Abstract Detail

Speciation Mechanisms in Plants

Christie, Kyle [1], Lowry, David [2].

The strength of reproductive isolating barriers in flowering plants redux: insights from studies quantifying pre- and postzygotic reproductive isolation over the past 15 years.

The process of speciation has fascinated biologists for centuries, yet can be difficult to study because it proceeds differently in different groups and often occurs over long timescales. Due to this complexity, we have thus far been limited in describing speciation using mathematical models, and instead have relied on generalizations based on the weight of available empirical evidence. Previous reviews of reproductive isolation (RI) in flowering plants have suggested that prezygotic, or extrinsic barriers to gene flow (such as habitat, flowering time, or pollinator differences), often have a stronger effect on reducing contemporary gene flow compared to postzygotic or intrinsic barriers (such has hybrid inviability or hybrid sterility). Such generalizations have previously rested on relatively few empirical studies; however, studies quantifying RI in angiosperms have become much more common over the past 15 years. We review data from ~75 recent studies quantifying both pre- and postzygotic barriers, and compare the strengths of isolating barriers across systems using a common set of RI metrics. Despite analyzing data from ~5x more studies than previous reviews, we come to much the same conclusions. Prezygotic isolating barriers are generally much stronger than postzygotic barriers, suggesting that ecological divergence, as opposed to solely the accumulation of genetic incompatibilities, is crucial to speciation and the maintenance of species boundaries in flowering plants. Overall, we find many instances in which prezygotic RI is complete for a species pair, but postzygotic RI is weak or totally absent. Alternatively, we find very few instances of complete postzygotic RI without concomitant prezygotic RI. Despite these general trends, we also find substantial variability in the strength of 12 reproductive isolating barriers as assessed in ~75 species pairs, highlighting the great diversity of mechanisms contributing to angiosperm diversification.

1 - Michigan State University, Plant Biology, 612 Wilson Road, Room 268A, East Lansing, MI, 48824, USA
2 - Michigan State University, Plant Biology, 612 Wilson Road Rm. 166, East Lansing, MI, 48824, United States

Keywords:
Speciation
Reproductive isolaton
Meta-analysis.

Presentation Type: Colloquium Presentations
Session: C09, Speciation Mechanisms in Plants
Location: /
Date: Thursday, July 22nd, 2021
Time: 12:45 PM(EDT)
Number: C09002
Abstract ID:87
Candidate for Awards:None