| Abstract Detail
Evolutionary Developmental Biology (Evo-Devo) Taylor, David W. [1], Hu, Shusheng [2], Tiffney, Bruce H. [3]. Developmental morphology of 75 million year old flowers: implications for the evolution of developmental novelties in fagaceous flowers. Living flowers of the Fagales have some unusual developmental characteristics related to delayed fertilization and pollen-tube growth. At anthesis the flowers are immature and have an orthotropous ovule. Later, the ovules increase in size and become anatropous and the ovary concurrently enlarges. At the same time, the pollen tubes extend from the stigma to the ovule with several phases of growth-cessation. Some species have porogamy while others have chalazogamy. Several of these characteristics may related to the Arabidopsis POP2 gene. Finally, the first ovule fertilized prevents the other ovule’s development resulting in a single seeded fruit. Three dimensionally preserved mesofossil flowers of a fagaceous fossil from the Campanian of Massachusetts, USA provide evidence on the evolution of these characters. The small fossil flowers have many fagalean characteristics (six tepals, mostly inferior, three-carpellate ovary with each locule initially containing two ovules, scabrate tricolporate pollen). A developmental sequence of flowers and fruits shows that several of these developmental characteristics existed 75 million years ago. We have definitive evidence of the delay fertilization. Smaller flowers have six orthotropous ovules while the larger, older flowers have anatropous ovules. Fruits have a single seed. We have preliminary evidence of pollen tubes that indicate porogamy. The oldest fossil evidence of the Fagales is about 85 million years old. Molecular clock data suggests the order diverged about same time. Our data suggest that these distinctive developmental patterns had already evolved at that time.
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1 - Indiana University Southeast, Biology, 4201 Grant Line Rd, New Albany, IN, 47150
2 - Indiana University Southeast, Biology, 4201 Grant Line Rd, New Albany, IN, 47150, USA
3 - University of California Santa Barbara, Dept. of Earth Sciences and College of Creative Studies, Santa Barbara, California, 93106, USA
Keywords:
development
flower
Floral development
Fagaceae
evolution
evo-devo.
Presentation Type: Poster:Posters for Topics
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P70006
Abstract ID:2043 |
