Lowland Counterparts Research Articles

COMPARATIVE REPRODUCTIVE BIOLOGY OF MONTANE AND PIEDMONT CHORUS FROGS

Sub-units of a species living in contrasting environments may respond to differences in their respective habitats by developing differentially adaptive traits. For example, Moore (1942, 1946, and 1949) has demonstrated differences in both developmental temperature tolerances and coefficients between northern and southern populations of R. pipiens. Also, Ruibal (1955) has shown that populations of R. pipiens from different elevations in Mexico exhibit different rates of development at all temperatures tested. Embryos from higher elevations develop more slowly than their lowland counterparts. Ruibal suggests that this difference may be due to a history of selection for rapid development in the lowland localities resulting from greater interspecific competition in the larval stage. This phenomenon, called special adaptation by Brown (1958), may be most conveniently elucidated by comparing different conspecific local populations which are geographically proximate, thus minimizing the effects of differentiation due to isolation by distance. An opportunity to study this mechanism under near optimal conditions is afforded by populations of the boreal chorus frog, Pseudacris triseriata (Weid), in northern Colorado. In this area populations of P. triseriata occur at elevations from less than 4900 ft to above 10,000 ft. A presumed result of this elevation gradient has been the development and maintenance of numerous differences between montane and and piedmont chorus frogs. Variations in body size, adult temperature tolerance, and metabolism have been described in a previous paper (Pettus and Spencer, 1964). The purpose of this paper is to report our observations on variations in the eggs of these frogs and the results of a series of experiments designed to reveal differences in temperature effects during development. Both Moore (1949) and Ruibal (1955) have reported geographic variation in egg size of Rana pipiens. Moore's data show, with one striking reversal, a correlation between increased egg diameter and increased latitude. Ruibal reported only minor variation in egg diameters in spite of the fact that his samples were drawn from populations over a wide range of elevations.

Mountain Land Use in Northern Japan

T HE rural mountain settlements ofJapan, buraku,' generally are poorer, and operate under more restrictive natural and social conditions, than their lowland counterparts. Although farming is the dominant economic pursuit, it suffers from the limits imposed by terrain and climate, the low level of farming skills, and the isolation from outside markets. Subsistence crops are the rule, and even when cash crops are cultivated, they bring small financial reward for inordinate amounts of hard work. The shortcomings of farming, aggravated by the absence of industry other than simple handicrafts, have led to dependence on the mountain forests for cash income. Some mountain households also carry on small-scale stock raising on the basis of local forage supplies and of the steady market for draft animals in lowland farming districts. This distinctive land-use system derives in part from the obvious limitations of the mountain resource base. But, of equal importance, it derives also from a prevailing conservatism, the heavy weight of favored groups in buraku economic affairs, and the observance of time-honored customs. An awareness of the combined impact of natural and social forces is essential for a geographical analysis of the mountain land-use system because it helps to explain both why certain practices prevail and why they are handed down from one generation to the next with little modification. The northern Kitakami Mountains, in northeastern Honshu, are used in this study as a datum area for the description and analysis of mountain land use in some detail. These mountains have an unenviable reputation as one ofJapan's poorest and economically most retarded areas. Hence the land-use practices and living standards described here can be considered a base level