Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cricket’s finicky mating behavior boosts biodiversity

07.02.2005


Speedy speciation curbs courtship options, says Nature article

Biologists at Lehigh University and the University of Maryland have identified a cricket living in Hawaii’s forests as the world’s fastest-evolving invertebrate. Finicky mating behavior appears to be the driving force behind the speedy speciation of the Laupala cricket, the scientists wrote in the Jan. 27 issue of Nature magazine.

Females in the Laupala genus detect tiny differences in the pulse rates of male courtship songs, which differ from one Laupala species to the next. They refuse to mate with males of other species, thus promoting the formation of new species.



The scientists say their findings shed light on the role of individual choices in the evolution of species and the growth of biodiversity. "Animals with nervous systems and brains have preferences and can make choices," says Tamra Mendelson, an evolutionary biologist at Lehigh. "Changes in these preferences and choices appear to drive speciation. "That raises the question: Can something seemingly so individual as a choice have macro-evolutionary consequences in terms of increasing biodiversity? If so, this affects how life on the planet looks. The more species you have, the more complex the ecology is going to be."

In down-to-earth terms:

"What turns a female cricket on? Why does she prefer one pulse rate over another? Whatever the reason, it’s very important that she exercise this preference in order to keep the species distinct."

Mendelson spent three and one-half years studying the Laupala cricket with Kerry Shaw, an evolutionary biologist at the University of Maryland.

The thumbnail-sized Laupala spawns new species at the rate of 4.17 every 1 million years, or more than 10 times faster than the average speciation rate for invertebrates. This rapid evolution is contributing to an "explosion" of new cricket species, especially on Hawaii, the largest and youngest island in the Hawaiian archipelago, say the two scientists. Some 38 different species of the cricket now inhabit the island chain.

Among all animals, say Mendelson and Shaw, only the African cichlid fish spawns new species more quickly. While early biologists based their estimates of speciation rates on morphological, or structural characteristics, Mendelson says, scientists today are more likely to use genetic data to come up with estimates.

Closely related species of Laupala have no clear morphological differences, Mendelson says. They are similar in appearance, they have similar diets, and they live in similar habitats. Members of closely related species possess no physiological differences that would prevent them from interbreeding. But closely related species are distinguished by subtle differences in the pulse rates of male crickets’ simple courtship songs, a secondary sexual trait that plays a large role in mate attraction.

Among all species of Laupala, pulse rates of male courtship songs range from .5 to 4.2 pulses per second. Female crickets can detect these differences, says Mendelson, and they tend to hop towards the pulse rate of their own species and to reject songs sung at a different tempo. The Laupala mating ritual lasts up to eight hours and consists of eight to 15 transfers of spermatophores between male and female, says Mendelson. The final spermatophore, or capsule, to be transferred contains the actual sperm cells that impregnate the female. As a species begins to split into two separate species, says Mendelson, "the songs appear to be the first characteristic that changes."

During the early part of the speciation process, says Mendelson, crickets of the two emerging lines interbreed. After a point, however, members of the two distinct species no longer mate with each other. This discovery led Mendelson to name one of her graduate-school papers after the pop song "Will You Still Love Me Tomorrow?" The Nature article was given the more conservative title of "Rapid Speciation in an Arthropod."

"Over time," says Mendelson, "lineages - species that have split - cease to recognize each other as mates. Although the ancestors recognized each other as mates, the descendants no longer do because of evolutionary change. In the case of Laupala, members of the two species are physiologically capable of mating. But they appear to lose the desire to interbreed before they lose the capacity to interbreed."

Mendelson and Shaw used a technique called amplified fragment-length polymorphisms to establish the evolutionary tree, or phylogeny, of the Laupala. They based their estimates of the cricket’s rate of speciation on the Laupala’s phylogeny and on the age of the islands in the Hawaiian archipelago. The youngest island, Hawaii, was formed less than 500,000 years ago.

Kurt Pfitzer | EurekAlert!
Further information:
http://www.lehigh.edu

More articles from Life Sciences:

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

nachricht The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Magnetic nano-imaging on a table top

20.04.2018 | Physics and Astronomy

Start of work for the world's largest electric truck

20.04.2018 | Interdisciplinary Research

Atoms may hum a tune from grand cosmic symphony

20.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>