Amelanchier contains about 20 species of trees and shrubs of the North Temperate Zone. These plants bear attractive flowers, their fruits are important to wildlife, and they are valued horticulturally. Shadbushes and serviceberries, as these plants are commonly called, are native to every state of the United States except Hawaii. It has been a challenge to define the species of Amelanchier because hybridization is frequent, and novel kinds of plants created by hybridization can be widely dispersed. Some forms of shadbushes are easy to distinguish while others differ from one another in minute ways. The goal of this research is to define species in this genus based on extensive field and laboratory data.
This research will provide a new classification of species in an ecologically important group of plants. Results will be disseminated in the scientific literature and on our web site (http://biology.umaine.edu/Amelanchier/) for botanists, horticulturists, wildlife ecologists, conservation biologists, land-use managers, and others. Training of undergraduate and graduate students in plant systematics (classification) is essential to maintaining our capacity to understand and communicate about plant species. This research will provide outreach through workshops to give K-12 teachers exercises in pollination biology for their students.
The genus Amelanchier contains shrubs and trees that are commonly called shadbushes and serviceberries. They are native in every U.S. state except Hawaii and in all Canadian provinces and territories. They grow in sunny spots from sea level to about 11,000 feet elevation, and from wetlands to deserts. These plants also occur in Eurasia and northern Africa, but they are less common there. The fruits of shadbushes, which are closely related to apples and pears, are eaten by many species of birds and small mammals. Fruits of the Saskatoon serviceberry are grown as a fruit crop, especially in Canada. Shadbushes are increasingly used horticulturally for their attractive white flowers in the spring, bright-red autumn leaves of some species, and smooth, gray bark. Shadbushes are either diploid, with two genomes, or polyploid, with three or four genomes. (People are diploid, with one genome inherited from their mother and one from their father.) Polyploid shadbushes are mostly created when there is mating between diploid plants of different species. The resulting hybrid plants differ from non-hybrids in their pollen and eggs. Normally pollen and eggs have one genome, and when they fuse to make a new plant it is diploid. Hybrid plants often make pollen and eggs that have an extra genome, and their offspring are therefore often polyploid. In most plants, seeds are the result of sex, but Amelanchier polyploids make seed asexually almost all the time. Plants that produce seeds without sex, a process called apomixis, form different kinds of groups than sexual plants. Apomixis clones individuals and can rapidly make a group of plants that are more or less identical to one another in appearance. Such groups are often called microspecies. They are numerous and have been named by the thousands in some genera that reproduce through apomixis, such as dandelions and blackberries. Because they differ in small ways, distinguishing these species can be difficult. Another challenge in working with genera with apomixis is that apomicts reproduce sexually some of the time. This occasional sex can generate new microspecies. The combination of microspecies and some sex in Amelanchier polyploid apomicts has created great complexity and difficulties in making a usable species classification. There has been considerable uncertainty among past workers about the number of species that should be recognized and about which species should be recognized. These problems have confused and frustrated people who need to identify these plants, including botanists, horticulturists, wildlife ecologists, conservation biologists, land-use managers, students, and anyone else who is interested in these common plants. The primary aim of this research is to create a new species classification for Amelanchier. Diploid shadbushes form groups that are quite distinct from one another, and, as already explained, defining groups of polyploid apomicts is challenging. For this challenge we have focused on understanding diversification, how groups of polyploids are formed. Diploids are important in understanding diversification because they contribute genomes to polyploids. We have undertaken extensive fieldwork and accumulated samples from 42 U.S. states, seven Canadian provinces, and 11 Eurasian countries. Some of our samples, especially ones from Eurasia, have been sent to us by colleagues. We have determined the number of genomes in over 1350 individuals, studied the appearance of thousands of individual plants, and analyzed evolutionary relationships with DNA sequences. Field and laboratory studies are claifying the nature of the groups that have evolved within the genus. Our work is intended to translate what we learn about diversification of the group into a systematic scheme that will make it easier to understand and identify shadbush diversity. We have made numerous presentations of our work at national meetings of botanical societies and to groups of botanists, ecologists, and the public. These presentations have provided important feedback on our approach to a new classification. We completed a treatment of Amelanchier for the Flora of North America (due to be publshed in early 2014). We plan to submit about nine manuscripts for publication in scientific journals. We have not published any of these manuscripts because we needed to do extensive fieldwork to sample Amelanchier adequately and to assemble diverse data to help us understand diversification in the genus. Earlier publication would have been premature. Our first two publications are foundations for understanding diversification and establishing a new species classification. The first publication concerns the impacts of apomixis and polyploidy on diversification and geographic distribution in Amelanchier. The second publication focuses on the nature of shadbush diploids. These papers are expected to be submitted for publication in the winter of 2013-2014 and will be followed by six papers dealing with individuals groups of polyploids. We also will publish a monograph, which pulls together information about the genus and presents a full species classification. Our monograph will also be maintained on our Amelanchier website (http://biology.umaine.edu/Amelanchier/)
