Navigation Links
Estimation of isolation times in the Drosophila simulans complex
Date:6/25/2008

Allentown, PA - The Drosophila simulans species complex continues to serve as an important model system for the study of new species formation. The complex is comprised of the cosmopolitan species, D. simulans, and two island endemics, D. mauritiana and D. sechellia. A substantial amount of effort has gone into reconstructing the natural history of the complex, in part to infer the context in which functional divergence among the species has arisen. In this regard, a key parameter to be estimated is the initial isolation time (t) of each island species.

In a study published on June 17, 2008 in PLoS ONE, Dr. Richard Kliman and colleague Shannon McDermott provide evidence that both island species were isolated at about the same time, estimated at ~250,000 years ago. They also show that the difference in divergence patterns of genes in regions of low and higher recombination can be reconciled by allowing a modestly larger effective population size for the ancestral population than for extant D. simulans.

"Essentially, this is about the formation of island species from mainland ancestors. We are particularly interested in the time that these isolation events occurred. Our approach is to estimate the key parameter, time in the past of initial isolation, from patterns of DNA sequence variation at several genes," says Dr. Richard Kliman, associate professor of biological sciences at Cedar Crest College. "The genes that we study show an unusual pattern of variation among species: those in parts of the genome characterized by low recombination appear to have become isolated more recently than those in the rest of the genome. This could mean that the low recombination genes were able to move between species after initial isolation. However, we show that this explanation is not necessary. If the effective population size of the current mainland species (Drosophila simulans) is just a little bit lower than that of the ancestral mainland population, the levels of variation at the two classes of genes can be reconciled."

New DNA sequence variation data for 17 loci corroborate the prior observation from 13 loci that DNA sequence divergence is reduced in genes of low recombination. Two models are presented to estimate t and other relevant parameters (substitution rate correction factors in lineages leading to the island species and, in the case of the 4-parameter model, the ratio of ancestral to extant effective population size) from the multilocus DNA sequence data.

Loci in regions of low recombination have lower divergence within the complex than do other loci, yet divergence from D. melanogaster is similar for both classes. This might reflect gene flow of the low-recombination loci subsequent to initial isolation, but it might also reflect differential effects of changing population size on the two recombination classes of loci when the low-recombination loci are subject to genetic hitchhiking or pseudohitchhiking.

"This 2-parameter model is of potential utility to researchers working on non-model organisms. DNA sequence data at multiple genes are required from the island or otherwise long-term isolated species of interest, its closest mainland ancestor and a third species that is closely related to both (although the island and mainland species must be more closely related to each than either is to the third species)," says Kliman.

"Also, with the number of researchers studying the functional divergence that contributes to speciation (specifically, to decreased fitness of hybrid offspring), getting accurate estimates of isolation times for the Drosophila simulans complex will allow researchers to estimate the rate at which functional divergence accumulated."


'/>"/>

Contact: Allison Goodin
allison.goodin@cedarcrest.edu
610-740-3790
Public Library of Science
Source:Eurekalert

Related biology news :

1. A fossilized giant rhino bone questions the isolation of Anatolia, 25 million years ago
2. Effects of social isolation traced to brain hormone
3. Stanfords nanowire battery holds 10 times the charge of existing ones
4. Brains timing linked with timescales of the natural visual world
5. Complex dynamics underlie bark beetle eruptions
6. Organic corn: Increasing rotation complexity increases yields
7. Simple model cell is key to understanding cell complexity
8. Finding God with biocomplexity
9. First rule of evolution suggests that life is destined to become more complex
10. Epigenetic regulation by the MMB/dREAM complex
11. Researchers visualize complex pigment mixtures in living cells
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/2/2016)... Technology Enhancements Accelerate Growth of X-ray Imaging ... and computed radiography markets in Thailand ... Indonesia (TIM). It provides an in-depth analysis ... as regional market drivers and restraints. The study offers ... market attractiveness, both for digital and computed radiography. Market ...
(Date:2/1/2016)... Canada , February 1, 2016 ... technological advancements to drive global touchfree intuitive gesture control ... --> Rising sales of consumer electronics coupled ... gesture control market size through ... consumer electronics coupled with new technological advancements to drive ...
(Date:1/28/2016)... -- Synaptics (NASDAQ: SYNA ), a leading developer of human ... December 31, 2015. --> --> ... 2 percent compared to the comparable quarter last year to $470.5 ... $35.0 million, or $0.93 per diluted share. ... quarter of fiscal 2016 grew 9 percent over the prior year ...
Breaking Biology News(10 mins):
(Date:2/4/2016)... -- Beike Biotechnology, the Shenzhen ... in late 2015 to mark their successful combined efforts ... --> --> The signing, ... Therapy" was hosted by the Shenzhen Cell Bank and ... Beike Biotechnology Co., Ltd. Shenzhen,s ...
(Date:2/4/2016)... , February 4, 2016 ... a biotechnology acceleration company is pleased to provide the following ... --> Over the last 3 months we have ... securities purchase agreements exceeding $1,000,000. As a result, we have ... Mannin Research Inc. license agreement and expect that development to ...
(Date:2/4/2016)... Feb. 4, 2016 Sinovac Biotech Ltd. ("Sinovac" ... provider of biopharmaceutical products in China ... board of directors received on February 4, 2016 a ... a consortium comprised of PKU V-Ming ( Shanghai ... Ltd., CICC Qianhai Development ( Shenzhen ) ...
(Date:2/4/2016)... ... February 04, 2016 , ... Many of the engineers at FireflySci, ... What sets them apart from other cuvette manufacturers is their supercharged customer service ... On top of this steady flow of inside information, they have recently revamped ...
Breaking Biology Technology: