so much that they were no longer capable of interbreeding, effectively becoming two different species. These changes occurred in large part due to environmental and ecological influences.
Dry areas produce different types and quantities of resources from wet, green areas. When the diets of the species diverged, beak size and beak shape also diverged. The research done over the 40 years comparing the evolution of multiple types of finches revealed the following:
Professor Rosemary Grant showed a short video of small finches following a large finch as the large bird forcefully cracked open the hard shell of a seed-laden fruit, scattering seeds that were picked up by the small birds with their small beaks.
She then posed questions bearing on the determinants of species evolution:
On the biotech front, Professor Grant noted that genes coding for small, blunt beaks in the finches were the same as genes associated with cleft palates in humans.
Why do lung cancer and colon cancer act differently? Research on cancer clones points to the variation within the anatomic environments and biosystems of the lungs vs. the colon.
The finding that genes conferring resistance or susceptibility to severe COVID-19 has been found in the DNA of our Neanderthal ancestors illustrates the presence of gene flow in evolution.
The take-home appears to be that for healthy environments and the flourishing of species, we must keep both capable of further natural change and concentrate on preserving a full group of species rather than individuals.
Professor Grant concluded the talk by showing an image of planet Earth taken by NASA with biodiversity shown in shades of green. During the Q & A session, she stressed the point that all human beings are one species!
Respectfully Submitted
Judith M Funches
Christine Danser introduced our speakers, Peter and Rosemary Grant, Professors in the Department of Ecology and Evolutionary Biology at Princeton University. Their body of work has received many prestigious awards and the research supporting today's topic inspired a Pulitzer Prize-winning book by Jonathan Weiner.
The topic of their talk was The Evolution of Darwin's Finches of The Galapagos Islands. Their 40 year-long work with the finches illuminated the route by which a single ancestral species can, over time, evolve into many species.
Professor Peter Grant began by telling us how they began their work on the uninhabited, pristine volcanic islands of Genovesa and Daphne Major. He showed images of their research camp, which was necessarily rustic with a cave for a kitchen. Care was taken to avoid importing insects, bacteria, or foreign vegetation. He briefly discussed how the birds were captured, weighed, measured, colorfully banded with identifying information, and how a drop of blood was collected for DNA analysis.
A chart showing ten different varieties of finches was displayed. The audience was invited to note the variation in the sizes and shapes of the beaks and reminded that the beaks are primarily tools for dealing with food.
We were shown an image from afar of the rocky island, Daphne Major, with a crater in its midst, emphasizing its volcanic state. Another image showed arid terrain with a type of cactus as the prominent vegetation. Other images showed the island after a period of intense and prolonged rainfall. An abundance of green foliage and vines almost obscured the cacti.
A diagram inspired by Darwin showed the divergence of one finch group into two, changing so much that they were no longer capable of interbreeding, effectively becoming two different species. These changes occurred in large part due to environmental and ecological influences.
Dry areas produce different types and quantities of resources from wet, green areas. When the diets of the species diverged, beak size and beak shape also diverged. The research done over the 40 years comparing the evolution of multiple types of finches revealed the following:
- Beak size and shape evolved to obtain maximum benefit from the type of food available and the means of processing that food.
- When events leading to the death of many birds occurred, small birds died at a lower rate than the larger ones.
- Over the 40 years of study, for multiple observable reasons, primarily food and climate, evolution favored smaller birds with smaller beaks.
Professor Rosemary Grant showed a short video of small finches following a large finch as the large bird forcefully cracked open the hard shell of a seed-laden fruit, scattering seeds that were picked up by the small birds with their small beaks.
She then posed questions bearing on the determinants of species evolution:
- What are the reproductive barriers between the diverse birds? Prior research shows that reproductive barriers between species are rarely breached, but sometimes "leak."
- Can individual birds distinguish their species by appearance and song? The research shows that they absolutely can! Song is very important. The male of the species sings. The female does not sing but recognizes the song of her species. The song is learned at a very early age by hearing the father sing it and it is learned for life. Interestingly, if the chick is exposed to the song of a different species during this vulnerable time, it will learn the song of that species and will breed with birds that sing or know that song.
On the biotech front, Professor Grant noted that genes coding for small, blunt beaks in the finches were the same as genes associated with cleft palates in humans.
Why do lung cancer and colon cancer act differently? Research on cancer clones points to the variation within the anatomic environments and biosystems of the lungs vs. the colon.
The finding that genes conferring resistance or susceptibility to severe COVID-19 has been found in the DNA of our Neanderthal ancestors illustrates the presence of gene flow in evolution.
The take-home appears to be that for healthy environments and the flourishing of species, we must keep both capable of further natural change and concentrate on preserving a full group of species rather than individuals.
Professor Grant concluded the talk by showing an image of planet Earth taken by NASA with biodiversity shown in shades of green. During the Q & A session, she stressed the point that all human beings are one species!
Respectfully Submitted
Judith M Funches