Seasonal distribution of drosophilid species in the Tallahassee, Florida, area Jeff Birdsley 16 July 2005
Bar width is an approximate indication of relative
abundance of species. An ‘x’
represents one or a few specimens taken on a single date.
These data are based primarily on weekly collections taken from fruit and
vegetable compost at my house on East College Avenue in central
Tallahassee. I collected a sample of about 100 to 500 flies nearly every
week from April 2001 through July 2005. I sampled less frequently from
July 2000 to April 2001. Also included are mine and David Houle's occasional collections from
elsewhere in Leon County, and Don Ohmes’ collections in Jefferson County,
Florida. Data on the
mushroom-feeding species comes mainly from samples taken from wild mushrooms at
the FSU Mission Road greenhouse facility and at Tom Brown Park and Myers Park in
Tallahassee.
Notes on patterns not apparent in the tables:
1. Winter 2000-1 was relatively cold in Tallahassee. Collections on compost were numerically dominated by D. affinis in January-February. After 1 March the community became much more diverse with D. simulans becoming dominant.
2. Winter 2001-2 was relatively warm in Tallahassee. D. simulans remained the numerical dominant it had been since the previous spring. D. affinis briefly increased in numbers during and just after the few cold snaps, but simulans remained present throughout the winter.
3. D. willistoni does not appear every year in north Florida. Following milder winters it was fairly common on my compost in late summer/fall (2000, 2002, 2004). Following colder winters it may make a brief appearance in late fall (2003) or not appear at all (2001). Other primarily tropical species (D. malerkotliana, D. cardini, and S. latifasciaeformis) have a similar seasonal distribution in north Florida. They appear to be re-colonizing north Florida each summer from a southern winter refuge, the size of which may be negatively correlated with the severity of the winter.