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Showing posts with label Biology. Show all posts
Showing posts with label Biology. Show all posts

Thursday, March 07, 2024

Why Philosophy of Biology?

Robert Lawrence Kuhn has published a series of videos on his "Closer to Truth" site. On March 4, 2024 he posted a teaser video introducing Season 23: "Why Philosophy of Biology." The video contains short clips of his interviews with philosophers of biology (see list below).

Here's the blurb covering the introduction to the new season.

How can philosophy advance biology? How can biology influence philosophy? In this first series on Philosophy of Biology, Closer to Truth explores the challenges and implications of evolution. We ask how life on earth came to be as it is, and how humans came to be as we are. We address biologically based issues, such as sex/gender, race, cognition, culture, morality, healthcare, religion, alien life, and more. When philosophy and biology meet, sparks fly as both are enriched.

Those are all interesting questions. Some of them can only be answered by philosophers but others require major input from scientists. One of the important issues for philosophy of science seems to be the confict between the philosophy of the early 20th century, which was developed with physics as the model science, and the the success of molecular biology in the latter half of the 20th century, which didn't play by the same rules. (See the short interview with Paul Griffiths, whom I greatly admire, for a succinct explanation of this problem.)

I'm very conflicted about the role of philosphy in understanding the science of biology and even more conflicted about whether philosophers can recognize good science from bad science (Richard Dawkins, Denis Noble). I'm also puzzled by the apparent reluctance of philosophers to openly challenge their colleagues who get the science wrong. Watch the video to see if my scepticism is warranted.


Monday, November 19, 2018

Latest Tango in Halifax

I've known Yana Eglit for many years. She frequently posts comments on this blog but you won't recognize her name because she uses a pseudonym.1 Yana is a graduate student in the lab of Alastair Simpson at Dalhousie University in Halifax, Nova Scotia, Canada. A few years ago she saw some strange organisms dancing in a Petri dish.2

The microorganisms belong to the group Hemimastigophora. Yana found them in a clump of dirt she picked up while hiking near Halifax. They named the species Hemimastix kukwesjijk. The group only contains a few other species.

Hemimastigophora is one of those protist groups that have been difficult to classify and difficult to place relative to other protists. It's traditionally been given the status of a phylum but its position in the eukaryotic tree was ambiguous.

The Simpson lab, in a collaboration with Andrew Roger's group, sequenced a number of genes (transcripts) from H. kukwesjijk and another species that they recently identified (Spirenema). The datasets contained samples of about 300 genes of each species. Trees constructed with this dataset place the Hemimastigophora near the base of the eukrayotic tree as a sister group to Diaphoretices. The work was published in a recent issue of Nature (Lax, Egrit, et al., 2018).

The details of eukaryotic taxonomy and the various subdivisions needn't concern us but the important take-home lesson is that there are a huge number of protists forming diverse groups that separated more than a billion years ago. The authors claim that Hemimastigophora deserves supra-kingdom status equivalent to the other supra-kingdoms shown in the figure (modified from Figure 4 of the paper).

The root of the eukaryotic tree is controversial. It could be at positions a, b, or c, shown in the figure. According to the authors, position a is the most favored these days. Regardless of where the root is actually placed, the new positioning of Hemimastigophora adds a lot of information to the deepest parts of the eukaryotic tree and brings us closer to identifying the most primitive features of the eukaryotic cell.

I wonder how many other strange species can be found in Canadian dirt?


Photo Credit: The photo of Yana Eglit at her microscope is from the Dalhousie University press office [Hidden in plain sight: Dal evolutionary biologists uncover a new branch on the Tree of Life]

1. Which she might accidentally reveal if she responds to this post!

2. The fact they were "dancing" gave me an excuse to use a corny title that refers to one of our favorite TV shows, "Last Tango in Halifax."

Lax, G., Eglit, Y., Eme, L., Bertrand, E. M., Roger, A. J., and Simpson, A. G. B. (2018) Hemimastigophora is a novel supra-kingdom-level lineage of eukaryotes. Nature. (in press) [doi: 10.1038/s41586-018-0708-8]

Monday, February 12, 2018

Dirty bacteria

Did you know that the dirt in your local park is full of bacteria? Each scoop of soil contains millions of bacteria. And it's not just in your local park, soil bacteria are everywhere. This is part of the reason why the total mass of bacteria on the planet outweighs all of the eukayotes combined, including elephants and whales.

There are hundreds of different species of bacteria in your local dirt. They are as different from each other as moose and mushrooms.

Did you ever wonder whether the bacteria in Australian soil are similar to the bacteria in Austrian soil? Delgado-Baquerizo and his colleagues did, so they tested soils from all over the world. The results are published in a recent issue of Science (Delgado-Baquerizo et al., 2018).

The answer is yes ... and no. They looked at 237 locations on all continents except Antarctica. Most samples had about 1000 different species—the authors call them "phylotypes" because it's hard to define what a species is in bacteria. Only a small number of species (phylotypes) were found in all locations (511 out of 25,224 = 2%) but they accounted for almost half of the total mass. Here's how the authors describe their result ...
Together, our results suggest that soil bacterial communities, like plant communities, are typically dominated by a relatively small subset of phylotypes.
Most of those 511 dominant phylotypes fall into two large and diverse clades (phyla?): Proteobacteria and Actinobacteria. The distribution is shown in Figure 1 of the paper (left). It illustrates a little-known fact about bacteria; namely, that they are a very diverse group. Scientists are only beginning to explore this diversity. Only 18% of the 511 dominant phylotypes were previously known to science!




Image Credit: Bacillus Sp. soil bacteria from The ecology of soil-borne human diseases

Delgado-Baquerizo, M., Oliverio, A.M., Brewer, T.E., Benavent-González, A., Eldridge, D.J., Bardgett, R.D., Maestre, F.T., Singh, B.K., and Fierer, N. (2018) A global atlas of the dominant bacteria found in soil. Science, 359(6373), 320-325. doi: doi: 10.1126/science.aap9516

Tuesday, October 31, 2017

Escape from X chromosome inactivation

Mammals have two sex chromosomes: X and Y. Males have one X chromosome and one Y chromosome and females have two X chromosomes. Since females have two copies of each X chromosome gene, you might expect them to make twice as much gene product as males of the same species. In fact, males and females often make about the same amount of gene product because one of the female X chromosomes is inactivated by a mechanism that causes extensive chromatin condensation.

The mechanism is known as X chromosome inactivation. The phenomenon was originally discovered by Mary Lyon (1925-2014) [see Calico Cats].

Saturday, April 08, 2017

Somatic cell mutation rate in humans

A few years ago, Tomasetti and Vogelstein (2015) published a paper where they noted a correlation between rates of cancer and the number of cell divisions. They concluded that a lot of cancers could be attributed to bad luck. This conclusion didn't sit well with most people for two reasons. (1) There are many well-known environmental effects that increase cancer rates (e.g. smoking, radiation), and (2) there's a widespread belief that you can significantly reduce your chances of getting cancer by "healthy living" (whatever that is). The first objection is based on solid scientific evidence but the second one is not as scientific.

Some of the objections to the original Tomasetti and Vogelstein paper were based on the mathematical models they used to reach their conclusions. The authors have now followed up on their original study with more data. The paper appears in the March 24, 2017 issue of Science (Tomasetti and Vogelstein, 2017). If you're interested in the debate over "bad luck" you should read the accompanying review by Nowak and Waclaw (2017). They conclude that the math is sound and many cancer-causing mutations are, in fact, due to chance mutations in somatic cells. They point out something that should be obvious but bears repeating.

Wednesday, August 03, 2016

More junk science in Science

The latest issue of the journal Science (Aug. 1, 2016) has an article on a recent paper by Aires et al. (2016) published in Developmental Cell. Here's the abstract of the paper ...

Vertebrates exhibit a remarkably broad variation in trunk and tail lengths. However, the evolutionary and developmental origins of this diversity remain largely unknown. Posterior Hox genes were proposed to be major players in trunk length diversification in vertebrates, but functional studies have so far failed to support this view. Here we identify the pluripotency factor Oct4 as a key regulator of trunk length in vertebrate embryos. Maintaining high Oct4 levels in axial progenitors throughout development was sufficient to extend trunk length in mouse embryos. Oct4 also shifted posterior Hox gene-expression boundaries in the extended trunks, thus providing a link between activation of these genes and the transition to tail development. Furthermore, we show that the exceptionally long trunks of snakes are likely to result from heterochronic changes in Oct4 activity during body axis extension, which may have derived from differential genomic rearrangements at the Oct4 locus during vertebrate evolution.
... those ignorant of history are not condemned to repeat it; they are merely destined to be confused.

Stephen Jay Gould
Ontogeny and Phylogeny (1977)
The results were written up by a freelance journalist named Diana Crow [‘Junk DNA’ tells mice—and snakes—how to grow a backbone]. She writes ...
‘Junk DNA’ tells mice—and snakes—how to grow a backbone

Why does a snake have 25 or more rows of ribs, whereas a mouse has only 13? The answer, according to a new study, may lie in "junk DNA," large chunks of an animal’s genome that were once thought to be useless. The findings could help explain how dramatic changes in body shape have occurred over evolutionary history.

Scientists began discovering junk DNA sequences in the 1960s. These stretches of the genome—also known as noncoding DNA—contain the same genetic alphabet found in genes, but they don’t code for the proteins that make us who we are. As a result, many researchers long believed this mysterious genetic material was simply DNA debris accumulated over the course of evolution. But over the past couple decades, geneticists have discovered that this so-called junk is anything but. It has important functions, such as switching genes on and off and setting the timing for changes in gene activity.
Sandwalk readers will see all the mistakes and misconceptions in these paragraphs. She's talking about regulatory sequences that were never, ever, thought to be junk. The paper being discussed has nothing to do with junk DNA and the results do not in any way alter our understanding of developmental gene regulation.

If you look carefully at the abstract, you'll see the word "heterochronic." This is one of Stephen Jay Gould's favorite words. He wrote about it in Ontogeny and Phylogeny.
I wish to emphasize one other distinction. Evolution occurs when ontogeny is altered in one of two ways: when new characters are introduced at any stage of development with varying effects upon subsequent stages, or when characters already present undergo changes in developmental timing. Together, these two processes exhaust the formal concept of phyletic change.; the second process is heterochrony. [my emphasis ... LAM] If change in developmental timing is important in evolution, then this second process must be very common.
This was written in 1977—that's almost 40 years ago! These ideas were around for decades before Gould wrote his book1 and they have been shown to be correct by numerous studies in the 1980s.

What's going on here? Science is supposed to be one of the leading science journals. How could it publish an article that misrepresents the field so badly? Do the editors send these "Latest News" articles out for review?


1. Ed Lewis shared the Nobel Prize in 1995 for his contribution to "the genetic control of early embryonic development" [The Nobel Prize in Physiology or Medicine 1995].

Thursday, January 14, 2016

Model organisms and translational research

Ewan Birney (Genomic's Big Talker of ENCODE notoriety) has a new post called In defence of model organisms.

He brings up two points that are worth discussing.

What is a model organism?

There are two common definitions. Birney leans toward defining a model organism as one that models human biochemistry and physiology. This is a common definition. It emphasizes the meaning of "model" as "model of something."

Tuesday, July 29, 2014

Walter Gehring (1939 - 2014)

I just learned today that Walter Gehring died in a car accident in Greece on May 29th. I learned of his death from the obituary by Michael Levine in Science [Walter Gehring (1939–2014)]. There's another obituary on the Biozentrum (Basel, Switzerland) website [Obituary for Walter Gehring (1939 – 2014)]. He was only seven years older than me.

I first met Walter Gerhing when I was a post-doc in Alfred Tissières lab in Geneva (Switzerland) in the mid-1070s. The two labs collaborated on cloning and characterizing the major heat shock gene (Hsp70) of Drosophila melanogaster. Paul Schedl and Spyros Artavanis-Tsakonis made the library in Gehring's lab in 1976-1977 and Marc-Edouard Mirault and I isolated the mRNA for screening and then identified the genes we cloned. The result was three papers in Cell (see below). (John Lis, then in David Hogness' lab, was cloning the same gene.)

I met Gerhing dozens of times but I only had a few conversations with him one-on-one. We always talked about evolution. I always found him to be very charming and very curious and not embarrassed to admit that he didn't know something. Other post-docs and students in his lab have different impressions.

As Michael Levine puts it ...
An amazing group of students and postdocs was attracted to the Gehring lab over the years: Eric Wieschaus (Nobelist), Christianne Nüsslein-Volhard (Nobelist), David Ish-Horowicz, Spyros Artavanis-Tsakonas, Paul Schedl, Alex Schier, Georg Halder, Hugo Bellen, and Markus Affolter, to mention just a few. I worked closely with two of my future lifelong friends and colleagues: Ernst Hafen and Bill McGinnis. The lab was an absolute blast, but a strange mix of anarchy and oppression. Walter permitted considerable independence, but was hardly laissez-faire. He could be confrontational, and did not hesitate to call us out (particularly me) when he felt we were misbehaving.

I found Walter to be a complicated character. He had the mannerisms of an authoritative Herr Doktor Professor, but was also folksy and unaffected and always ready to laugh and joke. He sometimes felt competitive with his students and postdocs, but was also highly supportive and proud of our independent careers. In short, I believe the key to Walter's success was his yin and yang embodiment of old-world scholar and modern competitive scientist. He was able to exude charm and empathy, but nothing we did seemed to be quite good enough. In other words, tough love, possibly the perfect prescription for eliciting the very best efforts from his students and postdocs.
Walter Gehring was one of a small group people who changed the way I think about science.


Artavanis-Tsakonas, S., Schedl, P., Mirault, M.-E., Moran, L. and J. Lis (1979) Genes for the 70,000 dalton heat shock protein in two cloned D. melanogaster DNA segments. Cell 17, 9-18. [doi: 10.1016/0092-8674(79)90290-3]

Moran, L., Mirault, M.-E., Tissières, A., Lis, J., Schedl, P., Artavanis-Tsakonas, S. and W.J. Gehring (1979) Physical map of two D. melanogaster DNA segments containing sequences coding for the 70,000 dalton heat shock protein. Cell 17, 1-8. [doi: 10.1016/0092-8674(79)90289-7]

Schedl, P., Artavanis-Tsakonas, S., Steward, R., Gehring, W. J., Mirault, M.-E., Goldschmidt-Clermont, M., Moran, L. and A. Tissières (1978) Two hybrid plasmids with D. melanogaster DNA sequences complementary to mRNA coding for the major heat shock protein. Cell 14, 921-929. [doi: 10.1016/0092-8674(78)90346-X]

Friday, February 07, 2014

Does an understanding of evolution help scientists understand the secrets of biology?

You're probably wondering why I would ask a question like, "Does an understanding of evolution help scientists understand the secrets of biology?" It's not my question. It's a paraphrase of a question asked by someone who goes by the pseudonym "PaV" on Uncommon Descent. Here's the full context from her post: Does Evolutionary Theory Really Help Scientists?
For a number of years, many of us at UD have made the argument that evolutionary theory, in practice, is of almost no help whatsoever in getting at the secrets of biology. I’ve taken the position personally that it actually hurts, and that it is not a matter of indifference to the study of biology whether evolution is employed or not. ID is the way to go.
Now, besides the fact that she is an IDiot, you may be asking why anyone would write such a thing.

Here's the scoop. Someone was looking at unknown RNAs in zebra fish and discovered that one of them encoded a protein that hadn't previously been characterized. This sort of thing happens all the time in various species so why is PaV so excited?

Here's the answer ...
They’ve studied this embryonic stage for 20 years, and couldn’t figure out the decisive signals for initiation of the gastrula. They had to look to “non-coding” RNA, i.e., “junk DNA,” in order to solve their new found secret.

And why didn’t they study “junk DNA” before? Well, evolutionary theory posits that it is “junk” (their word, not ours), so why investigate.
See? Evolutionary theory actually impedes scientific progress. And you wonder why we call them ....


Thursday, September 26, 2013

2013 Toronto Science Festival


The University of Toronto is sponsoring a "science" festival with three talks tomorrow and Saturday. You have to buy tickets at: tickets.

There's two technology talks and one science talk. I'm going to the only science talk at the science festival. There are a bunch of other things going on, see the entire program.

Friday, Sept. 27th 7pm– "Human Exploration of Space: 50 Years and Counting": Space Shuttle veteran and first Canadian on board the International Space Station, Julie Payette
“High achiever” barely begins to describe Julie Payette. Masters degree in engineering, pilot, IBM engineer, Officer of the Order of Canada, singer with symphonies in Montreal, Toronto, and Switzerland, conversant in six languages, and now Director of the Montreal Science Centre. Oh, did we mention she was orbiting the Earth, using a giant robot arm to build a space station by the time she was 35? Julie will kick off the festival by sharing her unique insights into the past, present, and future of human space exploration.

Friday, Sept. 27th 8pm– "Brave Genius: Jacques Monod, Chance, and our Place in the Universe": Evolutionary biologist and “evo devo” pioneer, Sean Carroll
Biologist and Nobel Laureate Jacques Monod once remarked that “the most important results of science have been to change the relationship of man to the universe, or the way he sees himself in the universe.” Discoveries in molecular biology, evolutionary biology, and geology over the past half-century have profoundly reshaped our picture of human origins, and revealed the enormous role of chance in the fate of life on Earth. Join evolutionary biologist Sean Carroll as he chronicles some of those discoveries through Monod’s eyes, whose own ascent from struggling graduate student to leader within the French Resistance, co-founder of molecular biology, and emergence as a public figure and leading voice of science involved a great deal of chance, and courage.

Saturday, Sept. 28th 7pm– "Postcards from Mars": Mars rover imaging scientist, Jim Bell
Don’t worry if your application to live on Mars was rejected. You can still visit the Red Planet through the spectacular imagery captured by a trio of Mars Rovers—Spirit, Opportunity and Curiosity. Planetary scientist Jim Bell was instrumental in developing cameras and processing images from the three robotic explorers and in his talk “Postcards from Mars”, he’ll share his favorite vistas of our planetary neighbour with you. Through the beauty of these photographs, you’ll see why Bell can be described as a scientist, an explorer and a nature photographer.

Saturday, June 08, 2013

Name this tree!

There are dozens of trees like this in Venice, California (USA) in the neighborhood where my grandchildren live. Can you name this tree (common name and species name)?

Can you come up with an adaptationist explanation for why this tree is so different from most other trees and bushes?




Friday, May 10, 2013

Almaleea subumbellata

Jerry Coyne says he will post a picture of a plant if he can find a cute one [A vertebrate]. I decided to help him out by pointing you to the latest Botany Photo of the Day.

This is Almaleea subumbellata, or wiry bushpea, from Tasmania, Australia. You can read all about it at the UBC Botanical Garden website. They have a high resolution photo.

Prettier than cats and they don't pee on your rug or scratch your furniture.


Friday, April 26, 2013

PZ's Wonderful Exam Question

PZ Myers has just given his students a take-home exam. Here's one of the questions [It’s another exam day! ] ...
Question 1: One of Sarah Palin’s notorious gaffes was her dismissal of “fruit fly research” — she thought it was absurd that the government actually funded science on flies. How would you explain to a congressman that basic research is important? I’m going to put two constraints on your answer: 1) It has to be comprehensible to Michele Bachmann, and 2) don’t take the shortcut of promising that which you may not deliver. That is, no “maybe it will cure cancer!” claims, but focus instead on why we should appreciate deeper knowledge of biology.
That first restriction is going to make answering the question a real challenge 'cause you have to take into account the mentality of someone who is not just scientifically illiterate but scientifically anti-literate.

Nevertheless, this is exactly the sort of thing you want your science graduates to know.


Hibiscus schizopetalus

It's been a while since I've linked to the Botany Photo of the Day even though I read it all the time.

Check it out. What is that dangling thing coming out of the flower? Does it have a function?


Monday, January 28, 2013

Guelph Biology Students

Here are the biology students at the University of Guelph (Guelph, Ontario, Canada) dancing and singing to "Anna Sun" by Walk the Moon.

I love this stuff. Some of these students are going to be scientists some day.



[Hat Tip: Ryan Gregory, Professor, University of Guelph.]

Tuesday, March 06, 2012

We Are Stardust

Helena Curtis was an amazing writer. She's famous for her introductory biology textbook published by Worth beginning in 1968 [Good Science Writers: Helena Curtis]. Here's the opening paragraphs.
Our universe began, according to current theory, with an explosion that filled all space, with every particle of matter hurled away from every other particle. The temperature at the time of the explosion—some 10 to 20 billion years ago—was about 100,000000000 degrees Celsius (1011 °C). At this temperature, not even atoms could hold together; all matter was in the form of subatomic, elementary particles. Moving at enormous velocities, even those particles had fleeting lives. Colliding with great force, they annihilated one another, creating new particles and releasing great energy.

As the universe cooled, two types of stable particles, previously present only in relatively small amounts, began to assemble. (By this time, several hundred thousand years after the "big bang" is believed to have taken place, the temperature had dropped to a mere 2500°C, about the temperature of white-hot wire in an incandescent light bulb.) These particles—protons and neutrons—are very heavy as subatomic particles go. Held together by forces that are still incompletely understood, they formed the central cores, or nuclei, of atoms. These nuclei, with their positively charged protons, attracted small, light, negatively charged particles—electrons—which moved rapidly around them. Thus, atoms came into being.

It is from these atoms—blown apart, formed, and re-formed over the course of several billion years—that all the stars and planets of our universe are formed, including our particular star and planet. And it is from the atoms present on this planet that living systems assembled themselves and evolved. Each atom in our own bodies had its origin in that enormous explosion 10 to 20 billion years ago. You and I are flesh and blood, but we are also stardust.
Neil DeGrasse Tyson tops that in his spontaneous answer to the question, "What is the most astounding fact you can share with us about the Universe?"


If you're going to sing "we are stardust" then you can't do it any better than this group. The song was written by Joni Mitchell (another Canadian) but her version is not as good.



[Hat Tip: Phil Plait of Bad Astronomy: Neil Tyson’s most astounding fact.]

Tuesday, December 20, 2011

These are not berries!

 

This is Juniperus communis from Botany Photograph of the Day. If you visit that website you'll learn two three things about juniper that you didn't know before: (1) juniper grows in lots of places, (2) the "berries" aren't berries, (3) gin comes from the French word for juniper.


Tuesday, April 19, 2011

Core Concepts: Evolution


The AAAS document, Vision and Change in Undergraduate Biology Education, defines five core concepts for biological literacy. Evolution is at the top of the list, right where it belongs.
1. EVOLUTION:

The diversity of life evolved over time by processes of mutation, selection, and genetic change. Darwin’s theory of evolution by natural selection was transformational in scientists’ understanding of the patterns, processes, and relationships that characterize the diversity of life. Because the theory is the fundamental organizing principle over the entire range of biological phenomena, it is difficult to imagine teaching biology of any kind without introducing Darwin’s profound ideas. Inheritance, change, and adaptation are recurring themes supported by evidence drawn from molecular genetics, developmental biology, biochemistry, zoology, agronomy, botany, systematics, ecology, and paleontology. A strong preparation in the theory of evolution remains essential to understanding biological systems at all levels.

Themes of adaptation and genetic variation provide rich opportunities for students to work with relevant data and practice quantitative analysis and dynamic modeling. Principles of evolution help promote an understanding of natural selection and genetic drift and their contribution to the diversity and history of life on Earth. These principles enable students to understand such processes as a microbial population’s ability to develop drug resistance and the relevance of artificial selection in generating the diversity of domesticated animals and food plants.
I would have written a different description—one that placed emphasis on Darwin's contribution but did not imply that his views represent modern evolutionary theory. I would also have mentioned genetics, especially population genetics, as the key to understanding modern evolution.

Nevertheless, one can't argue that evolution is the number one core concept in the biological sciences. Are we teaching it correctly in undergraduate courses. No, we are not. Are we teaching it enough in our undergraduate courses? No, again.

I think the main problem was completely ignored by the committee that drew up this document. The problem is that most professors don't understand evolution well enough to integrate this core concept into their courses. It's not enough for everyone to agree that evolution is a core concept. You also have to understand the core concept in order to teach it properly.

I see evidence in the description above suggesting that even the committee members were fuzzy on the core concept. What, for example, is "the theory of evolution"?


Vision & Change in Undergraduate Biology Education: Bruce Alberts


The American Association for the Advancement of Science (AAAS) has published a document called Vision and Change in Undergraduate Biology Education. Over the next few days I'm going to introduce the main recommendations and hopefully stimulate some discussion.

Today, we'll start with a video from Bruce Alberts the former head of the National Academies and currently editor-in-chief of Science magazine (published by AAAS). Pay attention to what he has to say. I agree with everything.1

Bruce Alberts understands that we (university professors) are the problem and it's up to us to fix it.
... the future of science education ... depends on what college professors do in their teaching much more than I would ever have expected ...

Dr. Bruce Alberts’ Message to Vision and Change


1. Bruce was my Ph.D. supervisor.

Wednesday, March 09, 2011

Why Has this Bee Landed on this Flower?


This is a photo from Botany Photo of the Day. The flower is Crepis barbigera.

Why is the bee visiting this flower? What is the evolutionary advantage of attracting bees? You may think you know the answer but you will be surprised by the comment at the bottom of the posting on the Botany Photo of the Day website. Nothing in biology is simple.