In this lesson, students explore a model of genetic drift in populations of varying sizes. The lesson uses the model to help students to understand the ramifications of population size and isolation on alleles in populations.
Learning Objectives:
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Describe how genetic drift influences the diversity (polymorphism) of alleles in a population
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Investigate the consequences of very small or very large populations for allele diversity.
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Compare the effects of genetic drift in isolated populations
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Apply these ideas to real-world populations of animals (including dog breeds and certain human ethnic groups)
Lesson Material:​
Tempe, Arizona
Current projects
Below you will find a description of the active research projects I am working on.
Ant collective behavior
In this 90 second video you can see how tiny Temnothorax ants share information through trophallaxis and recruitment (tandem-running) to feed their colony.
In this short video, you can see temnothorax ants engaged in trophallaxis (which is when they regurgitate liquid food to share with their nest-mates). The ant at the center of the action has discovered a source of sugar water (with green food-coloring in it). Trophallaxis is one of the most important interactions within an ant colony - with ants sharing food with their sisters, the queen, and larvae.
When they discover a food source or a nest for their colony, ants have a choice to make - should they communicate the location of this resource to their nest-mates? How does the colony organize the work of collective foraging or house-hunting and colony relocation? In this ongoing work in the Pratt Lab of ASU (in collaboration with Professor Stephen Pratt and Associate Professor Ted Pavlic and others), we are investigating these questions in the ant, Temnothorax rugatulus.
Student research assistants
Graduate students Brooke Goodland and Showmik Alam hunt for Temnothorax ant colonies on Mt. Lemmon near Tucson, AZ.
ASU undergraduate, Christopher Sanders individually paint-marks ants (using a microscope)
Temnothorax ants are able to collectively re-aggregate even after complete scattering. In this video a large colony has been randomly scattered throughout the circular arena - with two nests to choose from. Initially forming many separate clusters of homeless ants, the colony collectively chooses the top nest and then with still unhoused ants, the second nest is used for housing. Video by Brooke Goodland
Carpenter bee sociobiology and behavioral ecology
One of the challenges of studying carpenter bee societies is that a lot of their behavior takes place inside their wooden homes - out of sight. To get around this we used CT scanning (provided by St. Joseph's hospital) to visualize their hidden world.
Male carpenter bees are a striking golden color (a result of sexual selection). Here, this charmer cleans himself up before heading out to try and impress the ladies.
Being able to quickly navigate and return to their nest is an important skill. Here in this video (above) we can see a female returning home in a fairly typical flight. Speedy navigation at this stage is important - as the return home is a moment when carpenter bees can be attacked by predators. We have seen predation events by animals such as grackles and desert spiny lizards - as can be seen below - in an illustrated page from my carpenter bee field notebook.
Not all insect societies are as far along in their social evolution as the ants or honey bees. Social behavior can range from small family groups up to the incredible eusocial empires of, say, leaf-cutter ants. By studying non-kin or more facultative associations - small societies - we may gain insight into the early roots of the evolution of cooperation in insect societies. The valley carpenter bee, Xylocopa sonorina, is one such primitively social organism - with bees nesting in aggregations in old wood (usually found in riparian areas). These are among the biggest bees in the world - and relatively common here in The Valley of the Sun. The females are strikingly black large bees with the males being a beautiful golden color.
This work is led by PhD candidate, Maddie Ostwald and in collaboration with her advisor Professor Jennifer Fewell (and others).
Collaborators
Graduate student, Maddie Ostwald (right) manipulates visual cues in an experiment focusing on navigation in carpenter bees. High school student, Ella Shaffer (left) assists.
An illustration of carpenter bee nesting biology by undergraduate science illustration student, Maddy Howell.
In the video above you can see the results of one of Maddie Ostwald's bee navigation experiments. Colorful shapes were placed next to each nest entrance for one week prior to the experiment. Just before this video was filmed, Maddie shifted the symbols over one to the right from their original location (thus altering a small part of the visual field). Typically, bees take about 7 or 8 seconds to find their nest. Above you can see how this experiment influence the bee navigation return time!
Investigating the honey bee waggle dance
A view from inside the hive: honeybee observation hives give us a window into behavior in the nest.
Honey bees very famously make use of the 'waggle dance' to communicate the location of nectar to their sister foragers. In this study in collaboration with Professor Stephen Pratt and ASU Bee Facility director, Dr. Cahit Ozturk, we are exploring the nature of positive feedback in this famous dance language.
ASU researcher Dr. Cahit Ozturk preparing for our foraging experiments.
Student research assistants
Graduate student Showmik Alam observes and paint marks individual foraging honeybees in collective foraging experiments.
ASU undergraduates Jacob Stoltman and Muniba Abdumanobova give the all-clear sign while examining the bee facility at ASU's polytechnic campus
Studying the natural history of the Arizona paper wasp
Paper wasps can start colonies either with a single foundress (female wasp) or with multiple foundresses working together. This cooperative colony foundation has fascinated and inspired generations of biologists. In this long-term study (begun in spring 2022) we are examining the behavioral ecology of this native Arizona species.
A visual comparison of two paper wasp colonies. The top colony (13) was founded by a single female. The bottom colony was founded by a cooperative group. The cooperative-founded colony shows much stronger population growth.
Paper wasps are female-directed societies (similar to honey bees and ants). Phenotypically similar, one of the above individuals is the 'queen' and likely monopolizes reproduction. While other polistes species have been studied extensively, the Arizona paper wasp is but little examined.