Fierce Roller
Evolution, transitions, and volvocine algae
The beginning and the end of the story.
I’ve been reluctant to comment on the shooting of Scout Schultz. I don’t have any special insight or any information that’s not available on the news. I don’t want to rush to judgement and start throwing around blame for cops who, by every indication but one, were trying to avoid violence.
Comic by Randall Munroe, xkcd (of course).
Maybe by the time I have part 2 written up, someone will tell me in the comments why we evolutionary biologists shouldn’t just hang up our hats in light of pre-antibiotic antibiotic resistance.
I really didn’t mean to leave that hanging for three weeks. That was the end of part 1 of my look at Phillip Cunningham’s video, “Darwin vs. Microbes,” in which Cunningham argues that antibiotic resistance is not an example of evolution because (among other reasons),
…contrary to Darwinian thought, it is now found that antibiotic resistance, instead of being an ability that is new for bacteria, is an ability that is ancient.
Boom, game over, creationists win, right? I mean, how can antibiotic resistance have evolved millions of years ago if Alexander Fleming didn’t invent penicillin until 1928? [Read more…]
Can you be good without God? Of the various questions raised in the theist/atheist debate, this question has, I believe, occasioned more witless commentary than any other.
–Michael Egnor, Evolution News & Views 2017-09-05
I couldn’t agree more. And you’ll find no better example of that witless commentary than Egnor’s article itself.
Volvox and its relatives are a great model system for understanding the evolution of multicellularity. Their simplicity (relative to most other multicellular groups) and the variety of ‘intermediate’ species (‘intermediate’ in terms of size and complexity) make them especially suitable for comparative studies of their morphology, development, genetics, genomics, and so on. David Kirk’s book on the topic thoroughly reviews the work done up through the late ’90s, and advances since then have only increased the pace of discovery.
But in the last ten years or so, I would argue that the volvocine algae have emerged as a leading model system for an entirely different set of questions related to the evolution of the sexes. Males and females are defined by the gametes they produce, and the sexes came into existence when their gametes diverged into two different types. The existence of different male and female gametes (sperm and eggs, in most cases) is called anisogamy, and the ancestral condition of similar gametes is isogamy.
In 2006, Hisayoshi Nozaki and colleagues reported that volvocine males evolved from the minus (isogamous) mating type. To the best of my knowledge, this is the only group for which we know this. Since then, more clues have been forthcoming, and these were competently reviewed last year by Takashi Hamaji and colleagues. A new paper in PLoS ONE, by Kayoko Yamamoto and colleagues, adds another piece to the puzzle.
Figure S2 from Yamamoto et al. 2017. Light microscopic images of Volvox africanus (homothallic, monoecious with males type) and V. reticuliferus (heterothallic, dioecious type). Scale bars = 50 μm. sp: sperm packet, e: egg. A-C. V. africanus strain 2013-0703-VO4. A. Asexual spheroid. B. Monoecious spheroid. C. Male spheroid. D, E. V. reticuliferus. D. Male spheroid in male strain VO123-F1-7. E. Female spheroid in female strain VO123-F1-6.
From an advertising email for World Market:
You got the rights to put the Game of Thrones logo on wine, and the most creative thing you could come up with was “Game of Thrones Red Wine”?
Is it fair to judge everyone who marched against the removal of a Confederate monument in Charlottesville? Surely not everyone involved self-identifies as a white supremacist or Nazi. When I marched for science in Washington, DC, I didn’t agree with every single thing that was said on stage or written on signs, but I marched anyway. Same thing, right?
The Fourth International Volvox Meeting in St. Louis was everything I hoped. It was well organized, small enough to talk to everyone, and full of great talks. David Kirk was indeed there, briefly, though I failed to get a photo, and so was David Queller.
I thought I was pretty connected in the (relatively small) Volvox world, but there were several people there I’d never met and lots of research that was news to me. I’ll be blogging more about some of that research, but for now I’ll just share a few photos from the meeting.
The Donald Danforth Plant Science Center is the perfect setting for a movie with scientist working on super high-tech stuff.
I follow Uncommon Descent to keep up with what the cdesign proponentsists are up to, even though I’ve been banned from commenting. Uncommon Descent pushes out about three times as many articles as Evolution News & Views, and it’s clear that less than a third as much thought goes into each one. Worse, the articles’ authorship is rarely identified, robbing me of my second favorite sport after fly fishing, pointing out creationists’ self-contradictions. For both of these reasons, I don’t comment on their posts nearly as often. But if you read this blog at all, you must know that I can’t pass on a video that 1) claims to provide evidence against evolution and 2) has Volvox in it.
Right here. Confederate Vice President Alexander H. Stephens’ “Corner Stone” speech:
The new constitution has put at rest, forever, all the agitating questions relating to our peculiar institution African slavery as it exists amongst us the proper status of the negro in our form of civilization. This was the immediate cause of the late rupture and present revolution…
Those ideas [that slavery would pass away], however, were fundamentally wrong. They rested upon the assumption of the equality of races. This was an error. It was a sandy foundation, and the government built upon it fell when the “storm came and the wind blew.”
Our new government is founded upon exactly the opposite idea; its foundations are laid, its corner- stone rests, upon the great truth that the negro is not equal to the white man; that slavery subordination to the superior race is his natural and normal condition. This, our new government, is the first, in the history of the world, based upon this great physical, philosophical, and moral truth.