Reproductive effort in some Chihuahuan Desert annuals

Title	Reproductive effort in some Chihuahuan Desert annuals
Publication Type	Thesis
Year of Publication	1975
Authors	McKinney HH
Number of Pages	30
Date Published	1975
University	New Mexico State University
City	Las Cruces, New Mexico
Thesis Type	M.S. Thesispp
Call Number	00550
Keywords	annual plant, reproduction, Bouteloua,reproduction, dissertation, dissertations, Eriogonum,reproduction, Euphorbia,reproduction, reproduction, annual plant, theses, thesis
Abstract	Theoretically, desert annuals should expend more energy in reproduction during periods of environmental stress, such as water stress. In this work, the reproductive effort, in relation to moisture, of various Chihuahuan desert annuals was studied. Comparisons of reproductive effort under amended and natural soil moisture conditions were made. Under the amended water conditions, Euphorbia micromera had a lower reproductive effort. However, Bouteloua barbata and E. aristidiodes increased reproductive effort under watered conditions. Plasticity of reproductive effort was studied by comparison of reproductive effort in closely related species over a 3-year period. Species of the genera Euphorbia, Bouteloua, and Eriogonum responded to seasons with low rainfall by generally increasing reproductive effort. These results follow the expected theory that reproductive effort is higher during periods of moisture stress. Reproductive effort of summer and winter annuals in relation to moisture was also studied. A significant regression of reproductive effort onto a precipitation ratio was found in the summer annuals, but no significant relationship was found in the winter annuals.