Archaeology Excavation

The Greenish Warbler, long considered an idealized example of a single species that diverged into two as it expanded its range, has a much more checkered family history than biologists previously realized.

Ring species are a continuous loop of related populations, each adapted to its local environment, with two terminal populations in the loop meeting but now unable to mate. But an in-depth genomic analysis published today in Nature by University of British Columbia researchers reveals that the Greenish Warbler's genetic migration through central Asia involved periods of geographic separation and hybridization.

"We've shown that the evolution of ring species is much more complex than the smooth and continuous divergence envisioned by the classic model," says UBC zoologist Miguel Alcaide, the paper's lead author.
"If you view the ring of Greenish Warbler subspecies as a river, over the years the flow of populations has experienced periods of isolation--as if forming ponds during a draught--which accelerated genetic differences. This would have been interspersed with periods of flooding, or rapid exchange between populations. Interbreeding after range expansion has been, however, much more restricted among neighboring populations exhibiting substantial differences in morphology and behavior."

Originally expanding out of southern Asia, subspecies of greenish warbler have diverged around the expanse of the Tibetan plateau over thousands of years, with two distantly related populations meeting again in the north, in central Siberia. Since early observations in the 1930s, biologists have thought the terminal sub-species incapable of mating. The new analysis shows that small regions of the western Siberian genome can be found in some of the eastern Siberian birds, indicating some successful hybridization between those forms.
"Given the new genomic evidence for historical breaks in gene flow, it's remarkable that traits such as plumage and song show such gradual change around the ring," says UBC researcher Darren Irwin, senior author on the paper and an expert who has studied greenish warblers since the 1990s. "And despite the small amount of hybridization between the most distantly related forms in central Siberia, they remain highly distinct in songs, plumage and genomic patterns."


"Overall, despite the complex patterns of gene flow, the Greenish Warbler still has the central characteristics of a ring species: two mostly distinct populations connected by a chain of populations in which traits and genes change progressively from one species to the other," says Irwin.

The International Journal of Myriapodology recently published the first population genetic study of cave millipedes. This research highlights an important challenge in the conservation of cave biodiversity -- that for many species caves are 'islands' of habitat that support isolated and genetically distinct populations.

The southern Cumberland Plateau in Tennessee and Alabama, USA is known for its high cave density. In addition, it has the highest cave biodiversity of any region in North America. Millipedes of the genus Tetracion range across this biodiversity hotspot. These millipedes, which can grow up to 8 cm in length, are common scavengers in cave communities. Like many cave animals, Tetracion millipedes have reduced pigmentation and non-functional eyes.
The authors used genetic techniques to compare Tetracion populations and species. They found that Tetracion populations were generally isolated from one another. In addition, divergence between Tetracion species was high, suggesting that members of the genus diverged several million years ago.

This list of archaeological expeditions which accept volunteers is compiled by the Israel Foreign Ministry as a service to the public. The archaeology excavation details below been published by the archaeologists in charge of the individual expeditions, who bear responsibility for their contents.

VOLUNTEERING

Many archaeologists enlist volunteer help on their digs, as volunteers are highly motivated and wish to learn and gain experience, although the work is often difficult and tedious. Usually, no previous experience is necessary. The work includes digging, shoveling, hauling baskets of earth and shreds, cleaning pottery shreds and more. Volunteers are responsible for their own travel arrangements to and from Israel.

ACCOMMODATION

Accommodations for volunteers can range from sleeping bags in the field, to rooms in hostels or kibbutzim,
to 3-star hotels near a site. Each expedition has its own accommodation arrangements.

There is usually a charge for food and lodging, although on some excavations these are free. All charges listed are in US dollars. Volunteers who require kosher food should inquire in advance. Excavations conducted in or near a city often require volunteers to find their own accommodations.

CLOTHING AND EQUIPMENT

Volunteers should have comfortable, sturdy clothes for heavy work. Sunhats are absolutely compulsory in summer; warm clothing is suggested for summer evenings as the weather can be cool. Winters are wet and cold; warm clothes and water-proof boots are necessary.

Equipment that may be useful - depending on the conditions at the site and the type of accommodation available - includes work-gloves, sleeping bag, canteen, towels and sunscreen lotion.

WORK HOURS

The work schedule at an excavation is organized according to the conditions at the site. A day on an average dig begins before dawn and ends after noon. There is normally a rest period after lunch. The afternoons and early evenings may be devoted to lectures, additional excavation work, cleaning and sorting of pottery and other finds, or they may be free.

CREDIT COURSES

Some expeditions offer credit courses from sponsoring institutions. Details concerning subjects, conditions and cost may be obtained by contacting the expedition director.

LECTURES

Most expedition directors (or other staff members) offer informal lectures covering the history and archaeology of the site and discussion of the type of work involved. Volunteers should feel free to request information regarding an excavation in order to be able to appreciate all aspects of the work.

RECREATION AND TRIPS

Recreational facilities (swimming pools, beaches and sporting grounds) may be available, depending on the location of the site. Most expeditions organize sightseeing and field trips to sites in the area and to neighboring museums.

INSURANCE

In most cases, volunteers must arrange for medical and accident insurance in advance. Even in instances when accident insurance is provided, it is strongly advised that volunteers come fully insured as the insurance offered is minimal.

APPLICATION AND REGISTRATION

When applying to the director of an excavation you should indicate any previous studies you may have in archaeology or related fields, such as anthropology, architecture, geography, surveying, graphic arts; or experience in excavation work, pottery restoration or photography.

For registration, please contact the persons listed in the individual entries. Please note that a registration fee is often required.

Note: Israel Ministry of Interior regulations require that passports of all volunteers (other than Israeli) be stamped with a volunteer visa (B4). This request should be made by the volunteer at the point of entry into Israel.




EXCAVATIONS 2010
(Listed by starting date)
This is a preliminary list. Additional digs will be added as the information becomes available.

Note:
There will be no field excavations at Tel Gezer in 2010. The next excavations will take place June 13 - July 15, 2011.
The next excavations at Mount Zion will take place in June/July 2011.
Ein Gedi January 4-28
Omrit Late May - Late June
Bethsaida May 23 - June 5; June 6 - June 19
Zeitah June 6-30
Ashkelon June 6 - July 16
Megiddo June 12 - July 29
Tel Rehov June 15 - July 16
Tel Hazor June 20 - July 9; July 11-30
Khirbet Qeiyafa June 20 - July 30
Hippos (Sussita) July 4-31
Tell es-Safi/Gath

July 4-30
Tel Dor July 5 - August 12
Ramat Rahel

August 15-28