Speciation Clock Research Project

Project Brief
Start Date:,9 April 2019
Duration: 8 April 2020
Grant: University of Oslo, Norway
Project PI: Prof. Dr.Christian Brochmann and Dr Geoffrey Mwachala
Email: Christian.brochmann@nhm.uio.nogmwachala@museums.or.ke

Partner Institutions:

Natural History Museums, University of Oslo

Botany Department, National Museums of Kenya

Project Summary

Species are the most fundamental unit in nature, yet we know surprisingly little about how long it takes for new, reproductively isolated species to arise and what factors influence the rate of speciation. Recently, we found that postzygotic reproductive isolation (RI) may develop at astonishing speed in lineages that are self-fertilizing, a common mating system both in wild and cultivated plants and also found in animals. We hypothesize that although antagonistic effects can be expected, selfing may overall accelerate postzygotic RI accumulation rates. In this project, we will develop and empirically test theoretical models of the impact of mating systems on the genetic architecture and rate of speciation (i.e. the ticking of the ‘speciation clock’). 

We will 

1) establish a theoretical framework to understand and predict the effects of mating system,

2) measure the rate of intraspecific postzygotic RI accumulation (i.e. incipient speciation) in a large set of species representing the selfing-outcrossing spectrum and divergence times spanning the last ~1 million years,

3) test if the rate at which RI loci accumulate is higher in selfers, 

 4) quantify the role that selection has played on RI loci using population genomic analyses in one selfing and one outcrossing species.

We have selected the African ‘sky archipelago’ as a study system because the populations in these isolated high mountains represent a wide range of divergence times and levels of intermountain gene flow. We use this optimal system to study the rate and mode of plant speciation with a unique combination of novel genomic technologies, niche modeling through time, and classical field and crossing experiments. This project will make a significant contribution to our understanding of the process and speed of biodiversity generation, which has been a core issue in biology since Darwin and is especially relevant today, when we see accelerating extinction of species due to global change.

Herbarium documentation – May 2019

Field studies

Mount Kenya, June – July 2019

Mount Elgon , November 2019