Abstract Detail

Tropical Biology

Life history evolution within Hawaiian Metrosideros, a hyper-variable landscape-dominant tree species complex.

Plants have evolved a remarkable array of life history strategies to promote their persistence across a broad range of environments. Life history strategies are shaped by natural selection and include strategies for allocating resources across a life time for the purpose of making offspring. Remote oceanic islands boast some of the most extreme examples of life history evolution known (e.g., the evolution of long-lived, semelparous species in the Hawaiian silverswords). Little is known, however, about the diversification of life history characters in long-lived, landscape-dominant trees in these systems. The hyper-variable woody genus, Metrosideros (Myrtaceae), dominates native forests on the Hawaiian Islands, occurring in massive, continuous stands. Over its 3-4-MY history in the islands, the group has diversified into >20 vegetatively distinct, predominantly infraspecific taxa, that are distributed sympatrically or parapatrically across an exceptional range of environments within islands. All taxa have a high capacity for gene flow by pollen and seed, and the potential for an extended life span (ca. >650 years). Co-occurring Metrosideros taxa are differentially adapted to abiotic conditions that vary across both broad environmental gradients and narrow ecotones. My lab group has been examining the strengths and stages of reproductive isolating barriers through controlled crosses with Metrosideros on Hawaii Island and Oahu since 2006. Analysis of current data reveals striking variation among taxa in maturation time (from seed), leaf longevity, rates of flower and fruit retention, pollen tube density, duration of the fruit maturation period, timing of seed germination, and the number of germinants per fruit, with some traits differing between whole communities on the different islands. The Metrosideros community on Oahu shows the most dramatic diversification of life history strategies, consistent with the exceptional morphological and genetic diversity of this community. I will present these results within the framework of local adaptation of these taxa across the islands’ heterogeneous landscapes and the tentative evolutionary history of this incipient adaptive radiation.

1 - University Of Nevada Las Vegas, School Of Life Sciences, 4505 South Maryland Parkway, Mail Stop: 4004, Las Vegas, NV, 89154, United States

Keywords:
life history
correlated trait evolution
Floral longevity
Seed germination
Fruit development
maturation rate.

Presentation Type: Oral Paper
Number: TP1004
Abstract ID:1063
Candidate for Awards:None