Winter Movement and Home Range of White-Tailed Deer at Pilot Knob State Park, Iowa

Home ranges of nine radio-equipped white-tailed deer (Odocoileus virginianus) were determined during the winters of 1969-70 through 1971-72. For does and female fawns, the winter ranges varied from 145 to 307 acres, the major (longest) axes from 1.00 to 1.19 miles, and minimum daily movement from 0.78 to 1.00 mile. Home range sizes of adult does were more consistent than those of female fawns or bucks, varying from 198 to 215 acres. Their major (longest) axes ranged from 1.00 to 1.12 miles and minimum daily movement varied from 0.78 to 0.88 mile. Bucks exhibited the greatest variation in movement, with home ranges varying from 49 to 504 acres, major axes from 0.62 to 1.90 miles, and minimum daily movement, from 0.50 to 1.25 miles. Most major axes of movement led from the southeastern comer of the park, where deer bedded during daylight hours, to the croplands north of the western half of the park, where deer fed during nocturnal hours. The park provides one of few large stands of timber in a 4-county area. This timber serves as permanent cover and is used by deer for bedding during daylight. The park also serves as a refuge for deer which are highly vulnerable to hunting in the intensively farmed regions of Iowa

Variation and asymmetry in host-symbiont dependence in a microbial symbiosis

Background Symbiosis is a major source of evolutionary innovation and, by allowing species to exploit new ecological niches, underpins the functioning of ecosystems. The transition from free-living to obligate symbiosis requires the alignment of the partners’ fitness interests and the evolution of mutual dependence. While symbiotic taxa are known to vary widely in the extent of host-symbiont dependence, rather less is known about variation within symbiotic associations. Results Using experiments with the microbial symbiosis between the protist Paramecium bursaria and the alga Chlorella, we show variation between pairings in host-symbiont dependence, encompassing facultative associations, mutual dependence and host dependence upon the symbiont. Facultative associations, that is where both the host and the symbiont were capable of free-living growth, displayed higher symbiotic growth rates and higher per host symbiont loads than those with greater degrees of dependence. Conclusions These data show that the Paramecium-Chlorella interaction exists at the boundary between facultative and obligate symbiosis, and further suggest that the host is more likely to evolve dependence than the algal symbiont