I have a new website for the lab. Please visit michaelkasumovic.com for all the update information about the lab and our research! This website will be taken down soon.

Cheers,

Michael

Sexual selection has led to the evolution of some of nature’s most elaborate traits from peacock’s tails to stag’s horns. Decades of research demonstrates that these brighter, larger males are favoured by females and outcompete smaller rivals, thereby securing their place in evolutionary history. As smaller, drabber males have a competitive disadvantage and if selection works to remove these individuals from the gene pool—why do these males continue to exist?

The Australian redback spider provides some bizarre insight into this question. Male redbacks perform a curious behavior while mating—males somersault and place their body on the female’s jaws where she happily consumes his body while he continues to mate. This ultimate sacrifice means that males only have one chance to mate, and success depends on successfully locating mates and outcompeting rivals. My research demonstrates that immature males smell nearby females and rivals through pheromones and alter how they develop to match the competitive environment they will encounter.

When males smell more rivals, it means that competition is more intense, so males delay maturity in order to grow larger to outcompete rivals. In contrast, when females are abundant and rivals are scarce, males sacrifice size to mature more quickly in order to reach and mate with females first . By shifting their development, males can take advantage of their surroundings.

My research re-evaluates how we think about evolution, demonstrating that selection acts not on favoured traits alone, but also on the sensory system to recognize competition and the developmental system to correctly translate this information into the right phenotype. These results demonstrate that it’s not the size that counts, but how well you know your competition.

UNSW Faculty of Science – Spider love: little guys get lots more

ABC Science – Redback spiders sniff air then mature

The Daily Telegraph – Size doesn’t matter in killer redback mating ritual

National Geographic – Sexual prime peaks when males “smell” mates, spider study shows

Science Daily – In the animal world, bigger isn’t necessarily better

CBC Quirks and Quarks (Canadian radio program) – Spider Size Doesn’t Matter

NSW Science Young Tall Poppy:

UNSW Faculty of Science – Killer spiders and bad memories win Young Tall Poppy success