Environmental Genomics
Origins of biodiversity
Generating variation
New species arise from variation in natural populations. In order to understand the origin of biodiversity, we need to understand how this variation is generated.
A long-standing premise of evolutionary biology is that this variation is due to variation within a set of genes. However, one of the revelations of the genomic era is that the genomic structure (distribution of genes along the genetic map) also plays an important role in the generation of variation.
Genetic solutions to encourage genetic diversity
During sexual reproduction, genetic diversity arises from new combinations of genes forming on a chromosome (recombination) as well as combining genes from different parents.
In some plant species, mechanisms prevent individuals from mating with themselves because this causes genetic diversity to be lost. Self-incompatibility in the rock cress (Arabidopsis lyrata) involves two complementary genes which sit close together on a chromosome. Scientists found that there was reduced recombination between these genes than those sitting further away on the chromosome.
This finding supports the idea that natural selection has reduced the amount of recombination in this part of the genome to maintain the right gene combinations that prevent self-mating. It also helps us to understand why different genome regions evolve at different rates.
Genes that jump around the genome
Transposons are pieces of DNA that move around within a genome. It has been found that these 'jumping genes' comprise a large percentage of the genome of most plants and animals; but their role in generating biodiversity and enabling evolutionary adaptation has remained a mystery.
Using genomics tools, researchers measured the variation in the number
of copies of specific transposons in the genomes of white campion (Silene
latifolia) and related species. They found that the variation in transposable
elements within a species are related to traits such as flower size.