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In a series of papers Casas and coworkers explore the domestication of Stenocereus stellatus (Cactaceae) in Central Mexico. First, their morphological analysis of wild, managed in situ, and cultivated populations shows that indigenous peoples have especially influenced variation in fruit characters. Secondly, their examination of the reproductive biology of these cacti shows that bats are the most likely pollinators, so that spatial isolation is nonexistent, but that there are barriers to gene flow between wild and cultivated populations. (see p. 522 and p. 534)
Weed dispersal via epianthropochory
Vibrans presents evidence of a previously undocumented form of weed seed dispersalepianthropochory or systematic dispersal on human exteriors. Her survey of maize field weed species in Central Mexico shows an unusual number of weeds with burrs. The only possible vectors are humans, and interviews with farmers corroborate considerable long-distance transport of the clinging weed diaspores. (see p. 476)
Buzz pollination
The anthers of 68% of flowering plant species open via tiny pores that restrict pollen removal to bees capable of buzz pollination. Larson and Barrett investigate the response of bumble bees to cues provided by the buzz-pollinated flowers of Virginia meadow-beauty (Rhexia virginica, Melastomataceae). They found that bumble bees could discriminate against flowers that had previously been visited and that post-reproductive flowers which had undergone a color change were avoided.
Moss life history
Little is known about patterns of life history variation in populations of plants in which the haploid gametophyte stage is dominant. Shaw and Beer use a novel experimental design in which gametophytes are pedigreed through sporophytic family lines to describe variation in two gametophyte populations of the moss Ceratodon purpureus.
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