Resolution of male-female conflict in an hermaphroditic flower.

The flowers of most angiosperm species are hermaphroditic. Spatial separation of male and female organs within a flower (hercogamy) is a common character traditionally interpreted as an adaptation to reduce intrafloral self-fertilization, one potential cost of hermaphroditism. Another possible cost that may lead to selection for hercogamy is physical interference between male and female floral functions. Here, I present evidence demonstrating the role of a floral character in reducing female interference with male function. The bi-lobed stigma of the bush monkeyflower closes after receiving pollen, causing increased spatial separation of the anthers and stigma ('movement' hercogamy). Experimental manipulations show that flowers with closed stigmas export more than twice as much pollen to other flowers as those in which the stigma is prevented from closing. However, stigma closure only minimally reduces the potential for intrafloral self-pollination. This study provides the first experimental evidence that selection to reduce intrafloral male female interference can be a strong selective force and can drive the evolution of floral characters usually interpreted as mechanisms to reduce self-fertilization

Condition of California Perennial, Wadeable Streams Based on Algal Indicators Prepared By:

SWAMP-MR-RB9-2013-000

Honey bee (Apis mellifera) strains differ in avocado (Persea americana) nectar foraging preference

Avocado nectar is unusual because it contains perseitol, a 7-carbon sugar alcohol. We compared avocado-nectar collection by commonly used Italian-based (IT) honey bee colonies and New World Carniolan (NWC) colonies introduced in avocado orchards in Israel (IS) and California (CA). In IS, NWC colonies had greater honey yields (1.2–4.3 fold), with a higher perseitol content (1.1–5.4 fold), than IT colonies. Overall, we calculated that NWC bees collected 1.4 to 18.1 times more avocado nectar than IT bees in the IS orchards. In CA, analyses of the crop contents of foragers revealed non-significant strain-specific trends in visitation to avocado flowers that were consistent with those indicated by data from IS. The genetic basis for honey bee differences in visitation to avocado flowers was further supported by the consistently high honey perseitol content of selected colonies over two years. The implications of possible strain-specific difference in avocado-nectar preference are discussed in relation to the use of honey bees for avocado pollination