Speciation Clock

How fast does the "speciation clock" tick in selfing versus outcrossing lineages?

About the project

Species are the most fundamental unit in nature, yet we know surprisingly little about how long it takes for new species to arise and what factors influence the rate of speciation (‘ticking of the speciation clock’). Recently, we found that new species may develop at astonishing speed in self-pollinating plants. This is important because many wild and cultivated plants, and even quite a few animals, are more or less self-fertilizing. In this project, we will develop and test theoretical models of how self- and cross-fertilization can affect genetic architecture and rate of speciation. We will work with a large set of different species. For each species, we will cross different populations and examine the resulting hybrids for their fertility. If the hybrids are more or less sterile, the two parental populations can be considered to be on their way to evolve into two new species. We will then use genomic analyses to estimate for how long time the two populations have been separated and to what degree they are self-fertilizing. For one self-pollinating and one cross-pollinating species, we will also raise later-generation hybrids to enable more detailed genomic analyses.  We have selected the African 'sky archipelago' as our study system, because the populations in these isolated high mountains represent a wide range of separation times. The first part of the field work was carried out in October/November 2018 in the Bale Mountains in Ethiopia, aimed at testing about 100 plant species for their suitability to be selected for a final set of about 20-30 target species. This final set of species are collected in six of the highest African mountains, including Kilimanjaro and Mt Kenya. This project can 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. The results can also help to improve crop breeding. Since many crops are self-pollinating, it is important to know how and how fast they develop crossing barriers towards their wild relatives. Crop plants may need to be enriched by new genes from their wild relatives to improve their resistance against diseases and environmental change.

 

Objectives

The SpeciationClock project addresses the fundamental question of how fast new species arise, and specifically tests if the plant ‘speciation clock’ ticks faster in self-fertilizing than outcrossing lineages.

Our main objective is to 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(s)’.

  • WP1: Establish a theoretical framework to understand and predict the effects of mating system on the speciation process.
  • WP2: Measure the rate of intraspecific postzygotic RI accumulation (i.e. incipient speciation) in a large set of species representing the selfing-outcrossing continuum and divergence times spanning the last ~1 million years.
  • WP3: Test if the rate at which RI loci accumulate is higher in selfers.
  • WP4: Quantify the role of selection in the evolution of RI based on population genomic analyses of one selfing and one outcrossing species.

 

Financing

SpeciationClock is at toppforsk-project funded by the Research Council of Norway and the University of Oslo.

 

Sampling of living material to be used in crossing experiments.
Helichrysum formossissimum with love.
 
keying samples
Looking at key features from a selection of samples
preparing samples
Preparing material for shipment to Norway.
Field team from Mount Kilimanjaro.
virunga
African sky islands: View from a base camp at 3800 m in Virunga National Park in Uganda, with the volcanoes Gahinga, Sabyinyo and Karisimbi. Photo: Magnus Popp.

 

Published Feb. 2, 2018 3:09 PM - Last modified July 4, 2019 1:17 PM