Linnaean Society of New York General Meeting Minutes — September 6, 2022
(Note: This meeting and presentation took place online, via Zoom, due to social distancing protocols prompted by the ongoing COVID-19 pandemic.)
At 7:00 pm, President Rochelle Thomas called the meeting of the Society to order. After introducing herself, she thanked the attendees for joining. Rochelle hopes to have more information about resuming in-person meetings at the American Museum of Natural History soon. Rochelle promoted our upcoming field trips, the Family Walk, and the No Question Is Too Small Walk.
Motion 1: President Thomas announced that Debbie Becker was elected the Society’s newest board member.
Motion 2: President Thomas announced the results of a new-member vote, which passed with 138 votes of approval and 0 of disapproval.
The Society welcomed the following eighteen new members:
- Padma Vaidyanathan, Active, sponsored by Chuck McAlexander
- Judy Honig, Active, sponsored by Renee Lucier
- Jon Hartsel, Supporting, sponsored by Kathleen Howley
- Meryl Greenblatt, Active, sponsored by Mary Beth Kooper
- Christina Black, Active, sponsored by Amanda Bielskas
- Karen Yaeger, Active, sponsored by Amy Simmons
- Suzanne Zywicki, Supporting, sponsored by Debbie Mullins
- Neil Markowitz, Active, sponsored by Rochelle Thomas
- Lucy Oakley, Active, sponsored by Ken Chaya
- Laura Clark, Active, sponsored by Kevin Sisco
- Patricia Lindsay, Supporting, sponsored by Mary Normandia
- Shaibal Mitra, Supporting, sponsored by Mary Normandia
- Charlotte Levitt, Supporting, sponsored by Kathleen Matthews
- Alex Levitt, Supporting, sponsored by Kathleen Matthews
- Jud Feldman-Santos, Active, sponsored by Evelyn Huang
- Linda Freeman, Active, sponsored by Mary Beth Kooper
- Roberta Kravette, Supporting, sponsored by Elise Boeger
- Andrea Zuckerman, Active, sponsored by Kristin Ellington
Motion 3: President Thomas then announced the result of the online vote to approve the minutes of the May 2022 members’ meeting. The vote passed with 136 votes of approval and 0 of disapproval.
President Thomas announced that the annual Homecoming Picnic had been rescheduled for September 18th from 12:30 to 3:30. Members are welcome to bring guests interested in learning more about the Society.
At 7:10 pm, President Thomas introduced the evening’s speaker, Dr. Elizabeth Carlen.
Dr. Carlen is a National Science Foundation and Living Earth Collaborative postdoctoral fellow at Washington University in St. Louis, where her research focuses on the impacts of urbanization on Eastern Gray Squirrels. Dr. Carlen received a Ph.D. in biological sciences from Fordham University, where she worked on the evolutionary ecology of urban pigeons. Her dissertation work was featured on Saturday Night Live and written about in Wired magazine, and led The New York Times to refer to her as the “Pigeon Stalker.” In addition to her research, she is a co-founder and editor of the urban evolution blog Life in the City: Evolution in an Urbanizing World.
From the Ground Up: Urban Evolution in Pigeons and Squirrels
Urbanization is drastically increasing around the globe, causing massive changes in the surrounding environment, including habitat fragmentation, more buildings, roads, pollution, and environmental toxins. These changes have created a new ecosystem with novel selection pressures and barriers to gene flow. The ecology of this urban environment drives evolution, which in turn influences the ecology in a constant feedback system.
Since the mid-1990s, the field of Urban Evolution has flourished. Studies include morphological, physiological, and behavioral changes, gene flow, and drift. Researchers have identified many biological changes caused by urbanization. For example, urban birds have diverged at the SERT gene, which is associated with harm avoidance behavior. Lizards in Puerto Rico have developed longer legs and stickier feet, allowing them to move more easily across urban substrates.
White-footed mice in New York City parks diverged into separate forms genetically distinct to specific parks.
Pigeons, or Columba livia, are native to Asia, North Africa, and southern Europe, where they were domesticated around five to ten thousand years ago. They typically live on rocky cliffs and are known for their long-distance flight and homing ability, rapid reproduction, and population turnover. Pigeons can produce offspring every six weeks, making them perfect for evolution and genetic studies. Despite their long history, there have been few genetic studies on pigeon populations.
Dr. Carlen’s study focused on gene flow and genetic drift structure in the feral pigeon population along the Northeastern megacity corridor of I95 stretching across Boston, Providence, New York City, Philadelphia, Baltimore, and Washington, DC. Capturing blood samples from 473 pigeons distributed across this corridor, Dr. Carlen found that pigeons within a 50km radius are highly related and, beyond that, are unlikely to be related. In addition, she discovered that the pigeons formed two distinct genetically related groups, one living between Washington, DC and New York City, and the other between Boston and Providence. Dr. Carlen surmised that the physical barrier of suburban landscape across the state of Connecticut created this differentiation.
Another study Dr. Carlen conducted was to assess the variance of Flight Initiation Distance (FID) in New York City pigeons. This study examined how close a human can get to a pigeon before initiating a flight response. She conducted this test 519 times across New York City in multiple, diverse locations, such as open fields and forests in parks, tall buildings in Times Square, paths and grass and trees in St. John’s Cemetery, and suburban houses with yards in Jamaica, Queens. Next, she correlated the data, including pedestrian traffic and human population density, from the US census. As expected, she found that a human can get closer to a pigeon in areas where more people live and with more pedestrians.
Next, Dr. Carlen compared this data to locations with high counts of Cooper’s Hawk, Red-tailed Hawk, and Peregrine Falcons, known to feed on pigeons. She found that Cooper’s Hawk sightings do not influence the pigeons’ FID, whereas Red-tailed Hawk sightings increased the pigeon’s FID, and Peregrine Falcon sightings decreased the pigeons’ FID. The results were initially confusing, but after speaking with birders, Dr. Carlen began to look at differences in feeding habits across these three predators. For example, Peregrine Falcons will grab pigeons out of the air creating the behavior in pigeons of staying close to the ground. The Red-tailed Hawk will swoop among humans to capture a pigeon resulting in less of a safe space for pigeons. Dr. Carlen determined that pigeons calculate the most significant risks based on the array of dangers and are typically more comfortable around humans than avian predators.
What does this tell us about urban evolution? One is that urban landscape heterogeneity may contribute to variable spatial genetic and behavioral responses across a single city, and we must examine patterns at different spatial scales. Two organisms that depend on humans exhibit fine-scale spatial genetic structures that reflect human patterns and distributions; therefore, we need to sample across urban areas. Three, not all cities are equal, and historical and ongoing interactions taking place within each city must be taken into consideration.
Dr. Carlen’s post-doctorate work took place in St. Louis, MO, a racially divided city regarding physical location, housing, lead levels in soil, education, city services, and other resources. For this study, the Sciurus carolinensis, or Eastern Grey Squirrel, is the subject of study. These squirrels are common throughout the US. She questioned the relationship related to adaptive and non-adaptive evolution and how the urban barriers, human garbage, and racial divides affect squirrels’ health and development. This study is still underway, and Dr. Carlen will post her findings in the coming months.
The evening ended with the Linnaean thanking Dr. Carlen for sharing her fascinating body of work.
Notes amended on 10/10/2022 to reflect italicization of scientific names and correct one typo.