13 MAR 2014 by ideonexus
There is No Definition of "Species"
There is no authoritative definition of “species.” The most widely accepted definition describes a group of organisms that can procreate with one another and produce fertile offspring, but there are many exceptions. De-extinction operates under a different definition altogether. Revive & Restore hopes to create a bird that interacts with its ecosystem as the passenger pigeon did. If the new bird fills the same ecological niche, it will be successful; if not, back to the petri dish. ... 1 
notes
notesWhich raises the question of resurrecting species, is the resurrected the same species?
13 MAR 2014 by ideonexus
How to Resurrect a Species
The genome of a closely related species will have a high proportion of identical DNA, so it can serve as a blueprint, or “scaffold.” The passenger pigeon’s closest genetic relative is the band-tailed pigeon, which Shapiro is now sequencing. By comparing the fragments of passenger-pigeon DNA with the genomes of similar species, researchers can assemble an approximation of an actual passenger-pigeon genome.
[...]
Next the genome will have to be inscribed into a living cell... Molecular ... 1 notes
notesThe steps involved. It's like a recipe.
20 JUN 2012 by ideonexus
The Evolutionary Unit of Measurement
The starting point of Darwin's theory of evolution is precisely the existence of those differences between individual members of a race or species which morphologists for the most part rightly neglect. The first condition necessary, in order that any process of Natural Selection may begin among a race, or species, is the existence of differences among its members; and the first step in an enquiry into the possible effect of a selective process upon any character of a race must be an estimate ... 1 notes
notesIs the species, not individuals within the species.
23 MAR 2012 by ideonexus
The Earth Buries Older Forms with More Beautiful Ones
As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications. 1 notes
notesLike vines growing over a decaying tree.
28 JAN 2012 by ideonexus
Nature Progresses Gradually
Nature progresses by unknown gradations and consequently does not submit to our absolute division when passing by imperceptible nuances, from one species to another and often from one genus to another. Inevitably there are a great number of equivocal species and in-between specimens that one does not know where to place and which throw our general systems into turmoil. 1 notes
notesMaking it hard to distinguish between species.
21 SEP 2011 by ideonexus
There Are Human Races
In response to these distasteful episodes of racism, some scientists
have overreacted, arguing that human races have no biological reality
and are merely sociopolitical “constructs” that don’t merit scientific
study. But to biologists, race—so long as it doesn’t apply to humans!—
has always been a perfectly respectable term. Races (also called “subspecies”
or “ecotypes”) are simply populations of a species that are both
geographically separated and differ genetically in on... 1 notes
notesIt is wrong to pretend they do not exist, but we should remember that the differences between human races are minor compared to the genetic differences between individuals within a race.
21 SEP 2011 by ideonexus
1.5 Percent Gene Difference Translates to Thousands of Pr...
But recent work shows that our genetic resemblance to our evolutionary
cousins is not quite as close as we thought. Consider this. A
1.5 percent difference in protein sequence means that when we line up
the same protein (say, hemoglobin) of humans and chimps, on average
we’ll see a difference at just one out of every 100 amino acids. But
proteins are typically composed of several hundred amino acids. So a
1.5 percent difference in a protein 300 amino acids long translates into
about four di... 1 notes
notesThe analogy is made that if you change 1 percent of the words you change much more than 1 percent of the sentences, and the same applies to the genetic drift between humans and chimps.
21 SEP 2011 by ideonexus
Seeing How Species Arise is Similar to Understanding Star...
The way we discovered how species arise resembles the way
astronomers discovered how stars “evolve” over time. Both processes
occur too slowly for us to see them happening over our lifetime. But we
can still understand how they work by finding snapshots of the process
at different evolutionary stages and putting these snapshots together
into a conceptual movie. For stars, astronomers saw dispersed clouds
of matter (“star nurseries”) in galaxies. Elsewhere they saw those clouds condens... 1 notes
notesJust as astronomers search the skies for stars in varying stages of life, biologists look for species in varying degrees development.
21 SEP 2011 by ideonexus
Barriers that Keep Different Species from Interbreeding
What keeps members of two related species from mating with each
other? There are many different reproductive barriers. Species might not
interbreed simply because their mating or flowering seasons don’t overlap.
Some corals, for example, reproduce only one night a year, spewing
out masses of eggs and sperm into the sea over a several-hour period.
Closely related species living in the same area remain distinct because
their peak spawning periods are several hours apart, preventing eggs
of on... 1 notes
notesDifferent pheremones, blooming times, geographical isolation can keep members of two different species from breeding.
21 SEP 2011 by ideonexus
The Biological Species Concept (BSC)
And when we think of why we feel that brown-eyed and blue-eyed
humans, or Inuit and !Kung, are members of the same species, we realize
that it’s because they can mate with each other and produce offspring
that contain combinations of their genes. In other words, they belong
to the same gene pool. When you ponder cryptic species, and variation
within humans, you arrive at the notion that species are distinct
not merely because they look different, but because there are barriers
between them ... 1 notes
notesA species is defined by the fact that its members can breed with one another.
