The Bad and the Ugly of evolution: an introduction to maladaptation

Adaptation and natural selection

Adaptation via natural selection is one of the most fundamental components of understanding evolution. It describes how species can continually evolve new, innovative traits and produce the wondrous diversity of the natural world. This process is inevitably underpinned by particular heritable traits often linked to particular genetic variants (alleles). Remember that the underlying genetic trait (the allele) is referred to as the genotype; the physical outcomes of that allele (i.e. how it changes the physiological, behaviour or ecology of the organism) is the phenotype; and the scale of the benefit of possessing that trait is referred to as its fitness. Under the normal process of natural selection, phenotypes which increase fitness are selected for, which results in a shift in genotypes underpinning it.

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Managing genes in conservation and industry

The fundamentals of population genetics

Many times in the past, we’ve discussed the importance of genetic diversity within populations as a foundation for adaptation and evolution. It includes both adaptive variation (which encompasses genetic variation directly under natural selection), as well as neutral variation (which is predominantly generated and maintained by non-selective forces such as demographic history and genetic drift). This pool of genetic variation acts as the underlying architecture for evolution by natural selection, and is a critically important component for future and ongoing evolution.

This all sounds important from an academic perspective: that population genetics can reveal a significant amount of information about the processes and outcomes of evolution and provide novel insights into concepts that have been around for ages. But how can this information be applied to real scenarios? With the ever-growing availability of massive genetic datasets for an increasing number of species, the sheer volume of information in existence that can be used is monumental.

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Rebuilding the genomic architecture of evolution

Beyond mutations in the genome

Although genetic variation is, in itself, often considered to be one of the fundamental underpinnings of adaptation by natural selection, it can appear through a number of different forms. Typically, we think of genetic variation in terms of individual mutations at a single site (referred to as ‘single nucleotide polymorphisms’, or SNPs), which may vary in frequency across a population or species in response to selective pressures. However, we’ve also discussed some other types of genetic-related variation within The G-CAT before, such as differential gene expression or epigenetic markers.

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What’s yours is mine: evolution by adaptive introgression

Gene flow and introgression

Genetic variation remains a key component of not only understanding the process and history of evolution, but also for allowing evolution to continue into the future. This is the basis of the concept of ‘evolutionary potential’ – the available variation within a population or species which may enable them to adapt to new environmental stressors as they occur. With the looming threat of contemporary climate change and environmental transformations by humanity, predicting and supporting evolutionary potential across the diversity of life is critical for conserving the stability of our biosphere.

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Products of their time: the impact of demographic history on evolution

Demographic history

Many things in life are the product of their history, and nothing exemplifies this better than evolution. Given the often-gradual nature of evolution by natural selection, environmental stressors and factors operating on long-term scales (i.e. over thousands or millions of years) can have major impacts on evolutionary changes across the diversity of biota. While many of these are specific to the characteristics of the target organism (i.e. are related to adaptive traits), non-adaptive (neutral) traits are also critically important in driving the path of evolution.

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