Group items tagged

website with many symbiotic examples and images

Imagine you swallowed a small bird and suddenly gained the ability to fly … or you ate a cobra and were able to spit poisonous venom! Well, throughout the history of life (and specifically during the evolution of complex eukaryotic cells) things like this happened all the time. Adam Jacobson explains endosymbiosis, a type of symbiosis in which one symbiotic organism lives inside another.

Paul Andersen explains how eukaryotic cells were formed through a process of endosymbiosis. He describes how aerobic bacteria became mitochondria and cyanobacteria became chloroplasts. He mentions an example of symbiosis that occurs today and mentions the importance of Dr. Lynn Margulis in the development of this modern theory.

It turns out that some monkeys make better hunting partners than prey. That's the case on the Ethiopian highlands, where two unusual species have developed an equally unusual co-dependency. The relationship benefits both canine and primate, although at least one or two nearby rodent species might regret it.

New research shows butterflies use nectar to drug unsuspecting ants with mind-altering chemicals. The Japanese oakblue butterfly (Narathura japonica) enlists the help of ants (Pristomyrmex punctatus) to stand guard and protect its growing caterpillars (pictured) from predators such as wasps and spiders.

The Hawaiian Bobtail squid has a remarkable symbiotic relationship with a species of marine bacteria that can produce light by a controlled chemical reaction. Also featured on the HHMI DVD, Exploring Biodiversity: The Search for New Medicines, available free from HHMI.

Free secondary education from the UK!

This case study centers on symbiotic relationships between insects and bacteria using Drosophila melanogaster, the common fruit fly, and the recently discovered bacterial species Sodalis praecaptivus. Until recently, the only known Sodalis species of bacteria were symbiotically associated with several different species of insects. However, free-living non-symbiont Sodalis species are being tested in several different insect species to determine if they can transition into symbiotic relationships. A pre-class assignment (see Supplemental Materials) directs students to read an open access research journal article providing a comprehensive review of S. praecaptivus and describing an experimental weevil model that parallels that of the fruit fly. A PowerPoint presentation shown in class (see Supplemental Materials) provides further background before students work in small groups to complete the case study focusing on results from D. melanogaster and S. praecaptivus model experiments.  Although developed for a genetics course, this interrupted case is appropriate for an upper-level biology course. It can be completed within a 75-minute class meeting, or adapted for shorter time periods.

Symbiotic relationships are interactions between species that live closely with each other and are commonly separated into three types: parasitism, mutualism, and commensalism. Students are often under the impression that these types are distinct and mutually exclusive, but on closer examination some interactions appear to be at times mutualistic, at other times parasitic. Is it perhaps better to think of mutualism and parasitism as two ends of a sliding scale, with commensalism in the middle? In this case study, students consider this question by examining what is often considered to be a classic example of mutualism existing between oxpecker birds and African savanna large mammals. After students examine data from a research study on oxpecker behavior, they then apply a more nuanced understanding of species interactions to a set of additional scenarios. The learning objectives for the case align with the Four-Dimensional Ecology Education Framework. The case was written for an upper-level undergraduate ecology course, but could easily be adapted for an introductory biology course.