Nav: Home

Size not such a big thing for seed bugs

March 03, 2016

By the looks of it, size should be a big thing when it comes to seed bugs mating, but it only matters when more than one mating partner is around to choose from. That is what researchers Liam Dougherty and David Shuker of the University of St Andrews in Scotland found when investigating the mating strategies of two closely related black and red coloured seed bugs. The male sexual organs of these insects can be up to two-thirds the length of their bodies. The findings are published in Springer's journal Behavioral Ecology and Sociobiology.

Animal genitalia vary greatly in size and complexity across species, and the reasons why specific sizes or shapes of genitals are preferred can be complex. To this end, Dougherty and Shuker set out to analyse the specifics behind mate selection and fertility success in two seed bug species, Lygaeus equestris and Lygaeus simulans. The males of both species have very long external sexual organs which end in a hollow tube called the processus. At around 7 millimetres long, the processus is used to ejaculate sperm into a female and can stretch to two-thirds the length of a male's body. Why the processus has evolved to be so long in the first place is still unclear, though the extreme length would suggest that sexual selection has played a role in its evolution.

Two experiments were carried out to assess if males with a longer processus were either more likely to mate with a female, or more likely to fertilise a female's eggs during mating. The social context in which mating takes place was also assessed, to see whether the presence of more than one male or female influenced how important processus length is for males both before and during mating.

Dougherty and Shuker found that processus length did have an influence on a male's chances of mating in one of the species (L. equestris), but only in certain contexts. Processus length was most important when a rival male was present during a mating trial. This finding has relevance, because it suggests that in the wild the strength of selection on processus length will depend on the number of males competing to mate with each female.

The length of the processus is also important during mating for both species. This is because males commonly fail to fertilise any of a female's eggs during mating. In fact, the authors show that males with a medium-length processus are the most likely to successfully fertilise a female. Therefore in both species bigger isn't necessarily better when it comes to genital length.

"The length of the penis in two species of seed bug is subject to complex patterns of selection, varying depending on the social context and whether selection is measured before or after mating," said Dougherty in summarising the findings.

"Our results highlight the fact that genitalia may be subject to both direct and indirect selection at different stages of mating, and that to fully understand the evolution of such traits we should combine estimates of selection arising from these multiple episodes," elaborated Shuker.
-end-
Reference: Dougherty, L.R. & Shuker, D.M. (2016). Variation in pre- and post-copulatory sexual selection on male genital size in two species of lygaeid bug, Behavioral Ecology and Sociobiology
DOI 10.1007/s00265-016-2082-6

Springer

Related Species Articles:

Two new species of orchids discovered in Okinawa
Two new species of parasitic plants have been discovered on the main island of Okinawa, Japan, and named Gastrodia nipponicoides and Gastrodia okinawensis.
Cornering endangered species
Geographic areas occupied by certain species shrink as they decline in abundance, leaving them more vulnerable to extinction by harvest.
New species of Brazilian copepod suggests ancient species diversification and distribution
A new species and genus of a tiny freshwater copepod has been found in the Brazilian rocky savannas, an ecosystem under heavy anthropogenic pressure.
Redefining 'species'
What is a species? Biologists -- and ornithologists in particular -- have been debating the best definition for a very long time.
New species discovered in Antarctica
A team of Japanese scientists has discovered a new species of polychaete, a type of marine annelid worm, 9-meters deep underwater near Japan's Syowa Station in Antarctica, providing a good opportunity to study how animals adapt to extreme environments.
Genomic tools for species discovery inflate estimates of species numbers, U-Michigan biologists contend
Increasingly popular techniques that infer species boundaries in animals and plants solely by analyzing genetic differences are flawed and can lead to inflated diversity estimates, according to a new study from two University of Michigan evolutionary biologists.
Common US snake actually 3 different species
New research reveals that a snake found across a huge swath of the Eastern United States is actually three different species.
The origins of Cuban species
An international research team suggests the endangered Cuban solenodon evolved after the extinction of dinosaurs.
New rare species of whale identified
Researchers have identified a new rare species of beaked whale with a range in the remote North Pacific Ocean.
Unusual new zoantharian species is the first described solitary species in over 100 years
A very unusual new species of zoantharian was discovered by two researchers in Okinawa.

Related Species Reading:

Sapiens: A Brief History of Humankind
by Yuval Noah Harari (Author)

Inspired by Endangered Species: Animals and Plants in Fabric Perspectives
by Donna Marcinkowski DeSoto (Author), Kim O'Keefe Beck PhD (Foreword), J. Drew Lanham PhD (Foreword)

The Origin of Species: 150th Anniversary Edition
by Charles Darwin (Author), Julian Huxley (Introduction)

Charles Darwin's On the Origin of Species
by Sabina Radeva (Adapter), Sabina Radeva (Adapter)

On the Origin of Species: A Facsimile of the First Edition (Harvard Paperbacks)
by Charles Darwin (Author), Ernst Mayr (Introduction)

From So Simple a Beginning: Darwin's Four Great Books (Voyage of the Beagle, The Origin of Species, The Descent of Man, The Expression of Emotions in Man and Animals)
by Charles Darwin (Author), Edward O. Wilson (Editor)

The Female of the Species
by Mindy McGinnis (Author)

The Kintolf: New Alien Species

Slave Species of the Gods: The Secret History of the Anunnaki and Their Mission on Earth
by Michael Tellinger (Author)

On the origin of species

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Bias And Perception
How does bias distort our thinking, our listening, our beliefs... and even our search results? How can we fight it? This hour, TED speakers explore ideas about the unconscious biases that shape us. Guests include writer and broadcaster Yassmin Abdel-Magied, climatologist J. Marshall Shepherd, journalist Andreas Ekström, and experimental psychologist Tony Salvador.
Now Playing: Science for the People

#513 Dinosaur Tails
This week: dinosaurs! We're discussing dinosaur tails, bipedalism, paleontology public outreach, dinosaur MOOCs, and other neat dinosaur related things with Dr. Scott Persons from the University of Alberta, who is also the author of the book "Dinosaurs of the Alberta Badlands".