Molecular Ecology

Abstract Molecular ecology uses molecular genetic data (typically deoxyribonucleic acid (DNA) sequences) from natural populations to address ecological questions. Historically, either relatively short DNA sequences or highly variable sequences known as microsatellites were most commonly used to genetically characterise populations and species. More recently, however, large amounts of DNA sequences are being generated using a relatively new approach known as high‐throughput sequencing (HTS), which allows researchers to simultaneously sequence thousands of genes from one or numerous individuals. HTS allows whole‐genome sequencing, and also the characterisation of natural populations on the basis of numerous (often thousands of) single nucleotide polymorphisms (SNPs), which are DNA sequence variations that arise when a single nucleotide differs between individuals. Genetic characterisation allows researchers to quantify the genetic diversity within populations and the genetic similarity among populations, which in turn provides insight into specific questions pertaining to the ecology and evolution of populations and species. Key Concepts Molecular ecology uses molecular genetic data to address ecological questions. A variety of molecular markers can be used to genetically characterise species and populations. Next‐generation (high‐throughput) sequencing has greatly enhanced our ability to collect very large amounts of genetic data at relatively low cost. Molecular genetic data from natural populations allow researchers to quantify the genetic diversity within populations and the genetic similarity among populations. Genetic diversity is required for the long‐term survival of populations and species, and is influenced by a range of different factors. Gene flow among populations strongly influences their genetic similarity. Landscape genetics helps researchers to understand barriers to gene flow across different types of landscapes. Landscape genomics investigates ways in which local adaptation influences the distribution of conspecifics across different types of habitat. Behavioural molecular ecology uses highly variable molecular markers to quantify the relatedness among individuals, and thus describe dipsersal patterns or mating systems. Phylogeography uses molecular genetic data to infer some of the ways in which historical events and processes have shaped the current distributions of species.