It may not be impossible in the long term, but would probably be difficult to achieve. That said I don't think anyone has really tried very hard to select for a giant chicken  - presumably because there is a big market for "normal sized ones" and so there's little economic imperative. I think the largest chicken breeds come in around 5KG with occasional reports of c 10 KG birds.

Assuming it can't easily be done the short-term limitation is probably the absence of genes predisposing to gigantism in the populations people are working on. That said if a mutation arose that conferred much larger size, then provided birds carrying it can be readily identified, artificial selection could be used to fix it in a population (provided it didn't have deleterious effects that were too severe suh that natural selection counteracts the artificial). Worth noting that, for instance, dog breeders have managed to achieve something like a 100 fold difference in weight between smallest and largest breeds, so I would never say a 20KG chicken is impossible (just difficult!)

(posted in Research and Careers)

Both routes are options for a career in researching ageing/senescence. Which is best will depend a bit on the specifics of your interests. For instance, are you focussed only on humans and (for example) how research might improve human longevity (or quality of later life). If so a medical degree may be most appropriate. If however, you are interested in more "ultimate" questions  about why organisms sensence, how patterns of ageing evolve, how genes and environments drive then etc then a lot of this research is rooted in evolutionary theory with empirical studies spanning all kinds of organisms in the field and lab. So for this perspective a broader-based biological degree may be more appropriate.

I think its probably difficult to give a definitive answer... so I guess it's an unsatisfying "maybe"!

The original paper used our understanding of snake thermal biology (based on currently extant species) to try and infer the temperature when Titanoboa lived. While this is reasonable, there are a number of assumptions being made here, that people have argued about. There's a set of comments, and a reply from the authors of the original study you can look at here.

http://web.stanford.edu/group/denny/Pub … e_2009.pdf

Someone may correct me but I think your logic is sound. CO2 (and ethanol) is an endproduct of anaerobic respiration in plants and many microorganisms. In mammals, lactic acid is produced.

Not sure I fully understand the question, but in addition to David's point, there is certainly very strong evidence of polyploid events in many lineages. These can (roughly!) be viewed as events in which the genome is doubled in size (or more correctly the number of chromosomes increases by a factor of n where n is the haploid number of chromosomes).

Some info here
https://en.wikipedia.org/wiki/Polyploid

Recent occurrences of polyploidy are well documented in many plant systems (see examples in wiki page) and some fish groups (e.g. salmonids). In deeper evolutionary time a polyploid event is also implicated in the ancestral lineage of tetrapods. Some links to more technical summaries may also be of interest although you will probably have to e-mail the authors if you wnat more than the abstract (the rest will be behind  a paywall)

http://www.annualreviews.org/doi/full/1 … t.34.1.401

http://link.springer.com/article/10.102 … 2652814749

(posted in Fossils)

Great question. We have some paleontologists on this site who can may give you a more authoratative answer but my understanding is that while there are lots of different types of fossils (see e.g.
http://australianmuseum.net.au/what-are-fossils), the process you are referring which leads to mineralised fossils is - just that - a process.

So if your question is (simplistically) when does an old bone become a mineralised fossil, I rather suspect there is no defined threshold of mineralisation.  More generally however a fossil is usually defined as the preserved remains or traces of past life, so I would think (but am prepared for a paleontologists to contradict me) it is appropriate to refer to these more recent remains as fossils irrespective of degree of mineralisation.

This sounds like homework so I won't answer directly. Google your question and you'll find lots of answers but you should try and identiy a reliable source. If you can access it then lots of info here

http://jxb.oxfordjournals.org/content/48/4/821.full.pdf

There is actually a wiki page on bear hybrids that may be of interest.

https://en.wikipedia.org/wiki/Ursid_hybrid

Bottom line is hybrids can be possible but offspring are typically sterile. Black bear/grizzly hybridisation has happened in captivity. It has also been reported in the wild but - to me knowledge - all claims have been based on morphology and I'm not aware of any good DNA evidence (which is what is really needed to meet the standard of evidence these days). Grizzly/polar bear matings are indeed thought to be more common (with DNA evidence to back this up) and  - possibly on the rise as per the story circulating today that you highlight - some links here:

http://www.independent.co.uk/environmen … 46611.html

https://www.washingtonpost.com/news/ani … ow-mating/


"Grizzly" bears are North American subspecies of  Ursus arctos (brown bear) . In fact there are several subspecies recognised in N. America but all may be referred to as grizzlies. There is a long and complex history of subspecies designations for U. arctos, see https://en.wikipedia.org/wiki/Brown_bear , but bottom line is that they are all presently designated as one species, and most biologists would say that "supspecies" designations are pretty arbitrary/pointless in terms of biology (though they can be useful for conseravtion and management purposes).

No. That does not constitute compelling evidence for bigfoot (or anything else).

I like the idea that could be a viable population of a large hominid/ape (other than humans) in the North American woods, but it has no credibility in mainstream science. This is because of a total lack of hard evidence (if that were to change scientists would be enormously excited and you'd be hearing about it on national news, not just through youtube clips and cryptozoology websites).

(posted in General Biology)

Do you mean in terms of its value in our diet? If so, then it is not digestable (ie no nutritional value), but it is useful in your diet for maintaining healthy bowel function. Have a look at

http://www.nhs.uk/chq/pages/1141.aspx?categoryid=51

(posted in Genes, Genetics and DNA)

You will need a reasonable microscope (but one from a home science kit may be good enough) and then find a protocol for staining chromosomes. This one  - using onion cells - is similar to work I did at high school (but still calls for acid and stains that may or may not be readily available to you). Bear in mind that chromosomes are only tightly packed and visible at particular stages of cell division - more info at the link below.

http://w3.marietta.edu/~biol/introlab/O … itosis.pdf

Can't give you a certificate, but as far as I can tell the general concensus is that the alkaloid toxins these frogs secrete comes from dietary sources in the wild and so - unless deliberately fed to remain toxic - they become harmless in captivity.

Some links to paper abstract that may contain the info you are looking for are below.  You should be able to e-mail the authors and ask for a pdf if you'd like to read the full text.


https://www.ncbi.nlm.nih.gov/pubmed/15729640

https://www.ncbi.nlm.nih.gov/pubmed/17502597

Hard to tell from the photos but my first thought ws also caddis fly larvae of some type. Can you catch one and have a closer look at the "shell" to see if it really is part of the animal? individuals of particular species of caddis use the the same materials and "design" so if they are all using the same supply of small twigs or similar that could be what you are looking it.

Somewhat controversially I would add that  - in my view - the importance of epigenenetics as distinct from genetics is also overstated at the moment.

By this I don't mean that "epigenetic" mechanisms aren't important, but rather that an referring to DNA sequence changes as genetic and all other parts of inheritance as epigenetic rather misses the point that genetics as a field existed long before we knew the struture of DNA (let alone were able to sequence it). So in part the increasing prominance of "epigenetics" stems from (some) people narrowing the definition of "genetics" - which is fine in principle but is leading to some "wheel reinvention" as people discover "new evidence for epigenetic inheritance" that we've known about for a long time!

Sorry - personal gripe! I like Futuyma's definition too.

The picture is quite grainy and we don't know where in the world you live so - to be honest no, we can't give you a firm ID. I can tell you it's not a bed bug (which is good news ! see https://en.wikipedia.org/wiki/Bed_bug) and it's not a worm in any scientific sense (e.g., an annelid or nematode) either.

It is some sort of insect larva and just based on finding it in your bed it could possibly be a carpet beetle larva since they like to live in houses. Have a look here to see if this matches your find

http://utahpests.usu.edu/htm/utah-pests … e-beetles/

If so you may want to take some action as they can be damaging to carpets, textiles etc

There are no native stick insects in the UK, but there are some established populations of non-native species in the South West. Can you get in trouble for releasing them? Well you are unlikely to be prosecuted, but please don't. Either the animals will all die when the weather cools down or - if you live in Devon/Cornwall or the Channel islands it may be warm enough that they survive and become established, in which case you have just damaged the local ecology! So its a lose lose.

If you have some pet stick insects and they are reproducing too quickly, my tip is to clean them out more often and get rid of the eggs before they hatch.

That's pretty unlucky to be stung by a carpenter bee, they are known as being less aggressive than more social bee species. Note that people often think bees die after they sting, but this is only true for honey bees not all species.

Is the bee's behaviour normal? I don't think we can answer that I'm afraid since (as far as I can tell) nobody has ever really studies post-stinging behaviour in this group. My hunch - and it is just that - is that if the animal was not moving from the spot,  may have been recovering more from whatever caused your mother to be stung (e.g. handling, some accidental physical trauma to the insect) than to delivering the sting itself. That's just a hunch though - I have nothing to back it up!

I can't say what species but I would call this a "mole cricket" - some info on the family (Gryllotalpidae) here

https://en.wikipedia.org/wiki/Mole_cricket

That said, a couple of my Australian colleagues said they would call cooloquially call this a "sandgroper", although that common name seems now to be associated with species now assigned to the family Cylindrachetidae

https://en.wikipedia.org/wiki/Sandgroper_(insect)

Both these families are  part of the order Orthoptera which includes grasshoppers, crickets, locusts and their close relatives.

Hard to say I am afraid. It's possible that there's some factory coating on the new bench that is attracting them (or something in the paint on the old bench that is repelling them) but without being able to do some experiements this is only a working hypothesis!

If time travel was possible could time displacement even the illusion of time displacement be caused through vision problems.

I don't see exactly how, but don't let this stop you! The beauty of science fiction is that anything might be possible!

Good point - yes - if you interpret the question evolutionarily, then animals with muscle tissue arose before animals with muscle and bone. In a developmental sense then they differentiate simultaneously in a developing (vertebrate) embryo.

I cannot comment on either the text of the Quaran or its interpretation.

Embryologically, muscle, bone and cartilage are all derived from the mesoderm (one of the three germ cell layers) in bilaterian animals (i.e. most animals but not sponges, jellyfish etc). It is really the case that cells into the mesoderm begin to differentiate to form the various different tissue types, so I would characterise the development of muscle and bone as a simultaneous process not sequential one.

(posted in Evolution)

Not sure I completely follow your question. There is no particular expectation that selection will be stronger or weaker per se on islands than on mainlands, although isolation can be a key factor in speciation (selection typically - but not always - tends to drive divergence among local populations but this can be swamped by homogenising gene flow if the populations are well connected by individuals moving from one to another to breed).

There is however, a large body of theory called "island biogeography" that gives some good pointers about levels of diversity (e.g. number of species) we should find. Have a look here for the basics

https://en.wikibooks.org/wiki/Ecology/I … ogeography

(posted in General Biology)

Just to add that, despite suggested changes in terminology the vast majority of zoologists simply mean egg-laying when they say oviparous (i.e. internal vs external fertilisation is not really implied by this word as we normally use it - though this may change).

Also, if you want to add some more complexity... some frogs are actually ovoviviparous (as are qute a lot of fish). This involves eggs being internally fertilised but then retained within the female until they hatch and live young emerge.

https://en.wikipedia.org/wiki/Ovoviviparity

(posted in Evolution)

Actually termininology depends a bit on the taxon, so - for instance -people tend to talk abouty pre- vs post copulatory mechanisms of isolation. This makes it clearer where the dividing line is. Chomosomal incompatability of the sort you describe is post-copulatory since either the egg is not fertilised, or the egg is fertilised but the embryo not viable, or egg is fertilised and embry is viable but produced an infertile offspring. Regardless this is subsequent to the two parents copulating. In organisms with external fertilisation (many fish, plants etc) we often refer to pre- vs post fertilisation mechanisms (so a slightly different, buty nonethless clearly defined dividing line).

your question is rather unclear I'm afraid since these terms are used in different ways in different contexts. So rather than tell you something that may/may not fit what you are asking about have a look at these sites that define terms for slightly different contexts

http://www.bbc.co.uk/schools/gcsebitesi … rev1.shtml

https://www.beep.ac.uk/content/573.0.html

If you are really talking about statistical terminology then bear in mind that accuracy is a different thing to precision

https://en.wikipedia.org/wiki/Accuracy_and_precision

while reliability is often poorly defined but this site isn't bad

https://en.wikipedia.org/wiki/Reliability_(statistics)

I think you are conflating a bunch of different ideas here

1) Prokaryotes came first before eukaryotes. they are unicellular and (largely) reproduce by binary fission which is of course asexual (although gene transfer can occur horizontally).

2) Prokaryotes are not in any real sense the precursors of (or even analogous to) sperm of eukaryotes. Yes, sperm are typically small, motile cells and so are many prokaryotes, but that's about it.

3) What came first the sperm or the egg? Well it's more a case that anisogamy (=differentiation of gamete size) evolved between mating types, so I guess the real answer was that it was simultaneous. We basically define male and female gamete types by their relative size, meaning as one gets relatively bigger the other gets relatively smaller.

So the real question is .. what drove the evolution of anisogamy? I'm not really an expert in that but the wiki page at least gives an overview of the leading hypotheses

https://en.wikipedia.org/wiki/Anisogamy

(posted in General Biology)

>The problem with that is every single career that is associated with chemistry would bore me to death. I enjoy the homework and the problem solving, but I would prefer to study life and organisms rather than pollutants and drugs. I know that is incredibly general, but I haven't heard one chemistry career that makes me say "SIGN ME UP!!".

I think you have basically answered your own question here. Go with your passion and what you can happily see yourself doing in teh future . I had some amazing maths, chemistry and physics teachers at school and university, I've also had some appalling biology courses in my time to be honest (but not enough to put me off!). Once you get beyond "school" there is plenty of overlap of course (e.g. biochemistry!). I don't really use use chemistry much in my day to day research though many colleagues do. However I frequently find myself using maths and am very glad of the courses I took prior to focusing entirely on biology.

It is some form of "bee fly" which are the Bombyliidae family of true flies (order Diptera) that look quite a lot like bees (actually in the order Hymenoptera) at first glance. I won't try to guess the species as there are a lot of them globally and you haven't said where you saw this, but some info on teh family here

https://en.wikipedia.org/wiki/Bombyliidae

(posted in General Biology)

Looks like a polychaete worm egg mass - best guess (i.e. they are common and their eggs are thought to look like this, but there are other species!) would be the green leaf worm, Eulalia viridis which is a sort of paddleworm. Interestingly, nobody (to me knowledge) has yet to do the DNA work to totally confirm the widespread view that the green jelly blobs do indeed come from this beastie!

http://www.marlin.ac.uk/species/detail/1515

These look like eggs to me. I think they are from sort of bug (i.e. insect in the order hemiptera) but without seeing the animal it's hard to go further (there are c.2000 species in the UK).

The link to your additional photos is inconclusive, but the small insects you are finding could well be nymphs of whatever is hatching from here (short lifespan could be a consequence of no food!) if there is a route inside. If so they are unlikely to cause any damage apart. Alternatively the insects inside could be something slightly more irritating (i.e. capable of causing damage) - compare one to the pics and info on carpet beetles/here which would be the obvious suspect

http://www.bpca.org.uk/pages/?page_id=156

We don't know, and to a degree the jury is still out on how robust that pattern is (there have been some conflicting reports, and purported links between handedness and homosexuality also seem to be different in me and women).

If it turns out to be a robust, general pattern across human populations then, my arm waving (i.e. non-specific) hypothesis would be that this is not a causal relationship but rather that sexual orientation and handedness are both influenced by a common factor during development, probably early in life (e.g. perhaps in utero).

(posted in Birds)

Good question to which I think the answer is... we don't know.

Cuckoos are considered obligate brood parasites which means that - as far as we can tell - they always leave offspring care to the species they parasitise under relevant ecological conditions. In the scenario you suggest my best guess is they would not reproduce, but without doing the expt we won't know for sure.

Hard to say for sure what caused it but basically, if it is turning white then it will be dead/dying.

http://www.askabiologist.org.uk/answers … hp?id=8180

(posted in Fossils)

A colleague has just ID'd this as a "trilobite beetle". Although he doesn't know what species the latin name you have is definitley wrong since these are (I think) all memebers of the genus Duliticola. Cool looking insect! you can read a bit about them here:

http://blogs.scientificamerican.com/run … esent-day/

I don't think there is a single answer here. Instinct plays a role in cases, as does learned knowledge (e.g. in some animals parents may "teach" offspring about useful food resources) and/or experience (some toxic plants will taste bitter and a curious herbivore may be put off there and not ingest enough to do serious harm). Many plants also utilise chemical or even visual warning signals of various types.

Some good general info in the wiki page here

https://en.wikipedia.org/wiki/Plant_def … _herbivory

>However, from my understanding, mutation occurs in a cells, not on a whole body. Mutation shouldn't be a problem since cells with undesirable traits will die away, leaving normal cells intact.

Sadly not. Mutated cells sometimes proliferate in an out of control way (cancer) which can be disrupt organismal function to the point of death.

Courtesy of Dr Alistair Dove marine biologist we have an ID for your strange object. It is the swim bladder of a porcupine fish (aka blowfish)

https://en.wikipedia.org/wiki/Porcupinefish

Apparently the swim bladders are quite tough and leathery and so survive intact long enough after the fish has died to occasionally wash up on our beaches!

(posted in Genes, Genetics and DNA)

Similar in the sense that they carry the same genes, not identical however in the sense that they can carry different versions (alleles) of those genes. One X chromosome is inherited from the mother and one from the father

This happens (rarely) if you get strange cross over between X and Y chromosomes at meiosis during spermatogenesis such that SRY (the sex determining gene normally on the short arm of Y) gets onto an X chromosome. Simplistically SRY can be thoughts of as switching on male development, so if a sperm bearing SRY on an X chromosome combines with an egg (always bears an X), the result can be an offspring with XX karyotype that expresses SRY and shows at least some "male" development.

Some info on this in humans   

https://en.wikipedia.org/wiki/XX_male_syndrome

(posted in General Biology)

In evolutionary terms the general thinking behind this is that sexual dimorphism is driven primarily by sexual selection - which is occurs when one sex is "limiting" to the other as a "resource" for reproducing. Although it works the other way around in some species, typically females are the "limiting sex" and this can drives males to compete with each other (which may mean they need to be large in some species that fight physically, or carry weaponry like horns). It also means that females can be choosy, and this imposes selection on males for ornamental traits (e.g. tails in peacocks). In such cases the male traits would not be beneficial to the females and may in fact be costsly. So for instance in guppies, bright colours on the males are attractive to females, but also get you noticed by a predator. For males this cost is worth it, for females the colours carry only downsides - resulting in sexual dimorphism.

In many animals female fitness is limited by factors other than access to males. So, for example fecundity often increases with body size in insects and fish. So in these groups, and especially if males compete for females in ways that don't require overt strength (e.g. by trying to be more attractive, or through sperm competition) females are often larger than males.

There is lots more info here to get you started if you wnat to learn more

https://en.wikipedia.org/wiki/Sexual_dimorphism

Hi Ken,
I have no idea, and so far my attempts to get an answer by posting this out on Twitter have generated lots of confused biologists but no answer for you. I will keep trying, in the meantime do post again if you have any further information (e.g., was it solid, flexible, rubbery or bone-like in texture, did it appear air or fluid filled etc).

Sorry, but the pictures are too grainy for an ID here, If you can get a clear, high resolution one then do post again and we'll try  - but also tell us where you are in the world.

Based on shape and the fact they jump these are not woodlice which - at least in the UK is the common name for what Americans (I think) call pill bugs (which are isopod crustaceans not insects).

https://en.wikipedia.org/wiki/Woodlouse

Some sharks (e.g. dogfish) and rays lay egg cases about that size that get washed up, but these "mermaids purses" are fairly distinctive in appearance - see e.g

https://applecrosslifeblog.wordpress.co … ids-purse/

Clearly what you found is something different and to me it looks like some type of ascidian tunicate (=sea squirt). I don't dive so have to admit to not being at all familiar with any of this group except the few that pop up regularly in rock pools in the intertidal zone.

Hopefully someone else can give you a better ID, but in the meantime some general info here. They don't look much perhaps, but in evolutionary terms they are very cool - almost the missing link between vertebrates like us and the inverts. 

https://en.wikipedia.org/wiki/Tunicate

(posted in Genes, Genetics and DNA)

Yes, and it seems this as recently been done

http://www.telegraph.co.uk/news/science … bryos.html

The technology is not perfect but we are getting better and better at editing genes in other organisms. Clearly this has major ethical implications and I think ultimately technology will not be limiting, but society will have to judge when are why its application is appropriate.

I would think - although David would know better - that some aspects of sex reassignment surgery would remain in any event. Genetic therapy after development of   is unlikely to result in a complete transition of morphology for structures set early in ontogeny, e.g. external genitalia.

Although I am not aware of strong tests of the various hypotheses, broad concensus is that pubic hair is functional in several ways that may include some or all of: reduction of friction/chafing that could otherwise irritate sensitive areas; hosting beneficial bacteria with antibiotic properties that reduce infection risk; involvement in pheromone signalling for mate choice; visual signal of maturity status for mate choice). Insulation is not generally considered an inportant function of pubic hair.

If you have ever had to take a long walk in wet clothes you will recognize that chafing in the "gooch" area is far from pleasant.

(posted in Genes, Genetics and DNA)

For me it depends a little on who you are talking to - but in my area of biology (evolutionary ecology) the words are used fairly synonymously.

So for any individual in a population, I would say any particular phenotypic trait or characteristic value (which could be continuous e.g. body size, or categorial e.g., hair colour) can be determined by either genes or environmental effects but - more commonly - by both.

You are talking about endosymbiotic theory which basically tells us that eukaryotic mitochondria are ancestrally derived from bacteria living symbiotically within other cells.

https://en.wikipedia.org/wiki/Symbiogen … osymbiosis

Some of the experimental support for this theory came from classic experiements by Lyn Margulis. These, along with more intro to the topic are provided here

http://evolution.berkeley.edu/evolibrar … mbiosis_01

Does this "prove" evolution? Well science doesn't quite work like that - we falsify hypotheses rather than prove things to be true, but theories come to be accepted as true under the weight of evidence from many tests of many more specific hypotheses. Work on endosymbiosis provides one of many lines of evidence that support our wider theoretical understanding of evolution.

(posted in Genes, Genetics and DNA)

Unclear exactly what you mean, but assuming you are asking about genetic differences then have a read up on mitosis and meiosis and hopefully that will clear things up. This site is good.

http://www2.le.ac.uk/departments/geneti … is-meiosis