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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Islands of speciation and speciation on islands

The concept of a species

We’ve spent some time before discussing the nature of the term ‘species’ and what it means in reality. Of course, answers to questions in biology are always more complicated than we wish they might be, and despite the common nomenclature of the word ‘species’ the underlying definition is convoluted and variable.

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Evolutionary clocks out of sync

Evolutionary time

It shouldn’t come as a surprise to anyone with a basic understanding of evolution that it is a temporal (and also spatial concept). Time is a fundamental aspect of the process of evolution by natural selection, and without it evolution wouldn’t exist. But time is also a fickle thing, and although it remains constant (let’s not delve into that issue here) not all things experience it in the same way.

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