Horns vs. sperm: male beetles on tight equipment budget.A group of dung beetle dung beetle: see scarab beetle.
Any member of one subfamily (Scarabaeinae) of scarab beetles, which shapes manure into a ball (sometimes as large as an apple) with its scooperlike head and paddle-shaped antennae. They vary from 0. species that sprout horns like tiny elk elk, name applied to several large members of the deer family. It most properly designates the largest member of the family, Alces alces, found in the northern regions of Eurasia and North America. In North America this animal is called moose. , rhinos, or sci-fi invaders often face trade-otis between horn and testes testes
Male reproductive organs (see reproductive system). Humans have two oval-shaped testes 1.5–2 in. (4–5 cm) long that produce sperm and androgens (mainly testosterone), contained in a sac (scrotum) behind the penis. sizes, say researchers.
Among the 2,000 species of Onthophagus dung beetles, males sport various styles of swooping prongs, with which they wrestle other males for access to females. "That's like producing another leg and wearing it around on your head for the rest of your life For The Rest Of Your Life is a British game show on ITV, hosted by Nicky Campbell. It is produced by Initial, a company of Endemol. Format
Round One ," says Douglas J. Emlen of the University of Montana in Missoula. His earlier experiments showed that as an individual beetle develops horns, they steal resources from other organs, leading to smaller eyes, antennae, or wings.
To test for trade-otis between horns and testes, Emlen and Leigh W. Simmons of the University of Western Australia Western Australia, state (1991 pop. 1,409,965), 975,920 sq mi (2,527,633 sq km), Australia, comprising the entire western part of the continent. It is bounded on the N, W, and S by the Indian Ocean. Perth is the capital. in Crawley worked with immature Onthophagus nigriventris and cauterized cells that would have grown into horns. The prongless males grew testes that were about 30 percent larger than those of comparably sized, horned horned
Having a horn, horns, or a hornlike growth.
Adj. 1. horned - having a horn or horns or hornlike parts or horns of a particular kind; "horned viper"; "great horned owl"; "the unicorn--a mythical horned beast"; males, Simmons and Emlen report.
That finding, they note, fits with results from another research team, which stopped genital growth in an Onthophagus species. Unusually small males grew horns.
Sperm investment hasn't gotten its due respect, comments Scott Pitnick of Syracuse (N.Y.) University. He welcomes the beetle research as adding to the growing body of work demonstrating that "sperm production turns out not to be cheap, after all." Pitnick and his colleagues have reported that among species of small, insect-eating bats, investing in supersize supersize or supersized
larger than standard size
[-sizes, -sizing, -sized]
to increase the size of (something, such as a standard portion of food) testes tends to correspond to having smaller brains.
However, Simmons and Emlen didn't find such a straightforward pattern when they analyzed more than 20 species of Onthophagus beetles. Big horns didn't correspond to smaller testes, as would be expected if there were a simple constraint on growth.
Instead, some beetle species seem to protect their genital development. "Given enough [evolutionary] time, something will come up that's a way around a constraint," says Emlen.
The beetle species that broke the expected pattern had protected the development of their testes to an unusual degree. Emlen and Simmons report the findings online this week for an upcoming Proceedings of the National Academy of Sciences The Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS, is the official journal of the United States National Academy of Sciences. .
The relationships between horn and testes sizes "certainly suggest there's something going on--it's not random," says Gerald Wilkinson of the National Science Foundation in Arlington, Va.
The beauty of studying trade-offs between testes and horn sizes is that reproductive pressures drive them both, Wilkinson says. Onthophagus females mate with multiple males, so the competition favors males that deliver abundant sperm. Yet that delivery power doesn't matter unless a male uses his horns to reach the female.