Jaco Le Roux

Research interests

I am interested in the evolutionary mechanisms and dynamics of small populations, particularly those involved in invasive plant populations. Most of my research focuses on molecular ecology; using population genetic and phylogenetic approaches to better understand these evolutionary processes that underpin biological invasions.

Current and ongoing research projects

Cardiospermum grandiflorum (Balloon vine)

Cardiospermum grandiflorum (Balloon vine) invasions outside Kruger National Park. My lab is currently investigating the phylogeography of numerous species within Cardiospermum.

Molecular ecology of plant invasions

Invasive species represent an interesting paradox as they are often genetically depauperate and highly inbred, but seemingly so, without impediment on fitness. Reasons for this paradox are numerous and normally act in different combinations, such as release from natural enemies, pre-adaptations to the new environment, etc. Numerous research projects in my lab (mostly in collaboration with Prof. Dave Richardson and Dr. John Wilson ) are investigating the consequences of invasion histories (human usage, number of independent introductions, propagule pressure, etc.) on population genetic signatures left behind by various species that are naturalized, moderately or highly invasive in South Africa. This research aims to shed light on the genetic consequences faced by invasive species in general.

Lantana camara

Dave Richardson sampling Lantana camara in Kruger National Park.

Plant-microbe interactions during the invasion process

Interactions, such as competition with native species, have been fairly well-studied for many invasive taxa. However, surprisingly little is known about below-ground interactions associated with invasive plants. One of my research interests includes the interactions between nitrogen-fixing bacteria, commonly known as rhizobia, and invasive legumes. The rhizobia - legume relationship could, in some instances, be very taxon-specific and in other very promiscuous. This level of specificity may therefore dictate whether invasive legumes can find suitable bacteria in their newly introduced ranges.

Pennisetum setaceum

Pennisetum setaceum on the slopes of Table Mountain.

Epigenetic variation and phenotypic plasticity

The Modern Evolutionary Synthesis is based on the assumption that only heritable genetic variation and its random mutational origin explain evolution by natural selection. However, the line between genetic and environmental interactions is blurred by processes such as phenotypic plasticity and epigenetic variation and not well understood. To date no research has been directed towards understanding the importance of epigenetic variation (biochemical modification of DNA building blocks without changes in the actual DNA sequence) in the evolution of natural populations. This may in part be because of the difficulty to disentangle the relative contributions of epigenetic- vs. genetic variation in local adaptation. Ongoing research in my lab is aimed at partially addressing some of these issues.

Molecular Ecology Lab

PhD students

MSc students