speciation
grrlscientist | March 22, 2009tags: evolutionary biology, mate choice, sex determination, genetic compatibility, behavioral ecology, Gouldian Finch, Erythrura gouldiae, peer-reviewed paper
The three color morphs of Gouldian finches, Erythrura gouldiae.
Image: Sarah Pryke, Macquarie University.
Gouldian finches, Erythrura gouldiae, are small cavity-nesting passerines that are endemic to open savannahs adjacent to mangrove swamps in northern Australia. These finches eat a variety of native grass seeds, but to meet the increased energetic and nutritional demands of rearing chicks, they primarily eat insects when…
edyong | February 9, 2009This is the second of eight posts on evolutionary research to celebrate Darwin's bicentennial.
What do you get when one species splits into separate lineages? Two species? Think bigger...
When new species arise, they can set off evolutionary chain reactions that cause even more new species to spring forth - fresh buds on the tree of life create conditions that encourage more budding on different branches.
Biologists have long suspected that these "cascades of speciation" exist but have struggled to test them. Enter Andrew Forbes from the University of Notre Dame - his team of has found a…
grrlscientist | January 27, 2009tags: evolution, speciation, diversification rate, Zosterops, White-eyes, ornithology, birds, molecular phylogeny, South Pacific Islands
The Splendid (Ranongga) White-eye, Zosterops splendidus,
endemic to Ranongga Island in the Solomon Islands archipelago.
This species' home range is smaller than Manhattan Island.
Image: Chris Filardi [larger view].
For many decades, the white-eyes (Family: Zosteropidae) were known as the "Great Speciators" in honor of their apparent ability to rapidly give rise to new species while other birds in the same areas showed little or no diversification. But…
jwhitfield | January 19, 2009Mathematicians and physicists speak of a result 'falling out of the equations', implying that if you set things up properly, the rest takes care of itself. Chapter 4 of the Origin, 'Natural Selection', is where evolution falls out of the machinery that Darwin has spent the three previous chapters assembling.
And I hate to say it, but it's a bit of an anticlimax.
In retrospect, it's difficult to see how it could be otherwise. Darwin has manoeuvred us into position so carefully, showing the power of artificial selection, the mutability of species and nature's cutthroat struggle, that we're…
evolgen | December 16, 2008Over at Wilkins' cabana, there's a post (Some new work on speciation and species) on a paper by Nitin Phadnis and Allen Orr (doi:10.1126/science.1163934). Phadnis and Orr isolated a gene responsible for both reproductive isolation and sex-ratio distortion between two populations of Drosophila pseudoobscura. Wilkins doesn't like speciation genes, and he's rails on the concept in his post.
What I'm interested in are the comments on Wilkins' post -- primarily the confusion over what the speciation gene hunters mean when they talk about different flavors of speciation. Most population geneticists…
grrlscientist | December 15, 2008tags: evolution, honeyeaters, Meliphagidae, Mohoidae, birds, ornithology, birds, molecular phylogeny, extinct species, South Pacific Islands
Two nectar-feeding birds from Hawai'i, the kioea (brown-streaked, in middle) and an o'o species (lower left), looked so much like nectar specialists from the western Pacific (two species on right) that taxonomists put them all in the same honeyeater family, the Meliphagidae. All the Hawaiian birds are unfortunately extinct, but DNA evidence shows that their resemblance resulted from convergent evolution, because the Hawaiian birds were actually much…
grrlscientist | December 9, 2008tags: evolution, biogeography, ornithology, birds, avian
Kolo Sunset.
Photo credit: Christopher E. Filardi, American Museum of Natural History
(Click on image for a larger picture).
Two of my ornithologist colleagues, Chris Filardi and Rob Moyle, published a paper in the top-tier research journal, Nature. This paper is especially exciting because it shows that oceanic islands are not necessarily the evolutionary "dead ends" that they have traditionally been portrayed to be. In fact, Chris and Rob's data show that a group of birds have actually accomplished what scientists had never…
sb admin | November 16, 2008
Population biologists often want to infer the demographic history of the species they study. This includes identifying population subdivision, expansion, and bottlenecks. Genetic data sampled from multiple individuals can often be applied to study population structure. When phylogenetic methods are used to link evolutionary relationships to geography, the approaches fall under the guise of phylogeography.
The past decade has seen the rise in popularity of a particular phylogeographical approach for intra-specific data: nested clade analysis (Templeton et al. 1995; Templeton 2004). Many of…
grrlscientist | November 12, 2008tags: ecology, exotic species, introduced species, non-native species, invasive species, monk parakeets, quaker parrots, Myiopsitta monachus, Michael A Russello, Michael L Avery, Timothy F Wright
Monk (Quaker) parakeets, Myiopsitta monachus, with nest.
Image: Arthur Grosset [larger view].
Invasive species are everywhere: from plants such as Scotch (English) broom, Cytisus scoparius, whose yellow flowers bloom prolifically along roadways of North America, Australia and New Zealand to mammals such as human beings, Homo sapiens, which are the ultimate invasive species because we have…
grrlscientist | August 6, 2008tags: researchblogging.org, premature hair graying, autosomal dominant trait, genetics, horses, hair color, syntaxin-17, melanocortin-1 receptor, cis-acting regulatory mutation, melanoma, evolution
This horse is in the process of losing its pigment.
It will end up being all white by the time it is eight years old.
Image: Horse Wallpaper [larger view].
Even though I have always been a fan of black horses, my heart did leap at the sight of the noble Shadowfax racing towards Gandalf in response to his call in the Lord of the Rings. White horses have symbolized purity throughout most ages…
grrlscientist | August 5, 2008tags: researchblogging.org, begging calls, brood parasitism, coevolution, learning, social shaping, ornithology, Horsfield's Bronze-Cuckoo, Chalcites basalis, Chrysococcyx basalis
Horsfield's Bronze-Cuckoo, Chalcites (Chrysococcyx) basalis,
Capertee Valley, NSW, Australia, September 2003.
Image: Aviceda [larger view].
Brood parasites are birds, fish or insects that deceive unrelated animals of the same species or different species to care for their offspring. By doing so, the parasitic parent is relieved of the energetic demands of constructing a nest and raising its young to…
grrlscientist | August 1, 2008tags: researchblogging.org, evolution, speciation, ring species, phylogeography, landscape genetics, crimson rosella, Platycercus elegans, parrots, birds, Australia
Crimson Rosella, Platycercus elegans.
Image: Australian Broadcasting Corporation.
One of the challenges facing those who believe that evolution cannot create new species is explaining the problem of "ring species." Ring species are a group of geographically connected populations that can interbreed with nearby populations, but cannot breed with those populations that exist at each end of the cline (figure A). These populations…
grrlscientist | July 22, 2008tags: researchblogging.org, dichromatism, mating system, plumage color, sex allocation, eclectus parrots, Eclectus roratus, ornithology, birds, avian, parrots
Elektra, my female Solomon Islands eclectus parrot, Eclectus roratus solomonensis.
This is the smallest and most distinctively marked of all the subspecies of eclectus parrots.
Image: GrrlScientist 4 July 2008 [larger view].
Some of you might recall the recent story about scientists learning to identify plumage coloration from fossilized feathers. This might seem a sort of esoteric pursuit meant to entertain scientists with access…
grrlscientist | July 15, 2008tags: researchblogging.org, speciation, adaptive radiation, , diversification, ecological opportunity, community assembly, species interactions, North American wood-warblers, Dendroica species, Daniel L. Rabosky
Yellow-rumped warbler, Dendroica coronata, After Hatch Year male.
Image: Dave Rintoul, KSU [larger view].
Several questions that motivate my own research and thinking are; How do species arise? Where does all this biodiversity that we see on Earth come from? Does speciation occur as a series of slow and gradual accumulated changes or is it an explosive process that occurs within a…
grrlscientist | June 17, 2008tags: evolution, beak and body size, Geospiza fortis, inbreeding, mating patterns, reproductive isolation, sexual imprinting
A family tree depicts the evolution of the 14 species of "Darwin's finches".
(The focus of this study, the Medium Ground Finch, Geospiza fortis, is denoted with a red dot).
[larger image].
I have always been fascinated by the process of speciation throughout my scientific career because speciation is the "engine" that generates biological diversity. But what are the evolutionary mechanisms that lead to speciation? We know that mate choice can be one important…
grrlscientist | May 12, 2008tags: How and Why Species Multiply, evolution, ecology, Darwin's finches, Rosemary Grant, Peter Grant, book review
Peter and Rosemary Grant have been studying the phenomenon of speciation in Darwin's finches for 35 years, using every technique available to them from molecular biology to population ecology. They have written several books about various aspects of their work and even were the focus of a Pulitzer-prize winning book. But there has not been a comprehensive yet scholarly book that has captured the essential highlights of their lifetime work, until now. How and Why Species Multiply…
grrlscientist | April 23, 2008tags: researchblogging.org, evolution, speciation, Pod Mrcaru lizard, Podarcis sicula, reptiles
Pod Mrcaru lizard, Podarcis sicula.
Image: Anthony Herrel (University of Antwerp) [larger view]
Evolution has long been thought to occur slowly, due to small and gradual genetic changes that accumulate over millions of years until eventually, a new species arises. However, recent research has been calling this assumption into question. According to a study that was just published by an international team of scientists, dramatic physical changes can occur very rapidly -- on the order of just 30…
edyong | April 10, 2008Humans have been blamed for the disappearance of species before but never quite like this. Scientists at the University of Oxford have found evidence that two species of bacteria are merging into one. The two species are swapping genetic material at such a high rate that they are on the road to sharing a single, common genome. Their genetic merger is probably the result of being thrust into a new environment - the intestines of heavily farmed chickens, cattle and other domesticated livestock.
The two bacteria in question - Campylobacter jejuni and Campylobacter coli - are two of the most…
evolgen | April 8, 2008Us dudes are always accused of thinking with our dicks. Perhaps it's because the genes expressed in our brains are similar to those expressed in our 'nads:
Among the 17 tissues, the highest similarity in gene expression patterns was between human brain and testis, based on DDD and clustering analysis. Genes contributing to the similarity include ribosomal protein (RP) genes as well as genes involved in transcription, translation and cell division.
The authors of the paper allege that their result has something to do with speciation. They even claim, "Brain is the most important tissue in…
esiegel | March 24, 2008This is some very basic biology: when resources are unlimited and there are no pressures on a species, its population grows exponentially. There's also no evolution other than random mutations; without selection pressures (regardless of whether it's natural or artificial), the genetic information content of a species doesn't change appreciably.
Biologists make use of this to perform tests on certain cells. If you simply put a population of cells in a petrie dish and left them there, they start out by doing this:
They divide. They take over the dish. But then, they run out of room. And when…