Metapopulation and Metacommunity definitions and examples.
Metapopulations are a "series of variously connected demes of a single species" pg 59. "Demes" means "groups". The metapopulation is not the entire population, just the population within a set area.
In this example I'm going to use Jamaicans as the species (this may not be politically correct, but I mean no harm). Metapopulations of Jamaicans live in Kingston, Negril, London, Liverpool, New York, Chicago, Atlanta, Houston, etc. The populations in Chicago are connected through neighborhoods, restaurants, churches, and other local events to form a metapopulation. Southside and northside populations of Chicago Jamaicans live in different neighborhoods, go to different schools, and work in different places. So they belong to different demes (groups), but they are part of the same Chicago metapopulation. It is much more likely that a northside Jamaican in Chicago will meet and interact with a southside Jamaican in Chicago than a Jamaican from Atlanta.
Metapopulations are typically confined by regions, habitats, barriers, or some other form of border. So although Milwaukee is close to Chicago, Jamaicans in Milwaukee would not be part of the Chicago metapopulation, even if they originally relocated from Chicago. Once they crossed the established borders and settled in Milwaukee, they would be classified as part of the Milwaukee Jamaican metapopulation.
All metapopulations are not equal. Size, numbers, and resource availability make a difference in the sustainability of a metapopulation. The metapopulation of Jamaicans in Chicago is stable. The city is big enough to support large numbers and several neighborhoods of Jamaicans. Even if new Jamaican immigrants did not come from some other city, Chicago should always have a healthy metapopulation of Jamaicans maintaining a separate and distinct culture from the general populace.
The same could not be said for hypothetical Jamaicans in a small town like Pierre, South Dakota. A Jamaican there would likely find few other Jamaicans to interact with and the metapopulation may not be sustainable. The number of Jamaicans in Pierre might be so low that they would not even be recognized as a Jamaican metapopulation. Instead Pierre Jamaicans might be seen as individuals or lumped into the general minority metapopulation.
Metapopulations must have a certain size and vitality to be sustainable.
Metacommunity is "an array of patches of a particular type of community variously connected by dispersers." Pg 82. Here the focus is the components that make up the habitat, not a single species. This is useful in defining the actual area where species live. If you look at the range map for wood lily (Lilium philadelphicum), you’ll see it covers most of the eastern US. That’s obviously not true. Wood lilies don’t grow in lakes, rivers, buildings, interstates, mountaintops, or parking lots of the eastern US. They grow in prairies swale habitats throughout the eastern US. Metacommunity is analogous to habitat. It defines the parameters in which the metapopulations can exist. Metapopulations live in metacommunities.
Continuing with our example, the metacommunity would be the cities where Jamaicans reside. The urban areas are the habitats that contain the Jamaican metapopulations. Kingston, Negril, London, Liverpool, New York, Chicago, Atlanta, Houston would represent the metacommunities in which we could find our metapopulations of Jamaicans.
But Jamaicans would only be one of the metapopulations present in the metacommunity. Irish, Latino, African-American, German, Polish, Nigerian, Indian, Chinese, and other metapopulations are likely to exist in those metacommunities as well.
Other attributes of metacommunities with Jamaicans might include large populations, available employment, available housing, good transportation systems, urban radio, plentiful and diverse goods, etc. All of these living and non-living elements comprise the metacommunity. The removal of any one element may have unforeseen and cascading effects on the others. For example the removal of all Nigerians from Chicago, might worsen the already poor taxi service on the southside. That in turn could affect the public transit system and local shops, which could affect local tax revenues, and so on.
Metacommunities function independently, but are connected by dispersers (immigrants). A Jamaican from London can choose to move to New York, Chicago, or Atlanta and find suitable habitat. The cities are independent but they share qualities that make that should satisfy Jamaicans. I assume the same could not be said for Kandahar, Afghanistan. Jamaican festivals and events are much more likely to occur in New York City than in Kandahar. Although, Kandahar might not be an acceptable Jamaican metacommunity, I’m sure it functions fine as a Pashtun metacommunity. All but the most desolate and degraded areas are metacommunities for some type of life.
Getting a handle on the terms “metapopulation” and “metacommunity” makes it easier to tackle subjects like habitat restoration, conservation, and biodiversity.