Floral morphometrics and the evolution of sexual dimorphism in Lycium (Solanaceae)

Jill S. Miller, David L Venable

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Plants of Lycium californicum, L. exsertum, and L. fremontii produce flowers that are either male-sterile (female) or hermaphroditic, and populations are morphologically gynodioecious. As is commonly found in gynodioecious species, flowers on female plants are smaller than those on hermaphrodites for a number of floral traits. Floral size dimorphism has often been hypothesized to be the result of either a reduction in female flower size that allows reallocation to greater fruit and seed production, or an increase in hermaphroditic flower size due to the increased importance of pollinator attraction and pollen export for hermaphroditic flowers. We provide a test of these two alternatives by measuring 11 floral characters in eight species of Lycium and using a phylogeny to reconstruct the floral size shifts associated with the evolution of gender dimorphism. Our analyses suggest that female flowers are reduced in size relative to the ancestral condition, whereas flowers on hermaphrodites have changed only slightly in size. Female and hermaphroditic flowers have also diverged both from one another and from ancestral cosexual species in several shape characteristics. We expected sexual dimorphism to be similar among the three dimorphic taxa, as gender dimorphism evolved only a single time in the ancestor of the American dimorphic lineage. While the floral sexual dimorphism is broadly similar among the three dimorphic species, there are some species-specific differences. For example, L. exsertum has the greatest floral size dimorphism, whereas L. fremontii had the greatest size-independent dimorphism in pistil characters. To determine the degree to which phylogenetic uncertainty affected reconstruction of ancestral character states, we performed a sensitivity analysis by reconstructing ancestral character states on alternative topologies. We argue that investigations such as this one, that examine floral evolution from an explicitly phylogenetic perspective, provide new insights into the study of the evolution of floral sexual dimorphism.

Original languageEnglish (US)
Pages (from-to)74-86
Number of pages13
JournalEvolution
Volume57
Issue number1
StatePublished - Jan 1 2003

Fingerprint

Lycium
Solanaceae
sexual dimorphism
Sex Characteristics
dimorphism
flower
flowers
female flowers
hermaphrodite
phylogeny
seed productivity
gender
pistil
phylogenetics
floral trait
pollinators
topology
fruit production
ancestry
uncertainty

Keywords

  • Floral evolution
  • Gynodioecy
  • Lycium
  • Male-sterility
  • Phylogeny
  • Sensitivity analysis
  • Sexual dimorphism
  • Solanaceae

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Ecology, Evolution, Behavior and Systematics
  • Agricultural and Biological Sciences (miscellaneous)
  • Genetics(clinical)
  • Ecology
  • Genetics

Cite this

Floral morphometrics and the evolution of sexual dimorphism in Lycium (Solanaceae). / Miller, Jill S.; Venable, David L.

In: Evolution, Vol. 57, No. 1, 01.01.2003, p. 74-86.

Research output: Contribution to journalArticle

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