Plant diversification with respect to different sexual systems 1 Plant diversification with respect to different sexual systems Niv Sabath November 2014 N. Sabath, T. Ashman, E. Goldberg, R. Ming, S.P. Otto, J. Vamosi, M. Einhorn, L. Glick, and I. Mayrose. In prep.

Sexual reproduction Old – at least a billion years Primary method of reproduction in plants and animals Advantages: Increased genetic variation -> adaptation DNA repair Reduce accumulation of deleterious mutations Affects speciation – cost of rarity

Sexual systems Dioecy Hermaphrodite male and female organs in same individual separate male and female

Sexual systems Dioecy Hermaphrodite Animals 95% Plants 6% male and female organs in same individual separate male and female

Sexual systems Dioecy Hermaphrodite Animals 95% Plants 6% Speciation male and female organs in same individual separate male and female Speciation Extinction Transition

Association between sexual systems and diversification? Dioecy Hermaphrodite Animals 95% Plants 6% male and female organs in same individual separate male and female Speciation Extinction Transition Association between sexual systems and diversification? Diversification = Speciation - Extinction

Sexual systems in flowering plants Dioecy Hermaphrodite

Sexual systems in flowering plants Dioecy Hermaphrodite Disruption of self-incompatibility Dioecy – common in trees and in the tropics: - prevent inbreeding depression when SI is broken When there is an advantage to producing large seeds – enabled by separation of male and female functions. Where individuals of a species may occur at low density with large distances between them favored where non-specific pollinators, of the kind that tend to be associated with dioecy, tend to be found. Miller, J. S., & Venable, D. L. (2000). Polyploidy and the evolution of gender dimorphism in plants. Science

Sexual systems in flowering plants Dioecy Hermaphrodite

Sexual systems in flowering plants Strict Dioecy Dioecy Hermaphrodite

Sexual systems in flowering plants Broad Dioecy Dioecy Hermaphrodite

Methods Data collection (sequences, sexual systems, plant attributes) Phylogenetic reconstruction (MAFT, MrBayes) Diversification analysis – BiSSE Association with plant attributes (growth form, life cycle, …)

Diversification analysis – BiSSE Binary State Speciation and Extinction (Maddison et al. 2007) Likelihood function 1 speciation0 extinction0 speciation1 extinction1 q10 q01 calculate the probability that a group of extant species would have evolved as observed, given a particular model of the character's effect. describe the chance that a lineage beginning at time t with state 0 or 1 would evolve into a clade like that observed to have descended from node N, closer to the present 

Use MCMC for Bayesian analysis Diversification analysis – BiSSE Binary State Speciation and Extinction (Maddison et al. 2007) Use MCMC for Bayesian analysis calculate the probability that a group of extant species would have evolved as observed, given a particular model of the character's effect. Use MCMC for Bayesian analysis and obtain the posterior distribution of these parameters

PP(r0>r1) = %of MCMC steps in which r0 > r1 Diversification analysis – BiSSE Binary State Speciation and Extinction (Maddison et al. 2007) Asses significance To test whether extinction and speciation rates differ among sexual systems, we calculated the percentage of BiSSE MCMC steps in which a given rate (e.g., λ , μ, or r) was higher for non-dioecious lineages than for dioecious lineages (i.e., the posterior probability, PP, of a higher rate in N than in D lineages) for each genus. For example, PP(λN > λD) is the percentage of post burn-in steps in which λN > λD. To assess significance over the whole dataset, we used a one-sample t-test with a mean equal to 50%, testing the null hypothesis that diversification rates in the D state should be higher than those in the N state half of the time, treating the PP value of from each genus as a single data point.   Wilcoxon. PP(r0>r1) = %of MCMC steps in which r0 > r1

PP(r0>r1) = %of MCMC steps in which r0 > r1 Diversification analysis – BiSSE Binary State Speciation and Extinction (Maddison et al. 2007) Asses significance To test whether extinction and speciation rates differ among sexual systems, we calculated the percentage of BiSSE MCMC steps in which a given rate (e.g., λ , μ, or r) was higher for non-dioecious lineages than for dioecious lineages (i.e., the posterior probability, PP, of a higher rate in N than in D lineages) for each genus. For example, PP(λN > λD) is the percentage of post burn-in steps in which λN > λD. To assess significance over the whole dataset, we used a one-sample t-test with a mean equal to 50%, testing the null hypothesis that diversification rates in the D state should be higher than those in the N state half of the time, treating the PP value of from each genus as a single data point.   Wilcoxon. PP(r0>r1) = %of MCMC steps in which r0 > r1 For one dataset: 2.5 > PP(r0>r1) > 97.5 For multiple datasets: median(PP(r0>r1)) <> 50

Data 57 genera 3662 species 38% with state assignment 20% dioecy, 80% others

Filter out genera with less than 10 species and 2 in each state Data 57 genera 3662 species 38% with state assignment 20% dioecy, 80% others Filter out genera with less than 10 species and 2 in each state 38 genera

Filter out genera with less than 10 species and 2 in each state Data 57 genera 3662 species 38% with state assignment 20% dioecy, 80% others Filter out genera with less than 10 species and 2 in each state 38 genera Filter out genera with PP differ by >20% between runs with different priors 28 genera

Results Bimodal distribution: dioecy is associated with high diversification in some genera and low in others Diversification

Results Diversification is driven by speciation, not extinction

Results No association with plant attributes

self-compatibility (SC) vs. self-incompatibility (SI)?

self-compatibility (SC) vs. self-incompatibility (SI)? Bimodal distribution of self-incompatibility (Raduski et al. Evolution, 2011)

self-compatibility (SC) vs. self-incompatibility (SI)? Goldberg et al. (Science 2010) showed that hermaphrodite SC species diversify slower than SI species

Weak points Strong effect of sample size – a more conservative filter? Diversification

Weak points Effect of trait distribution