There are around 100 species of terrestrial fiddler crabs in the genus Uca. They are characterized by the extreme claw asymmetry of the males. I had the chance last week to see two talks from John Christy, a Smithsonian Tropical Research Institute scientist studying sexual selection and mate choice in the fiddler crab. The Uca genus is diverse in claw morphology, male displays, and burrow construction. As an example of the diversity across the species one species mentioned which is extremely understudy was the so-called styled fiddler crab (Uca stylifera) which can be seen below. The asymmetry normally exhibited in the claw has been extended in this case to the legs as well and includes the weird eye stalk (which is jointed!).
Photo by John Christy
Get your fiddler crab fix here by checking out the whole genus!
The Texas Blind Salamander (Eurycea rathbuni) is in the Plethodontidae family, also known as lungless salamanders. There are over 400 species of plethodontids making them the most speciose family of salamanders. These salamanders have elaborate and stereotyped courtship rituals. Research has suggested that in general, the male initiates the mating ritual in salamanders. While research and data are sparse for Texas Blind Salamander, it has been reported in captivity that the female actually initiates the courtship behavior.
The female has been reported to rub her nose on the dorsum and side of the male near the cloacal region. Next, the female was observed to rub her cloacal region against the rocks on the bottom of the tank nearby the male. The nearby male began to show interest at this point and courtship ensued. The courtship sequence proceeded with the male depositing a spermatophore, leading the female, and finally the female’s cloaca aligned over the spermatophore to pick it up.
Courtship and sperm transfer in pygmy salamanders, Desmognathus wrighti. From biocyclopedia.com
This courtship behavior account comes from a lovely paper in 1988 by Bechler in The Southwestern Naturalist.
Learn more about Plethodontidae here on the Amphibiaweb page.
Assortative mating is non-random mating where individuals mate with each other based on a shared genotypic or phenotypic characteristic. This phenomenon can increase inclusive fitness because of some degree of assumed relatedness which may result in altruism. However, if the degree of relatedness is too great assortative mating may lead to inbreeding and animals run the risk of decreased genetic diversity and increased recessive deleterious traits.
A recent article from Behavioral Ecology examines this phenomenon in the wall lizard (Podarcis muralis). (Click here for the link to the full article) The genus Podarcis has been often studied for color morphs and male alternative mating strategies associated with the morph. This study in particular examines the possible link between color morphs and mating patterns. They accomplish this by recording the color morph of the male and female in each mating pair over several seasons. The authors find that homomorphic pairs occur more frequently than heteromorphic pairs.
This study took place over a six year period and they also used mark and recapture to study the color morph development in juveniles (figure below). This also showed that once animals are adults (confirmed by SVL) the color morph is stable.
We commonly think of the blue-footed booby (Sula nebouxii) as living on the Galápagos Islands, but they are found on many other Pacific tropical islands. These birds are sexually dimorphic and the female is around 30% larger than the male. The blue-footed booby is best known for its elaborate mating dance which can be seen in the National Geographic video below.
Within the family Anablepidae, there is a genus Anableps which are known as four-eyed fish. They are found in Central and South America in fresh or brackish waters. These fish are live bearers and interestingly they exhibit a “sidedness”. Males that are left-handed may only mate with females that are right-handed.
Now the fish do not have four eyes exactly, but in both eyes they can see above and below water simultaneously. This is a good super power to have when you spend most of your time on the surface foraging insects.
Photo Credit: Paul Zahl/National Geographic
The retina is specialized so that half receives light from the aquatic environment and the other from the aerial environment. Recent research found that the dorsal and ventral retina have differential gene expression. Click here for a link to the article to learn more.
There are 6 species within the genus Ptychozoon commonly known as Flying Geckos. These geckos are found in Southeast Asia and exhibit cryptic coloration. The “flying” occurs as a results of extensive webbing around their body and limbs.
Flying Geckos use a variety of calls especially during mating season for communication. Check out the video below to see and HEAR some geckos in Bali!
The female rove beetle (Aleochara curtula) emits a sex pheromone which males can detect from a distance. This sex pheromone elicits a grasping response from males and subsequent mating. Once the male has mated with a female he transfer a spermatophore and also an antiaphrodisiac pheromone. Once the female has mated she is unreceptive to other males, but unfortunately for the other males she will still produce the sex pheromone. Once a male graps onto an already-mated female he can detect the antiaphrodisiac pheromone and will cease his behavior, but this has already been a costly endeavor.
In a recent publication from Animal Behaviour (click here for the full article), the authors examined the ability of males to avoid previously mated and thus unreceptive females. The male rove beetle is attracted to the sex pheromone even at a distance which is emitted from both appropriate and inappropriate partners, but he cannot distinguish between them until he has grasped them and can sense the antiaphrodisiac pheromone. What is stopping the males from repeatedly approaching the same inappropriate females? The rove beetles use cuticular hydrocarbons to recognize each other and the authors found that females have greater individual variation in this signature. Furthermore they found, that males were able to learn the individual signature of a female and associate this with their experience of her mating status. This is turn allows the male to waste less energy approaching inappropriate mates.