Sexual Selection: Big-brain vs. Small-brain

Gianna Amatucci, Nick Mulvey, Caitlin Welsh, & Cayleigh Shufelt (Stonehill College, BIO 323 Evolution, Fall 2019)

Predominantly residing in the tropics of South America, guppies are small and colorful freshwater fish. They are omnivorous animals, primarily consuming algae and brine shrimp. Unfortunately, guppies are preyed upon by a number of larger creatures, including birds, larger fish and mammals. While constantly having to avoid such predators, guppies are always in search of a suitable mate to spread their gene pools to future offspring. Alberto Corral-López and colleagues studied how predation pressure, in addition to cognitive ability and brain size, affected sexual behavior and sexual selection in guppies. The actions of both large-brained and small-brained female and male guppies were observed by Corral-López in order to study this phenomenon.

Domestic male guppy in an S-curve mating display. Image credit: “older guy 22feb08” by Alice Chaos is licensed under CC BY-NC-SA 2.0
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These Spiders Can Jump and Dance, but Can They Use Their Moves to Impress the Ladies?

By: Stefan Balestra, Adam Casey, Alessandro Puccio, and Walker Smith (Stonehill College, BIO323 Evolution, Spring 2018)

Spiders are considered by some as a source of fear, but many people find arachnids to be a cool group of arthropods. I mean, one of the most beloved superheroes is Spiderman, after all. Adding to the coolness factor associated with spiders, the spider discussed below is not only a jumping spider, but also a dancing spider with an interesting ritualized dance used to attract a mate. Additionally, the male individuals of the species exist in two morphs with different ritualized dances, competing in a spider dance battle of sorts to impress the ladies. Read on to learn more about the specific mode of sexual selection that contributes to the male morphs’ different looks and dance styles.

Listen now:

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