tailieunhanh - REPRODUCTIVE EFFORT IN SQUIRRELS: ECOLOGICAL, PHYLOGENETIC, ALLOMETRIC, AND LATITUDINAL PATTERNS

Grace period after the expiry of the 10 - year storage limit W e recommend amending clause 5 of the bill by substituting new text to repeal and replace section 10 of the Act. W e also recommend the adoption of the related new purpose clause 4(aa). These amend- ments would provide a grace period of six months upon the expiry of the 10 - year storage limit and any extensions to it. The grace period would lessen the burden of disposal management for fertility clin- ics. W e also recommend the adoption of replacement section 10(3), which would allow gametes and embryos to be stored and disposed of. | Journal of Mammalogy 89 3 582-606 2008 REPRODUCTIVE EFFORT IN SQUIRRELS ECOLOGICAL PHYLOGENETlC ALLOMETRIC AND LATITUDINAL PATTERNS Virginia Hayssen Department of Biological Sciences Smith College Northampton MA 01063 USA The distinctive features of reproduction in squirrels are the lack of allometric influences on the duration of reproductive investment the strong allometric influences on offspring mass and a trade-off between number and size of young suggesting an important developmental component to reproduction. Lengths of gestation and lactation do not vary with body size but neonatal and weaning mass do. Apparently the major constraint on reproduction in squirrels is not resources per se food calories minerals or water but rather the length of time such resources are available. Squirrels adjust growth rate to fit the timing of resource abundance. Within the familial reproductive pattern arboreal squirrels invest more into reproduction than do ground squirrels. Flying squirrels Pteromyini have a larger temporal investment into reproduction but a smaller energetic investment compared with other squirrels. Ground squirrels do not have a distinct reproductive profile because marmotine and nonmarmotine ground squirrels differ. Marmotine ground squirrels have a small temporal investment and a large energetic investment on a per litter but not on an annual basis. Nonmarmotine ground squirrels have a reproductive pattern similar to that of tree squirrels a pattern intermediate between marmotines and flying squirrels. Within this locomotor-ecological framework reproductive patterns differ among subfamilies. Tribes differ in having few 2-4 versus many 4-8 young and in the relative allocation of investment into gestation versus lactation. Specific environmental influences on reproduction in squirrels occur at lower taxonomic levels within the framework of a broad reproductive pattern set by earlier radiations into particular locomotor and nestsite niches. Key words .