By: Ali Alsaadi, Colton Burkhart, and Alexio Trichilo (Stonehill College, BIO323: Evolution, Spring 2026)
A recent study published in Science Advances by Emmanuel Cazottes and colleagues reveals that one of the most important genes in the human body is XIST. It has kept its function over millions of years of evolution, but the way it is controlled has changed dramatically across primates. This research shows that evolution can reshape genetic “control systems” without disrupting essential biological processes, offering new insight into how genes evolve and why this matters for human health.
By: Savannah Jeffrey, Julia Ciccolo, & Julia Bennett (Stonehill College, BIO323: Evolution, Spring 2025)
Overview: In many populations of cave-adapted animals, there is an increased presence of single-nucleotide premature termination codons, known as PTCs, that lead to traits losing function. PTCs are a type of mutation that cause a random stop to genetic replication processes, which can have deleterious effects on how traits are expressed. PTCs have been observed in the genetic makeup of many evolved cave species like cavefish, specifically the Mexican tetra, Astyanax mexicanus. Mexican tetras can be found in central and eastern Mexico, as well as in Texas. They originated in bodies of waters such as lakes and rivers, where eventually some Mexican tetras colonized cave systems and formed new populations. Due to these smaller population sizes in these environments, these mutations are subject to much stronger genetic drift, which occurs when alleles increase or decrease by chance in a population. This phenomenon causes traits to become more common or disappear entirely, thus making a population genetically distinct from their ancestors. Cave environments have their own unique selective pressures and allow the loss of traits to be advantageous for organisms, mainly features like eyesight, pigmentation, and circadian cycling. Allocating resources to these traits in an environment where they are not required provides no benefit to these organisms, therefore the loss of them actually positively impacts the species’ fitness, allowing them to invest in other metabolic processes. Additionally, the majority of PTCs arise in redundant genes, reducing the risk of losing genes that are vital for survival.
By: Rebecca Lancaster, Madilyn Robinson, and Savannah Ledo (Stonehill College, BIO323: Evolution, Spring 2025)
Overview
The Costus genus, commonly known as spiral gingers, is in the Costaceae family and is distinguished from other gingers by its unique spiraling leaves. Costus comprises over 80 species of perennial herbaceous plants native to Central and South America. Previous research demonstrates the Costus genus has independently evolved from the ancestral bee-pollination trait to hummingbird pollination multiple times. In The Convergent Evolution of Hummingbird Pollination Results in Repeated Floral Scent Loss Through Gene Downregulation, Dr. Kathy Darragh and her team examined over 30 Costus species’ floral scent compositions to understand how the species evolved from bee to hummingbird pollination. The study highlights the importance of selection, where certain traits are favored while others are lost to conserve energy costs. By comparing floral scent compounds, emission, and gene expression between bee-pollinated and hummingbird-pollinated Costus species, we gain a deeper understanding of the genetic factors driving floral scent evolution.
