Changes in the heritable attributes of populations of organisms over time. Major mechanisms include drift, natural selection, mutation, and gene flow (migration).

learn more… | top users | synonyms

5
votes
1answer
479 views

How and why did mouth and nasal cavity evolve separate?

My initial objection is that nose filters air, mouth is for eating but is used for breathing also, plus they both are used to create sounds. What is the cause and reason in this case, why do we need ...
5
votes
1answer
150 views

What evolutionary mechanism caused felines to develop purring?

And why can some felines roar while others meow?
5
votes
1answer
142 views

Empirical evidence for species selection

Do we have any empirical evidence in favor of species (or lineage) selection? Do we know some cases that can only be explained (or seem to be only explained) by lineage selection? What are today the ...
5
votes
2answers
188 views

Why are humans and almost every species on earth symmetrical?

I admit I'm not very learned on the subject of evolution, I just started researching it for myself about a week ago. One of the things that I don't understand is why humans and almost every other ...
5
votes
2answers
332 views

Why does sexual selection evolve beautiful features?

First question here. I have a very raw understanding of sexual selection: Say a group of females of a certain species "likes" some feature of a certain groups of males; by "like" I mean some ...
5
votes
2answers
107 views

Why is venom more common in fish and snakes than other vertebrates?

Reading this question, I wondered why is it that we associate vertebrate venoms so often with snakes and fish, and more rarely with lizards, amphibians, mammals, and birds (apparently never, in ...
5
votes
2answers
118 views

How to get smallest subtree containing a set of nodes from BioPhylo?

I'm testing out various phylogenetic libraries in Python. I want to read in a Newick tree, then, given a list of taxa, generate the smallest tree that contains them all. This task is quite simple and ...
5
votes
1answer
124 views

Homologies to insect wings

All winged vertebrates have wings which are homologous to each other and to the forelimbs of the non-winged vertebrates. But what about insect wings? Are all insect wings homologous, and are there any ...
5
votes
1answer
213 views

What is the benefit for cells having the ATP production regulated in mitochondria compared to being from the nucleus?

Mitochondria have their own DNA and appear to be loosely connected to the nucleus and it role. Why are the functions of mitochondria not in the nucleus? Why doesn't the nucleus control the ...
5
votes
1answer
38 views

Is there any evidence telling us what the oxidation state of early earth's atmosphere was?

I ask this question in relation to the origin of life. I realise it would probably be better suited to a geology stack exchange, but it does not yet exist. The Miller-Urey experiment gives a lab ...
5
votes
1answer
116 views

What selective factors drove the evolution of lactose in lactation?

As far as I can determine, lactose, and the monosaccharide galactose have few biological uses outside of mammalian lactation. It not only required enzymes for its production, but enzymes in offspring ...
5
votes
1answer
581 views

Difference in length of Okazaki fragments

The length of Okazaki fragments in the lagging strand is about 100-200 nucleotides in eukaryotes and about 1000-2000 nucleotides in prokaryotes. What (molecular mechanism, enzyme type ) ...
5
votes
1answer
147 views

Probability of Extinction under Genetic Drift

Here is the Wright-Fisher model of genetic drift: $$\frac{(2N)!}{k!(2N-k)!}p^kq^{2N-k} \Leftrightarrow \binom{2N}{k}p^kq^{2N-k}$$ where $\binom{2N}{k}$ is the binomial coefficient. This formula ...
5
votes
1answer
121 views

Why was polyploidy not lethal in certain octodontid rodents?

As discussed in Why is polyploidy lethal for some organisms while for others is not?, polyploidy is normally lethal in mammals. However, two species of Octodontidae (South American rodents), are ...
5
votes
1answer
114 views

Is extreme cladism a mainstream position in the species debate?

In the philosophy of biology it has been claimed many times that a popular position regarding the question of what species are, among biologists, is cladism. For my current purposes, the defining ...
5
votes
0answers
24 views

Linkage disequilibrium with $n_l$ loci $n_a$ alleles

Linkage disequilibrium $\left(D\right)$ for two bi-allelic loci is defined as: $$D=X_{11}X_{22} - X_{12}X_{21}$$ , where $X_{11}$, $X_{12}$, $X_{21}$, X$_{22}$ are the frequencies of the haplotypes ...
5
votes
1answer
56 views

Disproportion in cranial nerve innervation?

The cranial nerve innervation is highly disproportionate, as far as humans are concerned. I am not sure of the advantage of being innervated by cranial nerve versus being innervated by a normal ...
5
votes
0answers
37 views

Reformulation of Hamiton's rule

Who (and in which article) was the first to reformulate Hamilton's rule using the letters $B$ and $C$?. See below comments on this reformulation. Hamilton, in his 1964's article gave a mathematical ...
4
votes
3answers
910 views

Is the theory of evolution being disproved by bats?

For some species the Darwin's theory evolution makes perfect sense. I can easily imagine how, for example, the giraffe has evolved to its current appearance: the natural selection was favoring ...
4
votes
4answers
588 views

Which came first: The Chicken or the Egg? [closed]

Has there been any serious scientific inquiries into answering this age old question?
4
votes
4answers
215 views

Biodiversity is restricted by genome combinatorics?

Me and some friends are interested in opinions for the following: Conjecture The maximum number of species must be limited by the maximum combinatorial/permutational space that can be occupied ...
4
votes
3answers
2k views

How does Artificial Selection work?

As far as I know for evolution to work mutations are necessary. Mutations are the raw material on which natural selection works. But mutations are always completely random and human beings have no ...
4
votes
3answers
162 views

Why don't flies avoid the motorway?

Flies have a short lifespan, therefore evolution should technically happen over a shorter period of time (years). Flies die all the time from getting hit by cars on the motorway. Those flies that ...
4
votes
3answers
151 views

How does natural selection favour large body mass and size (or so it seems)

I was walking through a park this afternoon and observed a few birds having fun flying around and it got me thinking why would natural selection favour birds with flesh at all if it hinders their ...
4
votes
1answer
158 views

Why do farts stink, but perfume does not?

Why is it that natural things like farts, poop, halitosis etc., from which we are always surrounded smell "bad"; whereas manufactured products, such as perfume or glue smell "good" to most of us? In ...
4
votes
1answer
260 views

What is the evidence that australopithecines were bipedal?

Before the discovery of Australopithecus afarensis in the 1970s, most anthropologists believed that an increase in brain capacity had preceded bipedal locomotion. However, this reconstruction of the ...
4
votes
3answers
132 views

Since Darwinian times, has there been any striking/notable effects of evolution on humans?

I understand that evolution is constant process that acts on a population in successive generations. Thus, it is obvious that evolution is happening. However, I'm curious as to the stricking examples ...
4
votes
3answers
303 views

What is the viability of Intelligent Design as a supplement to chemical abiogenesis and Darwinian Evolution?

First of all I am not endorsing Intelligent Design (Wikipedia link); I'm asking this because I (someone who does not have a background in biology, organic chemistry, or philosophy) got into a ...
4
votes
1answer
179 views

Variations in Genome Sizes

Why is there wide variation in genome size amongst groups of protists, insects, amphibians and plants, but less variation within groups of mammals and reptiles?
4
votes
1answer
136 views

Birds from the Family Columbidae Feed Young “Crop Milk”

Birds from the family Columbidae (e.g., doves and pigeons) produce a fatty, milk-like substance in their crop. The secretion is often referred to as "crop milk." They feed crop milk to their young ...
4
votes
1answer
218 views

What did pangolin scales evolve from?

Were they developed anew or a heritage from fish?
4
votes
1answer
91 views

What are some examples of scaling laws in biology?

I've seen that metabolic rate scales logarithmically as function of mass for many animals over an extremely large span of parameters. What other scaling laws exist at the individual level?
4
votes
1answer
177 views

What evolutionary pressures pushed Galápagos tortoises to mature so slowly and live so long?

I read that they take up to 40 years (in the wild) to reach the age of reproduction and are thought to live over 100 years, with one in captivity reaching over 170 years. Can someone explain in ...
4
votes
1answer
149 views

Why would deers keep crossing a river full of crocodiles while some of them have been killed?

I recently watched a clip on Discovery Channel, where I saw deers crossing a river full of crocodiles, ignoring the fact that some of them would have been killed doing so. What could be an ...
4
votes
1answer
99 views

How do I calculate the change in allele frequency in a haploid population under selection?

From this book For simplicity, let us consider a haploid organism and assume that the frequencies of alleles $A_1$ and $A_2$ are given by $x$ and $y=1-x$, respectively. We also assume that the ...
4
votes
1answer
143 views

Why does the slope of parent-offspring regression equals the heritability in the narrow sense?

Background ---- Notations and assumptions ---- let $W_{ij}$ be the fitness associated to the genotype $AiAj$. $x$ is the frequency of the allele $A1$ in the population. The frequency of the allele ...
4
votes
3answers
114 views

Good book on Origin of Life [closed]

What is a book that goes into reasonable detail (but isn't textbook-level technical) about the origin of earth and in particular the origin of life on earth? Something intended for a broad audience, ...
4
votes
2answers
78 views

Evolution in fruits

So, I saw a video on YouTube that says the banana we eat today is not what a banana looked like years ago. Since the banana has been genetically modified over the years, does that qualify as ...
4
votes
3answers
99 views

Fisher's Fundamental Theorem of Natural Selection

Ronald Fisher discovered what he, with humility, called the Fundamental Theorem of Natural Selection. This theorem says (in its modern terminology): The rate of increase in the mean fitness of any ...
4
votes
1answer
87 views

Was life less colorful before color vision evolved?

According to Wikipedia, we know that color-vision photopigments appeared in the common ancestors of tetrapods and fish at least 360 MY ago. Would life have been less colorful before the evolution of ...
4
votes
1answer
209 views

Why are eggs “egg” shaped?

Is there a reason as to why chickens lay "egg" shaped eggs, as opposed to spherically shaped eggs (or a random shape)? <--- Main Question For extra points (actually just to add more words in ...
4
votes
1answer
232 views

Why did mammals evolve to have two testes?

What makes mammals tend to evolve to have two testes?
4
votes
2answers
246 views

Extraretinal photoreception in mammals? [duplicate]

A Finnish firm Valkee sells light-ear-plugs against thing such as jetlag. I asked a researcher in Aalto university how do they really work and he responded ...
4
votes
2answers
95 views

Why aren't we ambidextrous?

It seems so simple that if my brain can tell my right hand to do something, then it should be able to tell equally well to the left ? This seems like a pretty major evolutionary advantage. Why haven't ...
4
votes
2answers
74 views

How would constantly growing nails have aided early human?

Nails grow rapidly and constantly, such that without constant artificial trimming they would reach lengths difficult to manage. How did this benefit early humans, say 200kya? Were they used like ...
4
votes
1answer
87 views

Does conjugation support gene selection?

I have already posted this on chat but haven't got any response. A recent question on group selection stimulated me to ask this here. QUESTIONS: Why should bacteria conjugate? If we consider that a ...
4
votes
1answer
94 views

Natural enemies boost deep evolutionary fitness?

"Two species that reduce one another's fitness on microevolutionary (short-term) timescales can increase each other's macroevolutionary (long-term) fitness" Opinions? Intuitive Examples: ...
4
votes
1answer
65 views

Randomness in living systems

The point of my question is not to talk about events that are uncontrolled by living organisms. My question is about controlled randomness, or I'd like to say adaptive random process. Process that are ...
4
votes
1answer
90 views

How animals maintain their body shape after development to maturity?

I've recently read a book on evolutionary-developmental biology for laymen, and it described how a fetus is progressively divided into more refined zones of genetic activity. These zones, kinda like ...
4
votes
1answer
143 views

Evolutionary explanation to why we have such large memory capacities?

The scientific consensus is that no one ever fills up their memory capacity by learning facts and so on, even in the information age. My question is therefore, is there an evolutionary reason as to ...