Ancient Genetics that Still Occur Today: Atavisms Explained | Summary and Q&A

TL;DR

Some species have the ability to reacquire traits that were lost in previous generations, challenging traditional notions of evolutionary theory.

Key Insights

• 🌂 The concept of dolos law, which suggests that lost traits cannot be reacquired, is challenged by the occurrence of atavisms.
• 😚 Atavisms, such as the re-emergence of hind limbs in whales and dolphins, provide insights into the genetic information that is truly lost and what is simply dormant.
• 💱 Genetic changes, such as changes in timing or location of gene expression, can lead to the reactivation of lost traits.
• 😑 The re-evolution of coiled shells in limpets is a result of changes in gene expression during development.

Transcript

there's this idea in evolutionary theory often referred to as dolos law that once a complex trait disappears it can't come back which makes sense everything about a living creature can be traced back to the activity or expression of its genes once a gene stops being actively used tiny mutations start to build up so over time it deteriorates and soo... Read More

Questions & Answers

Q: What is dolos law and how do atavisms challenge it?

Dolos law states that once a complex trait disappears, it cannot come back. However, atavisms prove that certain traits can be reacquired, suggesting that genetic information is not completely lost.

Q: How do hind limbs occasionally reappear in dolphins and whales?

Dolphins and whales originally evolved from land-dwelling animals with hind limbs. Even though hind limbs have been lost for millions of years, genetic changes can sometimes reactivate the genes responsible for limb development.

Q: How have limpets re-evolved coiled shells?

Limpets lost their coiled shells about 20 million years ago. However, some limpet species have re-evolved coiled shells by expressing the genes responsible for coiling for a longer period of time during development.

Q: Why did the soil mite species regain the ability to have sex after being asexual for so long?

The soil mite species that began reproducing parthenogenetically eventually regained the ability to have sex. The reason for this reversal is still unclear, but it may be related to their change in habitat from soil to tree bark.

Summary & Key Takeaways

• The concept of dolos law suggests that once a complex trait disappears, it cannot come back in a species. However, atavisms challenge this idea.

• Atavisms are the reappearances of traits thought to be lost forever. Examples include dolphins and whales occasionally being born with hind limbs and limpets re-evolving coiled shells.

• Small genetic changes, such as changes in timing or location of gene expression, can lead to the reactivation of lost traits.